DS8313 Datasheet, PDF (8/18 Pages) Maxim Integrated Products – Smart Card Interface

Smart Card Interface
Detailed Description
The DS8313 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
DS8313 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-
V_DD
GND
XTAL1
XTAL2
CLKDIV1
CLKDIV2
1_8V
5V/3V
CMDVCC
RSTIN
PRES
OFF
I/OIN
POWER-SUPPLY CARD VOLTAGE
SUPERVISOR GENERATOR
CLOCK
GENERATION
TEMPERATURE
MONITOR
CONTROL
SEQUENCER
I/O TRANSCEIVER
DS8313
DS8314
*USED ONLY ON THE DS8313.
Figure 1. Functional Diagram
V_DDA
V_DDA*
V_CC
CGND
RST
CLK
I/O
tle current in active-mode operation (during a smart
card communication session), and is suitable for use in
battery-powered devices such as laptops and PDAs,
consuming only 10nA in stop mode. The DS8313 is
designed for applications that do not require communi-
cation using the C4 and C8 card contacts (AUX1 and
AUX2). It is suitable for SIM/SAM interfacing, as well as
for applications where only the I/O line is used to com-
municate with a smart card.
The DS8314 is nearly identical to the DS8313, but only
uses one V_DDA input; therefore, it has reduced capaci-
ty to deliver current to 5V smart cards. However, the
DS8314 can drop into many existing TDA8024 applica-
tions with minimal or no hardware changes. See Figure
1 for a functional diagram.
Power Supply
The DS8313/DS8314 are dual-supply devices. The sup-
ply pins for the devices are V_DD, GND, and V_DDA. V_DD
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 V_DD reaches V_TH2 + V_HYS2
and for the duration of the internal power-on reset
pulse, t_W. A deactivation sequence is executed when
V_DD falls below V_TH2.
An internal regulator generates the 1.8V, 3V, or 5V card
supply voltage (V_CC). The regulator should be supplied
separately by V_DDA. V_DDA should be connected to a
minimum 4.75V supply to provide the correct supply
voltage for 5V smart cards.
V_TH2 + V_HYS2
V_TH2
V_DD
ALARM
(INTERNAL SIGNAL)
Figure 2. Voltage Supervisor Behavior
t_W
POWER ON
t_W
SUPPLY DROPOUT
POWER OFF
8 _______________________________________________________________________________________