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PDF LTC1755EGN Data sheet ( Hoja de datos )
| Número de pieza | LTC1755EGN | |
| Descripción | Smart Card Interface | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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FEATURES
s Fully ISO 7816-3 and EMV Compliant
(Including Auxiliary I/O Pins)
s Buck-Boost Charge Pump Generates 3V or 5V
s 2.7V to 6.0V Input Voltage Range
s Very Low Operating Current: 60µA
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 3V ↔ 5V Signal Level Translators
s Shutdown Current: < 1µA
s Short-Circuit and Overtemperature Protected
s Alarm Output Indicates Fault Condition
s Multiple Devices May Be Paralleled for
Multicard Applications
s Available in 24-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
LTC1755
Smart Card Interface
October 1999
DESCRIPTION
The LTC®1755 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 on-chip level
shifters allow 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 6.0V, 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. Multiple
LTC1755 devices may be paralleled and connected to a
single controller for multicard applications.
Battery life is maximized by 60µA operating current and
1µA shutdown current. The 24-pin SSOP package mini-
mizes PCB area for compact portable systems.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
3.3V
SMART CARD
PRESENT SWITCH
C3
10µF
GND VCC
AUX1
SMART CARD
AUX2
I/O
RST
CLK
1
PRES
24
5V/3V
2
PWR
23
CARD
3
CS
22
ALARM
4 21
NC/NO READY
C2
10µF
5 20
GND DVCC
6 VIN LTC1755 C – 19
7
VCC
C + 18
8 17
AUX1 AUX1IN
9 16
AUX2 AUX2IN
10
I/O
15
DATA
11
RST
14
RIN
12
CLK
13
CIN
C1
0.68µF
µCONTROLLER
1755 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  
LTC1755
PIN FUNCTIONS
due to the pull-up current source. The I/O pin becomes a
low impedance to ground during the Idle state. It does not
become active until READY goes low indicating that VCC is
stable.
Once READY is low the I/O pin is protected against short
circuits to VCC by current limiting to 5mA maximum.
The DATA-I/O channel is bidirectional for half-duplex
transmissions. Its idle state is H-H. Once an L is detected
on one side of the channel the direction of transmission is
established. Specifically, the side which received an L first
is now the input, and the opposite side is the output.
Transmission from the output side back to the input side
is inhibited, thereby preventing a latch condition. Once the
input side releases its L, both sides return to H, and the
channel is now ready for a new L to be transmitted in either
direction. If an L is forced externally on the output side, and
it persists until after the L on the input side is released, this
illegal input will not be transmitted to the input side
because the transmission direction will not have changed.
The direction of transmission can only be established from
the idle (H-H) state and is determined by the first receipt
of an L on either side.
RST (Pin 11): (Output) Level-Shifted Reset Output Pin.
This pin should be connected to the Smart Card RST
contact. The RST pin becomes a low impedance to ground
during the Idle state (see the State Diagram). The reset
channel does not become active until the READY signal
goes low indicating that VCC is stable.
Short-circuit protection is provided on the RST pin by
comparing RST with RIN. If these signals differ for several
microseconds then the LTC1755 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).
CLK (Pin 12): (Output) Level-Shifted Clock Output Pin.
This pin should be connected to the Smart Card CLK
contact. The CLK pin becomes a low impedance to ground
during the Idle state (see the State Diagram). The clock
channel does not become active until the READY signal
goes low indicating that VCC is stable.
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 LTC1755 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 13): (Input) Clock Input Pin from the Microcon-
troller. During the Active state this signal appears on the
CLK pin after being level-shifted and buffered.
DVCC sets the logic reference level for the CIN pin.
RIN (Pin 14): (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.
DVCC sets the logic reference level for the RIN pin.
DATA (Pin 15): (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 or when CS is high
(see the State Diagram). It does not become active until the
READY signal goes low indicating that VCC is stable.
AUX2IN (Pin 16): (Input/Output) Microcontroller Side
Auxiliary I/O pin. This pin is used for bidirectional auxiliary
data transfer between the microcontroller and the Smart
Card. It has the same characteristics as the DATA pin.
AUX1IN (Pin 17): (Input/Output) Microcontroller Side
Auxiliary I/O Pin. This pin is used for bidirectional auxiliary
data transfer between the microcontroller and the Smart
Card. It has the same characteristics as the DATA pin.
C+, C– (Pins 18, 19): 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.
5
5 Page 
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
LTC1755
GN Package
24-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
0.337 – 0.344*
(8.560 – 8.738)
24 23 22 21 20 19 18 17 16 15 1413
0.033
(0.838)
REF
0.229 – 0.244
(5.817 – 6.198)
0.150 – 0.157**
(3.810 – 3.988)
1 2 3 4 5 6 7 8 9 10 11 12
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
0.053 – 0.068
(1.351 – 1.727)
0.008 – 0.012
(0.203 – 0.305)
0.004 – 0.0098
(0.102 – 0.249)
0.0250
(0.635)
BSC
GN24 (SSOP) 1098
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC1755EGN.PDF ] | |
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