NCP1631
Internal
Thermal
Shutdown
Vref
VDD
Iref
Vcc
Regul
TSD
Stdwn
UVP
Vcc_OK
BO_NOK
UVLO
12 V / 10 V
Rt(open)
R
S
Q
30−ms
blanking
time
IRt_Low
(Ipin3 < 7 mA)
OFF
Fault
management
Figure 20. Fault Management Block
When any of the following faults is detected:
− brown−out (“BO_NOK”)
− Under−Voltage Protection (“UVP”)
− Latch−off condition (“Stdwn”)
− Die over−temperature (“TSD”)
next operating sequence, where it must be slowly and
gradually charged to offer some soft−start.
− The “pfcOK” pin is grounded.
− The output of the “V
processing block” is
TON
grounded
− Too low current sourced by the R pin (“R
− “UVLO” (improper Vcc level for operation)
The circuit turns off. In this mode, the controller stops
operating. The major part of the circuit sleeps and its
consumption is minimized (< 500 mA). More specifically,
when the circuit is in OFF state:
”)
When the circuit recovers after a fault, the first watchdog
time is around 20 ms instead of 200 ms to allow a faster
re−start.
In OFF mode at startup, the consumption is very low (<
50 mA). The brown−out block is initialized not to allow
operation (“BO_NOK” high) by default. The PNP clamp is
active and maintains the BO pin level below 1 V. The 7−mA
t
t(open)
− The two drive outputs are kept low
− The 7−mA current source of the brown−out block is
current source is enabled only when V reaches V
CC
CC(on)
enabled to set the proper start−up BO threshold.
threshold.
− The pin5 capacitor (V ) is discharged and kept
control
grounded along the OFF time, to initialize it for the
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