CN117792372A - Infrared emission chip with constant current drive, cascading system and driving method - Google Patents
Infrared emission chip with constant current drive, cascading system and driving method Download PDFInfo
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Abstract
The invention belongs to the technical field of semiconductor chips, and particularly relates to an infrared emission chip with constant current drive, a cascading system and a driving method. Wherein, take constant current drive's infrared emission chip still includes: a main input; a main output terminal; the signal input end of the logic control circuit is connected with the main input end; the signal input end and the control end of the latch are respectively connected with the signal output end of the logic control circuit, and the signal output end of the latch is connected with the infrared emission tube through the constant current driving circuit; and the signal input end of the waveform shaping circuit is connected with the signal output end of the logic control circuit, and the signal output end of the waveform shaping circuit is connected with the main output end. The infrared emission chip occupies less external main control pins, a cascade system can be built, multistage cascade control is realized, and single-stage or multistage control can be completed only by occupying one IO of the external main control.
Description
Technical Field
The invention belongs to the technical field of semiconductor chips, and particularly relates to an infrared emission chip with constant current drive, a cascading system and a driving method.
Background
An optical isolator, an infrared transmitting tube and an infrared receiving tube are often used in occasions where electrical isolation or optical communication is required. In order to ensure the stability of the infrared receiving tube signals, the infrared transmitting tube needs to be driven by constant current.
The current solution is shown in fig. 1, and a constant current driving circuit is built around the infrared emission tube, and the constant current driving circuit can be realized by adopting a discrete component or a constant current driving chip existing in the market. The working principle is that the output current of the constant current driving circuit is controlled by n control pins of the MCU, and then the infrared emission tube is driven.
However, the implementation method has the disadvantages that firstly, more control pins are occupied by the MCU main control, secondly, when a plurality of transmitting tubes are used, a plurality of constant current driving circuits are needed to be matched, the number of the pins occupied by the MCU main control is increased in multiple, and the PCB wiring difficulty is high, so that the expansion and the use are not facilitated.
Disclosure of Invention
Aiming at the technical problems that the prior infrared emission chip with constant current drive occupies more control pins of a main control, and particularly when a plurality of emission tubes are used, the invention expands the difficulty in the process, and aims to provide the infrared emission chip with constant current drive, a cascade system and a driving method.
In order to solve the foregoing technical problem, a first aspect of the present invention provides an infrared emission chip with constant current drive, where the infrared emission chip with constant current drive includes a constant current drive circuit and an infrared emission tube that are connected to each other, and the infrared emission chip with constant current drive further includes:
a main input;
a main output terminal;
the signal input end of the logic control circuit is connected with the main input end;
the signal input end and the control end of the latch are respectively connected with the signal output end of the logic control circuit, and the signal output end of the latch is connected with the infrared emission tube through the constant current driving circuit;
and the signal input end of the waveform shaping circuit is connected with the signal output end of the logic control circuit, and the signal output end of the waveform shaping circuit is connected with the main output end.
Optionally, in the infrared emission chip with constant current drive as described above, the infrared emission chip with constant current drive further includes:
and the output end of the oscillating circuit is connected with the clock end of the logic control circuit.
Optionally, in the infrared emission chip with constant current driving as described above, the constant current driving circuit includes:
the driving switch groups comprise driving switches and driving resistors which are connected in series, the control end of each driving switch is respectively connected with the signal output end of the latch, and each driving switch group is connected in parallel;
the base electrode of the first PNP triode is connected with the power supply end through a first resistor for driving and grounded through a second resistor for driving, and the collector electrode of the first PNP triode is grounded;
the base electrode of the second NPN triode is connected with a power supply end through a third driving resistor, the base electrode of the second NPN triode is connected with the emitter electrode of the first PNP triode through a fourth driving resistor, and the collector electrode of the second NPN triode is connected with the power supply end through the infrared emission tube;
and the base electrode of the third NPN triode is connected with the emitter electrode of the first PNP triode, the collector electrode of the third NPN triode is connected with the emitter electrode of the second NPN triode, and the emitter electrode of the third NPN triode is grounded through the driving switch.
Optionally, in the infrared emission chip with constant current driving as described above, the driving switch is a first field effect transistor, a gate of the first field effect transistor is connected to a signal output end of the latch, a drain of the first field effect transistor is connected to an emitter of the third NPN triode through the driving resistor, and a source of the first field effect transistor is grounded.
Optionally, in the infrared emission chip with constant current driving as described above, the waveform shaping circuit includes:
the source electrode of the second field effect tube is connected with the signal output end of the logic control circuit, the grid electrode of the second field effect tube is connected with the power supply end through a first resistor for shaping driving, and the drain electrode of the second field effect tube is connected with the main output end;
the main output end is connected with a power supply end through a second resistor for driving.
In order to solve the technical problem, a second aspect of the present invention provides an infrared emission chip cascade system with constant current driving, the infrared emission chip cascade system with constant current driving includes:
the infrared emission chips are provided with constant current driving and are sequentially connected through a main input end and a main output end to form a cascade system;
the main input end of the infrared emission chip positioned at the first stage is used as a total input end and is connected with the signal output end of the external main control.
In order to solve the foregoing technical problem, a third aspect of the present invention provides a driving method of an infrared emission chip with constant current driving, the driving method comprising:
the logic control circuit receives an input signal through a main input end and judges the input signal;
when the input signal is a start signal and a plurality of input signals after the start signal are effective data, the logic control circuit sends a first group of effective data after the start signal into a latch one by one to be stored;
when the input signal is a termination signal, the logic control circuit finishes the transmission of the effective data, and the logic control circuit drives the latch to send the saved effective data to the constant current driving circuit, and the constant current driving circuit drives the infrared emission tube.
In order to solve the foregoing technical problem, a fourth aspect of the present invention provides a driving method of an infrared emission chip cascade system with constant current driving, the driving method comprising:
a logic control circuit in any one level of infrared emission chip receives an input signal through a main input end and judges the input signal;
when the input signal is an initial signal and a plurality of input signals after the initial signal are still initial signals, the logic control circuit outputs the initial signals after the initial signal to the next-stage infrared emission chip through a main output end by a waveform shaping circuit;
when the input signal is a start signal and a plurality of input signals after the start signal are effective data, the logic control circuit sends a first group of effective data after the start signal into a latch one by one to be stored, and the logic control circuit outputs other effective data except the first group of effective data to a next-stage infrared emission chip through a main output end by a waveform shaping circuit;
when the input signals are termination signals, the logic control circuit finishes the transmission of the effective data, if a plurality of input signals after the termination signals are still termination signals, the logic control circuit outputs the termination signals after the termination signals to the next-stage infrared emission chip through the main output end by the waveform shaping circuit, and the logic control circuit drives the latch to send the saved effective data to the constant current driving circuit, and drives the infrared emission tube by the constant current driving circuit.
Optionally, in the driving method of the infrared emission chip cascade system with constant current driving, the number of start signals, the number of end signals and the number of groups of valid data received by the main input end of the infrared emission chip at the first stage are all k times, and k is the number of the infrared emission chips in the cascade system.
Optionally, in the driving method of the infrared emission chip cascade system with constant current driving as described above, the start signal is a low level greater than 20 us;
the termination signal is at a low level greater than 20us, the termination signal being of a different duration than the initiation signal;
the 0 code and the 1 code of the effective data are represented by high and low levels with different time duty ratios in a preset period.
The invention has the positive progress effects that:
1. the infrared emission chip occupies less external main control pins, and the infrared emission chip adopts a communication mode of a single bus, and can complete control only by occupying one IO of the external main control.
2. The infrared emission chip can build a cascade system to realize multistage cascade control, and the multistage cascade control still can complete control by occupying only one IO of the external master control by adopting a single-bus communication mode, does not occupy the pin resource of the external master control additionally, saves the control pins of the master control, and is more flexible and changeable in control.
3. The invention can control the infrared emission tube according to the need, and can conveniently build a cascade system, expand and conveniently, and is suitable for large-scale popularization and transformation.
Drawings
The present disclosure will become more apparent with reference to the accompanying drawings. It is to be understood that these drawings are solely for purposes of illustration and are not intended as a definition of the limits of the invention. In the figure:
FIG. 1 is a prior art driving architecture for an infrared emitting tube;
FIG. 2 is a schematic diagram of an infrared emitting chip according to the present invention;
FIG. 3 is a write logic diagram of a latch of the present invention;
FIG. 4 is a circuit configuration diagram of the constant current drive circuit of the present invention;
FIG. 5 is a circuit diagram of a waveform shaping circuit of the present invention;
FIG. 6 is a coding rule diagram of a single-level infrared emission chip of the present invention;
FIG. 7 is a circuit diagram of an application of a single level infrared emitting chip of the present invention;
FIG. 8 is a communication protocol of the single-level infrared emitting chip of FIG. 7;
FIG. 9 is a circuit diagram of an application of the cascade system of the invention;
fig. 10 is a communication protocol of the cascade system of fig. 9.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which is to be read in light of the specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict.
In the description of the present invention, it should be noted that, for the azimuth terms, such as terms "outside," "middle," "inside," "outside," and the like, the azimuth and positional relationships are indicated based on the azimuth or positional relationships shown in the drawings, only for convenience in describing the present invention and simplifying the description, but not to indicate or imply that the apparatus or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and should not be construed as limiting the specific protection scope of the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features. Thus, the definition of "a first", "a second" feature may explicitly or implicitly include one or more of such feature, and in the description of the present invention, the meaning of "a number", "a number" is two or more, unless otherwise specifically defined.
Example 1:
referring to fig. 2, the present embodiment provides an infrared emission chip with constant current driving, which includes a main input terminal DIN, a main output terminal DOUT, a logic control circuit 1, a latch 2, a constant current driving circuit 3, an infrared emission tube 4, and a waveform shaping circuit 5.
The main input terminal DIN is used for being connected with the external main control MCU, and receives control data sent by the external main control MCU, wherein the control data comprises a start signal, valid data, a termination signal and the like.
The signal input of the logic control circuit 1 is connected to the main input DIN. The logic control circuit 1 is a microprocessor which is responsible for some simple data processing tasks, including in particular: (1) reading an input signal transmitted by a main input terminal DIN; (2) storing data into the latch 2; (3) part of the input signal is supplied to a waveform shaping circuit 5. Reading of the input signal can be accomplished using one IO port of the logic control circuit 1.
The signal input end and the control end of the latch 2 are respectively connected with the signal output end of the logic control circuit 1, and the signal output end of the latch 2 is connected with the infrared emission tube 4 through the constant current driving circuit 3. The latch is used for storing data output by the logic control circuit 1 and controlling the constant current driving circuit 3 according to the stored data.
The constant current driving circuit 3 adjusts the output current according to the control signal of the latch 2, and then drives the infrared emission tube 4 in the sheet.
The infrared transmitting tube 4 is packaged inside the chip and transmits signals to an infrared receiving tube outside the chip by transmitting infrared light.
The signal input end of the waveform shaping circuit 5 is connected with the signal output end of the logic control circuit 1, and the signal output end of the waveform shaping circuit 5 is connected with the main output end DOUT. The waveform shaping circuit 5 performs waveform shaping and driving capability amplification on the data output by the logic control circuit 1, so as to avoid waveform distortion during multistage connection, and the subsequent circuit cannot work.
In some embodiments, the infrared emitting chip of the present embodiment further includes an oscillating circuit 6, and an output end of the oscillating circuit 6 is connected to a clock end of the logic control circuit 1. The oscillating circuit 6 is used for generating an internal clock for the logic control circuit 1.
The oscillating circuit 6 is a common RC oscillating circuit in the chip. Of course, other circuits may be used for the oscillating circuit 6, as long as it can be used for the logic control circuit 1.
In some embodiments, the infrared emitting chip of the present embodiment further includes some necessary interfaces, such as a power supply terminal VCC and a ground terminal GND.
In some embodiments, the number of bits of the latch 2 and the significant number of bits of the input data remain identical, and may be 8 bits, 16 bits, 32 bits, or the like.
If the set of valid data is 8 bits, the latch 2 can select the type of 1-bit serial input and 8-bit parallel output, and the write logic diagram is shown in fig. 3, and only occupies 3 IO ports of the logic control circuit 1.
In some embodiments, latch 2 is a model 74HC595 latch.
In some embodiments, the constant current driving circuit 3 may be a constant current driving circuit that may drive the infrared emission tube 4 in the prior art.
The constant current drive circuit 3 preferably adopts the implementation shown in fig. 4 of the present embodiment.
Referring to fig. 4, the constant current driving circuit 3 includes a plurality of driving switch groups 31, a first PNP transistor Q31, a second NPN transistor Q32, a third NPN transistor Q33, a first driving resistor R31, a second driving resistor R32, a third driving resistor R33, and a fourth driving resistor R34.
The driving switch group 31 includes driving switches and driving resistors connected in series, and control ends of the driving switches are respectively connected to signal output ends of the latches 2, and the driving switch groups are connected in parallel.
The driving switch group 31 preferably corresponds to the output of the latch 2, that is, the latch 2 has several bits of output, and there are several driving switches, each driving switch corresponds to each output of the latch 2 one by one, and the data of each output of the latch 2 is used to control the turn-off of each driving switch. For example, as shown in fig. 4, when the latch 2 is an n (n-bit natural number greater than 0) bit latch, the driving switch groups are n groups, the driving switches in each driving switch group are the driving switch Q341 and the driving switch Q342 … …, and the driving resistors in each driving switch group are the driving resistor R351 and the driving resistor R352 … …, respectively, and the driving switch Q34n, respectively.
The base of the first PNP transistor Q31 is connected to the power supply terminal VCC through the first driving resistor R31, the base of the first PNP transistor Q31 is grounded through the second driving resistor R32, and the collector of the first PNP transistor Q31 is grounded.
The base of the second NPN triode Q32 is connected with a power supply end VCC through a third resistor R33 for driving, the base of the second NPN triode Q32 is connected with the emitter of the first PNP triode Q31 through a fourth resistor R34 for driving, the collector of the second NPN triode Q32 is connected with the negative electrode of an infrared emission tube IR, and the positive electrode of the infrared emission tube IR is connected with the power supply end VCC.
The base electrode of the third NPN triode Q33 is connected with the emitter electrode of the first PNP triode Q31, the collector electrode of the third NPN triode Q33 is connected with the emitter electrode of the second NPN triode Q32, the emitter electrode of the third NPN triode Q33 is respectively connected with one end of each driving switch group 31, and the other end of each driving switch group 31 is grounded.
The constant current driving circuit 3 of this embodiment is controlled by the output of the latch 2, and a set of valid data stored in the latch 2 controls each driving switch in the constant current driving circuit 3, so as to control the on-off of the driving resistor, and thereby adjust the constant current value flowing through the infrared emission tube IR.
In some embodiments, the driving switch adopts a first field effect transistor, a gate electrode of the first field effect transistor is connected with a signal output end of the latch 2, a drain electrode of the first field effect transistor is connected with an emitter electrode of the third NPN triode Q33 through a driving resistor, and a source electrode of the first field effect transistor is grounded.
The driving switches in each driving switch group in this embodiment all adopt field effect transistors, and a group of effective data stored in the latch 2 controls each field effect transistor, so as to control the on-off of the driving resistor.
In some embodiments, the first field effect transistor is an enhancement N-channel MOS transistor.
In some embodiments, the waveform shaping circuit 5 may employ a shaping circuit that may shape and/or amplify waveforms as in the prior art.
The waveform shaping circuit 5 preferably adopts the implementation shown in fig. 5 of the present embodiment.
Referring to fig. 5, the waveform shaping circuit 5 includes a second field effect transistor Q51, a first resistor R51 for driving, and a second resistor R52 for driving.
The source electrode of the second field effect transistor Q51 is connected with the signal output end of the logic control circuit 1, the grid electrode of the second field effect transistor Q51 is connected with the power supply end VCC through the first resistor R51 for shaping driving, and the drain electrode of the second field effect transistor Q51 is connected with the main output end DOUT. The main output terminal DOUT is connected to the power supply terminal VCC via the driving second resistor R52.
When the logic control circuit 1 outputs a high level, the second field effect transistor Q51 is cut off, and the main output end DOUT also outputs the high level; when the logic control circuit 1 outputs a low level, the second fet Q51 is turned on, and the main output terminal DOUT also outputs a low level. I.e. the level of the output of the main output terminal DOUT and the signal fed in by the logic control circuit 1 remain identical. The waveform shaping circuit 5 in this embodiment shapes the waveform, so as to avoid waveform distortion during multi-stage connection, and the signal integrity problem caused by error code in the later stage circuit.
In some embodiments, the second field effect transistor Q51 is an enhancement N-channel MOS transistor.
Example 2:
the embodiment provides a driving method of an infrared emission chip with constant current driving, which is suitable for driving the infrared emission chip with constant current driving provided by each embodiment in the embodiment 1. The driving method comprises the following steps:
the logic control circuit receives an input signal through the main input end and judges the input signal.
The input signals of the present embodiment include a start signal, valid data, and an end signal. The logic control circuit judges the received input signals one by one.
The start signal, valid data, and end signal may be preset with coding rules, for example, as shown in fig. 6, the start signal and the end signal are low levels greater than 20us and have different durations. The 0 code and 1 code of the effective data are distinguished by the high and low levels having different time duty ratios throughout the period T. For example, one distinguishing form in fig. 6, namely, the 0 code is high for the first 0.3us and low for the last 0.9us in one period T; the 1 code is high for the first 0.9us and low for the last 0.3us in one period T.
The number of valid data may be set in advance, which preferably coincides with the number of latch bits of the latch. For example, when a set of valid data is 8 bits, an 8-bit latch is selected for use. Of course, latches greater than the amount of valid data may also be selected for configuration.
When the logic control circuit judges that the input signal is the starting signal and a plurality of input signals after the starting signal are effective data, the logic control circuit sends the first group of effective data after the starting signal into the latch one by one for storage. For a single-stage infrared emission chip, other effective data are received after the first group of effective data, and the effective data can be ignored or can be output through a main output end by a waveform shaping circuit.
When the logic control circuit judges that the input signal is a termination signal, the logic control circuit finishes the transmission of the effective data, and the logic control circuit drives the latch to send the saved effective data to the constant current driving circuit, and drives the infrared emission tube through the constant current driving circuit. For example, a constant current drive circuit changes the drive current of the infrared emission tube. At this time, even if the main input end does not input valid data any more, the latch can also save driving data, so that the constant driving current of the infrared emission tube is ensured.
An application circuit of the infrared emission chip is shown in fig. 7, wherein the main input end DIN of the infrared emission chip is connected with one of the IO ports of the external main control MCU, and the external main control MCU can send control DATA DATA to the infrared emission chip, wherein the control DATA DATA is input DATA obtained by the main input end DIN of the infrared emission chip, namely, an input signal received by the logic control circuit through the main input end DIN.
Referring to fig. 8, a communication protocol for driving a single-stage infrared emitting chip is shown. After the single-stage infrared emission chip is powered on and reset, an input signal received by the logic control circuit sequentially comprises a start signal, a first group of effective data and a termination signal, and after the input signal is processed by the driving method of the embodiment, the latch stores the first group of effective data, and the infrared emission tube is driven by the first group of effective data. If the driving data of the infrared transmitting tube needs to be changed, the external main control MCU only needs to send the control data to the single-stage infrared transmitting chip shown in fig. 7 again according to the communication logic shown in fig. 8, and the latch can be refreshed once.
Example 3:
the embodiment provides an infrared emission chip cascade system with constant current drive, which comprises a plurality of infrared emission chips, wherein the infrared emission chips are the infrared emission chips with constant current drive provided by each embodiment in the embodiment 1, and the plurality of infrared emission chips are sequentially connected through a main input end DIN and a main output end DOUT to form the cascade system.
The main input end DIN of the infrared emission chip positioned at the first stage is used as a total input end to be connected with the signal output end of the external main control.
The infrared emission chip with constant current drive provided in each embodiment in embodiment 1 can build a cascade system to realize multistage cascade control, and adopts a single bus communication mode, the multistage cascade control still only occupies one IO of the external master control to complete control, does not occupy pin resources of the external master control additionally, saves control pins of the master control, and is more flexible and changeable in control.
For example, referring to fig. 9, a 3-stage cascade system is provided with three infrared emitting chips, namely a chip 1, a chip 2 and a chip 3, which are sequentially connected, wherein a main input terminal DIN of the chip 1 is used as a total input terminal to be connected with one IO terminal of an external main control MCU, and the external main control MCU can send control DATA to the chip 1, wherein the control DATA is input DATA obtained by the main input terminal DIN of the chip 1, that is, an input signal received by a logic control circuit through the main input terminal.
Example 4:
the embodiment provides a driving method of an infrared emission chip cascade system with constant current driving, which is suitable for driving the cascade system in embodiment 3. The driving method comprises the following steps:
a logic control circuit in any one level of infrared emission chip receives an input signal through a main input end, and judges the input signal.
The input signals of the present embodiment include a start signal, valid data, and an end signal. The logic control circuit judges the received input signals one by one.
Similar to embodiment 2, the start signal, the valid data, and the end signal may be preset with a coding rule, for example, as shown in fig. 6, the start signal and the end signal are low levels of more than 20us, and the durations of the two signals are different. The 0 code and 1 code of the effective data are distinguished by the high and low levels having different time duty ratios throughout the period T. For example, one distinguishing form in fig. 6, namely, the 0 code is high for the first 0.3us and low for the last 0.9us in one period T; the 1 code is high for the first 0.9us and low for the last 0.3us in one period T.
The number of valid data may be set in advance, which preferably coincides with the number of latch bits of the latch. For example, when a set of valid data is 8 bits, an 8-bit latch is selected for use. Of course, latches greater than the amount of valid data may also be selected for configuration.
Unlike embodiment 2, when driving a multi-stage system, it is necessary to extend the duration of the start signal and the end signal so that each stage achieves the purpose of driving infrared emitting tubes simultaneously as much as possible. For example, it would be desirable to extend the duration of the start and stop signals by more than k x 20us, where k is equal to the number of stages of the circuit, i.e., the number of infrared emitting chips in the cascade system. When the external master control MCU is applied, after the current stage circuit receives the low level of 20us, if the received low level is still low level, the low level is transmitted to the back stage through the main output end, so that as long as the duration of the start signal and the stop signal output by the external master control MCU is longer than k x 20us, all chips connected in a multistage manner can be ensured to receive the start signal and the stop signal.
When driving a multi-stage system, the number of groups of valid data should also be greater than 1 group, preferably k groups, where k is equal to the number of stages of the circuit, i.e. the number of infrared emitting chips in the cascade system.
When the logic control circuit judges that the input signal is the initial signal and a plurality of input signals after the initial signal are still initial signals, the logic control circuit outputs the initial signals after the initial signal to the next-stage infrared emission chip through the main output end by the waveform shaping circuit.
When the logic control circuit judges that the input signal is a starting signal and a plurality of input signals after the starting signal are effective data, the logic control circuit sends the first group of effective data after the starting signal into the latch one by one to be stored, and the logic control circuit outputs the second group of effective data and the following effective data to the next stage of infrared emission chip through the main output end by the waveform shaping circuit.
When the logic control circuit judges that the input signal is a termination signal, the logic control circuit finishes the transmission of the effective data, if a plurality of input signals after the termination signal are still termination signals, the logic control circuit outputs a plurality of termination signals after the termination signal to the next-stage infrared emission chip through the main output end by the waveform shaping circuit, and the logic control circuit drives the latch to send the saved effective data to the constant current driving circuit, and drives the infrared emission tube by the constant current driving circuit.
Referring to fig. 10, a communication protocol for driving the three-stage cascade system shown in fig. 9 is shown. After the three-stage cascade system is powered on and reset, an input signal received by a logic control circuit in the chip 1 sequentially comprises a 3-x starting signal, a first group of effective data, a second group of effective data, a third group of effective data and a 3-x ending signal. The input signal received by chip 2 from chip 1 includes, in order, a 2 x start signal, a second set of valid data, a third set of valid data, and a 2 x end signal. The input signal received by chip 3 from chip 2 comprises in sequence a start signal, a third set of valid data, and a stop signal. After the driving method of this embodiment, the latch of the chip 1 holds the first set of valid data, the latch of the chip 2 holds the second set of valid data, and the latch of the chip 3 holds the third set of valid data. The three sets of valid data can drive the respective infrared transmitting tubes simultaneously. At this time, even if the external main control MCU does not input effective data any more, each stage of latch can also store respective driving data, so that the constant driving current of the infrared emission tube is ensured.
The present invention has been described in detail with reference to the embodiments of the drawings, and those skilled in the art can make various modifications to the invention based on the above description. Accordingly, certain details of the embodiments are not to be interpreted as limiting the invention, which is defined by the appended claims.
Claims (10)
1. The infrared emission chip with the constant current drive comprises a constant current drive circuit and an infrared emission tube which are connected with each other, and is characterized by further comprising:
a main input;
a main output terminal;
the signal input end of the logic control circuit is connected with the main input end;
the signal input end and the control end of the latch are respectively connected with the signal output end of the logic control circuit, and the signal output end of the latch is connected with the infrared emission tube through the constant current driving circuit;
and the signal input end of the waveform shaping circuit is connected with the signal output end of the logic control circuit, and the signal output end of the waveform shaping circuit is connected with the main output end.
2. The infrared emitting chip with constant current drive according to claim 1, wherein the infrared emitting chip with constant current drive further comprises:
and the output end of the oscillating circuit is connected with the clock end of the logic control circuit.
3. The infrared emitting chip with constant current drive according to claim 1, wherein the constant current drive circuit comprises:
the driving switch groups comprise driving switches and driving resistors which are connected in series, the control end of each driving switch is respectively connected with the signal output end of the latch, and each driving switch group is connected in parallel;
the base electrode of the first PNP triode is connected with the power supply end through a first resistor for driving and grounded through a second resistor for driving, and the collector electrode of the first PNP triode is grounded;
the base electrode of the second NPN triode is connected with a power supply end through a third driving resistor, the base electrode of the second NPN triode is connected with the emitter electrode of the first PNP triode through a fourth driving resistor, and the collector electrode of the second NPN triode is connected with the power supply end through the infrared emission tube;
and the base electrode of the third NPN triode is connected with the emitter electrode of the first PNP triode, the collector electrode of the third NPN triode is connected with the emitter electrode of the second NPN triode, and the emitter electrode of the third NPN triode is grounded through the driving switch.
4. The infrared emission chip with constant current drive as claimed in claim 3, wherein the drive switch is a first field effect transistor, a gate of the first field effect transistor is connected to a signal output end of the latch, a drain of the first field effect transistor is connected to an emitter of the third NPN triode through the drive resistor, and a source of the first field effect transistor is grounded.
5. The infrared emitting chip with constant current drive according to claim 1, wherein the waveform shaping circuit comprises:
the source electrode of the second field effect tube is connected with the signal output end of the logic control circuit, the grid electrode of the second field effect tube is connected with the power supply end through a first resistor for shaping driving, and the drain electrode of the second field effect tube is connected with the main output end;
the main output end is connected with a power supply end through a second resistor for driving.
6. A driving method of the infrared emission chip with constant current drive according to any one of claims 1 to 5, characterized by comprising:
the logic control circuit receives an input signal through a main input end and judges the input signal;
when the input signal is a start signal and a plurality of input signals after the start signal are effective data, the logic control circuit sends a first group of effective data after the start signal into a latch one by one to be stored;
when the input signal is a termination signal, the logic control circuit finishes the transmission of the effective data, and the logic control circuit drives the latch to send the saved effective data to the constant current driving circuit, and the constant current driving circuit drives the infrared emission tube.
7. The infrared emission chip cascade system with the constant current drive is characterized by comprising:
a plurality of infrared emission chips, wherein the infrared emission chips are the infrared emission chips with constant current drive according to any one of claims 1 to 5, and the plurality of infrared emission chips are sequentially connected through a main input end and a main output end to form a cascade system;
the main input end of the infrared emission chip positioned at the first stage is used as a total input end and is connected with the signal output end of the external main control.
8. A driving method of the infrared emission chip cascade system with constant current driving according to claim 7, characterized in that the driving method comprises:
a logic control circuit in any one level of infrared emission chip receives an input signal through a main input end and judges the input signal;
when the input signal is an initial signal and a plurality of input signals after the initial signal are still initial signals, the logic control circuit outputs the initial signals after the initial signal to the next-stage infrared emission chip through a main output end by a waveform shaping circuit;
when the input signal is a start signal and a plurality of input signals after the start signal are effective data, the logic control circuit sends a first group of effective data after the start signal into a latch one by one to be stored, and the logic control circuit outputs other effective data except the first group of effective data to a next-stage infrared emission chip through a main output end by a waveform shaping circuit;
when the input signals are termination signals, the logic control circuit finishes the transmission of the effective data, if a plurality of input signals after the termination signals are still termination signals, the logic control circuit outputs the termination signals after the termination signals to the next-stage infrared emission chip through the main output end by the waveform shaping circuit, and the logic control circuit drives the latch to send the saved effective data to the constant current driving circuit, and drives the infrared emission tube by the constant current driving circuit.
9. The driving method as claimed in claim 8, wherein the number of start signals, the number of end signals, and the number of groups of valid data received at the main input terminal of the infrared emitting chip at the first stage are all k times, and k is the number of infrared emitting chips in the cascade system.
10. The driving method of claim 8, wherein the start signal is a low level of more than 20 us;
the termination signal is at a low level greater than 20us, the termination signal being of a different duration than the initiation signal;
the 0 code and the 1 code of the effective data are represented by high and low levels with different time duty ratios in a preset period.
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| CN203661025U (en) * | 2013-12-06 | 2014-06-18 | Tcl通力电子（惠州）有限公司 | Infrared emission tube regulating circuit and touch screen device |
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