TDA8034T Philips Semiconductors, TDA8034T Datasheet - Page 11

• Manufacturer Part Number: TDA8034T
• Description: Smart Card Interface
• Manufacturer: Philips Semiconductors

NXP Semiconductors
TDA8034T_TDA8034AT_1
Product data sheet
On card insertion or removal, bouncing can occur in the PRESN signal. This depends on
the type of card presence switch in the connector (normally open or normally closed) and
the mechanical characteristics of the switch. To correct for this, a debouncing feature is
integrated in to the TDA8034T/TDA8034AT. This feature operates at a typical duration of
4.5 ms (t
debouncing feature.
On card insertion, pin OFFN goes HIGH after the debounce time has elapsed. When the
card is extracted, the automatic card deactivation sequence is performed on the first
HIGH/LOW transition on pin PRESN. After this, pin OFFN goes LOW.
Fig 8.
•
OFFN
PRESN
RST
CLK
I/O
V
XTAL
OSCINT
In card sessions, pin CMDVCCN is LOW: when pin OFFN goes LOW, the fault
detection circuit triggers the automatic emergency deactivation sequence (see
Figure
deactivation sequence, pin OFFN is rechecked. If the card is still present, pin OFFN
returns to HIGH. This check identifies the fault as either a hardware problem or a card
removal incident.
CC
deb
Emergency deactivation sequence after card removal
8). When the microcontroller resets pin CMDVCCN to HIGH, after the
= 640
t10
(
1
Rev. 01 — 5 February 2010
fosc(int)low
high frequency
).
Figure 9 on page 12
t12
t
deact
TDA8034T; TDA8034AT
t13
t14
shows the operation of the
low frequency
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Smart card interface
© NXP B.V. 2010. All rights reserved.
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