
LTC4556
1
4556f
The LTC
4556 provides all necessary power control, level
translation and supervisory functions for a smart card or
S.A.M. card interface. The part contains a low noise charge
pump** plus LDO for generating V
CC
power, as well as all
necessary level shifting circuitry.
The card voltage can be set to either 1.8V, 3V or 5V. The
LTC4556 includes a card detection channel with automatic
debounce circuitry. To reduce wiring costs, the LTC4556
interfaces to a microcontroller via a simple 4-wire serial
interface. Multiple devices may be connected in daisy-
chain fashion so that the number of wires to the card
socket board is independent of the number of sockets.
Status data is returned over the same interface.
Extensive security features ensure proper deactivation
sequencing in the event of a supply fault or a smart card
electrical fault. The smart card pins can withstand greater
than 10kV ESD in-situ with no additional components.
The LTC4556 is available in a small, low profile (0.75mm),
4mm
×
4mm QFN package.
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Handheld Payment Terminals
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Pay Telephones
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ATM Machines
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POS Terminals
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Computer Keyboards
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Multiple S.A.M. Sockets
, LTC and LT are registered trademarks of Linear Technology Corporation.
*U.S. Patent No. 6,356,140
**U.S. Patent No. 6,411,531
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Electrical Specifications Are ISO7816-3 and EMV
Compatible
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Control/Status Serial Port May be Daisy-Chained
for Multicard Applications
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Automatic Shutdown on Electrical Faults
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Buck Boost Charge Pump Generates 5V, 3V or 1.8V
Outputs (Smart Card Classes A, B and C)
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Automatic Level Translation
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Dynamic Pull-Ups Deliver Fast Signal Rise Times*
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Supervisory Functions Prevent Smart Card Faults
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Low Operating Current: 250
μ
A Typical
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V
IN
: 2.7V to 5.5V
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Ultralow Shutdown Current
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>10kV ESD on Smart Card Pins
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Small 24-Pin 4mm
×
4mm QFN Package
APPLICATIU
Smart Card Interface
with Serial Control
DESCRIPTIOU
4-WIRE
COMMAND
INTERFACE
4-WIRE
CARD
INTERFACE
SMART CARD
C8
C4
I/O
RST
CLK
V
CC
18
17
16
15
14
13
19
20
12
9
11
6
1
10
8
2
3
4
5
21
22
23
24
DV
CC
V
BATT
GND
FAULT
D
IN
D
OUT
SCLK
LD
DATA
R
IN
SYNC
ASYNC
C
PRES
UNDERV
240k
LTC4556
1
μ
F
1
μ
F
4556
TA01
1
μ
F
1
μ
F
0.1
μ
F
C
–
CPO
180k
INPUT
POWER
RST
5V/DIV
10
μ
s/DIV
4556 G11.eps
Deactivation Sequence
I/O
5V/DIV
V
CC
5V/DIV
CLK
5V/DIV
FEATURES
TYPICAL APPLICATIO
U