DS8023 Datasheet, PDF(7/17 Page) Maxim Integrated Products

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DS8023 Datasheet, PDF (7/17 Pages) Maxim Integrated Products – Smart Card Interface

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DS8023

Smart Card Interface

Detailed Description

The DS8023 is an analog front-end for communicating

with 1.8V, 3V, and 5V smart cards. Using an integrated

charge pump, the DS8023 can operate from a single

input voltage. The device translates all communication

lines to the correct voltage level and provides power for

smart card operation. It can operate from a wide input

voltage range (3.0V to 6.0V) and provides an extremely

low-power stop mode, consuming only 10nA while in

stop mode. The DS8023 is very compatible with the

NXP TDA8024. Many applications can upgrade with

very minor hardware changes, and only need to add

support in software to activate the ultra-low-power stop

VDD

GND

XTAL1

XTAL2

CLKDIV1

CLKDIV2

1_8V

5V/3V

CMDVCC

RSTIN

OFF

I/OIN

AUX1IN

AUX2IN

POWER-SUPPLY

SUPERVISOR

CARD VOLTAGE

GENERATOR

AND

CHARGE PUMP

CLOCK

GENERATION

TEMPERATURE

MONITOR

CONTROL

SEQUENCER

I/O TRANSCEIVER

DS8023

Figure 1. Functional Diagram

VDDA

PGND

CP1

CP2

VUP

VCC

CGND

RST

CLK

PRES

I/O

AUX1

AUX2

mode. (Note that the PORADJ pin is not present in the

DS8023. It is replaced by the 1_8V selection pin.)

Power Supply

The DS8023 can operate from a single supply or a dual

supply. The supply pins for the device are VDD, GND,

VDDA, and PGND. VDD should be in the 2.7V to 6.0V

range, and is the supply for signals that interface with

the host controller. It should, therefore, be the same

supply as used by the host controller. All smart card

contacts remain inactive during power on or power off.

The internal circuits are kept in the reset state until VDD

reaches VTH2 + VHYS2 and for the duration of the inter-

nal power-on reset pulse, tW. A deactivation sequence

is executed when VDD falls below VTH2.

An internal charge pump and regulator generate the

3V or 5V card supply voltage (VCC). The charge pump

and regulator are supplied by VDDA and PGND. VDDA

should be connected to a minimum 3.0V (maximum

6.0V) supply and should be at a potential that is equal

to or higher than VDD.

The charge pump operates in a 1x (voltage follower) or

2x (voltage doubler) mode depending on the input

VDDA and the selected card voltage (5V or 3V).

â¢ For 5V cards, the DS8023 operates in a 1x mode

for VDDA > 5.8V and in a 2x mode for VDDA < 5.8V.

â¢ For 3V cards, the DS8023 operates in a 1x mode

for VDDA > 4.1V and in a 2x mode for VDDA < 4.1V.

â¢ For 1.8V cards, the DS8023 operates in a 1x mode

for VDDA > 2.9V and in a 2x mode for VDDA < 2.9V.

Voltage Supervisor

The voltage supervisor monitors the VDD supply. A

220Âµs reset pulse (tW) is used internally to keep the

device inactive during power on or power off of the VDD

supply. See Figure 2.

VTH2 + VHYS2

VTH2

VDD

ALARM

(INTERNAL SIGNAL)

Figure 2. Voltage Supervisor Behavior

Maxim Integrated

POWER ON

SUPPLY DROPOUT

POWER OFF

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