Overcurrent protection circuit

Abstract

An overcurrent protection circuit contains a first transistor, a first sensing transistor, a first current-limiting circuit, a first current-limiting switch, and a first current comparator. A grid of the first transistor is electrically connected to an output end of an output level circuit, and an output current flows over the output end. A first source and drain of the first transistor is electrically connected to a first current source, and a second source and drain of the first transistor are electrically connected to a first reference current source; the grid of the first sensing transistor is electrically connected to a first output end of an operational amplifier, and first source and drain of the first sensing transistor is electrically connected to a voltage source; the first current-limiting switch is electrically connected to the first current-limiting circuit and the output level circuit; and the first current comparator determines whether to conduct the first current-limiting switch based on the output current, the first current source, and the first reference current source.

Description

technical field [0001] The invention relates to an overcurrent protection circuit, in particular to an overcurrent protection circuit applied to an operational amplifier. Background technique [0002] In integrated circuits, when the output load circuit is short-circuited, for example, the output terminal of the output stage circuit is directly grounded or directly connected to a voltage source for limit testing. At this time, a huge current will be generated, exceeding the maximum allowable current. Flowing into the transistor will cause damage to the transistor and affect its reliability; even if the current does not exceed the maximum allowable current, it is sometimes necessary to limit the current in order to protect the load circuit connected to the transistor. [0003] In the prior art, in order to protect the transistor from being damaged by excessive current, or to limit the amount of current flowing into the load circuit, an overcurrent protection circuit with a cu...

AI Technical Summary

Problems solved by technology

[0004] However, using the over-current protection circuit will reduce the swing of the output voltage, which will reduce the range of the rail-to-rail voltage (Rail to Rail voltage), which will affect the performance of the circuit.

In detail, under the same VGS condition, the transistor of the output stage circuit is in the triode region (Triode Region), while the sensing transistor of the overcurrent protection circuit is in the saturation region (Saturation region), which will cause the protection circuit to misjudge the magnitude of the current and prematurely Start-up, the swing of the output voltage is reduced, which in turn affects the performance of the output voltage

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