tda8023 NXP Semiconductors, tda8023 Datasheet - Page 15

• Manufacturer Part Number: tda8023
• Description: Tda8023 Low Power Ic Card Interface
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8023_1
Product data sheet
8.6.2 Deactivation sequence
8.7 Protection
When the session is completed, the microcontroller resets bit START to logic 0 (t
Figure
The deactivation time t
counted from the moment bit START is reset.
All card contacts are protected against any short with any other card contact.
The currents on various pins are limited:
If any of these currents exceeds its limit, an emergency deactivation sequence is
performed: pin INT is pulled LOW and bit PROT in the Status register is set.
t
11
1. Card reset: pin RST falls to LOW (t
2. CLK is stopped (t
3. Pin I/O falls to 0 V (t
4. Pin V
5. The DC-to-DC converter is stopped and pins CLK, RST, V
6. The internal oscillator changes to its low frequency (t
Fig 6. Deactivation sequence
•
•
•
•
=
low-impedance with relation to GNDC (t
on pin CLK: limited to 70 mA
on pin I/O: limited to 10 mA (typical value)
on pin RST: limited (only when this pin is LOW) to 20 mA
on pin V
t
10
6). The circuit then executes an automatic deactivation sequence:
START
+
V UP
RST
CLK
V
CC
I/O
----- -
64
CC
T
CC
falls to 0 V with a controlled slew rate (t
,
t
: limited to 90 mA
12
=
t
10
t
11
12
t
deact
+
11
).
Rev. 01 — 16 July 2007
13
T
---
2
).
,
is the time that V
t
13
t
12
=
t
t
deact
11
+
t
13
T
11
,
).
t
14
t
14
15
CC
=
).
t
needs for going down to less than 0.4 V,
11
+
14
3T
------ -
2
).
t
and
15
15
).
Low power IC card interface
t
15
CC
=
and I/O become
t
11
+
TDA8023
7T
------ -
© NXP B.V. 2007. All rights reserved.
2
.
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10
, see
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