9

LTC1472

VPP Gate Charge and Discharge Control

The VPP switches are designed to ramp slowly (typically

tens of

µs) between output modes to reduce supply

glitching when powering large capacitive loads.

VPP Switch Protection

Both VPP power switches are protected against accidental

short circuits with SafeSlot fold-back current limit circuits

which limit the short-circuit (0V) output current to typi-

ing currents are allowed at higher output voltages). Both

switches also have thermal shutdown.

VPP Switch Truth Table

VPP EN0

VPP EN1

00

0V

01

1

0

1

1

Hi-Z

supply switch matrix with SafeSlot current limit protection

on both outputs. It is designed to interface directly with

industry standard PCMCIA card controllers and to indus-

try standard 12V regulators.

Interfacing to the CL-PD6710 and the LT

Figure 1 shows the LTC1472 interfaced to a standard

PCMCIA slot controller and an LT1301 step-up switching

regulator. The LTC1472 accepts logic control directly

from the CL-PD6710 and in turn, controls the LT1301 to

provide clean 12V VPP programming power when re-

quired. The LT1301 is then shutdown (10

µA standby

current) at all other times to conserve power.

Switch Truth Table). Therefore, no “glue” logic is required

to interface to this PCMCIA compatible controller.

The LTC1472 provides SafeSlot current-limit protection

for the LT1301 step-up regulator, the system 3.3V and 5V

regulators, the socket and the card. Further, depending

upon the system regulator’s own current limits, it may

allow the system power supplies to continue operation

during a card/slot short circuit without losing data, etc.

VPP EN0

VPP EN1

GND

GND

LTC1472

SEL

SHDN

PGND

SW

SENSE

GND

LT1301

3.3V

0.1

µF

5V

5V

0.1

µF

CL-PD6710

VPP_PGM

PCMCIA

CARD SLOT

VPP1

VPP2

0.1

µF

10k

1

µF

TANT

OFF,

3.3V, 5V

0.1

µF

0.1

µF

47

µF

16V

TANT

(12V)

100

µF

10V

10

µH

COILCRAFT

DO1608-103

3

2

10k

+

+

+

6

7

4

5

NC

MBRS130LT3

12V, Hi-Z

1

8

LTC1472-F01

Figure 1. Direct Interface to Industry Standard PCMCIA

Controller and LT1301 Step-Up Switching Regulator