tda8005ah NXP Semiconductors, tda8005ah Datasheet - Page 10

• Manufacturer Part Number: tda8005ah
• Description: Low-power 3 V/5 V Smart Card Coupler
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Low impedance supply (pin LIS)
For some applications, it is mandatory that the contacts to
the card (V
the card is inactive and also when the coupler is not
powered. An auxiliary supply voltage on pin LIS ensures
this condition where I
impedance situation is disabled when V
during activation, and re-enabled when the step-up
converter is stopped during deactivation. If this feature is
not required, the LIS pin must be tied to V
Step-up converter
Except for the V
buffers, the whole circuit is powered by V
If the supply voltage is 3 or 5 V, then a higher voltage is
needed for the ISO contacts supply. When a card session
is requested by the controller, the sequencer first starts the
step-up converter, which is a switched capacitors type,
clocked by an internal oscillator at a frequency of
approximately 2.5 MHz. The output voltage V
regulated at approximately 6.5 V and then fed to the V
generator. V
other cards contacts.
1998 Mar 20
handbook, full pagewidth
Low-power (3 V/5 V) smart card coupler
CC
CC
, RST, CLK and I/O) are low impedance while
V th(VDD)
and DGND are used as a reference for all
CC
generator and the other cards contacts
LIS
V hys(VthVDD)
V th(DELAY)
5 A for V
V th(VDD)
V DELAY
ALARM
V DD
LIS
= 5 V. This low
CC
DDD
DDD
starts rising
step-up
.
and V
Fig.4 Supply supervisor.
DDA
is
CC
.
10
The step-up converter may be chosen as a doubler or a
tripler by mask option, depending on the voltage and the
current needed on the card.
ISO 7816 security
The correct sequence during activation and deactivation of
the card is ensured through a specific sequencer, clocked
by a division ratio of the internal oscillator.
Activation (START signal P05; see Table 3) is only
possible if the card is present (PRES HIGH or LOW
according to mask option), and if the supply voltage is
correct (ALARM signal inactive); CLK and RST are
controlled by RSTIN (internal signal; port P04), allowing
the correct count of CLK pulses during answer-to-reset
from the card.
The presence of the card is signalled to the controller by
the OFF signal (port P10; see Table 3).
During a session, the sequencer performs an automatic
emergency deactivation in the event of card take-off,
supply voltage drop, or hardware problems. The OFF
signal falls thereby warning the controller.
MGL333
Preliminary specification
TDA8005A