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Current-limiting detection and protection circuit for NMOS load switch

A load switch and protection circuit technology, applied in circuits, electronic switches, electrical components, etc., can solve problems such as overcurrent, short circuit, and complicated conditions of electrical equipment, and achieve the effect of stable current limiting protection current threshold

Active Publication Date: 2018-02-23
NANJING MICRO ONE ELECTRONICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Because the output port of the USB port is directly plugged and unplugged by the user, and the connected electrical equipment is complicated, it is prone to over-current and short-circuit, so a load switch with current-limiting protection function is required

Method used

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  • Current-limiting detection and protection circuit for NMOS load switch
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  • Current-limiting detection and protection circuit for NMOS load switch

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Embodiment Construction

[0011] Such as figure 1 , the PART1 part is an NMOS load switch, including an NMOS power transistor M0, a charge pump CP, a clamp circuit Clamp1 and a clamp current limiting resistor R1. The drain of the NMOS power tube M0 is connected to the power supply VIN, the source of the power tube M0 is connected to the output voltage VOUT and the input terminal of the clamping circuit Clamp1, the gate of the power tube M0 is connected to one end of the clamping current-limiting resistor R1 and the clamping circuit Clamp1 The output terminal of the resistor R1 is connected to the output of the charge pump CP. During normal operation, the output of the charge pump CP provides a high voltage with limited driving capability, and then through the clamping current limiting resistor R1 and the clamping circuit Clamp1, the gate potential of the power transistor M0 is clamped to be about 4.5 higher than the source potential V, so that it is fully turned on, and M0 works in the linear region, ...

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Abstract

The invention discloses a current-limiting detection and protection circuit for an NMOS load switch. The load switch comprises an NMOS transistor M0, a charge pump (CP), a clamp circuit Clamp1 and a resistor R1; the current-limiting detection and protection circuit comprises NMOS transistors M1, M2, M3 and M4, a current reference Iref, a resistor R2, a comparator CMP and a clamp circuit Clamp2. The output voltage VOUT of the load switch is detected by differential pressures of the M1 and M2, and the changes of resistances of the M1 and M2 are accordant with the changes of temperature, supply voltage and technology, so that a stable proportional relation can be achieved, and thus a fixed proportional relation is formed between a voltage difference of the supply voltage VIN and a detection end and the voltage difference of the VIN and VOUT. Meanwhile, a current-limiting threshold reference voltage is generated via the M3 and Iref, so that the changes of the current-limiting threshold voltage and the resistance of M0 is accordant with the changes of temperature, supply voltage and technology, and thus a stable current-limiting protection current threshold is achieved.

Description

technical field [0001] The invention relates to a current-limiting switch, in particular to a current-limiting detection and protection circuit (Current Sense and Limit) for an NMOS load switch output by a 5V USB port. Background technique [0002] Because the output port of the USB port is directly plugged and unplugged by the user, and the connected electrical equipment is complex, it is prone to over-current and short-circuit situations, so a load switch with current-limiting protection function is required. Contents of the invention [0003] The purpose of the present invention is to provide a current-limiting detection and protection circuit for NMOS load switches, which can keep the current-limiting protection threshold stable when factors such as temperature, power supply voltage, and process conditions fluctuate, thereby realizing reliable current-limiting Protect. [0004] In order to achieve the above object, the technical solution of the present invention is as...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03K17/082H03K17/687
CPCH03K17/0822H03K17/687H03K2217/0027
Inventor 张宇锋张洪俞董泽芳
Owner NANJING MICRO ONE ELECTRONICS
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