1999 Dec 30 8
Philips Semiconductors Product specification
IC card interface TDA8004T
I/O circuitry
The three data lines I/O, AUX1 and AUX2 are identical.
The Idle state is realized by both lines (I/O and I/OUC)
being pulled HIGH via a 10 kΩ resistor (I/O to VCC and
I/OUC to VDD).
I/O is referenced to VCC and I/OUC to VDD, thus allowing
operation with VCC≠ VDD.
The first side on which a falling edge occurs becomes the
master.Ananti-latchcircuitdisablesthe detection of falling
edges on the other line, which becomes a slave.
After a time delay t
d(edge)
(approximately 200 ns), the
N transistor on the slave side is turned on, thus
transmitting the logic 0 present on the master side.
Whenthemastersidereturnstologic 1, the P transistor on
theslavesideisturnedon during the time delayt
d(edge)
and
then both sides return to their Idle states.
This active pull-up feature ensures fast LOW-to-HIGH
transitions; it is able to deliver more than 1 mA up to an
output voltage of 0.9VCCon a 80 pF load. At the end of the
active pull-up pulse, the output voltage only depends on
the internal pull-up resistor and on the load current (see
Fig.4).
The maximum frequency on these lines is 1 MHz.
Inactive state
Afterpower-onreset,the circuit enters the inactive state. A
minimumnumber of circuits are active while waiting forthe
microcontroller to start a session.
• All card contacts are inactive (approximately 200 Ω to
GND)
• I/OUC, AUX1UC and AUX2UC are high impedance
(10 kΩ pull-up resistor connected to VDD)
• Voltage generators are stopped
• XTAL oscillator is running
• Voltage supervisor is active.
Activation sequence
Afterpower-on and after the internal pulse width delay, the
system controller may check the presence of the card with
the signal OFF (OFF = HIGH while CMDVCC is HIGH
means that the card is present; OFF = LOW while
CMDVCC is HIGH means that no card is present).
If the card is in the reader (which is the case if PRES or
PRES is true), the system controller may start a card
session by pulling CMDVCC LOW.
The following sequence then occurs (see Fig.5):
• CMDVCC is pulled LOW (t0)
• The voltage doubler is started (t1~t0)
• VCC rises from 0 to 5 V with a controlled slope
(t2=t1+1⁄23T) (I/O, AUX1 and AUX2 follow VCC with a
slight delay)
• I/O, AUX1 and AUX2 are enabled (t3=t1+ 4T)
• CLK is applied to the C3 contact (t4)
• RST is enabled (t5=t1+ 7T).
In the timing informations above and below, T is 64 times
the period of the internal oscillator, about 25 µs.
The clock may be applied to the card in the following way:
• Set RSTIN HIGH before setting CMDVCC LOW and
reset it LOW between t3and t5; CLK will start at this
moment. RST will remain LOW until t5, where RST is
enabledto be the copy of RSTIN. After t5,RSTIN has no
further action on CLK. This is to allow a precise count of
CLK pulses before toggling RST.
If this feature is not needed, then CMDVCC may be set
LOWwithRSTINLOW.Inthiscase,CLKwillstart at t3and
after t5,RSTINmaybesetHIGHinordertoget the Answer
To Request (ATR) from the card.
handbook, halfpage
0
(2)
(1)
6
4
2
0
20 40
t (ns)
V
o
(V)
12
8
4
0
I
o
(mA)
60
FCE270
Fig.4 I/O, AUX1, and AUX2 output voltage and
current as a function of time during a
LOW-to-HIGH transition.
(1) Current.
(2) Voltage.