CN115237235A - USB equipment shift-out identification circuit and method and power supply system - Google Patents

USB equipment shift-out identification circuit and method and power supply system Download PDF

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CN115237235A
CN115237235A CN202211154257.3A CN202211154257A CN115237235A CN 115237235 A CN115237235 A CN 115237235A CN 202211154257 A CN202211154257 A CN 202211154257A CN 115237235 A CN115237235 A CN 115237235A
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pin
circuit
weak pull
dpdm
detection module
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CN115237235B (en
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梁源超
徐永志
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Zhuhai Zhirong Technology Co ltd
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Zhuhai Zhirong Technology Co ltd
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F1/00—Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00
    • G06F1/26—Power supply means, e.g. regulation thereof
    • G06F1/266—Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
    • G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F1/00—Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00
    • G06F1/26—Power supply means, e.g. regulation thereof
    • G06F1/28—Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/30—Monitoring
    • G06F11/3003—Monitoring arrangements specially adapted to the computing system or computing system component being monitored
    • G06F11/3041—Monitoring arrangements specially adapted to the computing system or computing system component being monitored where the computing system component is an input/output interface
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/30—Monitoring
    • G06F11/3058—Monitoring arrangements for monitoring environmental properties or parameters of the computing system or of the computing system component, e.g. monitoring of power, currents, temperature, humidity, position, vibrations
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
    • G06F13/38—Information transfer, e.g. on bus
    • G06F13/40—Bus structure
    • G06F13/4063—Device-to-bus coupling
    • G06F13/4068—Electrical coupling
    • G06F13/4081—Live connection to bus, e.g. hot-plugging

Abstract

The invention relates to a USB device removal identification circuit, a USB device removal identification method and a power supply system, belonging to the technical field of USB device removal identification. And enabling the DPDM detection module to judge whether the DP pin and the DM pin have external drives or not, so that the two states of the equipment shifting-out state and the equipment connection non-power-off state are discriminated, and the USB interface can be accurately distinguished from the equipment shifting-out state or the equipment connection non-power-off state.

Description

USB equipment shift-out identification circuit and method and power supply system
Technical Field
The invention relates to the technical field of USB equipment removal identification, in particular to a USB equipment removal identification circuit and method and a power supply system.
Background
With the rapid popularization of a series of portable electronic products such as mobile phones, tablets, wireless headsets, smart watches, notebook computers and the like, the USB charging technology has also come to rapid development. The plug state identification technology of the USB equipment is a key technology in the technical field of USB charging, and the accurate plug state identification of the USB equipment provides convenience for intelligent management means such as energy consumption management, quick charging control, multi-port power distribution and overcharge prevention protection of a charging system.
Currently, the output current is usually detected to identify whether the USB device is removed. When the current of the USB output port is lower than a certain preset current threshold, the USB device is judged to be moved out, then the power supply output of the USB output port is closed, the device access detection is started, and a new access identification is waited. However, in some application scenarios, a current of the USB output port being below a predetermined current threshold does not indicate that the USB device has been removed, and it is possible that the USB device is fully charged but still connected to the USB output port, and it is also possible that the USB device adopts a control strategy that temporarily does not power up based on its application or safety considerations.
Therefore, an effective USB device removal identification technique is needed to accurately distinguish whether the USB interface is in a device removal state or a device connection non-power-down state.
Disclosure of Invention
The invention aims to provide a USB device removal identification circuit, a USB device removal identification method and a power supply system, which can accurately distinguish whether a USB interface is in a device removal state or a device connection non-power-extraction state.
In order to achieve the purpose, the invention provides the following scheme:
in a first aspect, the present invention provides a USB device removal identification circuit, including: the device comprises an identification control module, a current detection module and a DPDM detection module;
the current detection module is used for detecting the output current of the USB interface and comparing the output current with a preset current threshold to obtain a comparison signal; the USB interface can be electrically connected with a USB device to charge the USB device;
the identification control module is respectively in communication connection with the current detection module and the DPDM detection module; the identification control module is used for receiving the comparison signal and controlling the DPDM detection module to work when the output current is lower than the preset current threshold;
the DPDM detection module is electrically connected with a DP pin and a DM pin of the USB interface; the DPDM detection module is used for detecting whether the DP pin and the DM pin are externally connected with a driver or not to obtain a detection result;
the identification control module is used for determining the state of the USB interface according to the detection result; the states include a device removed state and a device connected unpowered state.
In some embodiments, the identification control module is further configured to control the DPDM detection module to operate after a duration of the output current being lower than the preset current threshold reaches a preset time.
In some embodiments, the DPDM detection module includes a pull-up voltage source, a DP weak pull-up circuit, a DP weak pull-down circuit, a first voltage comparator, a DM weak pull-up circuit, a DM weak pull-down circuit, and a second voltage comparator;
one end of the DP weak pull-up circuit is connected with the pull-up voltage source, and the other end of the DP weak pull-up circuit is connected with the DP pin; one end of the DP weak pull-down circuit is connected with the DP pin, and the other end of the DP weak pull-down circuit is grounded; the non-inverting input end of the first voltage comparator is connected with the DP pin, the inverting input end of the first voltage comparator is connected with a first preset reference voltage when the DP weak pull-up circuit is enabled, and the inverting input end of the first voltage comparator is connected with a second preset reference voltage when the DP weak pull-down circuit is enabled; if the voltage of the DP pin is higher than the first preset reference voltage when the DP weak pull-up circuit is enabled, and the voltage of the DP pin is lower than the second preset reference voltage when the DP weak pull-down circuit is enabled, the DP pin is not externally connected with a driver;
one end of the DM weak pull-up circuit is connected with the pull-up voltage source, and the other end of the DM weak pull-up circuit is connected with the DM pin; one end of the DM weak pull-down circuit is connected with the DM pin, and the other end of the DM weak pull-down circuit is grounded; the non-inverting input end of the second voltage comparator is connected with the DM pin, the inverting input end of the second voltage comparator is connected with the first preset reference voltage when the DM weak pull-up circuit is enabled, and the inverting input end of the second voltage comparator is connected with the second preset reference voltage when the DM weak pull-down circuit is enabled; and if the voltage of the DM pin is higher than the first preset reference voltage when the DM weak pull-up circuit is enabled, and the voltage of the DM pin is lower than the second preset reference voltage when the DM weak pull-down circuit is enabled, the DM pin is not externally connected with a driver.
In some embodiments, the DP weak pull-up circuit comprises a first switch and a first resistor connected in series; the DP weak pull-down circuit comprises a second switch and a second resistor which are connected in series; the DM weak pull-up circuit comprises a third switch and a third resistor which are connected in series; the DM weak pull-down circuit comprises a fourth switch and a fourth resistor which are connected in series;
the identification control module is further used for controlling the first switch to be conducted so as to enable the DP weak pull-up circuit; the identification control module is further used for controlling the second switch to be conducted so as to enable the DP weak pull-down circuit; the identification control module is further used for controlling the third switch to be turned on so as to enable the DM weak pull-up circuit; and the identification control module is also used for controlling the fourth switch to be conducted so as to enable the DM weak pull-down circuit.
In some embodiments, the identification control module is further configured to determine that the USB interface is in a device removal state when neither the DP pin nor the DM pin is externally connected with a driver; and when at least one of the DP pin and the DM pin is provided with an external drive, determining that the USB interface is in a device connection non-power-off state.
In a second aspect, the present invention provides a USB device removal recognition method using the USB device removal recognition circuit, including:
the control current detection module detects the output current of the USB interface and receives a comparison signal obtained by comparing the output current with a preset current threshold by the current detection module;
judging whether the output current is lower than the preset current threshold or not according to the comparison signal;
if yes, controlling a DPDM detection module to work, and receiving a detection result that whether the DPDM detection module detects whether an external drive exists on a DP pin and a DM pin of the USB interface;
determining the state of the USB interface according to the detection result; the states include a device removed state and a device connected non-powered state.
In some embodiments, before controlling the operation of the DPDM detection module, the method further includes: judging whether the duration time of the output current lower than the preset current threshold reaches preset time or not; and if so, controlling the DPDM detection module to work.
In some embodiments, the controlling the DPDM detection module to operate and receiving a detection result of the DPDM detection module detecting whether the DP pin and the DM pin of the USB interface have the external driver specifically includes:
controlling enabling of a DP weak pull-up circuit in a DPDM detection module, and receiving a first comparison result of whether the voltage of a DP pin of the USB interface output by a first voltage comparator in the DPDM detection module is higher than a first preset reference voltage;
controlling enabling of a DP weak pull-down circuit in the DPDM detection module, and receiving a second comparison result of whether the voltage of the DP pin output by the first voltage comparator is lower than a second preset reference voltage;
controlling enabling of a DM weak pull-up circuit in the DPDM detection module, and receiving a third comparison result of whether the voltage of the DM pin of the USB interface output by a second voltage comparator in the DPDM detection module is higher than the first preset reference voltage;
controlling enabling of a DM weak pull-down circuit in the DPDM detection module, and receiving a fourth comparison result of whether the voltage of the DM pin output by the second voltage comparator is lower than the second preset reference voltage;
the first comparison result, the second comparison result, the third comparison result and the fourth comparison result form a detection result; if the first comparison result and the second comparison result are both yes, the DP pin is not externally connected with a drive, otherwise, the DP pin is externally connected with the drive; if the third comparison result and the fourth comparison result are both yes, the DM pin is not externally connected with a driver; otherwise, the DM pin is provided with an external drive.
In some embodiments, the determining, according to the detection result, the state of the USB interface specifically includes:
judging whether the DP pin and the DM pin are both not externally connected with a drive or not according to the detection result;
if yes, determining that the USB interface is in a device moving-out state;
otherwise, determining that the USB interface is in a device connection non-power-off state.
In a third aspect, the present invention provides a USB device removal identification power supply system, including a plurality of USB device removal identification circuits described above; the identification control module of the USB equipment shift-out identification circuit is used for controlling the power supply equipment to which the USB interface belongs by adopting different control strategies according to the state after the state of the USB interface is determined; the states include a device removed state and a device connected unpowered state.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a USB equipment removal identification circuit, a USB equipment removal identification method and a power supply system. And enabling the DPDM detection module to judge whether the DP pin and the DM pin have external drives or not, so that the two states of the equipment shifting-out state and the equipment connection non-power-off state are discriminated, and the USB interface can be accurately distinguished from the equipment shifting-out state or the equipment connection non-power-off state.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic diagram of a common USB device access detection circuit and its operating principle provided in embodiment 1 of the present invention;
fig. 2 is a schematic diagram of a Type-a to Type-C cable application scenario false trigger access identification provided in embodiment 1 of the present invention;
fig. 3 is a schematic diagram illustrating a structure and a connection of a USB device shift-out identification circuit according to embodiment 1 of the present invention;
fig. 4 is a circuit diagram of a current detection module according to embodiment 1 of the present invention;
fig. 5 is a circuit diagram of a DPDM detection module according to embodiment 1 of the present invention;
fig. 6 is a flowchart of a method for identifying USB device removal according to embodiment 2 of the present invention;
fig. 7 is a control flowchart of a USB device removal identification method according to embodiment 2 of the present invention;
fig. 8 is a functional block diagram of a power supply system according to embodiment 3 of the present invention.
Description of the symbols:
1-identifying a control module; 2-a current detection module; and the 3-DPDM detection module.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a USB device removal identification circuit, a USB device removal identification method and a power supply system, which can accurately distinguish whether a USB interface is in a device removal state or a device connection non-power-pumping state.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Example 1:
currently, when the current of the USB output port is lower than a certain preset current threshold, it is determined that the USB device has been removed, but in some application scenarios, the current of the USB output port is lower than the certain preset current threshold and does not represent that the USB device has been removed, it may be that the USB device is fully charged but still connected to the USB interface, or it may be that the USB device has adopted a control strategy of temporarily not powering up based on its application or safety considerations.
For example, in portable energy storage applications such as a mobile power supply and an outdoor power supply, if a charging device (USB device) is full and still connected to a USB interface, the power output of the USB interface needs to be turned off, and a low power consumption mode is entered, so as to prolong the endurance time of the energy storage system.
In the application of a multi-port charger, especially in the application of a multi-port shared single-path power supply, when two or more USB interfaces are connected to a charging device at the same time, if one of the charging devices is full, the USB interface power supply output of the full path needs to be closed, so that the charging devices of other USB interfaces can enter into rapid charging or obtain larger charging power.
In the application of preventing overcharging, when charging equipment is fully charged, the power supply output of the USB interface needs to be closed, and the reduction of the service life of a battery and other potential safety hazards caused by continuous charging of the equipment are avoided.
In the application scenarios, if the USB device is recognized to be removed by using a conventional current detection method, it cannot be distinguished whether the device is actually removed or the device is still connected to the USB interface after being fully charged. At this moment, if the current is lower than a certain preset current threshold as judgment, the USB interface is directly closed to supply power and output, and a series of charging experience problems exist.
In addition, if the device is fully charged and still connected to the USB interface, the power supply output of the USB interface is turned off at this time, and the access detection circuit is enabled, so that a new primary device access identification is frequently triggered by mistake, which results in re-opening the power supply path of the USB interface and failing to achieve the purpose of full-charge shutdown. In the scene that adopts Type-A to change Type-C cable to charge for Type-C mouth equipment, this kind of false triggering of access detection takes place more easily. The reason is as follows:
as shown in fig. 1, a predetermined weak driving voltage VSET is connected to a VBUS pin, where the predetermined weak driving voltage VSET is higher than a predetermined reference voltage VREF, and the VBUS pin voltage is compared with the predetermined reference voltage VREF by a comparator, where an output signal of the comparator is plug. When the charging equipment is connected, the input resistor R2 and the input capacitor C2 of the charging equipment can be pulled down, the voltage of the VBUS pin is instantly pulled to be lower than the preset reference voltage VREF, and the connection of the charging equipment can be judged by recognizing the action of pulling down the voltage of the VBUS pin.
However, the Type-C port of the charging device such as a mobile phone, a tablet, and a notebook is generally in a DRP role. As shown in fig. 2, when the VBUS voltage of the USB interface connected to these charging devices disappears, the CC1 and CC2 pins of these devices will enter a toggle state, and pull up and pull down periodically. 56k resistors are connected in series between the VBUS pin and the CC pin in the Type-A to Type-C cable. When the charging equipment Tongle reaches Rp, VBUS of the USB interface is pulled up through a 56k resistor; when charging devices Tongle to Rd, VBUS of the USB interface is pulled low through 56k resistor. Such pull-up and pull-down processes trigger the device access identification of the USB interface.
In addition, in the charging process, if the temperature of a detection point of some charging equipment reaches a specific value, a charging suspension strategy is adopted to ensure the charging safety and experience; also some battery charging outfits can intelligent recognition user's use habit, charge to and suspend when about 80% electric quantity and charge, when waiting that the user will pull out battery charging outfit, be full of the electric quantity in advance again, can avoid the battery of equipment to be in full charge state for a long time like this, can reach extension battery life's effect. If the power supply system only uses the output current lower than a certain preset current threshold as the judgment of the shifting-out of the charging equipment, the power supply output is closed, and the equipment cannot be fully charged.
Based on the above, in order to meet the requirements more flexibly, an effective USB device removal identification technology is urgently needed, which can accurately distinguish whether the USB interface is in a device removal state or a device connection non-power-down state.
The present embodiment is configured to provide a USB device removal identification circuit, which is disposed in a power supply device that supplies power to a charging device through a USB interface, as shown in fig. 3, and includes: the device comprises an identification control module 1, a current detection module 2 and a DPDM detection module 3.
The current detection module 2 is configured to detect an output current of the USB interface, compare the output current with a preset current threshold to obtain a comparison signal, and feed the comparison signal back to the identification control module 1, where the comparison signal is a comparison result of whether the output current is lower than the preset current threshold. The USB interface can be electrically connected with the USB equipment to charge the USB equipment.
The current detection module 2 may be electrically connected to an output power path of the USB interface, specifically, to a VBUS pin or a GND pin of the USB interface, so as to implement current detection. As an alternative embodiment, as shown in fig. 4, which is a circuit diagram of an alternative implementation manner of the current detection module 2, the current detection module 2 includes a current detection resistor Rcs, a resistor R1, an operational amplifier OP, a regulating tube M1, a resistor R2, and a voltage comparator CMP connected in series to VBUS. One end of a current detection resistor Rcs is connected with the resistor R1, the other end of the current detection resistor Rcs is connected with the inverting input end of the operational amplifier OP, and the current detection resistor Rcs is used for converting the current information Iout on VBUS into a voltage signal Vcs. The other end of the resistor R1 is connected with the non-inverting input end of the operational amplifier OP. The first end of the adjusting tube M1 is connected with the non-inverting input end of the operational amplifier OP, the second end is connected with the output end of the operational amplifier OP, and the third end is connected with one end of the resistor R2. The other end of the resistor R2 is grounded. The connection point of the adjusting tube M1 and the resistor R2 is connected with the inverting input end of a voltage comparator CMP, and the non-inverting input end of the voltage comparator CMP is connected with a reference voltage VREF. The feedback loop formed by the operational amplifier OP and the adjusting tube M1 ensures that the voltages of the non-inverting input end and the inverting input end of the operational amplifier OP are equal, so that the voltage difference between the two ends of the resistor R1 is equal to Vcs, and because the currents flowing through the resistor R1 and the resistor R2 are equal, the current detection output voltage (namely the input voltage of the inverting input end of the voltage comparator) Vcso as to realize the R2/R1 times amplification of the Vcs, namely
Figure 485333DEST_PATH_IMAGE001
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The non-inverting input terminal of the voltage comparator CMP is connected to the reference voltage VREF, and the inverting input terminal is connected to the current detection output voltage Vcso as to compare the two. The reference voltage VREF corresponds to a predetermined current threshold. If the reference voltage VREF is higher than the current detection output voltage Vcso, the comparison signal low _ current output by the voltage comparator is a high level signal "1", which represents that the output current of the USB interface is lower than a preset current threshold; if the reference voltage VREF is lower than the current detection output voltage Vcso, the comparison signal low _ current output by the voltage comparator is a low level signal "0", which represents that the output current of the USB interface is higher than the preset current threshold.
The circuit structure is only one implementation manner of the current detection module 2, and other implementation manners may also be adopted in this embodiment, for example, the current detection resistor Rcs is replaced by a VBUS path switch MOS, or current information acquisition is realized by MOS mirror image, which may realize the equivalent effect of acquiring output current and comparing the output current with a preset current threshold to output a comparison signal, and all of which belong to the protection scope of the present invention.
It should be noted that, when current is detected in a manner that the current detection resistor Rcs connected in series to the VBUS is not used, the identification circuit of this embodiment only needs to set the DP pin, the DM pin, and the GND pin, and these three pins are connected to the DP pin, the DM pin, and the GND pin of the USB interface connected to the charging device in a one-to-one correspondence manner through the USB cable. When the current is detected by using the current detection resistor Rcs connected in series to the VBUS, the identification circuit of this embodiment further needs to provide a VBUS pin, and is connected to the VBUS pin of the USB interface through the current detection resistor Rcs. When the current detection module 2 is electrically connected with the GND pin of the USB interface to realize current detection, the current detection resistor Rcs may be connected in series with the GND, and the charging current flows through the GND pin of the USB interface and then through the current detection resistor Rcs to the GND of the identification circuit.
The identification control module 1 is respectively connected with the current detection module 2 and the DPDM detection module 3 in a communication way. The identification control module 1 is configured to receive the comparison signal, and start the DPDM detection module 3 when the output current is lower than a preset current threshold, so as to control the DPDM detection module 3 to operate. Optionally, the identification control module 1 of this embodiment may further enable the current detection module 2 to detect an output current of the USB interface, so as to start the current detection module 2.
Preferably, to avoid the identification error caused by the short-time jump of the output current, the identification control module 1 of this embodiment is configured to control the DPDM detection module 3 to operate only after the duration that the output current is lower than the preset current threshold reaches the preset time, that is, after the output current is lower than the preset current threshold and maintains for a preset time T, it is determined that the USB interface is in the device removal state or the device connection non-power-off state. The preset time T of the present embodiment may be selected to be several seconds, several tens of seconds, several minutes or even several tens of minutes.
The DPDM detection module 3 is electrically connected with a DP pin and a DM pin of the USB interface, and the DPDM detection module 3 is used for detecting whether the DP pin and the DM pin are externally connected with a driver or not, obtaining a detection result and feeding the detection result back to the identification control module 1. The external drive means that when the charging device is connected with the USB interface, a drive with a certain strength is applied to the DP pin, the DM pin or the DP and DM pins, and the external drive may be a resistor pull-up, a resistor pull-down, or a specific drive voltage.
The identification control module 1 is used for determining the state of the USB interface according to the detection result, where the state includes a device removal state and a device connection non-power-off state. Specifically, the identification control module 1 is further configured to, when neither the DP pin nor the DM pin is externally connected to a driver, determine that the USB device has moved out of the USB interface, and determine that the USB interface is in a device moving-out state; when at least one of the two pins, namely the DP pin and the DM pin, is provided with an external drive, the USB device is judged to be connected to the USB interface although not powered, and the USB interface is determined to be in a device connection non-powered state. The USB interface of this embodiment may be a Type-a or Type-C interface.
As shown in fig. 5, the DPDM detection module 3 of this embodiment includes a pull-up voltage source Vup, a DP weak pull-up circuit, a DP weak pull-down circuit, a first voltage comparator CMP1, a DM weak pull-up circuit, a DM weak pull-down circuit, and a second voltage comparator CMP2.
One end of the DP weak pull-up circuit is connected with a pull-up voltage source Vup, and the other end of the DP weak pull-up circuit is connected with a DP pin. One end of the DP weak pull-down circuit is connected with the DP pin, and the other end of the DP weak pull-down circuit is grounded. The in-phase input end of a first voltage comparator CMP1 is connected with a DP pin, the reverse-phase input end is connected with a first preset reference voltage VREF1 when a DP weak pull-up circuit is enabled, and whether the voltage of the DP pin is higher than the first preset reference voltage VREF1 or not is judged by comparison to obtain a judgment signal det-DP; and when the DP weak pull-down circuit is enabled, connecting a second preset reference voltage VREF2, and comparing and judging whether the voltage of the DP pin is lower than the second preset reference voltage VREF2 to obtain a judgment signal det-DP. If the voltage of the DP pin is higher than a first preset reference voltage when the DP weak pull-up circuit is enabled, and the voltage of the DP pin is lower than a second preset reference voltage when the DP weak pull-down circuit is enabled, the DP pin is not externally connected with a driver; otherwise, the DP pin has an external drive.
One end of the DM weak pull-up circuit is connected with a pull-up voltage source Vup, and the other end of the DM weak pull-up circuit is connected with a DM pin. One end of the DM weak pull-down circuit is connected with the DM pin, and the other end of the DM weak pull-down circuit is grounded. The in-phase input end of a second voltage comparator CMP2 is connected with a DM pin, the reverse-phase input end is connected with a first preset reference voltage VREF1 when a DM weak pull-up circuit is enabled, and whether the voltage of the DM pin is higher than the first preset reference voltage VREF1 or not is judged by comparison to obtain a judgment signal det-DM; and when the DM weak pull-down circuit is enabled, connecting a second preset reference voltage VREF2, and comparing and judging whether the voltage of the DM pin is lower than the second preset reference voltage VREF2 to obtain a judgment signal det-DM. If the voltage of the DM pin is higher than a first preset reference voltage when the DM weak pull-up circuit is enabled, and the voltage of the DM pin is lower than a second preset reference voltage when the DM weak pull-down circuit is enabled, the DM pin is not externally connected with a driver; otherwise, the DM pin has an external drive.
The voltage of the pull-up voltage source Vup is higher than a first preset reference voltage VREF1, and the first preset reference voltage VREF1 is higher than a second preset reference voltage VREF2.
Optionally, the DP weak pull-up circuit includes a first switch S1 and a first resistor Rup1 connected in series, the DP weak pull-down circuit includes a second switch S2 and a second resistor Rdn1 connected in series, the DM weak pull-up circuit includes a third switch S3 and a third resistor Rup2 connected in series, and the DM weak pull-down circuit includes a fourth switch S4 and a fourth resistor Rdn2 connected in series. The present embodiment may further include a fifth switch S5, which is respectively connected to the inverting input terminals of the first voltage comparator CMP1 and the second voltage comparator CMP2, and is used for selecting VREF1 or VREF2 as the reference voltage for comparison. Rup1, rdn1, rup2 and Rdn2 may each be 1M Ω, VREF1 may be 3.675V, VREF2 may be 0.325V, and Vup may be 5V.
The identification control module 1 is further configured to control the first switch S1 to be turned on, so that the DP weak pull-up circuit is enabled, that is, the DP weak pull-up circuit is enabled, at this time, the fifth switch S5 is connected to the first preset reference voltage VREF1, and the comparison result is used to determine whether the voltage of the DP pin is higher than the first preset reference voltage VREF1. The recognition control module 1 is further configured to control the second switch S2 to be turned on, so that the DP weak pull-down circuit is enabled, that is, the DP weak pull-down is enabled, at this time, the fifth switch S5 is connected to the second preset reference voltage VREF2, and whether the voltage of the DP pin is lower than the second preset reference voltage VREF2 is determined by comparison. If the two comparison and judgment results are yes, the DP pin is represented to have no external drive; otherwise, it represents that the DP pin has external drive.
The identification control module 1 is further configured to control the third switch S3 to be turned on, so as to enable the DM weak pull-up circuit, that is, enable the DM weak pull-up circuit, at this time, the fifth switch S5 is connected to a first preset reference voltage VREF1, and compare and determine whether the voltage of the DM pin is higher than the first preset reference voltage VREF1. The recognition control module 1 is further configured to control the fourth switch S4 to be turned on, so as to enable the DM weak pull-down circuit, that is, enable the DM weak pull-down circuit, at this time, the fifth switch S5 is connected to the second preset reference voltage VREF2, and compare and determine whether the voltage of the DM pin is lower than the second preset reference voltage VREF2. If the two comparison and judgment results are yes, the DM pin is not externally connected with a drive; otherwise, it represents that the DM pin has an external drive.
The USB device removal recognition circuit provided in this embodiment includes a current detection module 2, a DPDM detection module 3, and a recognition control module 1, where the current detection module 2 is enabled in a first step to detect an output current of a USB interface, and when the output current is lower than a preset current threshold, it is determined that the USB interface is in a device removal state or a device connection non-power-extraction state; and enabling the DPDM detection module 3 to judge whether the DP pin and the DM pin have external drives or not in the second step, so that the two states of the equipment shifting-out state and the equipment connection non-power-on state are discriminated, and the USB interface can be accurately distinguished from the equipment shifting-out state or the equipment connection non-power-on state.
Example 2:
this embodiment is configured to provide a USB device removal identification method using the USB device removal identification circuit in embodiment 1, as shown in fig. 6, including:
s1: the control current detection module detects the output current of the USB interface and receives a comparison signal obtained by comparing the output current with a preset current threshold by the current detection module;
s2: judging whether the output current is lower than the preset current threshold or not according to the comparison signal;
s3: if yes, controlling a DPDM detection module to work, and receiving a detection result that whether the DPDM detection module detects whether an external drive exists on a DP pin and a DM pin of the USB interface;
preferably, before controlling the DPDM detection module to operate, the method further includes: and judging whether the duration time of the output current lower than the preset current threshold reaches the preset time or not, if so, controlling the DPDM detection module to work, thereby avoiding the identification error caused by short-time jump of the output current.
S3 may include: controlling enabling of a DP weak pull-up circuit in a DPDM detection module, and receiving a first comparison result of whether the voltage of a DP pin of a USB interface output by a first voltage comparator in the DPDM detection module is higher than a first preset reference voltage; controlling enabling of a DP weak pull-down circuit in a DPDM detection module, and receiving a second comparison result of whether the voltage of a DP pin output by a first voltage comparator is lower than a second preset reference voltage; controlling enabling of a DM weak pull-up circuit in a DPDM detection module, and receiving a third comparison result of whether the voltage of a DM pin of a USB interface output by a second voltage comparator in the DPDM detection module is higher than a first preset reference voltage or not; controlling the DM weak pull-down circuit in the DPDM detection module to enable and receiving a fourth comparison result of whether the voltage of the DM pin output by the second voltage comparator is lower than a second preset reference voltage or not; the first comparison result, the second comparison result, the third comparison result and the fourth comparison result form a detection result, if the first comparison result and the second comparison result are both yes, the DP pin is not externally connected with a drive, otherwise, the DP pin is externally connected with the drive; if the third comparison result and the fourth comparison result are both yes, the DM pin is not externally connected with a driver; otherwise, the DM pin has an external driver.
S4: determining the state of the USB interface according to the detection result; the states include a device removed state and a device connected unpowered state.
S4 may include: judging whether the DP pin and the DM pin are both not externally connected with a drive or not according to the detection result; if so, determining that the USB interface is in a device moving-out state; otherwise, the USB interface is determined to be in the state that the equipment is connected and is not powered up.
More specifically, as shown in fig. 7, the USB device removal identification method of this embodiment includes the following steps:
and step 701, detecting output current of the USB interface.
Step 702, comparing and judging whether the output current of the USB interface is lower than a preset current threshold. If the output current is not lower than the preset current threshold, returning to the step 701; if the output current is lower than the predetermined current threshold, step 703 is executed.
Step 703, determining whether the output current is lower than a preset current threshold and maintaining the preset time T. If the current is recovered to be above the preset current threshold within the preset time T, returning to step 701; if the output current is always lower than the preset current threshold within the preset time T, it is determined that the device is in one of the two states of being removed from the device or being connected to the device but not being powered, and step 704 is further performed.
Step 704, enable weak pull-up of DP and DM pins.
Step 705, comparing and determining whether the voltages of the DP and DM pins are both higher than a first preset reference voltage. If the voltages of the DP and DM are higher than the first preset reference voltage, go to step 706; if at least one of the voltages of the DP and DM is not higher than the first preset reference voltage, the DP or DM pin is considered to have the external driver, and step 709 is executed.
At step 706, weak pull-downs of the DP and DM pins are enabled.
And step 707, comparing and judging whether the voltages of the DP pin and the DM pin are both lower than a second preset reference voltage. If the voltages of DP and DM are lower than the second predetermined reference voltage, go to step 708; if at least one of the voltages of the DP and DM is not lower than the second preset reference voltage, it is determined that the external driver exists at the DP or DM pin, and step 709 is executed.
Step 708, determine that the device is in the removed state.
And step 709, judging that the device is in a non-power-pumping state when connected.
It should be noted that the flow of the USB device removal identification method of this embodiment is not limited to the flow diagrams shown in fig. 6 and fig. 7, and the steps in the flow diagrams shown in the embodiment may be added, changed in order, modified or removed according to different requirements, for example, the steps 704, 705, 706 and 707 may be split into a plurality of sub-steps, and the detection decisions are made for the DP pin and the DM pin, respectively, or adjusted to different detection orders.
In the method for identifying the USB device removal provided in this embodiment, the first step enables the current detection module to detect the output current of the USB interface, and when the output current is lower than the preset current threshold, it is determined that the USB interface is in the device removal state or the device connection non-power-extraction state. And the DPDM detection module is enabled in the second step, and whether external driving exists on the DP and DM pins is detected by judging whether the voltages of the DP and DM pins can be pulled up to the first preset reference voltage or not and whether the voltages of the DP and DM pins can be pulled down to the second preset reference voltage or not. If the DP and the DM are not externally connected with a drive, judging that the USB equipment is moved out; if at least one pin of the DP and the DM has an external drive, the USB device is judged to be connected to the USB interface although not powered, so that whether the USB interface is in a device removal state or a device connection non-powered state can be accurately distinguished.
Example 3:
the present embodiment is configured to provide a power supply system for identifying USB device removal, and as shown in fig. 8, the power supply system includes a plurality of USB device removal identification circuits according to embodiment 1, and performs power supply management on one or more USB interfaces by using the USB device removal identification method according to embodiment 2, specifically, an identification control module of the USB device removal identification circuit is configured to, after determining a state of the USB interface, adopt different control strategies to control a power supply device to which the USB interface belongs according to the state, where the state includes a device removal state and a device connection non-power-extraction state, that is, after two different states of device removal or device connection non-power-extraction are discriminated, respectively adopt different control strategies.
The power supply system of the embodiment can be a mobile power supply, an outdoor power supply, a multi-port charger or an overcharge-prevention charging management device and the like, and the control strategy can be that a power supply path is directly closed aiming at the equipment shifting-out state, and the power supply path is delayed to be closed aiming at the equipment connection non-power-extraction state; the power supply path may be closed and the device access detection may be enabled for the device removal state, and the power supply path may be closed and the device insertion detection may not be enabled for the device connection non-power-extraction state; the power supply path may be closed first in a non-power-extraction state of the device connection, and the power supply path may be re-opened after a certain time.
The power supply system provided by the embodiment adopts the USB equipment removal identification circuit and the USB equipment removal identification method, and different control strategies are adopted after two different states of equipment removal or equipment connection without power extraction are discriminated, so that a proper control strategy can be flexibly and effectively adopted according to an identification result, and the user experience is optimized.
In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principle and the embodiment of the present invention are explained by applying specific examples, and the above description of the embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (10)

1. A USB device removal identification circuit, comprising: the device comprises an identification control module, a current detection module and a DPDM detection module;
the current detection module is used for detecting the output current of the USB interface and comparing the output current with a preset current threshold to obtain a comparison signal; the USB interface can be electrically connected with a USB device to charge the USB device;
the identification control module is respectively in communication connection with the current detection module and the DPDM detection module; the identification control module is used for receiving the comparison signal and controlling the DPDM detection module to work when the output current is lower than the preset current threshold;
the DPDM detection module is electrically connected with a DP pin and a DM pin of the USB interface; the DPDM module is used for detecting whether the DP pin and the DM pin are externally connected with a driver or not to obtain a detection result;
the identification control module is used for determining the state of the USB interface according to the detection result; the states include a device removed state and a device connected unpowered state.
2. The USB device removal identification circuit of claim 1, wherein the identification control module is further configured to control the DPDM detection module to operate after a duration of the output current being lower than the preset current threshold reaches a preset time.
3. The USB device removal identification circuit of claim 1, wherein the DPDM detection module comprises a pull-up voltage source, a DP weak pull-up circuit, a DP weak pull-down circuit, a first voltage comparator, a DM weak pull-up circuit, a DM weak pull-down circuit, and a second voltage comparator;
one end of the DP weak pull-up circuit is connected with the pull-up voltage source, and the other end of the DP weak pull-up circuit is connected with the DP pin; one end of the DP weak pull-down circuit is connected with the DP pin, and the other end of the DP weak pull-down circuit is grounded; the non-inverting input end of the first voltage comparator is connected with the DP pin, the inverting input end of the first voltage comparator is connected with a first preset reference voltage when the DP weak pull-up circuit is enabled, and the inverting input end of the first voltage comparator is connected with a second preset reference voltage when the DP weak pull-down circuit is enabled; if the voltage of the DP pin is higher than the first preset reference voltage when the DP weak pull-up circuit is enabled, and the voltage of the DP pin is lower than the second preset reference voltage when the DP weak pull-down circuit is enabled, the DP pin is not externally connected with a driver;
one end of the DM weak pull-up circuit is connected with the pull-up voltage source, and the other end of the DM weak pull-up circuit is connected with the DM pin; one end of the DM weak pull-down circuit is connected with the DM pin, and the other end of the DM weak pull-down circuit is grounded; the non-inverting input end of the second voltage comparator is connected with the DM pin, the inverting input end of the second voltage comparator is connected with the first preset reference voltage when the DM weak pull-up circuit is enabled, and the inverting input end of the second voltage comparator is connected with the second preset reference voltage when the DM weak pull-down circuit is enabled; and if the voltage of the DM pin is higher than the first preset reference voltage when the DM weak pull-up circuit is enabled and the voltage of the DM pin is lower than the second preset reference voltage when the DM weak pull-down circuit is enabled, the DM pin is not externally connected with a driver.
4. The USB device removal identification circuit of claim 3, wherein the DP weak pull-up circuit comprises a first switch and a first resistor connected in series; the DP weak pull-down circuit comprises a second switch and a second resistor which are connected in series; the DM weak pull-up circuit comprises a third switch and a third resistor which are connected in series; the DM weak pull-down circuit comprises a fourth switch and a fourth resistor which are connected in series;
the identification control module is further used for controlling the first switch to be conducted so as to enable the DP weak pull-up circuit; the identification control module is also used for controlling the second switch to be conducted so as to enable the DP weak pull-down circuit; the identification control module is further used for controlling the third switch to be turned on so as to enable the DM weak pull-up circuit; and the identification control module is also used for controlling the fourth switch to be conducted so as to enable the DM weak pull-down circuit.
5. The USB device removal recognition circuit of claim 1, wherein the recognition control module is further configured to determine that the USB interface is in a device removal state when neither the DP pin nor the DM pin is externally connected to a driver; and when at least one of the DP pin and the DM pin is provided with an external drive, determining that the USB interface is in a device connection non-power-off state.
6. A USB device removal recognition method using the USB device removal recognition circuit according to any one of claims 1 to 5, comprising:
the control current detection module detects the output current of the USB interface and receives a comparison signal obtained by comparing the output current with a preset current threshold by the current detection module;
judging whether the output current is lower than the preset current threshold or not according to the comparison signal;
if yes, controlling a DPDM detection module to work, and receiving a detection result that whether the DPDM detection module detects whether an external drive exists on a DP pin and a DM pin of the USB interface;
determining the state of the USB interface according to the detection result; the states include a device removed state and a device connected non-powered state.
7. The method of claim 6, further comprising, before controlling the DPDM detection module to operate: judging whether the duration time of the output current lower than the preset current threshold reaches preset time or not; and if so, controlling the DPDM detection module to work.
8. The method of claim 6, wherein the controlling the DPDM module to operate and receiving the detection result of the DPDM module detecting whether the external driver is present on the DP pin and the DM pin of the USB interface specifically comprises:
controlling enabling of a DP weak pull-up circuit in a DPDM detection module, and receiving a first comparison result of whether the voltage of a DP pin of the USB interface output by a first voltage comparator in the DPDM detection module is higher than a first preset reference voltage; controlling enabling of a DP weak pull-down circuit in the DPDM detection module, and receiving a second comparison result of whether the voltage of the DP pin output by the first voltage comparator is lower than a second preset reference voltage;
controlling enabling of a DM weak pull-up circuit in the DPDM detection module, and receiving a third comparison result of whether the voltage of the DM pin of the USB interface output by a second voltage comparator in the DPDM detection module is higher than the first preset reference voltage; controlling enabling of a DM weak pull-down circuit in the DPDM detection module, and receiving a fourth comparison result of whether the voltage of the DM pin output by the second voltage comparator is lower than the second preset reference voltage;
the first comparison result, the second comparison result, the third comparison result and the fourth comparison result form a detection result; if the first comparison result and the second comparison result are both yes, the DP pin is not externally connected with a drive, otherwise, the DP pin is externally connected with the drive; if the third comparison result and the fourth comparison result are both yes, the DM pin is not externally connected with a driver; otherwise, the DM pin is provided with an external drive.
9. The method for identifying USB device removal according to claim 6, wherein the determining the state of the USB interface according to the detection result specifically includes: judging whether the DP pin and the DM pin are both not externally connected with a drive or not according to the detection result; if yes, determining that the USB interface is in a device moving-out state; otherwise, determining that the USB interface is in a device connection non-power-extraction state.
10. A USB device removal identification power supply system comprising a plurality of USB device removal identification circuits according to any one of claims 1 to 5; the identification control module of the USB equipment shift-out identification circuit is used for controlling the power supply equipment to which the USB interface belongs by adopting different control strategies according to the state after the state of the USB interface is determined; the states include a device removed state and a device connected unpowered state.
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