DS8113 Datasheet, PDF (8/17 Pages) Maxim Integrated Products – Smart Card Interface

Smart Card Interface
Detailed Description
The DS8113 is an analog front-end for communicating
with 1.8V, 3V, and 5V smart cards. It is a dual input-
voltage device, requiring one supply to match that of a
host microcontroller and a separate +5V supply for
generating correct smart card supply voltages. The
DS8113 translates all communication lines to the cor-
rect voltage level and provides power for smart card
operation. It is a low-power device, consuming very lit-
tle current in active-mode operation (during a smart
card communication session), and is suitable for use in
VDD
POWER-SUPPLY CARD VOLTAGE
GND
SUPERVISOR GENERATOR
XTAL1
XTAL2
CLKDIV1
CLKDIV2
1_8V
5V/3V
CMDVCC
RSTIN
PRES
PRES
OFF
I/OIN
AUX1IN
AUX2IN
CLOCK
TEMPERATURE
GENERATION
MONITOR
CONTROL
SEQUENCER
I/O TRANSCEIVER
DS8113
Figure 1. Functional Diagram
VDDA
PGND
CP1
CP2
VUP
VCC
CGND
RST
CLK
I/O
AUX1
AUX2
battery-powered devices such as laptops and PDAs,
consuming only 10nA in stop mode. See Figure 1 for a
functional diagram.
Power Supply
The DS8113 is a dual-supply device. The supply pins
for the device are VDD, GND, VDDA, and PGND. V_DD
should be in the range of 2.7V to 6.0V, and is the sup-
ply 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 internal power-on reset
pulse, tW. A deactivation sequence is executed when
VDD falls below VTH2.
An internal regulator generates the 1.8V, 3V, or 5V card
supply voltage (VCC). The regulator should be supplied
separately by VDDA and PGND. VDDA should be con-
nected to a minimum 5.0V supply in order to provide
the correct supply voltage for 5V smart cards.
Voltage Supervisor
The voltage supervisor monitors the VDD supply. A
220µs reset pulse (tW) is used internally to keep the
device inactive during power-on or power-off of the
VDD supply. See Figure 2.
The DS8113 card interface remains inactive no matter
the levels on the command lines until duration tW after
VDD has reached a level higher than VTH2 + VHYS2.
When VDD falls below VTH2, the DS8113 executes a
card deactivation sequence if its card interface is
active.
VTH2 + VHYS2
VTH2
VDD
ALARM
(INTERNAL SIGNAL)
Figure 2. Voltage Supervisor Behavior
tW
POWER ON
tW
SUPPLY DROPOUT
POWER OFF
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