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Pulse width modulation circuit with programmable current limit

A technology of pulse width modulation and programming current, applied in the direction of pulse duration/width modulation, etc., can solve the problems of low precision, noise generation, high precision, and achieve the effect of improving working speed, response speed and response speed.

Active Publication Date: 2022-01-11
NO 24 RES INST OF CETC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The accuracy and delay of the pulse width modulation circuit directly determine the accuracy of the duty cycle signal, so in order to increase the speed of the pulse width modulation circuit, multi-level high-speed comparators are generally used to achieve, but the structure of multi-level comparators is relatively complex, which increases the difficulty of design; Traditional current sampling circuits generally have three implementation methods. 1. Introduce resistance sampling in the current path. This method is simple to implement, but it will introduce large power consumption and reduce efficiency; 2. Use power tube on-resistance sampling. Although this method will not introduce power loss, the accuracy of this method is low and noise will be generated when the switch is switched; 3. Integral sampling circuit, this method has high accuracy and low loss, but it is difficult to design

Method used

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  • Pulse width modulation circuit with programmable current limit
  • Pulse width modulation circuit with programmable current limit
  • Pulse width modulation circuit with programmable current limit

Examples

Experimental program
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Effect test

Embodiment 1

[0044] In this embodiment, a specific implementation of a pulse width modulation circuit for programmable current is proposed. The circuit includes four P-type three-pole MP1 to MN20 and four R1 to R4, wherein :

[0045] The MP1 source is connected to the current source IB1 and the MP2 source connection, the gate is connected to the error amplifier, the drain and the drain / gate of the drain and the Mn1 are connected;

[0046] The MP2 source is connected to the current source IB1 and the MP1 source connection, the gate is connected to the MN1 source and the R1 positive end, the drain is connected to the MN2 drain and the MN4 gate;

[0047] The MN1 grid / drain is connected to the MN2 gate and the MP1 drain, the source and ground connection;

[0048] The MN2 drain is connected to the MP2 drain and the MN4 gate and the R1 positive terminal, the MN2 gate is connected to the MN1 grid / drain and the MP1 drain, the MN2 source is connected to ground;

[0049] The MP3 source is connected...

Embodiment 2

[0071] In the basis of the first embodiment, the present embodiment is attached. figure 2 Further explanation of the three circuit principles of the circuit and the error amplifier output and the ramp compensation signal acquisition circuit, the current sampling circuit, and the pulse width modulator main circuit.

[0072] Error amplifier output and slope compensation signal acquisition circuit work principle image 3 As shown, the signal after the error amplifier signal passes through the voltage transfer current comparator:

[0073]

[0074] Among them, I EA_OUT Current signal obtained by converting; V EA_OUT Voltage signal output for error amplifier; R 1 The resistance of the first resistance; R MN3 The resistance of the third N-type triode.

[0075] This current is superimposed to the source current of Mn5 after mirroring, subtracting the slope compensation current, etc., the final collecting signal is:

[0076] I DSMN6 = I DSMP4 + I DSMN5 -I SLOPE (2)

[0077] Among them, I ...

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Abstract

The invention belongs to a switching power supply chip technology in an analog integrated circuit, and particularly relates to a pulse width modulation circuit with a programmable current limit, which comprises an error amplifier output and slope compensation signal acquisition circuit, a current sampling circuit and a pulse width modulator main circuit, wherein a signal output by the error amplifier is output by the error amplifier and is subjected to voltage-to-current conversion through the slope compensation signal acquisition circuit, and an obtained current signal is compensated; the compensated current signal is sampled through a current sampling current to obtain a sampling signal; the sampling signal is input into the pulse width modulator main circuit for pulse width modulation. According to the pulse width modulation circuit with the programmable current limit, the response speed is improved by accurately sampling the current of the power tube and superposing an error amplifier signal and a slope compensation signal in a current mode; the response speed of the pulse width modulation circuit and the working speed of the switching power supply chip are improved; by introducing the programmable current limit, the pulse width modulator circuit can be applied to switching power supply chips of various loads.

Description

Technical field [0001] The present invention belongs to the switching power supply chip technology in an analog integrated circuit, and more particularly to a pulse width modulation circuit for programmable current limits. Background technique [0002] In the field of switching power supply, the pulse width modulation circuit is to output the output level, ramp compensation level and current sampling signal of the error amplifier, generate a signal for controlling the power tube switch. Conventional pulse width modulation circuit work block figure 1 As shown, there is mainly including the PWM comparator, a current limiting comparator COMP2, two inputs and non-door and dead time control buffers. The accuracy and delay of the pulse width modulation circuit directly determines the accuracy of the duty cycle signal, so in order to improve the speed of the pulse width modulation circuit, the multi-stage high speed comparator is generally used, but the multi-level comparator structure ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03K7/08
CPCH03K7/08
Inventor 雷旭彭克武廖鹏飞霍改青唐旭
Owner NO 24 RES INST OF CETC