Under voltage locking circuit with temperature compensation

A technology of undervoltage lockout circuit and temperature compensation circuit, which is applied in the direction of electrical components, output power conversion devices, etc., can solve the problems of poor stability of the switching threshold value of the undervoltage lockout circuit and insufficient system reliability, and achieves enhanced stability and reliability. Reliability, Avoiding Drift, Improving Accuracy

Inactive Publication Date: 2007-12-26
SUPEC SUZHOU
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The positive flipping threshold VCC(ON) and reverse flipping threshold VCC(OFF) of the existing undervoltage lockout circuit will drift with the cha

Method used

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  • Under voltage locking circuit with temperature compensation
  • Under voltage locking circuit with temperature compensation
  • Under voltage locking circuit with temperature compensation

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0021] Embodiment 1 As shown in Figure 1, an undervoltage lockout circuit with temperature compensation includes a voltage sampling circuit, a temperature compensation circuit, a buffer circuit and a feedback circuit. The voltage sampling circuit includes a first resistor R1, a second resistor R2, and a third resistor R3 connected in series between the first voltage source VCC and the ground terminal GND, and the output of the voltage sampling circuit is formed between the second resistor R2 and the third resistor R3 At terminal V1, a node C is formed between the first resistor R1 and the second resistor R2.

[0022] The temperature compensation circuit adopts a bandgap reference circuit, which includes a first field effect tube M1, a second field effect tube M2, a first transistor Q1, a second transistor Q2, a fourth resistor R4, and a fifth resistor R5. The gate and drain of the first field effect transistor M1 are connected together. The sources of the first field effect transi...

Example Embodiment

[0041] Embodiment 2 As shown in Fig. 2, in this embodiment, the first resistor R1, the second resistor R2, and the third resistor R3 used in the voltage sampling circuit in the embodiment 1 use the fourth field effect transistor M4 and the fifth field effect transistor M4, respectively. The effect tube M5 and the sixth field effect tube M6 are replaced. The field effect tube can not only play the role of resistor divider, but also can reduce the starting current of the circuit and reduce the static power consumption when the circuit is working normally. The other structure of the circuit and the principle of temperature compensation are the same as in Embodiment 1, and will not be repeated.

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Abstract

Characters are that the under voltage lock down circuit (UVLDC) includes a voltage sampling circuit (VSC), a temperature compensation circuit (TCC), a buffer circuit, and a feedback circuit. After sampling first voltage source, VSC provides voltage-sampled signal to TCC. Shaping the output signal from TCC, buffer circuit outputs the output signal of UVLDC. TCC makes threshold value of flip-flop of UVLDC not be influenced by temperature. The buffer circuit provides a feeding point. Being connected between the feeding point and VSC, the feedback circuit is in use for realizing retardation function of circuit. Beneficial effect is that inductive band-gap reference circuit makes temperature coefficient value of threshold value of flip-flop of UVLDC be zero theoretically so as to prevent temperature drift of threshold value. Thus, the invention raises precision, stability and reliability of system.

Description

technical field [0001] The invention relates to an undervoltage lockout circuit, in particular to an undervoltage lockout circuit with temperature compensation. Background technique [0002] The undervoltage lockout circuit, also known as the UVLO (Under Voltage Lock Out) circuit, is an important protection circuit in the PWM power module. The function of the undervoltage lockout circuit is that when the power supply voltage VCC is greater than the forward flipping threshold VCC(ON), the circuit starts to work and outputs PWM pulses; when the power supply voltage VCC is lower than the reverse flipping threshold VCC(OFF), the undervoltage lockout The circuit turns off other internal circuit modules to prevent circuit malfunction, ensure the stability and reliability of the power supply, and provide sufficient voltage to turn on the external power MOSFET. [0003] The forward flipping threshold VCC(ON) and reverse flipping threshold VCC(OFF) of the existing undervoltage locko...

Claims

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Application Information

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IPC IPC(8): H02M1/32
Inventor 刘伟
Owner SUPEC SUZHOU
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