tda8025hn NXP Semiconductors, tda8025hn Datasheet - Page 18

• Manufacturer Part Number: tda8025hn
• Description: Ic Card Interface
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8025_1
Product data sheet
8.8 Deactivation sequence
When a session is completed, the microcontroller sets pin CMDVCCN to HIGH. The
circuit then executes an automatic deactivation sequence by counting the sequencer back
to the inactive state (see
Calculation of the time delays is as follows:
Remark: The value of period T is 64 times the period interval of the internal oscillator (i.e.
1. pin RST is pulled LOW (t11)
2. the clock is stopped, pin CLK is LOW (t12)
3. pins I/O, AUX1 and AUX2 are pulled LOW (t13)
4. V
5. all card contacts become low-impedance to GND. However, pins I/OUC, AUX1UC and
6. The internal oscillator returns to its low frequency mode
25 s).
Fig 12. Deactivation sequence with a crystal oscillator
•
•
•
•
CMDVCCN
RST
CLK
I/O
V
XTAL
OSCINT
inactive state
AUX2UC remain pulled up to V
t11 = t10 + 3T/64
t12 = t11 + T/2
t13 = t11 + T
t14 = t11 + 3T/2
CC
CC
falls to zero (t14). The deactivation sequence is completed when V
t10
t11
Rev. 01 — 6 April 2009
Figure 12
high frequency
t12
DD(INTREGD)
and
t
deact
Figure
t13
13):
using the 11 k resistor
t14
low frequency
TDA8025
© NXP B.V. 2009. All rights reserved.
IC card interface
CC
reaches its
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