| 摘要 |
A current limiting circuit is electronically connected between a power source and a load, and comprises a MOSFET having a drain, a gate, and a source, a first operational amplifier, a voltage-limiting circuit, and a first transistor having an emitter, a base, and a collector. The drain is connected to the power source, the source is connected to the load and is grounded, and the gate is connected to the voltage-limiting circuit. The emitter is connected to the voltage-limiting circuit, the base is connected to the first operational amplifier, and the collector is grounded. The first operational amplifier detects an output voltage of the load to control a drain current of the MOSFET for protecting the MOSFET from being overloaded, and the current limiting circuit has no current limiting resistor, such that power consumption is reduced. |
| 主权项 |
1. A current limiting circuit for electronically connecting between a power source and a load, and comprising:
an input positive terminal and an input negative terminal, wherein the input positive terminal and the input negative terminal are adapted to electronically connect to the power source; a MOSFET having a drain, a source, and a gate, wherein the drain is electronically connected to the input positive terminal, and the source is grounded; an output positive terminal and an output negative terminal, wherein the output positive terminal and the output negative terminal are adapted to electronically connect to the load; a voltage dividing circuit electronically connected between a reference voltage source and the output negative terminal, and having a first resistor and a second resistor, wherein the first resistor and the second resistor are electronically connected in series; a first operational amplifier having a first positive input, a first negative input, and a first output, wherein the first positive input is electronically connected to a node between the first resistor and the second resistor, and the first negative input is grounded; a voltage-limiting circuit having a fixed-current output, wherein the fixed-current output is electronically connected to the gate of the MOSFET; and a first transistor having an emitter, a base, and a collector, wherein the emitter is electronically connected to the gate of the MOSFET, the base is electronically connected to the first output of the first operational amplifier, and the collector is grounded; wherein the voltage-limiting circuit comprises:
a second operational amplifier having a second positive input, a second negative input, and a second output;wherein the second positive input receives a limiting voltage, and the second negative input is electronically connected to receive a positive voltage through a third resistor; anda second transistor having an emitter, a base, and a collector;wherein the emitter of the second transistor is electronically connected to the second negative input of the second operational amplifier, the base of the second transistor is electronically connected to the second output of the second operational amplifier, and the collector of the second transistor is electronically connected to the gate of the MOSFET to be the fixed-current output of the voltage-limiting circuit. |
