LTC4214-1/LTC4214-2
APPLICATIO S I FOR ATIO
Shutdown Cooling Cycle (LTC4214-2)
Figure 15 shows the timer behavior of the LTC4214-2. At
time point 2, TIMER exceeds VTMRH, GATE pulls down
immediately and the LTC4214 shuts down. TIMER starts
a shutdown cooling cycle by discharging TIMER with 5µA
to the VTMRL threshold. TIMER then charges with 5µA to
the VTMRH threshold. There are four 5µA discharge phases
and three 5µA charge phases in this shutdown cooling
cycle spanning time points 2 and 3. At time point 3, the
LTC4214 automatic retry occurs with a start-up cycle.
Good thermal management techniques are highly recom-
mended; power and thermal dissipation must be carefully
evaluated when implementing the automatic retry scheme.
CIRCUIT BREAKER TIMES OUT
RETRY
12
3 4 5 6 78 9 10
40µA + 8 • IDRN
TIMER
5µA
VTMRH
5µA
5µA
5µA
5µA
5µA
5µA 40µA + 8 • IDRN
VTMRL
5µA
5µA
GATE
VGATEL50µA
50µA
VIN – VGATEH
20 • (VACL + VOS)
SS
20 • (VCB + VOS)
20 • VOS
SENSE
VACL
VCB
VOUT
DRAIN
VDRNCL
VDRNL
PWRGD
CB
SHUTDOWN COOLING
GATE
START-UP
4214 F15
Figure 15. Shutdown Cooling Timing Behavior of LTC4214-2 (All Waveforms are Referenced to VEE)
421412f
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