阅读说明：本技术 一种基于uc1843的可编程恒流源系统 (UC 1843-based programmable constant current source system ) 是由 杜建华 彭政 晏杰 周世安 赵兰 李荷丹 荣志民 王立伟 郭乐乐 于 2021-08-04 设计创作，主要内容包括：本发明公开了一种基于UC1843的可编程恒流源系统,包括：基准信号调理电路,用于对基准电流信号进行调理,输出与基准电流信号线性关系的第一信号；UC1843控制电路,用于接收基准信号调理电路输出的第一信号和输出电流采样电路输出的第二信号；根据第一信号和第二信号进行逻辑处理,输出脉宽调制信号；恒流源主电路,用于接收UC1843控制电路输出的脉宽调制信号,根据脉宽调制信号对输入电压进行隔离变换,输出恒定电流；输出电流采样电路,用于对恒流源主电路输出的恒定电流进行采样、调理,输出与恒定电流线性关系的第二信号。本发明解决了现有编程恒流源效率低、线路复杂的问题。(The invention discloses a UC 1843-based programmable constant current source system, which comprises: the reference signal conditioning circuit is used for conditioning the reference current signal and outputting a first signal in linear relation with the reference current signal; the UC1843 control circuit is used for receiving a first signal output by the reference signal conditioning circuit and a second signal output by the output current sampling circuit; performing logic processing according to the first signal and the second signal, and outputting a pulse width modulation signal; the constant current source main circuit is used for receiving the pulse width modulation signal output by the UC1843 control circuit, carrying out isolation transformation on input voltage according to the pulse width modulation signal and outputting constant current; and the output current sampling circuit is used for sampling and conditioning the constant current output by the constant current source main circuit and outputting a second signal linearly related to the constant current. The invention solves the problems of low efficiency and complex circuit of the existing programming constant current source.)

1. A UC 1843-based programmable constant current source system, comprising:

the reference signal conditioning circuit is used for conditioning the reference current signal and outputting a first signal in linear relation with the reference current signal;

the UC1843 control circuit is used for receiving a first signal output by the reference signal conditioning circuit and a second signal output by the output current sampling circuit; performing logic processing according to the first signal and the second signal, and outputting a pulse width modulation signal;

the constant current source main circuit is used for receiving the pulse width modulation signal output by the UC1843 control circuit, carrying out isolation transformation on input voltage according to the pulse width modulation signal and outputting constant current;

and the output current sampling circuit is used for sampling and conditioning the constant current output by the constant current source main circuit and outputting a second signal linearly related to the constant current.

2. The UC 1843-based programmable constant current source system according to claim 1, wherein UC1843 control circuit comprises: the control chip UC1843, the resistor R5, the resistor R6, the resistor R7, the capacitor C5, the capacitor C6, the capacitor C7 and the capacitor C8; the UC1843 of the control chip is provided with a Vref end, a Vcc end, an RT end, an Out end, a Vfb end, a Cs end, a Comp end, a PGnd end and a Gnd end;

the PGnd end and the Gnd end of the control chip UC1843 are grounded;

two ends of the capacitor C7 are respectively connected with a Vfb end and a Comp end of the control chip UC 1843;

the capacitor C8 is connected with the resistor R7 in series and then connected with the capacitor C7 in parallel;

two ends of the resistor R6 are respectively connected with a Vref end and an RT end of the control chip UC 1843;

two ends of the capacitor C6 are respectively connected with the RT end of the control chip UC1843 and the ground;

two ends of the capacitor C5 are respectively connected with the Cs end of the control chip UC1843 and the ground;

one end of the resistor R5 is connected to the Out end of the control chip UC 1843.

3. The UC 1843-based programmable constant current source system according to claim 2, wherein the constant current source main circuit comprises: a transformer T2, a MOS tube V1, a capacitor C1 and a diode D1; the transformer T2 is provided with four pins;

the drain electrode of the MOS transistor V1 is connected with the second pin of the transformer T2;

the anode of the diode D1 is connected to the third pin of the transformer T2, the cathode of the diode D1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the fourth pin of the transformer T2.

4. The UC 1843-based programmable constant current source system according to claim 3, wherein the output current sampling circuit comprises: the circuit comprises a resistor R1, a resistor R16, a resistor R17, a resistor R18, a resistor R19, an operational amplifier Q3 and a resistor R8;

one end of the resistor R1 is connected with the reverse input end of the operational amplifier Q3 after being connected with the resistor R16 in series, and the other end of the resistor R1 is connected with the forward input end of the operational amplifier Q3 after being connected with the resistor R18 in series;

two ends of the resistor R8 are respectively connected with the output end of the operational amplifier Q3 and the Vfb end of the control chip UC 1843;

the two ends of the resistor R17 are respectively connected with the resistor R16 and the resistor R8;

the two ends of the resistor R19 are respectively connected with the resistor R18 and the ground.

5. The UC 1843-based programmable constant current source system according to claim 4, wherein the reference signal conditioning circuit comprises: the circuit comprises a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14 and an operational amplifier Q4;

two ends of the resistor R9 are respectively connected with the Vfb end of the control chip UC1843 and the ground;

two ends of the resistor R10 are respectively connected with the output end of the operational amplifier Q4 and the Vfb end of the control chip UC 1843;

two ends of the resistor R11 are respectively connected with the reverse input end of the operational amplifier Q4 and the output end of the operational amplifier Q4;

two ends of the resistor R12 are respectively connected with the reference current signal V _ ZL and the reverse input end of the operational amplifier Q4;

two ends of the resistor R13 are respectively connected with a Vref end of the control chip UC1843 and a positive input end of the operational amplifier Q4;

the two ends of the resistor R14 are respectively connected with the resistor R13 and the ground.

6. The UC 1843-based programmable constant current source system as claimed in claim 4, wherein the resistor R1 of the output current sampling circuit is connected in series with the output ground of the constant current source main circuit, so as to sample the constant current output by the constant current source main circuit, and amplify the sampled signal through the operational amplifier Q3, and output the second signal in linear relation with the constant current to the Vfb terminal of the control chip UC1843 through the resistor R8.

7. The UC 1843-based programmable constant current source system according to claim 3, wherein the UC1843 outputs the pulse width modulation signal PWM according to the amplitude of the feedback signal after the logic processing of the first signal and the second signal; the pulse width modulation signal PWM is used for driving a MOS transistor V1 in the constant current source main circuit.

8. The UC 1843-based programmable constant current source system of claim 7, wherein the feedback signal is in negative correlation with the pulse width modulation signal PWM, and the output current sampling circuit implements amplitude adjustment of the constant current outputted by the constant current source main circuit through the feedback signal.

9. The UC 1843-based programmable constant current source system according to claim 8, wherein the feedback signal comprises: and outputting information of the current and the reference current signals.

Technical Field

The invention belongs to the technical field of programmable constant current sources, and particularly relates to a UC 1843-based programmable constant current source system.

Background

The programmable constant current source is as follows: and linearly adjusting the amplitude of the output current according to the reference current signal. At present, the common constant current source is mostly in a linear working mode, and the efficiency is low. In the programmable constant current source, the generation of the direct current constant current source is realized by adopting a programming method of a microcontroller, the circuit is complex, and the reliability is low.

Disclosure of Invention

The technical problem of the invention is solved: the defects of the prior art are overcome, the UC 1843-based programmable constant current source system is provided, and the problems of low efficiency and complex circuit of the conventional programmable constant current source are solved.

In order to solve the technical problem, the invention discloses a UC 1843-based programmable constant current source system, which comprises:

the reference signal conditioning circuit is used for conditioning the reference current signal and outputting a first signal in linear relation with the reference current signal;

the UC1843 control circuit is used for receiving a first signal output by the reference signal conditioning circuit and a second signal output by the output current sampling circuit; performing logic processing according to the first signal and the second signal, and outputting a pulse width modulation signal;

the constant current source main circuit is used for receiving the pulse width modulation signal output by the UC1843 control circuit, carrying out isolation transformation on input voltage according to the pulse width modulation signal and outputting constant current;

and the output current sampling circuit is used for sampling and conditioning the constant current output by the constant current source main circuit and outputting a second signal linearly related to the constant current.

In the UC 1843-based programmable constant current source system, the UC1843 control circuit includes: the control chip UC1843, the resistor R5, the resistor R6, the resistor R7, the capacitor C5, the capacitor C6, the capacitor C7 and the capacitor C8; the UC1843 of the control chip is provided with a Vref end, a Vcc end, an RT end, an Out end, a Vfb end, a Cs end, a Comp end, a PGnd end and a Gnd end;

the PGnd end and the Gnd end of the control chip UC1843 are grounded;

two ends of the capacitor C7 are respectively connected with a Vfb end and a Comp end of the control chip UC 1843;

the capacitor C8 is connected with the resistor R7 in series and then connected with the capacitor C7 in parallel;

two ends of the resistor R6 are respectively connected with a Vref end and an RT end of the control chip UC 1843;

two ends of the capacitor C6 are respectively connected with the RT end of the control chip UC1843 and the ground;

two ends of the capacitor C5 are respectively connected with the Cs end of the control chip UC1843 and the ground;

one end of the resistor R5 is connected to the Out end of the control chip UC 1843.

In the UC 1843-based programmable constant current source system, the constant current source main circuit includes: a transformer T2, a MOS tube V1, a capacitor C1 and a diode D1; the transformer T2 is provided with four pins;

the drain electrode of the MOS transistor V1 is connected with the second pin of the transformer T2;

the anode of the diode D1 is connected to the third pin of the transformer T2, the cathode of the diode D1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the fourth pin of the transformer T2.

In the UC 1843-based programmable constant current source system, the output current sampling circuit includes: the circuit comprises a resistor R1, a resistor R16, a resistor R17, a resistor R18, a resistor R19, an operational amplifier Q3 and a resistor R8;

one end of the resistor R1 is connected with the reverse input end of the operational amplifier Q3 after being connected with the resistor R16 in series, and the other end of the resistor R1 is connected with the forward input end of the operational amplifier Q3 after being connected with the resistor R18 in series;

two ends of the resistor R8 are respectively connected with the output end of the operational amplifier Q3 and the Vfb end of the control chip UC 1843;

the two ends of the resistor R17 are respectively connected with the resistor R16 and the resistor R8;

the two ends of the resistor R19 are respectively connected with the resistor R18 and the ground.

In the UC 1843-based programmable constant current source system, the reference signal conditioning circuit includes: the circuit comprises a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14 and an operational amplifier Q4;

two ends of the resistor R9 are respectively connected with the Vfb end of the control chip UC1843 and the ground;

two ends of the resistor R10 are respectively connected with the output end of the operational amplifier Q4 and the Vfb end of the control chip UC 1843;

two ends of the resistor R11 are respectively connected with the reverse input end of the operational amplifier Q4 and the output end of the operational amplifier Q4;

two ends of the resistor R12 are respectively connected with the reference current signal V _ ZL and the reverse input end of the operational amplifier Q4;

two ends of the resistor R13 are respectively connected with a Vref end of the control chip UC1843 and a positive input end of the operational amplifier Q4;

the two ends of the resistor R14 are respectively connected with the resistor R13 and the ground.

In the programmable constant current source system based on UC1843, the resistor R1 of the output current sampling circuit is connected in series to the output ground of the constant current source main circuit, so as to sample the constant current output by the constant current source main circuit, amplify the sampled signal by the operational amplifier Q3, and output the second signal linearly related to the constant current to the Vfb end of the control chip UC1843 by the resistor R8.

In the programmable constant current source system based on UC1843, the control chip UC1843 outputs a pulse width modulation signal PWM according to the amplitude of the feedback signal after the logic processing of the first signal and the second signal; the pulse width modulation signal PWM is used for driving a MOS transistor V1 in the constant current source main circuit.

In the programmable constant current source system based on UC1843, the feedback signal and the pulse width modulation signal PWM are in a negative correlation relationship, and the output current sampling circuit realizes the amplitude adjustment of the constant current output by the constant current source main circuit through the feedback signal.

In the above UC 1843-based programmable constant current source system, the feedback signal includes: and outputting information of the current and the reference current signals.

The invention has the following advantages:

(1) the invention has the characteristic of controlling the output current to be constant in the switch working mode, thereby having higher efficiency when solving the problem of heat consumption.

(2) The invention has the characteristics of simple structure and high availability of components, thereby having low cost and high reliability.

Drawings

Fig. 1 is a block diagram of a UC 1843-based programmable constant current source system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a circuit structure of a reference signal conditioning circuit according to an embodiment of the present invention;

fig. 3 is a schematic circuit diagram of a UC1843 control circuit according to an embodiment of the present invention;

FIG. 4 is a schematic circuit diagram of a main circuit of a constant current source according to an embodiment of the present invention;

fig. 5 is a schematic circuit diagram of an output current sampling circuit according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to fig. 1, in this embodiment, the UC 1843-based programmable constant current source system includes:

and the reference signal conditioning circuit is used for conditioning the reference current signal and outputting a first signal in linear relation with the reference current signal.

In this embodiment, as shown in fig. 2, the reference signal conditioning circuit may specifically include: the circuit comprises a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14 and an operational amplifier Q4. Preferably, the specific circuit connection relationship of the reference signal conditioning circuit is as follows: two ends of the resistor R9 are respectively connected with the Vfb end of the control chip UC1843 and the ground; two ends of the resistor R10 are respectively connected with the output end of the operational amplifier Q4 and the Vfb end of the control chip UC 1843; two ends of the resistor R11 are respectively connected with the reverse input end of the operational amplifier Q4 and the output end of the operational amplifier Q4; two ends of the resistor R12 are respectively connected with the reference current signal V _ ZL and the reverse input end of the operational amplifier Q4; two ends of the resistor R13 are respectively connected with a Vref end of the control chip UC1843 and a positive input end of the operational amplifier Q4; the two ends of the resistor R14 are respectively connected with the resistor R13 and the ground.

The UC1843 control circuit is used for receiving a first signal output by the reference signal conditioning circuit and a second signal output by the output current sampling circuit; and performing logic processing according to the first signal and the second signal to output a pulse width modulation signal.

In this embodiment, the UC1843 control circuit may specifically include: the control chip UC1843, the resistor R5, the resistor R6, the resistor R7, the capacitor C5, the capacitor C6, the capacitor C7 and the capacitor C8. The UC1843 of the control chip is provided with a Vref end, a Vcc end, an RT end (oscillation resistance end), an Out end (output end), a Vfb end (feedback signal input end), a Cs end (sampling current input end), a Comp end, a PGnd end, and a Gnd end. Referring to fig. 3, the specific circuit connection relationship of the UC1843 control circuit is as follows: the PGnd end and the Gnd end of the control chip UC1843 are grounded; two ends of the capacitor C7 are respectively connected with a Vfb end and a Comp end of the control chip UC 1843; the capacitor C8 is connected with the resistor R7 in series and then connected with the capacitor C7 in parallel; two ends of the resistor R6 are respectively connected with a Vref end and an RT end of the control chip UC 1843; two ends of the capacitor C6 are respectively connected with the RT end of the control chip UC1843 and the ground; two ends of the capacitor C5 are respectively connected with the Cs end of the control chip UC1843 and the ground; one end of the resistor R5 is connected to the Out end of the control chip UC 1843.

And the constant current source main circuit is used for receiving the pulse width modulation signal output by the UC1843 control circuit, carrying out isolation conversion on the input voltage according to the pulse width modulation signal and outputting constant current.

In this embodiment, as shown in fig. 4, the constant current source main circuit may specifically include: transformer T2, MOS transistor V1, capacitor C1, and diode D1. The transformer T2 is provided with four pins (pins 1-4 in FIG. 4). Preferably, the specific circuit connection relationship of the constant current source main circuit is as follows: the drain electrode of the MOS transistor V1 is connected with the second pin of the transformer T2; the anode of the diode D1 is connected to the third pin of the transformer T2, the cathode of the diode D1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the fourth pin of the transformer T2.

And the output current sampling circuit is used for sampling and conditioning the constant current output by the constant current source main circuit and outputting a second signal linearly related to the constant current.

In this embodiment, as shown in fig. 5, the output current sampling circuit may specifically include: the circuit comprises a resistor R1, a resistor R16, a resistor R17, a resistor R18, a resistor R19, an operational amplifier Q3 and a resistor R8. Preferably, the specific circuit connection relationship of the output current sampling circuit is as follows: one end of the resistor R1 is connected with the reverse input end of the operational amplifier Q3 after being connected with the resistor R16 in series, and the other end of the resistor R1 is connected with the forward input end of the operational amplifier Q3 after being connected with the resistor R18 in series; two ends of the resistor R8 are respectively connected with the output end of the operational amplifier Q3 and the Vfb end of the control chip UC 1843; the two ends of the resistor R17 are respectively connected with the resistor R16 and the resistor R8; the two ends of the resistor R19 are respectively connected with the resistor R18 and the ground.

In the present embodiment, it is preferred that,

the resistor R1 of the output current sampling circuit is connected in series with the output ground wire of the constant current source main circuit, so as to realize sampling of the constant current output by the constant current source main circuit, and after the constant current is amplified by the operational amplifier Q3 and conditioned (such as inversion, constant value superposition, amplification and other processing) and added with a reference current signal, the constant current is sent to the Vfb end of the control chip UC1843 through the resistor R8. Further, the control chip UC1843 outputs a pulse width modulation signal PWM according to the amplitude of the feedback signal (the signal at the Vfb end) logically processed by the first signal and the second signal, and drives the MOS transistor V1 of the constant current source main circuit through the pulse width modulation signal PWM. The feedback signal and the pulse width modulation signal PWM are in a negative correlation relationship, the output current sampling circuit adjusts the amplitude of the constant current output by the constant current source main circuit through the feedback signal, and the feedback signal contains information of the output current and the reference current signal.

The operating principle of the UC 1843-based programmable constant current source system is as follows:

during the steady-state operation of the circuit, the Vfb terminal voltage expression of the UC1843 control circuit is:

it can be seen that I₀The linear adjustment can be carried out according to the amplitude of the V _ ZL. Wherein, Vfb is Vfb terminal voltage, V _ ZL is reference current signal level, I₀Meter type constant current source main circuitThe constant current of output, the sampling amplification factor of the constant current of K table output, Vref table formula Vref terminal voltage, R8-R14 respectively table resistance of R8-R14.

In this embodiment, the level of the UC1843 control circuit at the time of steady-state operation at Vfb terminal is 2.5V, if Vfb terminal voltage is lower than 2.5V, the duty ratio of PWM at the Out terminal becomes larger, and if Vfb terminal voltage is higher than 2.5V, the duty ratio of PWM at the Out terminal of the control chip UC1843 becomes smaller. When the duty ratio of the PWM is increased, the on time of the MOS transistor V1 is increased, and the constant current I is output₀And the voltage at the Vfb becomes higher according to the formula (1), and the circuit enters a stable working state until the voltage at the Vfb reaches 2.5V. When the duty ratio of PWM is reduced, the conduction time of MOS transistor V1 is shortened, and the output constant current I₀And when the voltage becomes smaller, the voltage at the Vfb becomes lower according to the formula (1), and the circuit enters a stable working state until the voltage at the Vfb reaches 2.5V.

Preferably, when Vfb is 2.5, the formula 1 is substituted to obtain: v _ ZL and I₀And the linear relation realizes that the output current changes along with the change of the command level. Furthermore, the resistances of the resistors R8-R14 can be designed to satisfy the following formula (2), thereby realizing V _ ZL and I₀Linear proportionality:

although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.

Those skilled in the art will appreciate that the invention may be practiced without these specific details.