LTC1472 Linear Technology, LTC1472 Datasheet - Page 6

• Manufacturer Part Number: LTC1472
• Description: Protected PCMCIA VCC and VPP Switching Matrix
• Manufacturer: Linear Technology

LTC1472
PIN
Enable Input (Pins 3,4,7,8)
The two V
interface directly with industry standard PCMCIA control-
lers. They are high impedance CMOS gates with ESD
protection diodes to ground, and should not be forced
below ground. Both sets of inputs have about 100mV of
built-in hysteresis to ensure clean switching between
operating modes.
Shutdown Output (Pin 6)
The LTC1472 is designed to operate without continuous
12V power. The gates of the V
powered by charge pumps from the 5V
gates of the VPP NMOS switches are powered by charge
pumps powered from the V
present at the VPP
more details). Therefore, the external 12V regulator can be
shut down most of the time, and only turned on when
programming the socket VPP pin to 12V.
The shutdown output is active high; i.e. the system 12V
regulator is shut down when this output is held high and
turned on when this output is held low.
VPP
The VPP
purpose is to provide power and gate drive for the VPP
VPP
12V gate drive for the V
this 12V power is not available, gate drive is obtained
automatically from the 5V V
12V charge pump converter.
V
The V
and control circuitry for the VPP section of the LTC1472
and therefore must be continuously powered. The standby
quiescent current is typically 0.1 A when the VPP
is programmed to 0V or Hi-Z and only rises to micropower
levels when the VPP switches are active.
6
DD
U
IN
OUT
Supply (Pin 9)
DD
Supply (Pin 5)
FUNCTIONS
switch. The second purpose is to provide optional
IN
pin provides power for the input, charge pump
CC
U
supply pin serves two purposes. The first
and two VPP Enable inputs are designed to
IN
pin (see Application Information for
U
CC(IN)
DD
-VPP
DD
supply by an internal 5V to
supply when 12V is not
CC
OUT
NMOS switches are
switch. If, however,
IN
supply, and the
OUT
pin
IN
-
V
The V
V
It can also be connected directly to a 3.3V or 5V power
supply if desired. This supply pin does not provide any
power to the internal control circuitry and is simply the
input to the V
consume any power when unloaded or turned off.
5V
The 5V
pose is as the power supply input for the 5V NMOS switch.
The second purpose is to provide power for the input, gate
drive and protection circuitry for both the 3.3V and 5V V
switches, this pin must be continuously powered .
The enable inputs should be turned off (both asserted high
or both asserted low) at least 100 s before the 5V
is removed to ensure that both V
fully discharged and both switches are in the high imped-
ance mode.
3V
The 3V
the 3.3V switch. This pin does not provide any power to the
internal control circuitry and therefore does not consume
any power when unloaded or turned off.
V
The V
three operating states: OFF, 3.3V, and 5V. The VPP output
is switched between four operating states: 0, V
Hi-Z. Both pins are protected against accidental short-
circuit conditions to ground by independent SafeSlot
foldback current-limit circuitry which protects the socket,
card and the system power supplies against damage. A
second level of protection is provided by independent
thermal shut down circuitry which protects each switch
against overtemperature conditions.
CC(IN)
CC(OUT)
CC(OUT)
IN
IN
Supply (Pin 2)
Supply (Pins 14,15)
CC(IN)
CC
IN
IN
Supply (Pin 12)
output of the LTC1472 is switched between the
pin from the V
and VPP
supply pin serves as the power supply input for
supply pin serves two purposes. The first pur-
supply pin is typically connected directly to the
CC(IN)
OUT
-VPP
Output (Pins 1,11,16)
CC
OUT
switch section of the LTC1472.
switch and therefore does not
CC
NMOS switch gates are
CC
, 12V and
IN
power
CC