ACR3901T-W1 – Reference Manual
Version 1.02
www.acs.com.hk
Page 12 of 100
5.5. Smart Card Interface
The interface between the ACR3901T-W1 and the inserted smart card follows the specification of ISO
7816-3 with certain restrictions or enhancements to increase the practical functionality of ACR3901T-
W1.
5.5.1.
Smart Card Power Supply VCC (C1)
The current consumption of the inserted card must not be higher than 50 mA.
5.5.2.
Programming Voltage VPP (C6)
According to ISO 7816-3, the smart card contact C6 (VPP) supplies the programming voltage to the
smart card. Since all common smart cards in the market are EEPROM-based and do not require the
provision of an external programming voltage, the contact C6 (VPP) has been implemented as a
normal control signal in the ACR3901T-W1. The electrical specifications of this contact are identical to
those of the signal RST (at contact C2).
5.5.3.
Card Type Selection
The controlling computer must always select the card type through the proper command sent to the
ACR3901T-W1 prior to activating the inserted card. This includes both the memory cards and MCU-
based cards.
For MCU-based cards, the reader allows to select the preferred protocol, T=0 or T=1. However, this
selection is only accepted and carried out by the reader through the PPS when the card inserted in
the reader supports both protocol types. Whenever an MCU-based card supports only one protocol
type, T=0 or T=1, the reader automatically uses that protocol type, regardless of the protocol type
selected by the application.
5.5.4.
Interface for Microcontroller-based Cards
For microcontroller-based smart cards, only the contacts C1 (VCC), C2 (RST), C3 (CLK), C5 (GND)
and C7 (I/O) are used. A frequency of 4.8 MHz is applied to the CLK signal (C3).
5.5.5.
Card Tearing Protection
The ACR3901T-W1 provides a mechanism to protect the inserted card when it is suddenly withdrawn
while it is powered up. The power supply to the card and the signal lines between the ACR3901T-W1
and the card is immediately deactivated while the card is being removed.
However, as a rule, to
avoid any electrical damage, a card should only be removed from the reader while it is powered down.
Note: ACR3901T-W1 never switches on the power supply to the inserted card by itself. The
controlling computer through the proper command sent to the reader must explicitly do this.
