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PDF LTC1756EGN Data sheet ( Hoja de datos )
| Número de pieza | LTC1756EGN | |
| Descripción | Smart Card Interface | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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FEATURES
s Fully ISO 7816-3 and EMV Compliant
s Buck-Boost Charge Pump Generates 3V or 5V
s 2.7V to 5.5V Input Voltage Range
s 3V↔ 5V Signal Level Translator
s > 10kV ESD on All Smart Card Pins
s Dynamic Pull-Ups Deliver Fast Signal Rise Times
s Soft Start Limits Inrush Current at Turn On
s Very Low Operating Current: 75µA
s Shutdown Current: < 2.5µA
s Short-Circuit and Overtemperature Protected
s Available in 16-Pin SSOP Package
U
APPLICATIONS
s Handheld Payment Terminals
s Pay Telephones
s ATMs
s Key Chain Readers
s Smart Card Readers
Final Electrical Specifications
LTC1756
Smart Card Interface
February 2000
DESCRIPTION
The LTC®1756 universal Smart Card interface is fully
compliant with ISO 7816-3 and EMV specifications. It
provides the smallest and simplest interface circuit be-
tween a host microcontroller and general purpose Smart
Cards.
An internal charge pump DC/DC converter delivers regu-
lated 3V or 5V to the Smart Card, while an on-chip level
shifter allows a connection to a low voltage controller. All
Smart Card contacts are rated for 10kV ESD, eliminating
the need for external ESD protection devices.
Input voltage may range from 2.7V to 5.5V, allowing direct
connection to a battery. Automatic DC/DC converter soft
start mitigates start-up problems that may result when the
input power is provided by another regulator.
Battery life is maximized by 75µA operating current and
2µA shutdown current. The 16-pin SSOP package mini-
mizes PCB area for compact portable systems.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
SMART CARD
PRESENT SWITCH
N.O.
C3
10µF
GND VCC
SMART CARD
I/O
RST
CLK
3.3V
C2
10µF
1
PRES
16
5V/3V
2
PWR
15
CARD
3
GND
14
READY
4
VIN
C – 13
5
LTC1756
VCC
C+
12
6
I/O
11
DATA
7
RST
10
RIN
8
CLK
9
CIN
C1
0.68µF
µCONTROLLER
1756 TA01
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
1
1 page  
LTC1756
PIN FUNCTIONS
Short-circuit protection is provided on the CLK pin by com-
paring CLK with CIN. If these signals differ for several mi-
croseconds then the LTC1756 switches to the Alarm state.
This fault checking is only performed after the VCC pin has
reached its final value (as indicated by the READY pin).
The clock channel is optimized for signal integrity in order
to meet the stringent duty cycle requirements of the EMV
specification. Therefore, to reduce power in low power
applications, clock stop mode is recommended when data
is not being exchanged.
CIN (Pin 9): (Input) Clock Input Pin from the Microcontrol-
ler. During the Active state this signal appears on the CLK
pin after being level-shifted and buffered.
RIN (Pin 10): (Input) Reset Input Pin from the Microcon-
troller. During the Active state this signal appears on the
RST pin after being level-shifted and buffered.
DATA (Pin 11): (Input/Output) Microcontroller Side Data
I/O Pin. This pin is used for bidirectional data transfer
between the microcontroller and the Smart Card. The
microcontroller data pin must be open drain and must be
able to sink up to 250µA when driving the DATA pin low
due to the pull-up current source. The DATA pin becomes
high impedance during the Idle state (see the State Dia-
gram). It does not become active until the READY signal
goes low indicating that VCC is stable.
C+, C– (Pins 12, 13): Charge Pump Flying Capacitor
Terminals. Optimum values for the flying capacitor range
from 0.68µF to 1µF. Best performance is achieved with a
low ESR X7R ceramic capacitor.
READY (Pin 14): (Output) Readiness Indicator of the
Smart Card Supply Voltage (VCC). When the LTC1756 is
placed in the Active state the soft start feature slowly
ramps the VCC voltage. A low on the READY pin indicates
that VCC has reached its final value.
The READY pin is configured as an open-drain pull-down
with a weak pull-up current source.
The READY pin also indicates if the LTC1756 is in Alarm
mode. The LTC1756 detects faults such as VCCunderrange
for at least 5µs, overtemperature shutdown, CLK or RST
invalid output levels and card removal during Active
state. CLK or RST invalid and overtemperature faults are
detected only after VCC has reached its final value. VCC
underrange and card removal during Active faults are
detected at any time during the Active period (i.e., once
PWR = 0V).
If the LTC1756 has been activated normally and VCC, the
card voltage, has reached its final value then READY will
go low indicating normal operation. If, following this, a
fault occurs and the LTC1756 enters the Alarm state, the
READY pin will return high.
In the event that a fault precedes the activation of VCC,
such as a direct short circuit from VCC to GND, the
LTC1756 will attempt to operate until the fault is detected
and then automatically shut down and enter the Alarm
state. In this case the READY pin will never go low after the
command to start the smart card is given (i.e., PWR = 0V).
If the LTC1756 enters the Alarm state it can only be
cleared by returning the PWR pin high.
CARD (Pin 15): (Output) Level-Shifted and Debounced
PRES Signal from the Smart Card Acceptor Switch. When
a valid card indication appears, this pin communicates the
presence of the Smart Card to the microcontroller. The
CARD pin has an open-drain active pull-down with a weak
pull-up current source. The debounce circuit ensures that
a card has been present for a continuous period of at least
40ms before asserting CARD low. The CARD pin returns
high within 50µs of card removal.
5V/3V (Pin 16): (Input) Controls the output voltage (VCC)
of the DC/DC converter during the Active state. A valid high
sets VCC to 5V. A valid low sets VCC to 3V. The 5V/3V pin
is latched on the falling edge of the PWR pin. When PWR
is low, changes on the 5V/3V pin are ignored. To change
the voltage on VCC the LTC1756 must first be returned to
the Idle state by bringing the PWR pin high.
5
5 Page 
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
LTC1756
GN Package
16-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
0.189 – 0.196*
(4.801 – 4.978)
16 15 14 13 12 11 10 9
0.009
(0.229)
REF
0.229 – 0.244
(5.817 – 6.198)
0.150 – 0.157**
(3.810 – 3.988)
0.007 – 0.0098
(0.178 – 0.249)
0.015
(0.38
±
±
0.004
0.10)
×
45°
0° – 8° TYP
0.016 – 0.050
(0.406 – 1.270)
* DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1 234 5678
0.053 – 0.068
(1.351 – 1.727)
0.004 – 0.0098
(0.102 – 0.249)
0.008 – 0.012
(0.203 – 0.305)
0.0250
(0.635)
BSC
GN16 (SSOP) 1098
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC1756EGN.PDF ] | |
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