VNH7070AY datasheet(28/48 Pages) STMICROELECTRONICS

28 / 48 page

Protections

VNH7070AY

28/48

DS12207 Rev 5

Protections

3.1

Power limitation (high-side driver)

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

junction temperature swing ∆Tj 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 ∆Tj exceeds the safety level of ∆Tj_SD. The protection prevents fast thermal transient

effects and, consequently, reduces thermo-mechanical fatigue. When Power Limitation is

reached, The device enters in latch mode and generates the Fault Flag on

Multisense=VsenseH when the faulty leg diagnostic is selected (please refer to Table 13).

3.2

Thermal shutdown (high-side and low-side)

In case the junction temperature of the device exceeds the maximum allowed threshold

(typically 175 °C), the device enters in latch mode and generates the Fault Flag on

Multisense = VsenseH (please refer to Table 13). The concerned high side can be switched

ON again as soon as Tj drops below TTR_HSD, INX is set low for a duration >

TLATCH_RST_HS and set high again.

3.3

Current limitation and over current detector

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. High-side current limitation: in case of short-circuit,

overload or during load power-up, the output current is clamped to a safety level, ILIM_HSD,

by operating the output power MOSFET in the active region.

Low-side overcurrent detector: this protection senses the current flowing in the low-side. If

the current exceeds a safety level ISD_LS, the device will switch off after a filtering time

tsd_ld.

In case of fault conditions caused by Power Limitation or overtemperature or open

load/short to VCC in OFF state, the fault is indicated by the MultiSense pin being internally

switched to a “current limited” voltage source pulled to level VSENSEH (please refer to

Table 13).

VNH7070AY Datasheet(PDF) 28 Page - STMicroelectronics