Datasheet

9
LTC1472
1472fa
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-
OPERATION
U
APPLICATIONS INFORMATION
WUU
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cally 100mA when protecting the 12V VPP
IN
supply and
60mA when protecting the V
CC(IN)
supply. (Higher operat-
ing currents are allowed at higher output voltages). Both
switches also have thermal shutdown.
VPP Switch Truth Table
VPP EN0 VPP EN1 VPP
OUT
000V
01V
CC(IN)
1 0 VPP
IN
1 1 Hi-Z
The LTC1472 is a complete single slot V
CC
and VPP power
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
®
1301
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 (10µA standby
current) at all other times to conserve power.
The XOR V
CC
input function allows the LTC1472 to inter-
face directly to the active-low V
CC
control outputs of the
CL-PD6710 for 3.3V/5V voltage selection (see the V
CC
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.
3V
IN
3V
IN
SHDN
5V
IN
V
DD
VPP EN0
VPP EN1
V
CC
EN0
V
CC
EN1
VPP
IN
VPP
OUT
V
CC(IN)
V
CC(OUT)
V
CC(OUT)
GND
GND
LTC1472
V
IN
SEL
SHDN
PGND
SW
SENSE
I
LIM
GND
LT1301
3.3V
0.1µF
5V
5V
0.1µF
CL-PD6710
VPP_V
CC
VPP_PGM
V
CC
_3
V
CC
_5
PCMCIA
CARD SLOT
VPP1
VPP2
V
CC
V
CC
0.1µF
10k
1µF
TANT
OFF,
3.3V, 5V
0.1µF
0.1µF
47µF
16V
TANT
(12V)
100µF
10V
10µH
COILCRAFT
DO1608-103
3
2
10k
+
+
+
6
7
4
5
NC
MBRS130LT3
0V, V
CC
,
12V, Hi-Z
1
8
LTC1472-F01
Figure 1. Direct Interface to Industry Standard PCMCIA
Controller and LT1301 Step-Up Switching Regulator