1640AH Просмотр технического описания (PDF) - Linear Technology

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1640AH

Negative Voltage Hot Swap Controller

Linear Technology 

LT1640AL/LT1640AH

PIN FUNCTIONS

OV (Pin 2): Analog Overvoltage Input. When OV is pulled

above the 1.223V low-to-high threshold, an overvoltage

condition is detected and the GATE pin will be immediately

pulled low. The GATE pin will remain low until OV drops

below the 1.203V high-to-low threshold.

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.

VEE (Pin 4): Negative Supply Voltage Input. Connect to

the lower potential of the power supply.

SENSE (Pin 5): Circuit Breaker Sense Pin. With a sense

resistor placed in the supply path between VEE and

SENSE, the circuit breaker will trip when the voltage

across the resistor exceeds 50mV. Noise spikes of less

than 2µs are filtered out and will not trip the circuit

breaker.

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, VEE and SENSE can be shorted together.

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 (VSENSE – VEE) < 50mV. The GATE pin is pulled

high by a 45µA 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 – pin

of the power module. When the DRAIN pin is below VPG,

the PWRGD or PWRGD pin will toggle. In some condi-

tions, the DRAIN pin is pulled below VEE. The part is not

damaged if the reverse DRAIN pin current is limited to

50mA.

VDD (Pin 8): Positive Supply Voltage Input. Connect this

pin to the higher potential of the power supply inputs and

the V + pin of the power module. The input supply voltage

ranges from 10V to 80V.

BLOCK DIAGRA

–

UV

+

REF

–

+

OV

50mV

–+ –

+

VEE SENSE

VDD

VCC AND

VCC

REFERENCE

GENERATOR

REF

OUTPUT

DRIVE

PWRGD/PWRGD

LOGIC

AND

GATE DRIVE

GATE

+–

+– VPG

VEE

DRAIN

1640A BD

5

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