Chemical sensor power-down protection circuit
A chemical sensor, power-down protection technology, applied in emergency protection circuit devices, electrical components, etc., can solve the problems of increasing peripheral circuits and circuit costs, and achieve the effect of reducing external devices and reducing costs.
Active Publication Date: 2021-07-13
SG MICRO
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Problems solved by technology
The inventor found that the disadvantage of this solution is that the peripheral circuits must be increased, thereby increasing the circuit cost
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[0014] Below with the accompanying drawings ( figure 1 ) to illustrate the present invention.
[0015] figure 1 It is a schematic diagram of the structure and principle of the chemical sensor power-down protection circuit implemented in the present invention. Such as figure 1 As shown, the chemical sensor power-down protection circuit includes an operational amplifier circuit board, a first operational amplifier OP1 is arranged in the operational amplifier circuit board, and the positive input terminal INP (+) of the first operational amplifier OP1 is connected to the ground terminal , the negative input terminal INN(-) of the first operational amplifier OP1 is the access terminal of the positive terminal WE of the sensor, and the negative input terminal (-) of the first operational amplifier OP1 is connected to the drain of the first NMOS transistor M1 pole, the source of the first NMOS transistor M1 is connected to the source of the second NMOS transistor M2, the drain of...
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The chemical sensor power-down protection circuit can control the drain terminals of the two NMOS transistors to form a power-down short-circuit state or a power-on disconnection state through a combination of two NMOS transistors interconnected at the source and a charge pump, thereby Realize the short-circuit protection of the chemical sensor when the circuit is powered off, so as to avoid the polarization damage of the chemical sensor due to the excessive voltage of the two poles. It is characterized in that it includes an operational amplifier circuit board, and a first An operational amplifier, the positive input terminal of the first operational amplifier is connected to the ground terminal, the negative input terminal of the first operational amplifier is the access terminal of the positive terminal of the sensor, and the negative input terminal of the first operational amplifier is Connect the drain of the first NMOS transistor, the source of the first NMOS transistor is connected to the source of the second NMOS transistor, the drain of the second NMOS transistor is the access terminal of the negative terminal of the sensor, and the first NMOS transistor The gate of the transistor and the gate of the second NMOS transistor are respectively connected to a charge pump, and the charge pump is connected to an oscillator.
Description
technical field [0001] The invention relates to a power-down protection technology for sensors, in particular to a chemical sensor power-down protection circuit, which can control the drain terminal of the two NMOS tubes through the combination of two NMOS tubes interconnected at the source and a charge pump. A power-down short-circuit state or a power-on disconnection state is formed between them, so as to realize the short-circuit protection of the chemical sensor when the circuit is powered off, so as to avoid polarization damage to the chemical sensor. Background technique [0002] At present, the two output terminals of the carbon monoxide sensor (CO sensor) should be short-circuited after the circuit is powered off, that is, the positive terminal WE of the sensor is short-circuited with the negative terminal CE of the sensor, so as to ensure that the sensor will not generate extreme voltage due to the voltage difference between the two poles exceeding the rated voltage....
Claims
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IPC IPC(8): H02H7/20
CPCH02H7/20
Inventor 孙德臣张海冰张利地
Owner SG MICRO