Rail-to-rail output control guide circuit

Abstract

This invention provides a rail-to-rail output control and guidance circuit, comprising a constant current generation module and a control and guidance module. The constant current generation module generates an adjustable constant drive current; the control and guidance module receives a PWM control signal and generates a PWM control guidance signal based on the PWM control signal and the constant drive current. By using the constant current generation module and the control and guidance module, this invention eliminates the voltage difference between the output voltage and the input voltage. Simultaneously, the controllable output current effectively avoids excessive power consumption or heat generation, thus improving the working efficiency of the control and guidance circuit.

Description

Technical Field

[0001] This invention relates to the field of circuits, and in particular to a control and guidance circuit for rail-to-rail output. Background Technology

[0002] The control and guidance PWM signal output generally uses a push-pull circuit. The specific push-pull circuit structure is as follows: Figure 1 As shown, Figure 1 In the push-pull circuit with an upper N-type and lower P-type transistor, the output voltage amplitude of the NPN transistor's emitter is 0.7V lower than the input voltage amplitude of its base. Furthermore, there is a risk that both the upper and lower transistors may conduct simultaneously during input voltage signal switching. Additionally, when the input signal voltage is low, if the output current of the push-pull circuit is too large, the power consumption and heat generation on the NPN transistor will increase. Therefore, the existing control and guidance circuits have relatively low operating efficiency.

[0003] Therefore, a rail-to-rail output control and guidance circuit is needed to solve the above-mentioned technical problems. Summary of the Invention

[0004] This invention provides a rail-to-rail output control and guidance circuit that is free from pressure differential and highly efficient, thereby solving the technical problem of low operating efficiency in existing rail-to-rail output control and guidance circuits.

[0005] This invention provides a control and guidance circuit for rail-to-rail output, comprising:

[0006] A constant current generation module is used to generate an adjustable constant drive current; and

[0007] The control guidance module is used to receive the PWM control signal and generate the PWM control guidance signal based on the PWM control signal and the constant drive current.

[0008] In the rail-to-rail output control and guidance circuit of the present invention, the control and guidance circuit further includes:

[0009] A buffer module is used to buffer the PWM control guide signal.

[0010] In the rail-to-rail output control and guidance circuit of the present invention, the constant current generation module includes a first PMOS transistor, a second PMOS transistor, and an adjustment resistor R1. The gate of the first PMOS transistor is connected to the gate of the second PMOS transistor and the first terminal of the adjustment resistor R1, respectively. The source of the first PMOS transistor is connected to the source of the second PMOS transistor and the power supply VCC, respectively. The drain of the first PMOS transistor is connected to the first terminal of the adjustment resistor R1, and the second terminal of the adjustment resistor R1 is grounded. The drain of the second PMOS transistor outputs the constant drive current.

[0011] In the rail-to-rail output control and guidance circuit of the present invention, the constant current generation module includes a first PNP transistor, a second PNP transistor, and an adjustment resistor R2. The base of the first PNP transistor is connected to the base of the second PNP transistor and the first end of the adjustment resistor R2, respectively. The emitter of the first PNP transistor is connected to the emitter of the second PNP transistor and the power supply VCC, respectively. The collector of the first PNP transistor is connected to the first end of the adjustment resistor R2, and the second end of the adjustment resistor R2 is grounded. The collector of the second PNP transistor outputs the constant drive current.

[0012] In the rail-to-rail output control and guidance circuit of the present invention, the control and guidance module includes a switching transistor. The control terminal of the switching transistor receives the PWM control signal. The input terminal of the switching transistor is connected to the output terminal of the constant current generation module, and the output terminal of the switching transistor is grounded.

[0013] In the rail-to-rail output control and guidance circuit of the present invention, the control and guidance circuit further includes a grounding resistor R3. The first end of the grounding resistor R3 is connected to the output end of the constant current generating module, and the second end of the grounding resistor R3 is grounded.

[0014] In the rail-to-rail output control and guidance circuit of the present invention, the buffer module includes a third PMOS transistor and a fourth NMOS transistor. The source of the third PMOS transistor is connected to the output of the constant current generation module, and the gate of the third PMOS transistor is connected to the gate of the fourth NMOS transistor and the first terminal of the blocking resistor R4. The drain of the third PMOS transistor outputs a high-level signal of the PWM control guidance signal. The second terminal of the blocking resistor R4 is grounded. The source of the fourth NMOS transistor is connected to the output of the constant current generation module, and the drain of the fourth NMOS transistor outputs a low-level signal of the PWM control guidance signal.

[0015] In the rail-to-rail output control and guidance circuit of the present invention, the control and guidance circuit further includes a grounding resistor R5, the first end of the grounding resistor R5 is connected to the output of the constant current generating module, and the second end of the grounding resistor R5 is grounded.

[0016] In the rail-to-rail output control and guidance circuit of the present invention, the control and guidance circuit further includes a grounding resistor R6, the first end of the grounding resistor R6 is connected to the output of the buffer module, and the second end of the grounding resistor R6 is grounded.

[0017] In the rail-to-rail output control and guidance circuit of the present invention, the control and guidance circuit includes:

[0018] A comparison module is used to generate the PWM control signal based on the reference voltage and the input voltage.

[0019] Compared with the prior art, the beneficial effects of this invention are as follows: This invention provides a control and guidance circuit for rail-to-rail output, which, through the setting of a constant current generation module and a control and guidance module, can eliminate the voltage difference between the output voltage and the input voltage. At the same time, the output current is controllable, which can effectively avoid excessive power consumption or heat generation, thereby improving the working efficiency of the control and guidance circuit. It effectively solves the technical problem of low working efficiency of existing rail-to-rail output control and guidance circuits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an existing push-pull circuit structure;

[0021] Figure 2 This is a schematic diagram of an embodiment of the rail-to-rail output control and guidance circuit of the present invention;

[0022] Figure 3 This is a schematic diagram of a first embodiment of the rail-to-rail output control and guidance circuit of the present invention;

[0023] Figure 4 This is a schematic diagram of a second embodiment of the control and guidance circuit for rail-to-rail output of the present invention;

[0024] Figure 5 This is a schematic diagram of the structure of a third embodiment of the rail-to-rail output control and guidance circuit of the present invention;

[0025] Figure 6 This is a schematic diagram of the fourth embodiment of the rail-to-rail output control and guidance circuit of the present invention;

[0026] Figure 7 This is a schematic diagram of the fifth embodiment of the rail-to-rail output control and guidance circuit of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the diagram, units with similar structures are represented by the same labels.

[0029] The control and guidance circuit of this invention can be used in various charging drive circuits. Since there is no voltage difference between the output voltage and the input voltage, it can achieve efficient rail-to-rail output and improve the working efficiency of the control and guidance circuit.

[0030] Please refer to Figure 2 , Figure 2 This is a schematic diagram of an embodiment of the rail-to-rail output control and guidance circuit of the present invention. The control and guidance circuit 10 of the present invention includes a constant current generation module 11, a control and guidance module 12, and a buffer module 13. The constant current generation module 11 is used to generate an adjustable constant drive current; the control and guidance module 12 is used to receive a PWM control signal and generate a PWM control and guidance signal based on the PWM control signal and the constant drive current; the buffer module 13 is used to buffer the PWM control and guidance signal to avoid generating a large current signal (the large current generated when the drive voltage is directly applied to an external small load).

[0031] This invention eliminates the voltage difference between the output and input voltages through the constant current generation module 11 and the control guidance module 12, and allows for controllable output current, preventing excessive power consumption or heat generation of the switching transistor and improving the efficiency of the control guidance circuit. Simultaneously, the buffer module 13 buffers the output current, preventing large current signals generated when no output load is connected. Of course, the buffer module 13 can be selected and configured according to customer needs.

[0032] Please refer to Figure 3 , Figure 3 This is a schematic diagram of a first embodiment of the rail-to-rail output control and guidance circuit of the present invention. The control and guidance circuit 30 in this embodiment includes a constant current generation module 31, a control and guidance module 32, and a grounding resistor R3. The constant current generation module 31 includes a first PMOS transistor Q1, a second PMOS transistor Q2, and an adjustment resistor R1. The gate of the first PMOS transistor Q1 is connected to the gate of the second PMOS transistor Q2 and the first terminal of the adjustment resistor R1, respectively. The source of the first PMOS transistor Q1 is connected to the source of the second PMOS transistor Q2 and the power supply VCC, respectively. The drain of the first PMOS transistor Q1 is connected to the first terminal of the adjustment resistor R1, and the second terminal of the adjustment resistor R1 is grounded. The drain of the second PMOS transistor Q2 outputs a constant drive current.

[0033] The control guidance module 32 includes a switching transistor Q3. The control terminal of the switching transistor Q3 receives a PWM control signal, the output terminal of the switching transistor is connected to the output terminal of the constant current generation module, and the output terminal of the switching transistor is grounded.

[0034] The first end of the grounding resistor R3 is connected to the output terminal of the constant current generating module, and the second end of the grounding resistor R3 is grounded so as to provide a grounded load when the charging circuit is not in use.

[0035] In this embodiment, to ensure the output is unaffected by the operating states of the switching transistors (first and second PMOS transistors), a constant current generation module outputs a constant drive current. The gate voltage of the second PMOS transistor is determined by the fixed gate-source voltage drop of the first PMOS transistor, the adjusting resistor R1, and the voltage value of the power supply VCC. That is, once the adjusting resistor R1 and the power supply VCC are determined, the drain output current of the second PMOS transistor will not change with its operating state (such as amplification factor). Therefore, given a fixed power supply VCC voltage, the constant drive current output by the constant current generation module can be determined by adjusting the adjusting resistor R1. Thus, when the switching transistor Q3 is off, the control circuit can output a constant drive current unaffected by the voltage drop within the second PMOS transistor.

[0036] In this embodiment, the switching transistor Q3 is an NMOS transistor. When the control terminal (gate) of the switching transistor Q3 receives a high-level signal, the input terminal (drain) and output terminal (source) of the switching transistor Q3 are turned on. At this time, the drain output of the second PMOS transistor is directly grounded, and the control guidance circuit outputs a low-level signal. When the control terminal of the switching transistor Q3 receives a low-level signal, the input terminal and output terminal of the switching transistor Q3 are turned off. At this time, the drain of the second PMOS transistor is connected to the output terminal of the control guidance circuit and outputs a high-level signal. Therefore, when the control terminal of the switching transistor Q3 receives a PWM control signal, the output terminal of the control guidance circuit will output a constant drive current generated by the constant current generation module based on the low-level signal interval of the PWM control signal.

[0037] Please refer to Figure 4 , Figure 4 This is a schematic diagram of a second embodiment of the control and guidance circuit for rail-to-rail output of the present invention. In this embodiment, the control and guidance circuit 40 includes a constant current generation module 41, a control and guidance module 42, and a grounding resistor R3.

[0038] The difference between this embodiment and Embodiment 1 of the control and guidance circuit is that the constant current generating module 41 in this embodiment includes a first PNP transistor Q4, a second PNP transistor Q5, and an adjusting resistor R2. The base of the first PNP transistor Q4 is connected to the base of the second PNP transistor Q5 and the first end of the adjusting resistor R2, respectively; the emitter of the first PNP transistor Q4 is connected to the emitter of the second PNP transistor Q5 and the power supply VCC, respectively; the collector of the first PNP transistor Q4 is connected to the first end of the adjusting resistor R2, and the second end of the adjusting resistor R2 is grounded; the collector of the second PNP transistor Q5 outputs the constant drive current.

[0039] In this embodiment, when the control and guidance circuit 40 is used, to ensure that the output voltage is not affected by the operating state of the switching transistors (first PNP transistor Q4 and second PNP transistor Q5), the constant current generation module 41 outputs a constant drive current. The base voltage of the second PNP transistor Q5 is determined by the fixed base-emitter voltage drop of the first PNP transistor Q4, the adjusting resistor R2, and the voltage value of the power supply VCC. That is, once the adjusting resistor R2 and the voltage value of the power supply VCC are determined, the collector output current of the second PNP transistor Q5 will not change with the operating state of the second PNP transistor Q5 (such as the amplification factor). Therefore, under the condition that the voltage value of the power supply VCC is determined, the constant drive current output by the constant current generation module can be determined by adjusting the value of the adjusting resistor R2.

[0040] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the structure of a third embodiment of the rail-to-rail output control and guidance circuit of the present invention. The control and guidance circuit 50 in this embodiment includes a constant current generation module 51, a control and guidance module 52, a buffer module 53, and a grounding resistor R5.

[0041] The constant current generation module 51 and the control and guidance module 52 are completely identical in structure and working principle to the constant current generation module 31 and the control and guidance module 32 in Embodiment 1.

[0042] The first end of the grounding resistor R5 is connected to the output terminal of the constant current generating module 51, and the second end of the grounding resistor R5 is grounded.

[0043] This embodiment, based on the first embodiment of the control and guidance circuit, also includes a buffer module 53. The buffer module 53 buffers the PWM control and guidance signal to prevent the drive voltage or drive current from being directly applied to the external load (current following), thereby meeting the user's various external load usage needs.

[0044] The buffer module 53 includes a third PMOS transistor Q6, a fourth NMOS transistor Q7, and an isolation resistor R4. The source of the third PMOS transistor Q6 is connected to the output of the constant current generation module 51. The gate of the third PMOS transistor Q6 is connected to the gate of the fourth NMOS transistor Q7 and the first end of the isolation resistor R4. The drain of the third PMOS transistor Q6 outputs a high-level signal of the PWM control guide signal. The second end of the isolation resistor R4 is grounded to isolate some fluctuation interference at the ground terminal. The source of the fourth NMOS transistor Q7 is connected to the output of the constant current generation module. The drain of the fourth NMOS transistor Q7 outputs a low-level signal of the PWM control guide signal.

[0045] To reduce losses, the third PMOS transistor Q6 and the fourth NMOS transistor Q7 can be selected as switching transistors with low on-resistance. Of course, the third PMOS transistor Q6 and the fourth NMOS transistor Q7 can also be corresponding types of transistors.

[0046] When the PWM control guidance signal output by the control guidance module 52 is a high-level signal (e.g., +12V), the gate voltage of the third PMOS transistor Q6 is lower than the source voltage of the third PMOS transistor Q6, so the third PMOS transistor Q6 is turned on, and the drain of the third PMOS transistor Q6 outputs a high-level signal of the PWM control guidance signal. At this time, the gates of the third PMOS transistor Q6 and the fourth NMOS transistor Q7 are both low-level relative to the PWM control guidance signal, so the fourth NMOS transistor Q7 is turned off.

[0047] When the PWM control guidance signal output by the control guidance module 52 is a low-level signal (e.g., -12V), the gate voltage of the fourth NMOS transistor Q7 is higher than the source voltage of the fourth NMOS transistor Q7, so the fourth NMOS transistor Q7 is turned on, and the drain of the fourth NMOS transistor Q7 outputs a low-level signal of the PWM control guidance signal. The gates of the third PMOS transistor Q6 and the fourth NMOS transistor Q7 are both high-level relative to the PWM control guidance signal, so the third PMOS transistor Q6 is turned off.

[0048] The buffer module 53 provides a buffering operation to interrupt the constant drive current. This is achieved through the internal resistance of the third PMOS transistor Q6 and the fourth NMOS transistor Q7, which acts as a current follower, preventing a large constant drive current from being directly applied to the external load. Thus, when the PWM control pilot signal is high, the buffer module 53 can be used as an active load, achieving current following and avoiding the large current generated at the moment of turn-on.

[0049] Please refer to Figure 6 , Figure 6 This is a schematic diagram of the fourth embodiment of the control and guidance circuit for rail-to-rail output of the present invention. The control and guidance circuit 60 in this embodiment includes a constant current generation module 61, a control and guidance module 62, a buffer module 63, and a grounding resistor R6.

[0050] The constant current generation module 61 and the control and guidance module 62 are exactly the same in structure and working principle as the constant current generation module 51 and the control and guidance module 52 in Embodiment 3.

[0051] In this embodiment, the first end of the grounding resistor R6 is connected to the output of the buffer module 63, and the second end of the grounding resistor R6 is grounded.

[0052] In this embodiment, the grounding resistor R6 is set at the drain terminals of the third PMOS transistor Q6 and the fourth NMOS transistor Q7. In this way, the gate, drain, and source of the third PMOS transistor Q6 and the fourth NMOS transistor Q7 are all directly or indirectly grounded, and there is no phenomenon of the pins of the switching transistors being floating. This avoids the problem that the switching transistors are easily affected by external interference or high-frequency radiation during operation.

[0053] Please refer to Figure 7 , Figure 7 This is a schematic diagram of the fifth embodiment of the control and guidance circuit for rail-to-rail output of the present invention. The control and guidance circuit 70 of this embodiment includes a constant current generation module 71, a control and guidance module 72, a buffer module 73, and a comparison module 74.

[0054] The constant current generation module 71, control and guidance module 72, and buffer module 73 are completely identical in structure and working principle to the constant current generation module 51, control and guidance module 52, and buffer module 53 in Embodiment 3.

[0055] Based on Embodiment 3, the control guidance circuit 70 of this embodiment further includes a comparison module 71, which is used to generate a PWM control signal based on the reference voltage and the input voltage.

[0056] Specifically, the negative input terminal of the comparison module 74 receives the reference voltage REF, the positive input terminal receives the input voltage VI N, and the output terminal of the comparison module 74 outputs a PWM control signal. Specifically, it can be configured so that when the input voltage VI N is greater than or equal to the reference voltage REF, the output terminal outputs a high-level PWM control signal; and when the input voltage VI N is less than the reference voltage REF, the output terminal outputs a low-level PWM control signal.

[0057] The configuration of the comparison module 74 can effectively avoid the high-level signal fluctuation of the PWM control signal caused by the positive fluctuation of the input voltage, thereby outputting a stable PWM control signal.

[0058] The rail-to-rail output control and guidance circuit of the present invention does not have high requirements for the slew rate of the input PWM control signal. It can output rail-to-rail PWM control and guidance signals without considering the voltage difference inside the switching transistor. The load capacity can also be controlled by adjusting the constant drive current generated by the constant current generation module. It has strong driving capability and low cost.

[0059] The rail-to-rail output control and guidance circuit of the present invention can use common power supplies on the market, such as 12V units, without the need to customize uncommon power supplies based on the output voltage, such as 12.7V power supplies.

[0060] By setting up a comparison module, the requirements for the input voltage (drive signal) are reduced, which effectively avoids oscillation of the PWM control signal and simplifies the implementation.

[0061] This invention provides a rail-to-rail output control and guidance circuit. By setting up a constant current generation module and a control and guidance module, it can eliminate the voltage difference between the output voltage and the input voltage. At the same time, the output current is controllable, which can effectively avoid excessive power consumption or heat generation and improve the working efficiency of the control and guidance circuit. It effectively solves the technical problem of low working efficiency of existing rail-to-rail output control and guidance circuits.

[0062] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A rail-to-rail output control and guidance circuit, characterized in that, include: A constant current generation module is used to generate an adjustable constant drive current; as well as A control guidance module is used to receive a PWM control signal and generate a PWM control guidance signal based on the PWM control signal and the constant drive current. The control guidance circuit also includes: A buffer module is used to buffer the PWM control guide signal; The constant current generation module includes a first PMOS transistor, a second PMOS transistor, and an adjustment resistor R1. The gate of the first PMOS transistor is connected to the gate of the second PMOS transistor and the first terminal of the adjustment resistor R1. The source of the first PMOS transistor is connected to the source of the second PMOS transistor and the power supply VCC. The drain of the first PMOS transistor is connected to the first terminal of the adjustment resistor R1, and the second terminal of the adjustment resistor R1 is grounded. The drain of the second PMOS transistor outputs the constant drive current; or The constant current generation module includes a first PNP transistor, a second PNP transistor, and an adjustment resistor R2. The base of the first PNP transistor is connected to the base of the second PNP transistor and the first terminal of the adjustment resistor R2. The emitter of the first PNP transistor is connected to the emitter of the second PNP transistor and the power supply VCC. The collector of the first PNP transistor is connected to the first terminal of the adjustment resistor R2, and the second terminal of the adjustment resistor R2 is grounded. The collector of the second PNP transistor outputs the constant drive current.

2. The control and guidance circuit for rail-to-rail output according to claim 1, characterized in that, The control guidance module includes a switching transistor. The control terminal of the switching transistor receives the PWM control signal. The input terminal of the switching transistor is connected to the output terminal of the constant current generation module, and the output terminal of the switching transistor is grounded.

3. The control and guidance circuit for rail-to-rail output according to claim 2, characterized in that, The control guidance circuit also includes a grounding resistor R3, the first end of which is connected to the output terminal of the constant current generating module, and the second end of which is grounded.

4. The control and guidance circuit for rail-to-rail output according to claim 1, characterized in that, The buffer module includes a third PMOS transistor and a fourth NMOS transistor. The source of the third PMOS transistor is connected to the output of the constant current generation module. The gate of the third PMOS transistor is connected to the gate of the fourth NMOS transistor and the first terminal of the blocking resistor R4. The drain of the third PMOS transistor outputs a high-level signal of the PWM control guide signal. The second terminal of the blocking resistor R4 is grounded. The source of the fourth NMOS transistor is connected to the output of the constant current generation module. The drain of the fourth NMOS transistor outputs a low-level signal of the PWM control guide signal.

5. The control and guidance circuit for rail-to-rail output according to claim 4, characterized in that, The control guidance circuit also includes a grounding resistor R5, the first end of which is connected to the output of the constant current generating module, and the second end of which is grounded.

6. The control and guidance circuit for rail-to-rail output according to claim 4, characterized in that, The control guidance circuit also includes a grounding resistor R6, the first end of which is connected to the output of the buffer module, and the second end of which is grounded.

7. The control and guidance circuit for rail-to-rail output according to claim 1, characterized in that, The control guidance circuit includes: A comparison module is used to generate the PWM control signal based on the reference voltage and the input voltage.

Images