TDE1708DFT 查看數據表（PDF） - STMicroelectronics

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TDE1708DFT

Intelligent power switch

STMicroelectronics 

TDE1708DFT

Application information

3.1

Figure 5.

Adjustable input hysteresis circuit

The TDE1708DFT is a device realized in bipolar technology and therefore it has the usual

problems of temperature compensation that such technology involves; despite all it

maintains an input dynamics within 1 V over industrial temperatures range.

In all input voltage range it will guarantee a high impedance of 1 MΩ determining an input

current about 2 µA.

Exploiting this input high impedance is possible connects a sensor directly on it and bypass

the obstacle of active signal conditioning circuit using a voltage firm point as ground of

sensor, the delay capacitor, connected on the pin 3, as low pass filter and capacitor on Vreg

pin to minimize the noise on it and protect for errors the low-voltage internal circuits,

according AN495.

In Figure 5. the input external network is optimized for accepting both a sensor with ground

connected to the body and a sensor with independent ground.

In order to ground the body of the sensor, J1 has to be shorted, while J2 opened and

connect the sensor on M3; in case of independent ground J1 must be opened, J2 shorted

and the sensor connected on M4.

DL1 indicate commutation status of the device output and C3 realize a simple output filtering

in case is used an inductive load. With C2 about 10 nF we obtain a good filtering and

immunity from input voltage noise. C4 is 4,7nF according AN495.

R2 is an optional resistor plugged only when the sensor needs to adapt its impedance with

the input impedance of device.

Application circuit for adjustable input hysteresis

TDE1708DFT

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