LTC4556_15 Datasheet, PDF (1/22 Pages) Linear Technology – Smart Card Interface with Serial Control

Features
n _{Electrical Specifications Are ISO7816-3 and EMV}
Compatible
n _{Control/Status Serial Port May be Daisy-Chained}
for Multicard Applications
n _{Automatic Shutdown on Electrical Faults}
n _{Buck Boost Charge Pump Generates 5V, 3V or 1.8V}
Outputs (Smart Card Classes A, B and C)
n _{Automatic Level Translation}
n _{Dynamic Pull-Ups Deliver Fast Signal Rise Times}
n _{Supervisory Functions Prevent Smart Card Faults}
n _{Low Operating Current: 250µA Typical}
n _{VIN: 2.7V to 5.5V}
n _{Ultralow Shutdown Current}
n _{>10kV ESD on Smart Card Pins}
n _{Small 24-Lead 4mm × 4mm QFN Package}
Applications
n _{Handheld Payment Terminals}
n _{Pay Telephones}
n _{ATM Machines}
n _{POS Terminals}
n _{Computer Keyboards}
n _{Multiple S.A.M. Sockets}
LTC4556
Smart Card Interface
with Serial Control
Description
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.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents, including 6356140, 6411531.
Typical Application
INPUT
POWER _0.1µF
1µF
4-WIRE
COMMAND
INTERFACE
240k
180k
20
1
UNDERV
19
10 ^DVCC
PRES
V_BATT
LTC4556
8
GND
18
C8
C4 ¹⁷
6
FAULT
I/O ¹⁶
RST ¹⁵
21
14
22 ^DIN
23 ^DOUT
CLK
V_CC ¹³
SCLK
24
1µF
LD
4-WIRE
CARD
INTERFACE
2 _DATA
3
4
R_IN
SYNC
5 _ASYNC
C⁺ C^–
11
9
1µF
CPO
12
1µF
SMART CARD
4556 TA01
RST
5V/DIV
CLK
5V/DIV
I/O
5V/DIV
V_CC
5V/DIV
For more information www.linear.com/LTC4556
Deactivation Sequence
10µs/DIV
4556 G11.eps
4556fb
1