DS8005 查看數據表（PDF） - Maxim Integrated
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DS8005 Datasheet PDF : 20 Pages
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DS8005
Smart Card Interface
Inactive Mode
The device powers up with the card interface in the inac-
tive mode. Minimal circuitry is active while waiting for the
host to initiate a smart card session.
• All card contacts are inactive (approximately 200Ω to
GND).
• The I/OIN pin in the high-impedance state (11kΩ
pullup resistor to VDD).
• Voltage generators are stopped.
• XTAL oscillator is running (if included in the device).
• Voltage supervisor is active.
• The internal oscillator is running at its low frequency.
Activation Sequence
After power-on and the reset delay, the host microcon-
troller can monitor card presence with signals OFF and
CMDVCC, as shown in Table 2.
If the card is in the reader (if PRES_ is active), the host
microcontroller can begin an activation sequence (start
a card session) by pulling CMDVCC low. The following
events form an activation sequence (Figure 3):
1) CMDVCC is pulled low.
2) The internal oscillator changes to high frequency (t0).
3) The voltage generator is started (between t0 and t1).
Table 2. Card Presence Indication
SEL_AB
Low
Low
High
High
SEL_AB
Low
Low
High
High
OFF
High
Low
High
Low
OFF2
High
Low
High
Low
CMDVCC
High
High
High
High
CMDVCC
High
High
High
High
STATUS
Card A present.
Card A not present.
Card B present.
Card B not present.
STATUS
Card B present.
Card B not present.
Card A present.
Card A not present.
CMDVCC
VCC_
I/O_
CLK_
RSTIN
RST_
I/OIN
t0 t1
t2
t3
t4
t5 = tACT
Figure 3. Activation Sequence Using RSTIN and CMDVCC
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