LTC1647 LINER [Linear Technology], LTC1647 Datasheet - Page 32

• Manufacturer Part Number: LTC1647
• Description: Hot Swap Controller
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
LTC4211
Low Side (Output) Overvoltage Protection
A Zener diode can be used in a similar fashion to detect/
protect the system against a supply overvoltage condition
on the load (or low) side of the pass transistor. In this
case, the Zener diode is connected from the load to the
LTC4211’s FILTER pin, as shown in Figure 25. An additional
diode, D1, prevents the FILTER pin from pulling low during
an output short-circuit. Figure 26 illustrates the timing
32
FILTER
TIMER
RESET
FAULT
GATE
V
V
OUT
CC
1
2
>V
ON
REF
– 80mV
2A
OVERVOLTAGE
DUE TO A START-UP OVERVOLTAGE PROBLEM
FAULT IS PULLED LOW (BUT NOT LATCHED)
3
4
Figure 24. High Side Overvoltage Protection
IF OVERVOLTAGE GOES
AWAY, SECOND CYCLE
CONTINUES
IF ANY FAULT HAPPENS
AFTER THIS POINT, THE
CIRCUIT BREAKER TRIPS
AND FAULT LATCHES LOW
5
diagram for a low side output overvoltage condition. In
this example, V
but the LTC4211 can only sense the overvoltage supply
condition at Time Point 6 when the GATE pin has ramped
up. At Time Point 6, V
circuit breaker is tripped, the GATE pin voltage is pulled
to ground and FAULT is asserted low and latched.
6
POWER GOOD
V
FB
> V
GATE
V
OUT
REF
SLOW COMPARATOR ARMED
7
CC
8
starts up in an overvoltage condition
>V
REF
FILTER
FPD
A B C
OVERVOLTAGE CIRCUIT BREAKER
TRIPS, GATE PULLS DOWN AND
FAULT LATCHES LOW
is greater than 1.236V, the
POWER BAD
V
FB
4211 F24
FAULT
LATCHED LOW
< V
REF
4211fb