LTC4245 LINER [Linear Technology], LTC4245 Datasheet - Page 9

• Manufacturer Part Number: LTC4245
• Description: Multiple Supply Hot Swap Controller with I2C Compatible Monitoring
• Manufacturer: LINER [Linear Technology]

PI FU CTIO S
12V
MOSFET. An internal 20μA current source charges the gate
of the external N-channel MOSFET. An internal clamp limits
the gate voltage to 6.2V above 12V
1.3mA pull-down current discharges 12V
During short-circuit a 250mA pull-down current between
12V
12V
internal low voltage supply V
An undervoltage lockout circuit, with 38mV hysteresis,
prevents any external MOSFET from turning on when this
pin is below 10.5V.
12V
Bad Input. Connect this pin to the source of the 12V supply
external N-channel MOSFET switch for gate drive return.
Power is considered bad if this pin drops below 11.1V. The
comparator on this pin has a built-in hysteresis of 40mV.
This pin is also an input to the ADC and the current limit
foldback circuit. A 1000Ω active pull-down discharges
12V
off.
12V
Connect this pin to the output of the 12V current sense
resistor. The current limit circuit controls the 12V
to limit the sense voltage between the 12V
pins to 50mV or less during start-up and 150mV thereafter.
During start-up a foldback feature reduces the current
limit to 15mV as the 12V
circuit breaker, enabled after start-up, trips when the sense
voltage exceeds 50mV for 22μs. To disable current limit,
connect this pin to 12V
3V
MOSFET. An internal 20μA current source charges the gate
of the external N-channel MOSFET. An internal clamp limits
the gate voltage to 6.2V above 3V
1.3mA pull-down current discharges 3V
During short-circuit a 310mA pull-down current between
3V
GATE
GATE
U
GATE
GATE
IN
OUT
OUT
SENSE
: 12V Supply, Current Sense and ADC Input. The
: Gate Drive for 3.3V Supply External N-Channel
: 12V Gate Drive Return; Foldback, ADC and Power
and 3V
: Gate Drive for 12V Supply External N-Channel
to ground when the external MOSFET is turned
and 12V
: 12V Supply Current Sense and ADC Input.
U
OUT
OUT
is activated.
U
is activated.
IN
.
OUT
CC
pin approaches ground. A
is generated from 12V
OUT
OUT
. During turn-off a
. During turn-off a
IN
GATE
GATE
and 12V
to ground.
to ground.
GATE
SENSE
pin
IN
.
3V
precharge circuit draws its power and reference voltage
from 3V
hysteresis, prevents any external MOSFET from turning
on when this pin is below 2.8V.
3V
Bad Input. Connect this pin to the source of the 3.3V supply
external N-channel MOSFET switch for gate drive return.
Power is considered bad if this pin drops below 2.9V. The
comparator on this pin has a built-in hysteresis of 11mV.
This pin is also an input to the ADC and the current limit
foldback circuit. A 190Ω active pull-down discharges 3V
to ground when the external MOSFET is turned off.
3V
Connect this pin to the output of the 3.3V current sense
resistor. The current limit circuit controls the 3V
to limit the sense voltage between the 3V
pins to 25mV or less during start-up and 75mV thereafter.
During start-up a foldback feature reduces the current
limit to 7.5mV as the 3V
circuit breaker, enabled after start-up, trips when the sense
voltage exceeds 25mV for 22μs. To disable current limit,
connect this pin to 3V
5V
FET. An internal 20μA current source charges the gate of
the external N-channel MOSFET. An internal clamp limits
the gate voltage to 6.2V above 5V
1.3mA pull-down current discharges 5V
During short-circuit a 250mA pull-down current between
5V
5V
voltage lockout circuit, with 16mV or 10mV of hysteresis,
prevents any external MOSFET from turning on when this
pin is below 4.38V or 2.8V depending on the state of the
CFG pin.
IN
OUT
SENSE
GATE
GATE
IN
: 3.3V Supply, Current Sense and ADC Input. The 1V
: 5V Supply, Current Sense and ADC Input. An under-
: 3.3V Gate Drive Return; Foldback, ADC and Power
: Gate Drive for 5V Supply External N-Channel MOS-
and 5V
: 3.3V Supply Current Sense and ADC Input.
IN
. An undervoltage lockout circuit, with 10mV
OUT
is activated.
IN
.
OUT
pin approaches ground. A
OUT
. During turn-off a
LTC4245
GATE
IN
and 3V
to ground.
GATE
SENSE
4245fa
9
OUT
pin