LTC1472 Linear Technology, LTC1472 Datasheet - Page 10

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

APPLICATIONS
LTC1472
Interfacing to “365” Type Controllers
The LTC1472 also interfaces directly with “365” type
controllers as shown in Figure 2. The V
are connected differently than to the CL-PD6710 control-
ler because the “365” type controllers use active-high
logic control of the V
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
VPP
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
10
IN
pin. Internal circuitry automatically senses its pres-
Figure 2. Direct Interface to Industry Standard PCMCIA Controller and LT1301 Step-Up Switching Regulator
12V SHUTDOWN
U
(OPTIONAL)
CC
switches (see the V
INFORMATION
3.3V
12V
CONTROLLER
U
5V
“365”TYPE
A_VPP_EN0
A_VPP_EN1
A_V
A_V
CC
CC
_EN0
_EN1
W
0.1 F
0.1 F
CC
CC
Enable inputs
Switch Truth
5V
V
VPP EN0
VPP EN1
V
V
3V
DD
CC
CC
U
IN
GND
IN
EN0
EN1
LTC1472
3V
IN
GND
V
V
VPP
CC(OUT)
CC(OUT)
V
SHDN
VPP
CC(IN)
OUT
IN
10k
at the V
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 s after the V
have been programmed to the Hi-Z or 0V states. This
ensures that the gates of the NMOS switches are com-
pletely discharged.
Also, the V
out 5V power. They must be programmed to the off state
at least 100 s 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 F
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 F 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.
10k
DD
+
and 5V
CC
(0V, V
0.1 F
1 F
TANT
(OFF, 3.3V, 5V)
switches cannot be operated properly with-
CC
, 12V, Hi-Z)
IN
supply pins for proper operation and
VPP1
VPP2
V
V
CARD SLOT
CC
CC
PCMCIA
LTC1472-F02
CC
and VPP switches