LTC1955_15 Datasheet, PDF (1/22 Pages) Linear Technology – Dual Smart Card Interface with Serial Control

LTC1955
Dual Smart Card Interface
with Serial Control
Features
Description
n _{Compatible with ISO7816-3 and EMV Electrical}
Specifications
n _{Power Management and Control for Two Smart Cards}
n _{Control/Status Serial Port May Be Daisychained 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 _{Independent 5V/3V/1.8V Level Control for Both Cards}
n _{Automatic Level Translation}
n _{Supervisory Functions Prevent Smart Card Faults}
n _{Low Operating Current: 250µA Typical}
n _{Ultralow Shutdown Current}
n _{>10kV ESD on Smart Card Pins}
n _{Small 32-Lead 5mm × 5mm 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}
The LTC^®1955 provides all necessary supervisory and
power control functions for two smart cards, two S.A.M.
cards or a combination of S.A.M. and smart cards. It
provides a charge pump for battery-powered applications
as well as all necessary level shifting circuitry.
The card voltages can be independently set to 1.8V, 3V or
5V. Both card interfaces include a card detection channel
with automatic debounce circuitry. To reduce wiring costs,
the LTC1955 interfaces to a microcontroller via a simple
4-wire serial interface. Multiple devices may be connected
in daisychain 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 LTC1955 is available in a low profile (0.75mm) 5mm
× 5mm QFN package.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6356140, 6411531.
Typical Application
Deactivation Sequence
RST A
5V/DIV
CLK A
5V/DIV
I/O A
5V/DIV
V_CCA
5V/DIV
10µs/DIV
1955 TA01a
INPUT
POWER
4-WIRE
COMMAND
INTERFACE
4-WIRE
CARD
INTERFACE
0.1µF
240k
180k
23
1
UNDERV
2
12,13 ^DVCC
PRES A
V_BATT
4.7µF
LTC1955
9, 10
GND
3
C8A
C4A ⁴
24
FAULT
I/O A ⁵
6
RST A
27
7
28 ^DIN
26 ^DOUT
CLK A
V_CCA ⁸
SCLK
25
21
LD
PRES B
29 _DATA
30
32
R_IN
SYNC
31 _ASYNC
22 _NC/NO
C⁺ C^–
14
11
1µF
I/O B ²⁰
RST B ¹⁹
CLK B ¹⁸
V_CCB ¹⁷
CPO
15
4.7µF
CARD
DETECT
1µF
1µF
For more information www.linear.com/LTC1955
SMART CARD
VENDOR CARD
1955 TA01b
1955fd
1