DS8005 Datasheet, PDF (9/20 Pages) Maxim Integrated Products – Smart Card Intergace

Smart Card Interface
1_8V
5V/3V
V_DDA
V_DDA2
CLKDIV1
CLKDIV2
XTAL1
XTAL2
RSTIN
I/OIN
SEL_AB
CMDVCC
OFF
OFF2
REGULATOR
CLOCK
GENERATION
I/O
XCVR
CONTROL QSEL_AB
SEQUENCER
QSEL_AB
INTERRUPT
GENERATION
FAULT
DETECTION
CARD
INTERFACE A
CARD
INTERFACE B
DS8005
POWER
SUPPLY
CGND
I/OA
V_CCA
RSTA
CLKA
PRESA
I/OB
V_CCB
RSTB
CLKB
PRESB
V_DD
GND
Figure 1. Functional Diagram
Detailed Description
The DS8005 is an analog front-end for communicating
with 1.8V, 3V, and 5V dual smart cards. It is a dual
input-voltage device, requiring one supply to match
that of a host microcontroller and a separate +5V sup-
ply for generating correct smart card supply voltages.
The device translates all communication lines to the
correct 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
battery-powered devices such as laptops and PDAs,
consuming only 10nA in stop mode. The device 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.
Power Supply
The device has dual supplies. The supply pins for the
device 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 dura-
tion of the internal power-on reset pulse, t_W. A deacti-
vation 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 sup-
plied separately by V_DDA. V_DDA should be connected
to a minimum 4.75V supply to provide the correct sup-
ply voltage for 5V smart cards.
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