NCP1236
and the DRV switching starts only if it is allowed; whereas
the Low latch (typically sensing an overtemperature) is
taken into account only after the soft−start is finished. In
t
SSTARTmin @ INTC(SSTART)min
CLATCHmax
+
+
Vclamp0min
(eq. 2)
2.8 @ 10−3 @ 130 @ 10−6
addition, the NTC current is doubled to I
during
NTC(SSTART)
F + 364 nF
the soft−start period, to speed up the charging of the Latch
pin capacitor. The maximum value of Latch pin capacitor is
given by the following formula (The standard start−up
condition is considered and the NTC current is neglected) :
1.0
VCC
VCC(on)
VCC(min)
Start-up
initiated by
VCC(on)
time
Noise spike
ignored
(tLatch blanking)
Internal Latch Signal
Latch signal
high during
pre-start phase
time
DRV
Latch-off
Switching
allowed (no
latch event)
time
Figure 51. Latch−off Function Timing Diagram
Temperature Shutdown
instantaneously, and the HV current source is turned off.
Internal logic state is reset. When the temperature falls
below the low threshold, the HV start−up current source is
enabled, and a regular start−up sequence takes place.
The die includes a temperature shutdown protection with
a trip point guaranteed above 135C and below 165C, and
a typical hysteresis of 30C. When the temperature rises
above the high threshold, the controller stops switching
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