Software adjustable voltage reference circuit

Abstract

The utility model provides a software adjustable voltage reference circuit which comprises a micro-control unit which comprises a PWM (Pulse Width Modulation) signal output interface and an ADC (Analog to Digital Converter) sampling interface; the PWM signal output interface is connected with one input end of the voltage comparator U1; one input end of the voltage comparator U1 receives PWM signals output by the micro-control unit, the other input end of the voltage comparator U1 receives + VrefA reference voltage, the output end of the voltage comparator U1 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected with a base electrode of the triode Q1 and one end of the resistor R4. The triode Q1 works in a linear interval, and a collector electrode of the triode Q1 is connected with a voltage dividing network composed of a resistor R5, a resistor R6 and a resistor R7 and used for generating + VrefA reference voltage and + VrefB reference voltage. And the feedback loop feeds the + VrefA reference voltage back to an ADC sampling interface of the micro-control unit to form closed-loop control. Software adjustable voltage reference can be realized.

Description

TECHNICAL FIELD

[0001] The utility model relates to motor drive circuit technical field especially relates to a software adjustable voltage reference circuit. BACKGROUND

[0002] General motor drive, a plurality of voltage references are needed in battery management system, usually adopts the fixed reference voltage of special voltage reference chip setting, cannot realize software adjustable voltage reference. SUMMARY

[0003] In order to solve the above problem, the utility model discloses a kind of software adjustable voltage reference circuit.

[0004] A kind of software adjustable voltage reference circuit, comprising: micro control unit, the micro control unit includes PWM signal output interface and ADC sampling interface;PWM signal output interface accesses one input end of voltage comparator U1;Voltage comparator U1, one input end of voltage comparator U1 receives the PWM signal output by micro control unit, another input end receives +VrefA reference voltage, output end is connected to the one end of resistance R3, resistance R3 other end connects the base of triode Q1 and the one end of resistance R4;Triode Q1 works in linear interval, the collector of triode Q1 is connected by the voltage division network of resistance R5, resistance R6 and resistance R7, for generating +VrefA reference voltage and +VrefB reference voltage;Feedback loop, +VrefA reference voltage is fed back to the ADC sampling interface of micro control unit, forms closed loop control.

[0005] Preferably, the PWM signal output interface of micro control unit is connected to voltage comparator U1 through first RC filtering module;Feedback loop includes second RC filtering module, +VrefA reference voltage is fed back to the ADC sampling interface of micro control unit through second RC filtering module.

[0006] Preferably, one end of resistance R5 is connected to the emitter of triode Q1, and the other end is grounded;One end of resistance R6 is connected to +VrefB reference voltage node, and the other end is connected to the collector of triode Q1;One end of resistance R7 is connected to +VrefB reference voltage node, and the other end is connected to the collector of triode Q1.

[0007] In the above scheme, the PWM output of the micro control unit is input to the input of the comparator, at this time the output of the voltage comparator will pass through the resistor R3, the resistor R4 to control the voltage comparator Q1 to make the voltage comparator Q1 work in the linear region, the voltage comparator Q1 is equivalent to an adjustable resistor, Q1 and the resistor R5, R6, R7 constitute a resistor voltage divider, to adjust the reference voltage A and the reference voltage B, at the same time the reference voltage A is fed back to the voltage comparator and the micro control unit, forming a closed loop adjustment, so as to realize the micro control unit to adjust the reference voltage through the output PWM, so that the circuit can provide adjustable voltage reference. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 The circuit structure diagram of the present application is shown in the figure. DETAILED DESCRIPTION

[0009] The embodiments of the present application will be described in detail below.

[0010] As Figure 1 shown, the present embodiment discloses a software adjustable voltage reference circuit, comprising: a micro control unit, the micro control unit comprising a PWM signal output interface and an ADC sampling interface; the PWM signal output interface is connected to one

[0011] input end of the voltage comparator U1 after passing through the resistor R2 and the capacitor C2, and the resistor R2 and the capacitor C2 constitute a first RC filter module; the output end of the voltage comparator U1 is connected to one end of the resistor R3, the other end of the resistor R3 is connected to the base of the triode Q1 and one end of the resistor R4, the collector of the triode Q1 is connected to the resistor R7 and the resistor R6 to the reference voltage B output end, the emitter of the triode Q1 is connected to the resistor R4 and the resistor R5, the resistor R5 is connected to the reference voltage A output end, one way of the reference voltage A output end is connected to the other input end of the voltage comparator U1, the other way of the reference voltage A output end is connected to the resistor R1 and the capacitor C1 to the ADC sampling interface of the micro control unit, and the resistor R1 and the capacitor C1 constitute a second RC filter module.

[0012] The micro control unit changes the amplitude of the analog signal output by the RC filter circuit by adjusting the duty cycle of the PWM signal, and then adjusts the ratio of the voltage divider network through the linear working state of the voltage comparator U1 and the triode Q1, to realize the dynamic calibration of the reference voltage +VrefA and +VrefB.

[0013] In the above circuit, the PWM signal outputted by the micro control unit is filtered into an analog signal by the RC filter circuit composed of the resistor R2 and the capacitor C2, the analog signal is inputted into the input end of the voltage comparator U1, and the reference voltage A output end +VrefA is inputted into the voltage comparison driving voltage comparator U1, the output voltage of the voltage comparator U1 drives the base of the triode Q1 through the resistor R4 and the resistor R3, and the triode Q1 is caused to work in the linear region to change the voltage reference +VrefA and +VrefB composed of the resistor R5, the resistor R6 and the resistor R7, at the same time, the reference voltage +VrefA is sent into the ADC1 of the micro control unit through the RC filter circuit composed of the resistor R1 and the capacitor C1 to collect the voltage +VrefA, the micro control unit compares the voltage +VrefA with the duty cycle voltage set by the PWM, adjusts the voltage set by the PWM, and thus realizes the software setting of the reference voltage A output end +VrefA and the reference voltage B output end +VrefB by the micro control unit.

[0014] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A software-adjustable voltage reference circuit, characterized in that, include: The microcontroller unit includes a PWM signal output interface and an ADC sampling interface; the PWM signal output interface is connected to one input terminal of the voltage comparator U1. Voltage comparator U1 receives the PWM signal output from the microcontroller unit at one input terminal and the +VrefA reference voltage at the other input terminal. Its output terminal is connected to one end of resistor R3, and the other end of resistor R3 is connected to the base of transistor Q1 and one end of resistor R4. Transistor Q1 operates in the linear range, and its collector is connected to a voltage divider network composed of resistors R5, R6, and R7 to generate the +VrefA and +VrefB reference voltages. The feedback loop feeds the +VrefA reference voltage back to the ADC sampling interface of the microcontroller unit, forming a closed-loop control.

2. The software-adjustable voltage reference circuit according to claim 1, characterized in that, The PWM signal output interface of the microcontroller unit is connected to the voltage comparator U1 through the first RC filter module; the feedback loop includes the second RC filter module, and the +VrefA reference voltage is fed back to the ADC sampling interface of the microcontroller unit through the second RC filter module.

3. The software-adjustable voltage reference circuit according to claim 1, characterized in that, One end of resistor R5 is connected to the emitter of transistor Q1, and the other end is grounded; one end of resistor R6 is connected to the +VrefB reference voltage node, and the other end is connected to the collector of transistor Q1; one end of resistor R7 is connected to the +VrefB reference voltage node, and the other end is connected to the collector of transistor Q1.

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