tda8004at-c1 NXP Semiconductors, tda8004at-c1 Datasheet - Page 11

• Manufacturer Part Number: tda8004at-c1
• Description: Ic Card Interface
• Manufacturer: NXP Semiconductors

Philips Semiconductors
TDA8004AT_3
Product data sheet
There are two different cases (see
Depending on the type of card presence switch within the connector (normally closed or
normally open), and on the mechanical characteristics of the switch, a bouncing may
occur on presence signals at card insertion or withdrawal.
There is no debounce feature in the device, so the software has to take it into account;
however, the detection of card take off during active phase, which initiates an automatic
deactivation sequence is done on the first true / false transition on PRES or PRES, and is
memorized until the system controller sets CMDVCC HIGH.
So, the software may take some time waiting for presence switches to be stabilized
without causing any delay on the necessary fast and normalized deactivation sequence.
1. CMDVCC HIGH: (outside a card session) then, OFF is LOW if the card is not in the
2. CMDVCC LOW: (within a card session) then, OFF falls LOW if the card is extracted,
Fig 7. Behavior of OFF, CMDVCC, PRES and V
•
Overheating
reader, and HIGH if the card is in the reader. A supply voltage drop on V
by the supply supervisor which generates an internal power-on reset pulse, but does
not act upon OFF. The card is not powered-up, so no short-circuit or overheating is
detected.
or if a short-circuit has occurred on V
too high. As soon as the fault is detected, an emergency deactivation is automatically
performed (see
When the system controller sets CMDVCC back to HIGH, it may sense OFF again in
order to distinguish between a hardware problem or a card extraction. If a supply
voltage drop on V
deactivation will be performed, but OFF remains HIGH.
CMDVCC
software decision algorithm on OFF signal)
PRES
OFF
V
CC
Figure
DD
Rev. 03 — 9 February 2006
is detected whilst the card is activated, then an emergency
8).
Deactivation caused by
cards withdrawal
Figure
CC
7)
, or if the temperature on the IC has become
CC
(see also application note AN97036 for
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Deactivation caused by
short circuit
TDA8004AT
IC card interface
DD
is detected
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