73S8009CN Maxim, 73S8009CN Datasheet - Page 21

• Manufacturer Part Number: 73S8009CN
• Manufacturer: Maxim

DS_8009CN_026
73S8009CN Data Sheet
3.8
Chip Selection
The CS pin allows multiple circuits to operate in parallel, driven from the same host control bus. When
CS is high, the pins RSTIN, CMDVCC%, CMDVCC# and CLKIN control the chip as described. The pins
I/OUC, AUX1UC, and AUX2UC have 11kΩ pull-up resistors and operate to transfer data to the smart card
via I/O, AUX1, and AUX2 when the smart card is activated. The signals OFF and RDY have 20kΩ pull-up
resistors.
When CS goes low, the states of the pins RSTIN, CMDVCC%, CMDVCC, and CLKIN are latched and held
internally. The pull-up for pins I/OUC, AUX1UC, and AUX2UC become a very weak pull-up of
approximately 3 microamperes. No transfer of data is possible between I/OUC, AUX1UC, AUX2UC and
the smart-card signals I/O, AUX1, and AUX2. The signals OFF and RDY are set to high impedance and
the internal pull-up resistors of 20kΩ are disconnected. With regard to de-activation, CS does not affect
the operation of the fault sensing circuits and card sense input. CS does not affect the action of SC/USB.
t
DZ
CS
t
SL
OFF, I/OUC,
HI-Z STATE
HI-Z STATE
FUNCTIONAL
AUX1UC, AUX2UC
CONTROL SIGNALS
t
t
IS
ID
t
t
DI
SI
Figure 8: CS Timing Definitions
Rev. 1.4
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