10

LTC1472

Interfacing to “365” Type Controllers

The LTC1472 also interfaces directly with “365” type

are connected differently than to the CL-PD6710 control-

ler because the “365” type controllers use active-high

Table). No “glue logic” is required to interface to this type

of PCMCIA compatible controller.

12V Power Requirements

Note that in Figure 2, a “local” 5V to 12V converter is not

used. The LTC1472 works equally well with or without

continuous 12V power. If the main power supply system

has 12V continuously available, simply connect it to the

ence and uses it to switch the internal VPP switches.

The 12V shutdown output can be used to shut down the

system 12V power supply (if not required for any purpose

other than VPP programming).

5V Power Requirements

The LTC1472 has been designed to operate without con-

tinuous 12V power, but continuous 5V power is required

should always be present when a card is powered (whether

it is a 5V or 3.3V only card).

If the 5V power must be turned off, for example, to enter

a 3.3V only full system “sleep” mode, the 5V supply must

be turned off at least 100

have been programmed to the Hi-Z or 0V states. This

ensures that the gates of the NMOS switches are com-

pletely discharged.

out 5V power. They must be programmed to the off state

at least 100

µs prior to turning the 5V supply off, or they

may be left in an indeterminate state.

Supply Bypassing

For best results, bypass the supply input pins with 1

µF

capacitors as close as possible to the LTC1472. Some-

times, much larger capacitors are already available at the

outputs of the 3.3V, 5V and 12V power supply. In this case,

it is still good practice to use 0.1

µF capacitors as close as

possible to the LTC1472, especially if the power supply

output capacitors are more than 2" away on the printed

circuit board.

VPP EN0

VPP EN1

GND

GND

LTC1472

3.3V

0.1

µF

5V

“365”TYPE

CONTROLLER

A_VPP_EN0

A_VPP_EN1

PCMCIA

CARD SLOT

VPP1

VPP2

10k

1

µF

TANT

(OFF, 3.3V, 5V)

10k

+

0.1

µF

0.1

µF

LTC1472-F02

12V SHUTDOWN

(OPTIONAL)

12V

Figure 2. Direct Interface to Industry Standard PCMCIA Controller and LT1301 Step-Up Switching Regulator