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Constant-current output control circuit and design method thereof

A control circuit, constant current output technology, applied in the direction of converting DC power input to DC power output, AC power input converting to DC power output, output power conversion device, etc., can solve the problem of inconstant output current

Pending Publication Date: 2019-01-04
SHENZHEN LII SEMICON CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the flyback AC / DC switching power supply circuit in the prior art, the output voltage of the circuit and the reference voltage amplified by the error amplifier will change in different cycles with the change of the output voltage of the circuit, thus causing the output current to vary. constant

Method used

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  • Constant-current output control circuit and design method thereof
  • Constant-current output control circuit and design method thereof
  • Constant-current output control circuit and design method thereof

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Embodiment Construction

[0031] The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0032] See figure 1 and figure 2 , the flyback AC / DC switching power supply constant current circuit in the prior art includes a first switch, a second switch, a first capacitor, an inverter and a waiting circuit, and the waiting circuit includes a first comparator, a second Two comparators, a control chip, a switch tube, a second resistor, a primary coil and a secondary coil, the first terminal of the first switch is connected to the input voltage, the second terminal of the first switch is connected to the first terminal of the first capacitor terminal connection, the first terminal of the second switch is connected to the first terminal of the first capacitor, the se...

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PUM

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Abstract

The invention relates to a constant current output control circuit and a design method thereof. The circuit comprises a control module, a first resistor, a capacitor and an error amplifier. A controlmodule is connected with an adjustable control voltage and a detection signal, The noninverting input of the error amplifier is connected to the reference voltage. The reverse input terminal of the error amplifier is connected with the first terminal of the first resistor, the output terminal of the error amplifier is connected with the circuit to be connected, the first terminal of the capacitoris connected with the first terminal of the first resistor, the second terminal of the capacitor is connected with the output terminal of the error amplifier, and the second terminal of the first resistor is connected with the control module. By connecting a reference voltage to the noninverting input terminal of the error amplifier, An adjustable control voltage is indirectly connected to the reverse input, so that the ratio of the product of the variable control voltage and the on-time of the secondary side diode to the power supply switching period is the reference voltage, the reference voltage is a fixed value, the primary side current detection resistor and the coil turn ratio are also fixed, so that the average output current of the circuit is constant.

Description

technical field [0001] The invention relates to a constant current output control circuit and a design method thereof, belonging to the field of circuit control. Background technique [0002] Flyback AC / DC switching power supply is widely used in battery chargers, adapters and other fields because of its simple circuit, small size, low cost, and high safety. Although there are various types of flyback AC / DC switching power supplies and their internal control modules are becoming more and more complex, all control modules are designed to obtain precise constant voltage (CV) and constant current (CC) outputs. For precise constant voltage output, it can be obtained through the dual-loop control of current and voltage feedback, while for precise constant current output, the usual method is to adjust the duty cycle of the conduction time of the secondary diode. However, in the flyback AC / DC switching power supply circuit in the prior art, the output voltage of the circuit and th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/217
CPCH02M7/217H02M3/33569H02M1/0009H02M1/0025H03K4/12H02M3/335
Inventor 张杰朱敏王福龙
Owner SHENZHEN LII SEMICON CO LTD