TDA8029 Datasheet, PDF (44/58 Pages) NXP Semiconductors – Low power single card reader

Philips Semiconductors
Low power single card reader
Product specification
TDA8029
8.12 DC/DC converter
Except for V_CC generator, and the other card contacts
buffers, the whole circuit is powered by V_DD and DCIN.
If the supply voltage is 2.7 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
DC/DC converter, which is a switched capacitors type,
clocked by an internal oscillator at a frequency of
approximately 2.5 MHz.
There are several possible situations:
• V_DCIN = 3 V and V_CC = 3 V: In this case the DC/DC
converter is acting as a doubler with a regulation of
about 4.0 V
• V_DCIN = 3 V and V_CC = 5 V: In this case the DC/DC
converter is acting as a tripler with a regulation of about
5.5 V
• V_DCIN = 5 V and V_CC = 3 V: In this case, the DC/DC
converter is acting as a follower, V_DD is applied on VUP
• V_DCIN = 5 V and V_CC = 5 V. In this case, the DC/DC
converter is acting as a doubler with a regulation of
about 5.5 V
• V_CC = 1.8 V. In this case, whatever value of V_DCIN, the
DC/DC converter is acting as a follower, V_DD is applied
on VUP.
The switch between different modes of the DC/DC
converter is done by the TDA8029 at about V_DCIN = 3.5 V.
The output voltage is fed to the V_CC generator. V_CC and
GNDC are used as a reference for all other card contacts.
8.13 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 (bit START = 1 in register PCR) is only possible
if the card is present (pin PRES is HIGH) and if the supply
voltage is correct (supervisor not active).
The presence of the card is signalled to the controller by
the HSR.
Bit PR1 in register MSR is set if the card is present. Bit
PRL1 in register HSR is set if PR1 has toggled.
During a session, the sequencer performs an automatic
emergency deactivation on the card in the event of card
take-off, short-circuit, supply dropout or overheating. The
card is also automatically deactivated in case of supply
voltage drop or overheating. The HSR register is updated
and the INT0_N line falls down, so the system controller is
aware of what happened.
8.14 Protections and limitations
The TDA8029 features the following protections and
limitations:
• I_CC limited to 100 mA, and deactivation when this limit is
reached
• Current to or from pin RST limited to 20 mA, and
deactivation when this limit is reached
• Deactivation when the temperature of the die exceeds
150 °C
• Current to or from pin I/O limited to 10 mA
• Current to or from pin CLK limited to 70 mA
• ESD protection on all cards contacts and pin PRES at
minimum 6 kV, thus no need of extra components for
protecting against ESD flash caused by a charged card
being introduced in the slot
• Short circuit between any card contacts can have any
duration without any damage.
8.15 Power reduction modes
On top of the standard controller power reduction features
described in the microcontroller section, the TDA8029 has
several power reduction modes that allow its use in
portable equipment, and help protecting the environment:
• Shut-down mode: when SDWN_N pin is LOW, then the
bit SDWN within HSR will be set, causing an interrupt on
INT0_N. The TDA8029 will read the status, deactivate
the card if it was active, set all ports to logic 1 and enter
Power-down mode by setting bit PD in the controller’s
PCON register. In this mode, it will consume less than
20 µA, because the internal oscillator is stopped, and all
biasing currents are cut.
When SDWN_N returns to HIGH, a Power-on reset
operation is performed, so the chip is in the same state
than at power-on.
• Power-down mode: the microcontroller is in
Power-down mode, and the card is deactivated. The
bias currents in the chip and the frequency of the internal
oscillator are reduced. In this mode, the consumption is
less than 100 µA.
• Sleep mode: the microcontroller is in Power-down
mode, the card is activated, but with the clock stopped
HIGH or LOW. In this case, the card is supposed not to
draw more than 2 mA from V_CC. The bias currents and
the frequency of the internal oscillator are also reduced.
With a current of 100 µA drawn by the card, the
consumption is less than 500 µA in tripler mode, 400 µA
in doubler mode, or 300 µA in follower mode.
2003 Oct 30
44