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TDA8005AH Datasheet(PDF) 10 Page - NXP Semiconductors |
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TDA8005AH Datasheet(HTML) 10 Page - NXP Semiconductors |
10 / 36 page 1998 Mar 20 10 Philips Semiconductors Preliminary specification Low-power (3 V/5 V) smart card coupler TDA8005A Fig.4 Supply supervisor. handbook, full pagewidth MGL333 Vth(VDD) + Vhys(VthVDD) Vth(VDD) Vth(DELAY) VDELAY ALARM VDD Low impedance supply (pin LIS) For some applications, it is mandatory that the contacts to the card (VCC, RST, CLK and I/O) are low impedance while the card is inactive and also when the coupler is not powered. An auxiliary supply voltage on pin LIS ensures this condition where ILIS ≤ 5 µA for VLIS = 5 V. This low impedance situation is disabled when VCC starts rising 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 VDDD. Step-up converter Except for the VCC generator and the other cards contacts buffers, the whole circuit is powered by VDDD and VDDA. 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 Vstep-up is regulated at approximately 6.5 V and then fed to the VCC generator. VCC and DGND are used as a reference for all other cards contacts. 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. |
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