VNF9D5F datasheet(16/108 Pages) STMICROELECTRONICS

16 / 108 page

Note:

In parallel mode, the I²t protection function is available. In this case, the configuration data are applied only to

CH0. Effectively the INOM value is doubled.

The value of INOM represents the level of steady state current, which can be accepted for infinite time in the

system consisting of IC, routing, connectors, wiring, and load. The value of tNOM specifies how fast the staircase

curve reaches the INOM value.

The Figure 8 depicts the I²t staircase protection curve with a configuration of INOM = 10 A and tNOM = 300 s and

for comparison the I-t isothermic curve of a wire with 0.5 mm2 cross section at TA = 85 °C heating up to 150 °C. It

can be seen that the I²t staircase protection curve is always left below the wire isothermic curve, which means the

I²t protection algorithm protects the wire from carrying an RMS current, which would lead to a higher temperature

increase than the one of the isothermic curve.

CH0 and CH1 can be paralleled by setting a specific bit in the OTP memory map. In this case only the

configuration data of channel 0 applies and the value of INOM is effectively doubled while RDSon is effectively

halved.

Figure 8. Protection curve with INOM = 10 A and tNOM = 300 s vs a 0.5 mm2 wire isothermic curve

VNF9D5F

Protections

DS13946 - Rev 8

page 16/108

VNF9D5F Datasheet(PDF) 16 Page - STMicroelectronics