8

LTC1314/LTC1315

+

1

µF

SHDN

Q1A

1/2 Si9956DY

Si9956DY

Q2A

Q2B

VPP1

VPP2

1314/15 F03

LTC1314

PCMCIA

CONTROLLER

EN0

EN1

GND

PGND

2N7002

13V TO 20V

(MAY BE FROM

AUXILLARY

WINDING)

200pF

121k

1%

56.2k

1%

LT1121

SHDN

5V

5V

ADJ

DRV5

DRV3

GND

5V

3.3V

PC CARD

SOCKET

+

1

µF

0.1

µF

+

10

µF

100k

the asymmetrical turn-on and turn-off of the MOSFETs.

The LT1301 switching regulator is in shutdown mode and

consumes only 10

µA until the VPP pins require 12V.

The VPP switching is accomplished by a combination of

the LTC1314/LTC1315 and LT1301. The LT1301 is in

shutdown mode to conserve power until the VPP pins

require 12V. When the VPP pins require 12V, the LT1301

is activated and the LTC1314/LTC1315’s internal switches

capable of delivering 12V at 120mA maintaining high

efficiency. The LTC1314/LTC1315’s break-before-make

and slope-controlled switching will ensure that the output

voltage transition will be smooth, of moderate slope, and

without overshoot. This is critical for flash memory prod-

ucts to prevent damaging parts from overshoot and

ringing exceeding the 13.5V device limit.

With Higher Voltage Supplies Available

Often systems have an available supply voltage greater

than 12V. The LTC1314/LTC1315 can be used in conjunc-

tion with an LT1121 linear regulator to supply the PC card

socket with all necessary voltages. Figures 3 and 4 show

these circuits. The LTC1314/LTC1315 enable the LT1121

linear regulator only when 12V is required at the VPP pins.

In all other modes the LT1121 is in shutdown mode and

consumes only 16

µA. The LT1121 also provides thermal

shutdown and current limiting features to protect the

socket, the card and the system regulator.

Supply Bypassing

with 1

capacitor for noise reduction and electrostatic discharge

(ESD) damage prevention. Larger values of output capaci-

tor will create large current spikes during transitions,

pins.

Figure 3. LTC1314 with the LT1121 Linear Regulator