Datasheet

TIMER
GATE
DRAIN
SENSE
PWRGD
Gate Ramp-up
Normal Mode
Circuit
Breaker
Limit
Circuit Breaker
Timeout Mode
1 2 3 4 5 6 7
V
THVT
V
TLVT
V
CB
V
AC
240PA
6PA
30mA
6PA
60PA
Normal Mode
LM5068
SNVS254C –JANUARY 2004–REVISED MARCH 2013 www.ti.com
Figure 33. Shutdown Cooling Timing Behavior
Figure 33 shows the timer behavior for LM5068-2, -4 during fault re-try time. During normal operation, whenever
the SENSE pin exceeds the 50mV, circuit breaker fault limit, the timer capacitor begins to charge. If the TIMER
pin voltage exceeds 4V, the GATE is pulled down immediately, and LM5068-2, -4 disconnects power to the load.
The TIMER starts the fault re-try cycle by discharging C
T
with 30mA to the V
TLVT
threshold. The TIMER then
charges C
T
with 6µA to the V
THVT
threshold. After eight charging phases and nine discharging phases, LM5068-
2, -4 initiates an automatic retry start-up cycle.
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