LTC1470 Просмотр технического описания (PDF) - Linear Technology

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LTC1470

Single and Dual PCMCIA Protected 3.3V/5V VCC Switches

Linear Technology 

LTC1470/LTC1471

PIN FUNCTIONS

LTC1471

AOUT, BOUT(Pins 1, 16, 8, 9): Output Pins. The outputs

of the LTC1471 are switched between three operating

states: OFF, 3.3V and 5V. These pins are protected against

accidental short circuits to ground by SafeSlot current

limit circuitry which protects the socket, the card, and the

system power supplies against damage. A second level of

protection is provided by thermal shutdown circuitry.

5VIN (Pins 2, 10): 5V Input Supply Pins. The 5VIN supply

pins serve two purposes. The first purpose is as the power

supply input for the 5V NMOS switches. The second

purpose is to provide power for the input, gate drive, and

protection circuitry. These pins must therefore be con-

tinuously powered.

EN1, EN0 (Pins 3, 4, 11, 12): Enable Inputs. The enable

inputs are designed to interface directly with industry

standard PCMCIA controllers and are high impedance

CMOS gates with ESD protection diodes to ground, and

should not be forced above 5VIN or below ground. All four

inputs have about 100mV of built-in hysteresis to ensure

clean switching between operating modes. The LTC1471

is designed to operate without 12V power. The gates of the

VCC NMOS switches are powered by charge pumps from

the 5VIN supply pins (see Applications Information section

for more detail). The enable inputs should be turned off at

least 100µs before the 5VIN power is removed to ensure

that all NMOS switch gates are fully discharged and are in

the high impedance mode.

GND (Pins 5, 13): Ground Connections.

3VIN (Pins 6, 7, 14, 15): 3V Input Supply Pins. The 3VIN

supply pins serve as the power supply input for the 3.3V

switches. These pins do not not provide any power to the

internal control circuitry, and therefore, do not consume

any power when unloaded or turned off.

BLOCK DIAGRAM (LTC1470 or 1/2 LTC1471)

TTL-TO-CMOS

EN0

CONVERTER

TTL-TO-CMOS

EN1

CONVERTER

BREAK-BEFORE-

MAKE SWITCH

AND CONTROL

GATE CHARGE

AND

DISCHARGE

CONTROL LOGIC

OSCILLATOR

AND BIAS

CHARGE

PUMP

GATE CHARGE

AND

DISCHARGE

CONTROL LOGIC

5VIN

0.14Ω

CURRENT LIMIT

AND THERMAL

SHUTDOWN

OUTPUT

0.12Ω

3VIN

LTC1470-BD01

14701fa

5

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