73S8024RN Data Sheet DS_8024RN_020
10 Rev. 2
7 Activation Sequence
The 73S8024RN smart card interface IC has an internal 10ms delay at power on reset or on the
application of V
DD
> V
DDF
. No activation is allowed at this time. The CMDVCC (edge triggered) must then
be set low to activate the card. In order to initiate activation, the card must be present; there can be no
over-temperature fault or no V
DD
fault.
The following steps show the activation sequence and the timing of the card control signals when the
system controller sets CMDVCC low while the RSTIN is low:
• CMDVCC is set low.
• Next, the internal V
CC
control circuit checks the presence of V
CC
at the end of t
1
. In normal operation,
the voltage V
CC
to the card becomes valid during t
1
. If V
CC
does not become valid, the OFF goes low
to report a fault to the system controller, and the power V
CC
to the card is shut off.
• Turn I/O (AUX1, AUX2) to reception mode at the end of (t
2
).
• CLK is applied to the card at the end of (t
3
).
• RST is a copy of RSTIN after (t
4
). RSTIN may be set high before t
4
, however the sequencer will not
set RST high until 42000 clock cycles after the start of CLK.
CMDVCC
VCC
I/O
CLK
RSTIN
t
1
t
2
t
3
t
4
RST
t
1
= 0.510 ms (timing by 1.5MHz internal Oscillator)
t
2
= 1.5µs, I/O goes to reception state
t
3
= >0.5µs, CLK starts
t
4
≥ 42000 card clock cycles. Time for RST to become the copy of RSTIN
Figure 2: Activation Sequence – RSTIN Low When CMDVCC Goes Low
