TDA8031 Datasheet, PDF (32/57 Pages) NXP Semiconductors – USB smart card reader (OTP or ROM)

Philips Semiconductors
USB smart card reader (OTP or ROM)
Product specification
TDA8030; TDA8031
handbook, full pagewidth
START
VUP
VCC
I/O
CLK
RST
t0 t1 t2
t3 t4 ₌ tact
ATR
MGU889
Fig.9 Activation sequence.
8.3.4 DEACTIVATION SEQUENCE
When the session is completed, the microcontroller resets
START (t₁₀). The circuit then executes an automatic
deactivation sequence as follows:
1. Card reset (RST falls LOW; t₁₁)
2. Clock (CLK) is stopped LOW (t₁₂)
3. I/O, C4 and C8 fall to 0 V (t₁₃)
4. V_CC falls to 0 V with typical 0.17 V/µs slew rate (t₁₄)
5. The DC-to-DC converter is stopped and CLK, RST,
V_CC, I/O, C4 and C8 become low-impedance to CGND
(t₁₅).
Thus:
t₁₁ = t₁₀ + ¹â„₆₄t
t₁₂ = t₁₁ + ¹â„₂t
t₁₃ = t₁₁ + t
t₁₄ = t₁₁ + ³â„₂t
t₁₅ = t₁₁ + ⁷⁄₂t
t_de = time that V_CC needs to decrease to less than 0.3 V.
Automatic emergency deactivation is performed in the
following cases:
1. Withdrawal of the card (PRES LOW)
2. Overcurrent detection on V_CC (bit PRTL set)
3. Overcurrent detection on RST (bit PRTL set)
4. Overheating (bit PTL set)
5. Supply too low (bit SUPL set)
6. RESET pin active HIGH.
In all of these cases, the deactivation sequence as
described above occurs.
If the reason for the deactivation is a card take-off, an
overcurrent or overheating, then INT0 will be LOW and the
corresponding bit in the Hardware Status Register will be
set. The START bit is automatically reset.
If the reason is a supply drop-out, then the deactivation
sequence occurs and a complete reset of the chip is
performed. When the supply recovers, then the SUPL bit
will be set in the HSR.
2003 Jul 04
32