SMH4803A
Preliminary
Resetting FAULT#
When the circuit breaker trips the VGATE output is turned
off and FAULT# is driven low. There are two methods to
reset the circuit breaker which are selectable with the
MODE pin. When MODE is held high or left floating the
circuit breaker is in the duty-cycle mode, and the breaker
resets automatically after a time of t
CYC
. When the MODE
pin is held low the circuit breaker can be reset by bringing
RESET# low. T
PDD
after bringing RESET# back high again
the VGATE output will attempt to restart the MOSFET slew
control circuitry. In either case, cycling power to the board
will also reset the circuit breaker. If the over current
condition still exists after the MOSFET switches back on
the circuit breaker will re-trip.
<T
CBD
V
QCB
50mV
CBSENSE
T
FSTSHTDN
VGATE
2051 Fig04 1.0
Figure 4. Circuit Breaker Timing — Quick Trip
2.5V
T
CBD
CBSENSE
50mV
T
CBD
OV / UV
t
UOFLTR
T
CYC
VGATE
FAULT#
2051 Fig02 1.0
2051 Fig05 2.0
Figure 2. Circuit Breaker Cycle Mode, RESET# High
Figure 5. Under-/Over-Voltage Filter Timing
T
CBD
CBSENSE
50mV
13
12
VDD (V)
T
PDD
VGATE
11
10
Temp, ºC
–40
0
25
85
125
T
RST
RESET#
2051 Fig03 1.0
9
0
2
4
6
IDD (mA)
8
10
12
2051 Fig06
Figure 3. Circuit Breaker Timing — Reset Mode
SUMMIT MICROELECTRONICS, Inc.
Figure 6. Effect of Temperature on Current Con-
sumption Over Voltage Range
9
2051 4.4 3/15/01
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
