19
LTC4230
4230f
1 3 65 74
20µA PULL-UP 20µA PULL-UP
LOAD CURRENT > 150mV/R
SENSE
n
4230 F08
CHECK FOR FILTER LOW (< V
REF
)
CHECK FOR FAULT HIGH (> V
REF
+ 50mV)
2
CHECK FOR GATE
n
< 0.25V
FAST COMPARATOR
ARMED
SLOW COMPARATOR
ARMED
CIRCUIT BREAKER TRIPS,
ALL GATE
n
PINS PULL
LOW IMMEDIATELY
ON
TIMER
FAULT
GATE
n
GATE
n
V
OUT
n
V
OUT
n
I
OUT
n
FILTER
1.6µA PULL-DOWN
8 9
CHECK FOR TIMER < 0.3V
LOAD CURRENT < 50mV/R
SENSE
n
Figure 8. Output Short Circuit Causes Fast Comparator to Trip the Circuit Breaker
APPLICATIO S I FOR ATIO
WUU
U
RESETTING THE ELECTRONIC CIRCUIT BREAKER
Once the LTC4230’s circuit breaker is tripped, FAULT is
asserted low and the GATE
n
pin is pulled to ground. The
LTC4230 remains latched OFF in this fault state until the
external fault is cleared. To clear the internal fault detect
circuitry and to restart the LTC4230, its ON pin must be
driven low (V
ON
< 1.234V) for at least 30µs, after which
time FAULT goes high. Toggling the ON pin from low to
high (V
ON
> 1.314V) initiates a restart sequence in the
LTC4230. The timing diagram in Figure 10 illustrates a
