CN109696937B - Overcurrent protection circuit with external resistor and current source generating circuit with external resistor - Google Patents

Overcurrent protection circuit with external resistor and current source generating circuit with external resistor Download PDF

Info

Publication number
CN109696937B
CN109696937B CN201910117380.XA CN201910117380A CN109696937B CN 109696937 B CN109696937 B CN 109696937B CN 201910117380 A CN201910117380 A CN 201910117380A CN 109696937 B CN109696937 B CN 109696937B
Authority
CN
China
Prior art keywords
current
switching tube
driving current
external resistor
tube
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201910117380.XA
Other languages
Chinese (zh)
Other versions
CN109696937A (en
Inventor
吴斯敏
殷晓文
杜黎明
孙洪军
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Awinic Technology Co Ltd
Original Assignee
Shanghai Awinic Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Awinic Technology Co Ltd filed Critical Shanghai Awinic Technology Co Ltd
Priority to CN201910117380.XA priority Critical patent/CN109696937B/en
Publication of CN109696937A publication Critical patent/CN109696937A/en
Application granted granted Critical
Publication of CN109696937B publication Critical patent/CN109696937B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/461—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using an operational amplifier as final control device
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/468—Regulating voltage or current wherein the variable actually regulated by the final control device is dc characterised by reference voltage circuitry, e.g. soft start, remote shutdown
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
    • G05F1/569—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • H02H9/025—Current limitation using field effect transistors

Abstract

The invention discloses an overcurrent protection circuit of an external resistor and a current source generating circuit of the external resistor, which comprise a first comparing unit, a second comparing unit and a generating unit; the first comparison unit is used for comparing the reference current with the first driving current to obtain a first comparison result, and outputting a difference value or zero between the reference current and the first driving current according to the first comparison result; a generating unit for generating a second driving current; the second comparison unit is used for comparing the difference value between the reference current and the first driving current with the second driving current to obtain a second comparison result, and outputting the reference current according to the second comparison result; or comparing the zero with the second driving current to obtain a third comparison result, and outputting the second driving current according to the third comparison result. The invention can realize that under the condition that the external resistor is short-circuited or the external resistor is a very small resistor, the overlarge first driving current is pulled down to the reference current, so that an external circuit applying the first driving current can work normally.

Description

Overcurrent protection circuit with external resistor and current source generating circuit with external resistor
Technical Field
The invention relates to the field of integrated circuits, in particular to an overcurrent protection circuit with an external resistor and a current source generating circuit with the external resistor.
Background
With the diversification of market demands, different customers have different demands on the LED driving current.
In the prior art, different resistors are selected by connecting an external resistor unit, so that different first driving currents, namely different LED driving currents, are obtained.
However, if the external resistor in the conventional external resistor unit is short-circuited or the external resistor is a small resistor, the bias current of the external resistor unit may be too large. Under the condition that the bias current is too large, the output first driving current is a large current after amplification, the components of an external circuit applying the current are damaged by the too large current, and the external circuit cannot work normally.
Disclosure of Invention
Based on the defects of the prior art, the invention provides an overcurrent protection circuit of an external resistor and a current source generating circuit of the external resistor, so that an overlarge first driving current is pulled down to a reference current under the condition that the external resistor is short-circuited or the external resistor is a small resistor, and the circuit can work normally.
In order to achieve the above object, the following solutions are proposed:
the invention provides an overcurrent protection circuit with an external resistor in a first aspect, which comprises:
the device comprises a first comparison unit, a second comparison unit connected with the first comparison unit and a generation unit connected with the second comparison unit;
the first comparison unit is used for respectively receiving a reference current and a first driving current, comparing the reference current with the first driving current to obtain a first comparison result, and outputting a difference value or zero between the reference current and the first driving current according to the first comparison result;
the generating unit is used for generating a second driving current;
the second comparing unit is configured to receive the difference or zero between the reference current and the first driving current and the second driving current, compare the difference between the reference current and the first driving current with the second driving current to obtain a second comparison result, and output the reference current according to the second comparison result; or comparing zero with the second driving current to obtain a third comparison result, and outputting the second driving current according to the third comparison result.
Optionally, the first comparing unit includes:
the first switch tube and the second switch tube;
the first end of the first switch tube is grounded, the second end of the first switch tube receives the reference current, the control end of the first switch tube is connected with the control end of the second switch tube, the control end of the first switch tube is connected with the second end of the first switch tube, the first end of the second switch tube is grounded, and the second end of the second switch tube receives the first driving current and is connected with the second comparison unit.
Optionally, the second comparing unit includes:
a third switching tube and a fourth switching tube;
the first end of the third switch tube is grounded, the second end of the third switch tube is connected with the first comparison unit, the control end of the third switch tube is connected with the control end of the fourth switch tube, the second end of the third switch tube is connected with the control end of the third switch tube, the first end of the fourth switch tube is grounded, and the second end of the fourth switch tube is connected with the generation unit.
Optionally, the generating unit includes:
a fifth switching tube;
and the first end of the fifth switching tube is connected with a power supply voltage, the control end of the fifth switching tube is connected with a reference voltage, and the second end of the fifth switching tube is connected with the second comparison unit.
Optionally, the first switching tube and the second switching tube include at least one NMOS field effect tube.
Optionally, the third switching tube and the fourth switching tube comprise at least one NMOS field effect transistor.
Optionally, the fifth switch tube includes a PMOS field effect transistor.
The second aspect of the present invention discloses a current source generating circuit with an external resistor, comprising:
the overcurrent protection circuit comprises an external resistor unit and an overcurrent protection circuit of the external resistor disclosed by the first aspect of the invention; the external resistor unit is connected with an overcurrent protection circuit of the external resistor.
Optionally, the external resistance unit includes:
the amplifier, an external resistor, a sixth switching tube, a seventh switching tube and an eighth switching tube;
the inverting input end of the amplifier is connected with the reference voltage, the non-inverting input end of the amplifier is connected with the first end of the sixth switching tube, and the output end of the amplifier is connected with the control end of the sixth switching tube;
the first end of the sixth switching tube is grounded through the external resistor, and the second end of the sixth switching tube is respectively connected with the second end of the seventh switching tube and the control end of the seventh switching tube;
the first end of the seventh switching tube is connected with the power supply voltage, and the control end of the seventh switching tube is connected with the control end of the eighth switching tube;
the first end of the eighth switching tube is connected to the power supply voltage, the second end of the eighth switching tube is connected to the overcurrent protection circuit of the external resistor, and the control end of the eighth switching tube is connected to the overcurrent protection circuit of the external resistor.
Optionally, the first driving current, the second driving current and the current passing through the external resistor have a ratio relation; wherein a ratio relation between the first driving current and the second driving current is 1: 1, the ratio relation between the current passing through the external resistor and the first driving current is 1: k, the ratio relation between the current passing through the external resistor and the second driving current is 1: and K, wherein the value of K comprises the multiple of the width-length ratio of the seventh switching tube to the eighth switching tube.
According to the technical scheme, the overcurrent protection circuit of the external resistor obtains a first comparison result by comparing the reference current with the first driving current through the first comparison unit, outputs the difference value or zero between the reference current and the first driving current according to the first comparison result, compares the difference value between the reference current and the first driving current with the second driving current generated by the generation unit through the second comparison unit to obtain a second comparison result, and outputs the reference current according to the second comparison result. The first comparison result reflects whether the first driving current is too large, and the second comparison unit pulls down the too large first driving current to the reference current according to the second comparison result when the first driving current is too large. Therefore, the overlarge first driving current is pulled down to the reference current, so that the external circuit applying the first driving current can work normally.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic circuit diagram of a conventional current source generating circuit with an external resistor;
fig. 2 is a schematic structural diagram of an overcurrent protection circuit with an external resistor according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of an overcurrent protection circuit with an external resistor according to an embodiment of the present invention;
FIG. 4 is a schematic circuit diagram of an alternative over-current protection circuit with an external resistor according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a current source generating circuit with an external resistor according to an embodiment of the present invention;
fig. 6 is a schematic circuit diagram of a current source generating circuit with an external resistor according to an embodiment of the present invention.
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.
As shown in fig. 1, if the external resistor R in the current source generating circuit of the external resistor is short-circuited or the external resistor R is a small resistor, the current passing through the external resistor R, i.e., the bias current, is a large current. Since the seventh switching tube M7 and the eighth switching tube M8 have 1: the ratio relation of K is that the output current, i.e. the first driving current, is a very large current after being amplified by the eighth switching tube M8 under the condition that the bias current is very large.
Aiming at the problems, a corresponding protection circuit needs to be designed for a current source generating circuit of an external resistor, the invention provides an overcurrent protection circuit of the external resistor and a current source generating circuit of the external resistor, so that an overlarge first driving current is pulled down to a reference current when the external resistor R is in a short circuit or the external resistor R is a small resistor.
In the figure, the grid of the switch tube has a circle for distinguishing the NMOS field effect tube from the PMOS field effect tube, wherein the grid of the NMOS field effect tube has no circle, and the grid of the PMOS field effect tube has a circle.
Referring to fig. 2, an embodiment of the present invention discloses an overcurrent protection circuit with an external resistor, including:
a first comparing unit 201, a second comparing unit 202 connected to the first comparing unit 201, and a generating unit 203 connected to the second comparing unit 202.
The first comparing unit 201 is configured to receive the reference current and the first driving current, respectively, compare the reference current with the first driving current to obtain a first comparison result, and output a difference value or zero between the reference current and the first driving current according to the first comparison result.
It should be noted that, as a first comparison result, when the first driving current is greater than the reference current, a difference between the reference current and the first driving current is output, and when the first driving current is less than the reference current, zero is output.
It should also be noted that the reference current can be set manually, and the reference current can be set precisely to the desired current.
A generating unit 203 for generating the second driving current.
A second comparing unit 202, configured to receive the difference or zero between the reference current and the first driving current and the second driving current, compare the difference between the reference current and the first driving current with the second driving current to obtain a second comparison result, and output the reference current according to the second comparison result; or comparing the zero with the second driving current to obtain a third comparison result, and outputting the second driving current according to the third comparison result.
It should be noted that the second comparison result is that the difference between the reference current and the first driving current is smaller than the second driving current, and the reference current is output, and the third comparison result is that the difference is zero and smaller than the second driving current, and the second driving current is output.
In the over-current protection circuit of the external resistor provided by the embodiment of the present invention, the first comparing unit 201 compares the reference current with the first driving current to obtain a first comparing result, and outputs a difference value or zero between the reference current and the first driving current according to the first comparing result, and the second comparing unit 202 compares the difference value between the reference current and the first driving current with the second driving current generated by the generating unit 203 to obtain a second comparing result, and outputs the reference current according to the second comparing result. The first comparison result reflects whether the first driving current is too large, and the second comparison unit 202 pulls down the too large first driving current to the reference current according to the second comparison result when the first driving current is too large. Therefore, the overlarge first driving current is pulled down to the reference current, so that the external circuit applying the first driving current can work normally.
Optionally, referring to fig. 3, in another embodiment of the present invention, an implementation manner of the first comparing unit 301 includes:
a first switching tube M1 and a second switching tube M2.
The first end of the first switch tube M1 is grounded, and the second end receives the reference current I1The control end of the second switch tube M2 is connected to the control end of the first switch tube M1, the control end of the first switch tube M1 is connected to the second end of the first switch tube M1, the first end of the second switch tube M2 is grounded, and the second end receives the first driving current I2And to a second comparing unit 302.
It should be noted that the first switch transistor M1 and the second switch transistor M2 may be NMOS field effect transistors, the first terminal of the first switch transistor M1 is used as the source, the second terminal of the first switch transistor M1 is used as the drain, and the control terminal of the first switch transistor M1 is used as the gate. Similarly, the first terminal of the second switch M2 serves as the source, the second terminal of the second switch M2 serves as the drain, and the control terminal of the second switch M2 serves as the gate.
When the gate of the first switch transistor M1 is connectedReceive reference current I1When the source electrode is grounded, the conduction condition of the NMOS field effect transistor is met, and the first switch tube M1 is conducted. Meanwhile, the gate of the second switch tube M2 receives the reference current I1The source is grounded to satisfy the conduction condition of the NMOS fet, the second switch tube M2 is turned on, the first comparing unit 301 forms a path, and the second switch tube M2 can generate the reference current I in a mirror image manner due to the connection relationship between the first switch tube M1 and the second switch tube M21Therefore, the drain of the second switch tube M2 outputs the reference current I1。
Referring to FIG. 3, when the first driving current I is applied2Greater than the reference current I1Meanwhile, two switching tubes in the second comparing unit 302 are in a conducting state, which is equivalent to connecting another branch circuit to cause shunting, and the first comparing unit 301 outputs the first driving current I2Minus a reference current I1Difference value of (I)2-I1。
Referring to FIG. 4, when the first driving current I is applied2Less than the reference current I1At this time, the two switching tubes in the second comparing unit 402 are in the off state, and the current flowing through the second comparing unit 402 is zero.
Optionally, referring also to fig. 3, in another embodiment of the present invention, an implementation manner of the second comparing unit 302 includes:
a third switching tube M3 and a fourth switching tube M4.
The first end of the third switching tube M3 is grounded, the second end is connected to the first comparing unit 301, the control end is connected to the control end of the fourth switching tube M4, the second end of the third switching tube M3 is connected to the control end of the third switching tube M3, the first end of the fourth switching tube M4 is grounded, and the second end is connected to the generating unit 303.
It should be noted that the third switching transistor M3 and the fourth switching transistor M4 may be NMOS field effect transistors, a first terminal of the third switching transistor M3 serves as a source, a second terminal of the third switching transistor M3 serves as a drain, and a control terminal of the third switching transistor M3 serves as a gate. Similarly, the first terminal of the fourth switching transistor M4 serves as the source, the second terminal of the fourth switching transistor M4 serves as the drain, and the control terminal of the fourth switching transistor M4 serves as the gate.
Referring to fig. 3, when the gate of the third switch transistor M3 receives the first driving current I2Minus a reference current I1Difference value of (I)2-I1When the source electrode is grounded, the conduction condition of the NMOS field effect transistor is met, and the third switching tube M3 is conducted. Meanwhile, the gate of the fourth switching tube M4 receives the first driving current I2Minus a reference current I1Difference value of (I)2-I1The source is grounded, the conduction condition of the NMOS field effect transistor is met, the fourth switching tube M4 is turned on, the second comparing unit 302 forms a path, and due to the connection relationship between the third switching tube M3 and the fourth switching tube M4, the fourth switching tube M4 can mirror the current received by the third switching tube M3, so the drain of the fourth switching tube M4 outputs the first driving current I2Minus a reference current I1Difference value of (I)2-I1. Output first drive current I2Minus a reference current I1Difference value of (I)2-I1And a second drive current I3Comparing the two currents to obtain a second drive current I3Must be larger than the first drive current I2Minus a reference current I1Difference value of (I)2-I1After the two currents are subtracted, the second comparing unit 302 outputs the reference current I1。
Referring to fig. 4, when the gate of the third switching transistor M3 receives zero, the third switching transistor M3 is turned off, and the current flowing through the third switching transistor M3 is zero. Meanwhile, the gate of the fourth switching tube M4 receives zero, the fourth switching tube M4 is turned off, and due to the connection relationship between the third switching tube M3 and the fourth switching tube M4, the fourth switching tube M4 can mirror the current received by the third switching tube M3, so that the current flowing through the fourth switching tube M4 is also zero, and the drain of the fourth switching tube M4 outputs zero. Zero and a second drive current I3Comparing the two currents to obtain a second drive current I3Must be larger than zero, the second comparing unit 402 outputs the second driving current I3。
It should be noted that the ratio relationship among the first switching tube M1, the second switching tube M2, the third switching tube M3 and the fourth switching tube M4 may be changed to reduce power consumption.
Optionally, referring to fig. 3, an embodiment of the generating unit 303 includes:
and a fifth switch tube M5. A first end of the fifth switching tube M5 is connected to the power voltage, a control end is connected to the reference voltage, and a second end is connected to the second comparing unit 302.
It should be noted that the fifth switch transistor M5 may be a PMOS fet, the first terminal of the fifth switch transistor M5 is used as the source, the second terminal of the fifth switch transistor M5 is used as the drain, and the control terminal of the fifth switch transistor M5 is used as the gate.
The source of the fifth switching tube M5 is connected to a power supply voltage VCC, the voltage of the gate is a reference voltage VREF, the power supply voltage VCC is greater than the reference voltage VREF, the fifth switching tube M5 is turned on, and the drain outputs a generated second driving current I3Second drive current I3And a first drive current I2Are equal in size.
Referring to fig. 5, an embodiment of the present invention discloses a current source generating circuit with an external resistor, including:
an external resistor unit 501 and an overcurrent protection circuit 502 of an external resistor; the external resistor unit 501 is connected to an overcurrent protection circuit 502 of the external resistor.
The external resistor over-current protection circuit 502 includes:
the device comprises a first comparison unit, a second comparison unit connected with the first comparison unit and a generation unit connected with the second comparison unit;
a first comparing unit for respectively receiving the reference current I1A first drive current I2And comparing the reference current I1And a first drive current I2Obtaining a first comparison result, and outputting a reference current I according to the first comparison result1And a first drive current I2Difference value of (I)2-I1Or zero;
a generating unit for generating a second drive current I3；
Second comparison units for respectively receiving reference currents I1And a first drive current I2Difference value of (I)2-I1Or zero, and a second drive current I3And comparing the reference current I1And a first drive current I2Difference value of (I)2-I1And a second drive current I3Obtaining a second comparison result, and outputting a reference current I according to the second comparison result1(ii) a Or comparing zero with the second drive current I3Obtaining a third comparison result, and outputting a second driving current I according to the third comparison result3。
Alternatively, referring to fig. 6, in another embodiment of the present invention, the first comparing unit includes: a first switching tube M1 and a second switching tube M2.
The first end of the first switch tube M1 is grounded, and the second end receives the reference current I1The control end of the second switch tube M2 is connected to the control end of the first switch tube M1, the control end of the first switch tube M1 is connected to the second end of the first switch tube M1, the first end of the second switch tube M2 is grounded, and the second end receives the first driving current I2And a second comparison unit is connected.
Alternatively, referring to fig. 6, in another embodiment of the present invention, the second comparing unit includes: a third switching tube M3 and a fourth switching tube M4.
The first end of the third switching tube M3 is grounded, the second end is connected to the first comparing unit, the control end is connected to the control end of the fourth switching tube M4, the second end of the third switching tube M3 is connected to the control end of the third switching tube M3, the first end of the fourth switching tube M4 is grounded, and the second end is connected to the generating unit.
Optionally, referring to fig. 6, in another embodiment of the present invention, the generating unit includes: and a fifth switch tube M5.
A first end of the fifth switching tube M5 is connected to the power supply voltage VCC, a control end is connected to the reference voltage VREF, and a second end is connected to the second comparing unit.
The specific implementation process of the over-current protection circuit 502 with an external resistor is consistent with the implementation principle and the over-current protection circuit with an external resistor shown in the above embodiments, and it can be referred to here and will not be described again.
Optionally, referring to fig. 6, in another embodiment of the present invention, an implementation manner of the external resistor unit 601 includes:
the amplifier, an external resistor R, a sixth switching tube M6, a seventh switching tube M7, and an eighth switching tube M8.
The inverting input end of the amplifier is connected with a reference voltage VREF, the non-inverting input end of the amplifier is connected with the first end of a sixth switching tube M6, and the output end of the amplifier is connected with the control end of a sixth switching tube M6;
a first end of the sixth switching tube M6 is grounded through an external resistor R, and a second end is respectively connected to a second end of the seventh switching tube M7 and a control end of the seventh switching tube M7;
a first end of the seventh switching tube M7 is connected to a power supply voltage VCC, and a control end of the seventh switching tube M7 is connected to a control end of the eighth switching tube M8;
the first end of the eighth switching tube M8 is connected to the power supply voltage VCC, the second end is connected to the overcurrent protection circuit 602 of the external resistor R, and the control end is connected to the overcurrent protection circuit 602 of the external resistor R.
It should be noted that the sixth switching transistor M6 may be an NMOS field effect transistor. The seventh switch transistor M7 and the eighth switch transistor M8 may be PMOS fets. The first terminal of the sixth switch transistor M6 serves as the source, the second terminal of the sixth switch transistor M6 serves as the drain, and the control terminal of the sixth switch transistor M6 serves as the gate. Similarly, the first terminal of the seventh switch M7 serves as the source, the second terminal of the seventh switch M7 serves as the drain, and the control terminal of the seventh switch M7 serves as the gate. Similarly, the first terminal of the eighth switch transistor M8 serves as the source, the second terminal of the eighth switch transistor M8 serves as the drain, and the control terminal of the eighth switch transistor M8 serves as the gate.
The amplifier may be an operational amplifier, the voltage at the positive phase input end of the operational amplifier is equal to the voltage at the negative phase input end, and the output end outputs the voltage after amplifying the reference voltage VREF, so that the gate voltage of the sixth switching tube M6 is greater than the source voltage, the sixth switching tube M6 is turned on, and the drain outputs the bias current.
The source of the seventh switch tube M7 is connected to the power supply voltage VCC, the gate is connected to the reference voltage VREF, the source voltage is greater than the gate voltage, and the seventh switch tube M7 is turned on. Meanwhile, the source of the eighth switch tube M8 is connected to the power supply voltage VCC, the gate is connected to the reference voltage VREF, the source voltage is greater than the gate voltage, and the eighth switch tube M8 is turned on. Wherein, the seventh switch tube has the ratio relation with the eighth switch tube, is 1: k, that is, the current output after the eighth switching tube is turned on is a bias current amplified by K times, that is, the ratio relationship between the current passing through the external resistor and the first driving current is 1: K. the value of K comprises the multiple of the width-length ratio of the seventh switch tube M7 and the eighth switch tube M8.
It should be further noted that the ratio of the width-to-length ratio of the eighth switching tube M8 to the fifth switching tube M5 is 1: 1, that is, the current output by the fifth switch M5 in the on state is equal to the current output by the eighth switch M8 in the on state, that is, the ratio of the first driving current to the second driving current is 1: 1. it can also be found that the ratio of the current passing through the external resistor to the second driving current is 1: K.
referring to fig. 6, when the operational amplifier is connected to the reference voltage VREF, the sixth switching tube M6, the seventh switching tube M7 and the eighth switching tube M8 are turned on, and the external resistor unit 601 outputs the first driving current I2. The external resistor over-current protection circuit 602 receives the first driving current I2And a reference current I1Meanwhile, the fifth switch tube M5 is connected to the reference voltage VREF and the power voltage VCC, the fifth switch tube M5 is turned on, and outputs the second driving current I3. If the comparison process of the over-current protection circuit 602 with the external resistor shows that the first driving current I is obtained2If the current is too large, a reference current I is output1If the first driving current I is compared2If not, outputting the first driving current I2。
The comparison process of the overcurrent protection circuit with the external resistor comprises the comparison of a reference current I1And a first drive current I2If the first driving current I2Greater than the reference current I1Then the first comparing unit outputs a reference current I1And a first drive current I2Difference value of (I)2-I1If the first driving current I2Less than the reference current I1Zero is output. In different cases, the second comparing unit receives the reference current I1And a first drive current I2Difference value of (I)2-I1Or zero. When the second comparing unit receives the reference current I1And a first drive current I2Difference value of (I)2-I1While comparing the reference current I1And a first drive current I2Difference value of (I)2-I1And a second drive current I3Due to the second drive current I3Is equal to the first drive current I2Second drive current I3Must be greater than the reference current I1And a first drive current I2Difference value of (I)2-I1So as to output a second driving current I3Minus a reference current I1And a first drive current I2Difference value of (I)2-I1I.e. output a reference current I1. When the second comparison unit receives zero, comparing the zero with the second driving current I3Second drive current I3Must be greater than zero, output the second driving current I3Reducing to zero, i.e. outputting the second drive current I3Due to the second drive current I3Is equal to the first drive current I2Equivalent to outputting the first driving current I2。
Those skilled in the art can make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims (7)

1. A current source generating circuit with an external resistor, comprising:
the overcurrent protection circuit comprises an external resistor unit and an overcurrent protection circuit of an external resistor, wherein the external resistor unit is connected with the overcurrent protection circuit of the external resistor;
wherein, external resistance unit includes:
the amplifier, an external resistor, a sixth switching tube, a seventh switching tube and an eighth switching tube;
the inverting input end of the amplifier is connected with a reference voltage, the non-inverting input end of the amplifier is connected with the first end of the sixth switching tube, and the output end of the amplifier is connected with the control end of the sixth switching tube;
the first end of the sixth switching tube is grounded through the external resistor, and the second end of the sixth switching tube is respectively connected with the second end of the seventh switching tube and the control end of the seventh switching tube;
a first end of the seventh switching tube is connected with a power supply voltage, and a control end of the seventh switching tube is connected with a control end of the eighth switching tube;
a first end of the eighth switching tube is connected to the power supply voltage, a second end of the eighth switching tube is connected with the overcurrent protection circuit of the external resistor, and a control end of the eighth switching tube is connected with the overcurrent protection circuit of the external resistor;
wherein, external resistance's overcurrent protection circuit includes:
the device comprises a first comparison unit, a second comparison unit connected with the first comparison unit and a generation unit connected with the second comparison unit;
the first comparing unit is configured to receive a reference current and a first driving current, compare the reference current with the first driving current to obtain a first comparison result, and output a difference value between the reference current and the first driving current or zero according to the first comparison result, where the first comparison result is a difference value between the reference current and the first driving current when the first driving current is greater than the reference current, and the first comparison result is zero when the first driving current is less than the reference current;
the generating unit is used for generating a second driving current;
the second comparing unit is configured to receive the difference or zero between the reference current and the first driving current and the second driving current, compare the difference between the reference current and the first driving current with the second driving current to obtain a second comparison result, and output the reference current according to the second comparison result; or comparing zero with the second driving current to obtain a third comparison result, and outputting the second driving current according to the third comparison result, wherein the second comparison result is that the difference value between the reference current and the first driving current is smaller than the second driving current, and the third comparison result is that zero is smaller than the second driving current;
wherein the generating unit includes:
a fifth switching tube;
the first end of the fifth switching tube is connected with the first end of the eighth switching tube, the first end of the fifth switching tube is connected with a power supply voltage, the control end of the fifth switching tube is connected with the control end of the eighth switching tube, the second end of the fifth switching tube is connected with the second comparing unit, and the ratio of the width-to-length ratio of the eighth switching tube to the width-to-length ratio of the fifth switching tube is 1: 1.
2. the current source generation circuit according to claim 1, wherein the first comparison unit includes:
the first switch tube and the second switch tube;
the first end of the first switch tube is grounded, the second end of the first switch tube receives the reference current, the control end of the first switch tube is connected with the control end of the second switch tube, the control end of the first switch tube is connected with the second end of the first switch tube, the first end of the second switch tube is grounded, and the second end of the second switch tube receives the first driving current and is connected with the second comparison unit.
3. The current source generation circuit according to claim 1, wherein the second comparison unit includes:
a third switching tube and a fourth switching tube;
the first end of the third switch tube is grounded, the second end of the third switch tube is connected with the first comparison unit, the control end of the third switch tube is connected with the control end of the fourth switch tube, the second end of the third switch tube is connected with the control end of the third switch tube, the first end of the fourth switch tube is grounded, and the second end of the fourth switch tube is connected with the generation unit.
4. The current source generating circuit of claim 2, wherein the first and second switching transistors comprise at least one NMOS field effect transistor.
5. The current source generating circuit of claim 3, wherein the third and fourth switching tubes comprise at least one NMOS field effect transistor.
6. The current source generation circuit of claim 1, wherein the fifth switching tube comprises a PMOS field effect tube.
7. The current source generating circuit of claim 1, wherein the first driving current, the second driving current and the current through the external resistor have a ratio relationship; wherein a ratio relation between the first driving current and the second driving current is 1: 1, the ratio relation between the current passing through the external resistor and the first driving current is 1: k, the ratio relation between the current passing through the external resistor and the second driving current is 1: and K, wherein the value of K comprises the multiple of the width-length ratio of the seventh switching tube to the eighth switching tube.
CN201910117380.XA 2019-02-15 2019-02-15 Overcurrent protection circuit with external resistor and current source generating circuit with external resistor Active CN109696937B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201910117380.XA CN109696937B (en) 2019-02-15 2019-02-15 Overcurrent protection circuit with external resistor and current source generating circuit with external resistor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201910117380.XA CN109696937B (en) 2019-02-15 2019-02-15 Overcurrent protection circuit with external resistor and current source generating circuit with external resistor

Publications (2)

Publication Number Publication Date
CN109696937A CN109696937A (en) 2019-04-30
CN109696937B true CN109696937B (en) 2021-02-19

Family

ID=66233362

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910117380.XA Active CN109696937B (en) 2019-02-15 2019-02-15 Overcurrent protection circuit with external resistor and current source generating circuit with external resistor

Country Status (1)

Country Link
CN (1) CN109696937B (en)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100589058C (en) * 2007-12-27 2010-02-10 北京中星微电子有限公司 Current limitation circuit as well as voltage regulator and DC-DC converter including the same
CN102566640B (en) * 2011-12-24 2014-03-12 西安启芯微电子有限公司 Voltage-stabilizing circuit with hiccup mode over-current protection function
CN104142701B (en) * 2013-05-06 2016-08-24 意法半导体研发(深圳)有限公司 Current-limiting circuit
CN204904127U (en) * 2015-06-26 2015-12-23 深圳市安派电子有限公司 Electric current limit circuit and integrated circuit
CN106774595A (en) * 2017-01-09 2017-05-31 电子科技大学 A kind of current foldback circuit for low pressure difference linear voltage regulator

Also Published As

Publication number Publication date
CN109696937A (en) 2019-04-30

Similar Documents

Publication Publication Date Title
US11474546B2 (en) Method of operating a low dropout regulator by selectively removing and replacing a DC bias from a power transistor within the low dropout regulator
WO2018100390A1 (en) Reference voltage generator
US20150048886A1 (en) Temperature detecting apparatus, switch capacitor apparatus and voltage integrating circuit thereof
CN109164865B (en) Overshoot protection circuit, linear voltage regulator and power module
CN114047798A (en) High-precision current detection device inside integrated circuit chip
JP4714353B2 (en) Reference voltage circuit
WO2018100375A1 (en) Voltage regulator
CN109696937B (en) Overcurrent protection circuit with external resistor and current source generating circuit with external resistor
JP6912350B2 (en) Voltage regulator
US6768677B2 (en) Cascode amplifier circuit for producing a fast, stable and accurate bit line voltage
JP4811157B2 (en) amplifier
KR20160073902A (en) Audio switch circuit with slow turn-on
CN108227814B (en) Source follower circuit
US20160363945A1 (en) Linear regulator circuit
CN109194292B (en) Power amplifier circuit and chip with overcurrent protection function
TWI630403B (en) Core power detection circuit and associated input/output control system
JP2753144B2 (en) Potential generation circuit
JP2017005609A (en) Overvoltage detection circuit
JP2021096554A (en) Constant current circuit
CN216434792U (en) Current regulating circuit
JP7438694B2 (en) amplifier circuit
CN108306642B (en) Low power compact voltage sensing circuit
WO2023223468A1 (en) Bias voltage generation circuit and electronic circuit
JP4332522B2 (en) Differential amplifier circuit
WO1999056139A1 (en) Apparatus for detecting trouble with solenoid-operated device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant