Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsInterface ICsInterface IC - customised SSOP 24

LTC1755/LTC1756

Smart Card Interface

■

Fully ISO 7816-3 and EMV Compliant

(Including Auxiliary I/O Pins)

■

Buck-Boost Charge Pump Generates 3V or 5V

■

2.7V to 6.0V Input Voltage Range (LTC1755)

■

Very Low Operating Current: 60µA

■

>10kV ESD on All Smart Card Pins

■

Dynamic Pull-Ups Deliver Fast Signal Rise Times

■

Soft-Start Limits Inrush Current at Turn On

■

↔

5V Signal Level Translators

■

Shutdown Current: <1µA

■

Short-Circuit and Overtemperature Protected

■

Alarm Output Indicates Fault Condition

■

Multiple Devices May Be Paralleled for

Multicard Applications (LTC1755)

■

Available in 16- and 24-Pin SSOP Packages

The LTC

1755/LTC1756 universal Smart Card interfaces

are fully compliant with ISO 7816-3 and EMV specifica-

tions. The parts provide the smallest and simplest inter-

face circuits between 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. Internal soft-start mitigates start-

up problems that may result when the input power is

provided by another regulator. Multiple 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 narrow SSOP packages mini-

mize PCB area for compact portable systems.

, LTC and LT are registered trademarks of Linear Technology Corporation.

■

Handheld Payment Terminals

■

Pay Telephones

■

ATMs

■

Key Chain Readers

■

Smart Card Readers

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

LTC1755

PRES

PWR

NC/NO

GND

AUX1

AUX2

I/O

RST

CLK

10µF

AUX1

AUX2

I/O

RST

CLK

0.68µF

GND

SMART CARD

17556 TA01

SMART CARD

PRESENT SWITCH

µCONTROLLER

3.3V

5V/3V

CARD

ALARM

READY

–

AUX1IN

AUX2IN

DATA

RIN

CIN

Summary of content (16 pages)

PAGE 1
LTC1755/LTC1756 Smart Card Interface U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LTC®1755/LTC1756 universal Smart Card interfaces are fully compliant with ISO 7816-3 and EMV specifications. The parts provide the smallest and simplest interface circuits between a host microcontroller and general purpose Smart Cards. Fully ISO 7816-3 and EMV Compliant (Including Auxiliary I/O Pins) Buck-Boost Charge Pump Generates 3V or 5V 2.7V to 6.
PAGE 2
LTC1755/LTC1756 W W W AXI U U ABSOLUTE RATI GS (Note 1) VIN to GND (LTC1755) ............................. – 0.3V to 6.5V VIN to GND (LTC1756) ............................. – 0.3V to 6.0V DVCC to GND (LTC1755) .......................... – 0.3V to 5.5V VCC to GND .............................................. – 0.3V to 5.5V Digital Inputs to GND (LTC1755) .............................. – 0.3V to DVCC + 0.3V Digital Inputs to GND (LTC1756) ................................. – 0.3V to VIN + 0.
PAGE 3
LTC1755/LTC1756 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full specified temperature range, otherwise specificatons are at TA = 25°C. PARAMETER CONDITIONS MIN TYP MAX UNITS LTC1755 (VIN = 2.7V to 6V, DVCC = 2V to 5.5V, unless otherwise noted) VIN Operating Voltage DVCC Operating Voltage ● 2.7 ● 2.0 6 V 5.
PAGE 4
LTC1755/LTC1756 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full specified temperature range, otherwise specificatons are at TA = 25°C. DVCC = 2V to 5.5V, unless otherwise noted (Note 4). PARAMETER CONDITIONS MIN TYP MAX UNITS Controller Inputs/Outputs DATA, AUX1IN, AUX2IN, DVCC = 3V High Input Voltage Threshold (VIH) (Note 4) ● DVCC – 0.6 0.5 • DVCC Low Input Voltage Threshold (VIL) (Note 4) ● 0.
PAGE 5
LTC1755/LTC1756 U W TYPICAL PERFOR A CE CHARACTERISTICS 100 150 IL = 35mA TA = 25°C I/O, AUX1, AUX2 Short-Circuit Current vs Temperature I/O, AUX1, AUX2 SHORT-CIRCIUT CURRENT (mA) Card Detection Debounce Period vs Temperature Power Efficiency vs Input Voltage CFLY = 0.68µF 125 DEBOUNCE DELAY (ms) EFFICIENCY (%) 75 VCC = 3V 50 VCC = 5V 25 100 VIN = 6V 75 VIN = 3.3V VIN = 2.7V 50 25 0 3 0 –50 6 4 5 VIN INPUT VOLTAGE (V) 0 25 50 TEMPERATURE (°C) –25 17556 G01 12 DVCC = 5.
PAGE 6
LTC1755/LTC1756 U W TYPICAL PERFOR A CE CHARACTERISTICS DVCC, VIN Supply Current In Shutdown 9.0 VIN Shutdown Current vs Input Voltage 1.0 VIN = 3V TA = 25°C 6.0 4.5 DVCC 3.0 VIN 0 1 5 3 4 DVCC INPUT VOLTAGE (V) 2 6 17556 G10 U U U PI FU CTIO S 0.6 0.4 0.2 1.5 0 DVCC = 0 TA = 25°C 0.8 INPUT CURRENT (µA) INPUT CURRENT (µA) 7.
PAGE 7
LTC1755/LTC1756 U U U PI FU CTIO S LTC1755/LTC1756 Note: If a normally closed switch is used, a small current (several microamperes) will flow through the switch whenever a Smart Card is not present. For ultralow power consumption in shutdown, a normally open switch is optimum. DVCC sets the logic reference level for the NC/NO pin. GND (Pins 5/3): Ground Reference for the IC. This pin should be connected to a low impedance ground plane.
PAGE 8
LTC1755/LTC1756 U U U PI FU CTIO S LTC1755/LTC1756 microseconds then the LTC1755/LTC1756 switch 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.
PAGE 9
LTC1755/LTC1756 U U U PI FU CTIO S LTC1755/LTC1756 The READY pin is configured as an open-drain pull-down with a weak pull-up current source. This permits wiredOR connections of multiple LTC1755/LTC1756s to a single microcontroller. ALARM (Pin 22, LTC1755 Only): (Output) A low on this pin indicates that a fault has occurred and that the LTC1755 is in the Alarm state (see the State Diagram).
PAGE 10
LTC1755/LTC1756 W BLOCK DIAGRA DVCC PRES 5V/3V τ PWR CARD CS (LTC1755 ONLY) ALARM (LTC1755 ONLY) NC/NO (LTC1755 ONLY) READY DC/DC CONVERTER AND CONTROL LOGIC GND DVCC (LTC1755 ONLY, CONNECTED INTERNALLY TO VIN ON LTC1756) VIN C– VCC C+ * * AUX1 (LTC1755 ONLY) AUX1IN (LTC1755 ONLY) * * AUX2 (LTC1755 ONLY) AUX2IN (LTC1755 ONLY) * * I/O DATA RST RIN CLK CIN *DYNAMIC PULL-UP CURRENT SOURCE 10 17556 BD
PAGE 11
LTC1755/LTC1756 U W U U APPLICATIO S I FOR ATIO 10kV ESD Protection All Smart Card pins (CLK, RST, I/O, AUX1, AUX2, VCC and GND) can withstand over 10kV of human body model ESD in situ. In order to ensure proper ESD protection, careful board layout is required. The GND pin should be tied directly to a ground plane. The VCC capacitor should be located very close to the VCC pin and tied immediately to the ground plane.
PAGE 12
LTC1755/LTC1756 U W U U APPLICATIO S I FOR ATIO released by comparing its slew rate with an internal reference value. If a valid transition is detected, a large pull-up current enhances the edge rate on the node. The higher slew rate corroborates the decision to charge the node thereby effecting a dynamic form of hysteresis. Once the node has reached the power supply voltage the internal comparator requires several hundred nanoseconds to reset.
PAGE 13
LTC1755/LTC1756 U W U U APPLICATIO S I FOR ATIO I2CTM Compatibility Some smart cards still require I2C compatibility. In the I2C format it is permissible to impose an L before the signal line has returned H. This is used, for example, as an acknowledge signal. Such a scenario will cause a collision as shown in Figure 3. Figure 4 shows an analog level translation technique that can be used along with the LTC1755 to support I2C smart cards.
PAGE 14
LTC1755/LTC1756 U W U U APPLICATIO S I FOR ATIO Overtemperature Fault Protection An overtemperature circuit disables the chip and activates the ALARM pin if the IC’s junction temperature exceeds 150°C. deactivation sequence. Once PWR is brought high the builtin deactivation sequence occurs as shown in Figure 7. In the event of a fault, the LTC1755/LTC1756 automatically implement the built-in deactivation sequence.
PAGE 15
LTC1755/LTC1756 U W U U APPLICATIO S I FOR ATIO The only possible next state is Idle/Deactivation which is achieved by disabling the LTC1755/LTC1756 via the PWR pin (i.e., PWR = DVCC). The alarm indication can be cleared by rapidly cycling the PWR pin. However, a new activation cycle will not begin until VCC is or has dropped below approximately 1V. FAULT TIMEOUT Same as Active except: The duration of a fault is being measured.
PAGE 16
LTC1755/LTC1756 U TYPICAL APPLICATIO Asynchronous Smart Card Interface 3.3V SMART CARD PRESENT SWITCH 1 2 N.O. 3 C3 10µF GND VCC I/O C2 10µF 4 5 6 PRES 5V/3V PWR CARD GND READY VIN I/O 15 14 C– 13 C+ 12 LTC1756 VCC 16 DATA C1 0.