73s8009r-il Maxim Integrated Products, Inc., 73s8009r-il Datasheet - Page 17

• Manufacturer Part Number: 73s8009r-il
• Description: Low Cost Versatile Smart Card Interface
• Manufacturer: Maxim Integrated Products, Inc.

DS_8009R_056
73S8009R Data Sheet
OFF is low by
OFF is low by
card extracted
any fault
PRES
OFF
CMDVCC
VCC
outside card session
within card session
within card
session
Figure 7: OFF Activity Outside and Inside a Card Session
3.8
Power-down Operation
A power-down function is provided that disables all analog functions. The power-down state is only
allowed in the de-activated condition. The host invokes the power-down state when it is desirable to save
power.
The signals PRES and PRES are functional in the power-down state so that a card insertion asserts OFF
high. If there is no card present (OFF = low) in power-down mode, the pull-up resistor is disabled so that
no current is drawn from VDD. If a card is inserted, the pull-up resistor is enabled and OFF goes high.
Upon receiving the OFF indication, the host must then de-assert power down (PWRDN) and wait until the
circuit is ready. When PWRDN is de-asserted, OFF goes low to indicate that the circuit is not ready (it is
going through the power-on recovery time). When the circuit is ready, OFF will go high if the card is
present.
Figure 8
illustrates the behavior of the circuit for PWRDN events.
OFF will go high if card is present and there are no faults
PRES
OFF goes low when PWRDN is de-asserted while circuit starts up
OFF going high indicates
OFF
circuit is ready
PWRDN while CMDVCCx=0
PWRDN
has no effect
PWRDN will have effect
when CMDVCCx=1
RC OSC
~30 µs
Controller must wait for OFF=1 after
~30 µs
setting PWRDN=0 before setting
CMDVCC(3/5)=0
CMDVCC3 /
CMDVCC5
RDY - indicates VCC is OK
Figure 8: Power-down Operation
Rev. 1.3
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