LT1640 Linear Technology, LT1640 Datasheet - Page 5

• Manufacturer Part Number: LT1640
• Description: Negative Voltage Hot Swap Controller
• Manufacturer: Linear Technology

BLOCK DIAGRA
PIN
UV (Pin 3): Analog Undervoltage Input. When UV is
pulled below the 1.223V high to low threshold, an under-
voltage condition is detected and the GATE pin will be
immediately pulled low. The GATE pin will remain low
until UV rises above the 1.243 low to high threshold.
The UV pin is also used to reset the electronic circuit
breaker. If the UV pin is cycled low and high following the
trip of the circuit breaker, the circuit breaker is reset and
a normal power-up sequence will occur.
V
the lower potential of the power supply.
SENSE (Pin 5): Circuit Breaker Sense Pin. With a sense
resistor placed in the supply path between V
SENSE, the circuit breaker will trip when the voltage
across the resistor exceeds 50mV. Noise spikes of less
than 2 s are filtered out and will not trip the circuit
breaker.
EE
U
(Pin 4): Negative Supply Voltage Input. Connect to
FUNCTIONS
U
UV
OV
U
REF
W
–
–
+
+
V
EE
50mV
SENSE
–
+
–
+
EE
and
If the circuit breaker trip current is set to twice the normal
operating current, only 25mV is dropped across the
sense resistor during normal operation. To disable the
circuit breaker, V
GATE (Pin 6): Gate Drive Output for the External
N-Channel. The GATE pin will go high when the following
start-up conditions are met: the UV pin is high, the OV pin
is low and (V
high by a 45 A current source and pulled low with a
50mA current source.
DRAIN (Pin 7): Analog Drain Sense Input. Connect this
pin to the drain of the external N-channel and the V
of the power module. When the DRAIN pin is below V
the PWRGD or PWRGD pin will toggle.
V
pin to the higher potential of the power supply inputs and
the V
ranges from 10V to 80V.
DD
GENERATOR
GATE DRIVE
REFERENCE
V
(Pin 8): Positive Supply Voltage Input. Connect this
CC
LOGIC
GATE
+
V
AND
DD
pin of the power module. The input supply voltage
AND
SENSE
V
REF
CC
EE
V
+
+
–
– V
EE
and SENSE can be shorted together.
V
EE
PG
DRAIN
) < 50mV. The GATE pin is pulled
–
LT1640L/LT1640H
OUTPUT
DRIVE
1640 BD
PWRGD/PWRGD
–
5
pin
PG
,