LTC4244IGN datasheet(9/28 Pages) LINER

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LTC4244/LTC4244-1

42441f

3.3VIN (Pin 17): 3.3V Supply Sense Input. An undervolt-

age lockout circuit prevents the switches from turning on

when the voltage at the 3.3VIN pin is less than 2.5V. If no

3.3V input supply is available, short the 3.3VIN pin to the

5VIN pin.

3.3VOUT (Pin 18): Analog Input Used to Monitor the 3.3V

Output Supply Voltage. The PWRGD pin cannot pull low

until the 3.3VOUT pin voltage exceeds 2.9V. If no 3.3V input

supply is available, tie the 3.3VOUT pin to the 5VOUT pin. A

200

Ω active pull-down discharges 3.3VOUT to ground

when the power switches are turned off.

PI FU CTIO S

VEEOUT (Pin 19): -12V Supply Output. A 1Ω switch is

connected between VEEIN and VEEOUT. VEEOUT must be less

than –11.1V before the PWRGD pin pulls low. The VEEOUT

power good comparator is disabled for the LTC4244-1. A

390

Ω active pull-up discharges VEEOUT to ground when

the power switches are turned off.

12VOUT (Pin 20): 12V Supply Output. A 0.5Ω switch is

connected between 12VIN and 12VOUT. 12VOUT must

exceed 11.1V before the PWRGD pin can pull low. A 440

Ω

active pull-down discharges 12VOUT to ground when the

power switches are turned off.

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