Smart MOS or Intelligent Power Device (IPD)

What is a Smart MOSFET?

It is an automotive dedicated device, typically for lighting, engine management, power train or seat heating applications. It combines four basic functions:

1. A Power switch, usually a MOSFET (single or multi channel)
2. A drive circuit to interface directly the single or multi channel switches with a microcontroller
3. Over temperature and over current protections
4. A diagnostic function

Block Diagram

Over current protection

The over current protection has a short reaction time and continuously monitors the output current. It reacts if the output of the device is shorted to ground in a very low impedance path. The over current protection must be designed to allow, for lighting applications, the inrush current of the lamp flow. When an over current is detected, the device reacts to prevent power switch destruction, either by limiting the current or switching the device off. Usually, diagnostic information will be output at one dedicated pin of the device.

Over temperature protection

Excessive output current due to a temporary or permanent overload at the driver output may cause the channel temperature to rise above the maximum value. In this case, the over temperature protection prevents the destruction of the device by switching off. Typically, the over temperature protection will react to a short circuit occurring in a light module at the cable termination.