AN1625 datasheet(18/39 Pages) STMICROELECTRONICS

18 / 39 page

AN1625 APPLICATION NOTE

18/39

The total intervention time is

where

tOCD(OFF), tOCD(ON), tD(ON)EN, tD(OFF)EN, and ROPDR are device intrinsic parameters, VDD is the pull-up voltage

applied to REN.

The external RC network, CEN in particular, must be chosen obtaining a reasonable fast OCD intervention (short

tDELAY) and a safe disable time (long tDISABLE). Figure 19 shows both tDISABLE and tDELAY as a function of CEN:

at least 100µs for tDISABLE are recommended, keeping the delay time below 1÷2µs at the same time.

The internal open drain can also be turned on if the device experiences an over temperature (OVT) condition.

The OVT will cause the device to shut down when the die temperature exceeds the OVT threshold (TJ>165 °C

typ.).

Since the OVT is also connected directly to the gate drive circuit (see Figure 1), all the Power DMOS will shut

down, even if EN pin voltage is still over Vth(OFF). When the junction temperature falls below the OVT turn-off

threshold (150 °C typ.), the open drain turns off, CEN is recharged up to VTH(ON) and then the PowerDMOS are

turned on back.

EN LO W

()

TH O FF

() e

DO FF

()

OCD O FF

()

OPD R

⋅

--------------------------------------------------





⋅

DE LAY

OC D O N

()

EN F ALL

()

DO FF

()EN

EN F ALL

()

OPD R

TH OF F

()

-------------------------





⋅⋅

AN1625 Datasheet(PDF) 18 Page - STMicroelectronics

AN1625 Datasheet(HTML) 18 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

Datasheet Download

Link URL