VN7140AS12 datasheet(21/39 Pages) STMICROELECTRONICS

21 / 39 page

VN7140AS12

Protections

DocID029756 Rev 2

21/39

Protections

3.1

Power limitation

The basic working principle of this protection consists of an indirect measurement of the

junction temperature swing ΔTj through the direct measurement of the spatial temperature

gradient on the device surface in order to automatically shut off the output MOSFET as

soon as ΔTj exceeds the safety level of ΔTj_SD. The protection prevents fast thermal

transient effects and, consequently, reduces thermo-mechanical fatigue.

3.2

Thermal shutdown

If the junction temperature of the device exceeds the maximum allowed threshold (typically

175°C), it automatically switches off and the diagnostic indication is triggered. The device

switches on again as soon as its junction temperature drops to TR.

3.3

Current limitation

The device is equipped with an output current limiter in order to protect the silicon as well

as the other components of the system (e.g. bonding wires, wiring harness, connectors,

loads, etc.) from excessive current flow. Consequently, in case of short circuit, overload or

during load power-up, the output current is clamped to a safety level, ILIMH, by operating the

output power MOSFET in the active region.

3.4

Negative voltage clamp

If the device drives inductive load, the output voltage reaches a negative value during turn

off. A negative voltage clamp structure limits the maximum negative voltage to a certain

value, VDEMAG, allowing the inductor energy to be dissipated without damaging the device.

VN7140AS12 Datasheet(PDF) 21 Page - STMicroelectronics