73S8004R
Low Cost Smart Card Interface
POWER SUPPLY
The TDK 73S8004R smart card interface IC incorporates a LDO voltage regulator. The voltage output is
controlled by the digital input 5V/#V. This regulator is able to provide either 3V or 5V card voltage from the power
supply applied on the VPC pin. Three voltage supervisors constantly check the presence of the voltages VDD, VPC
and VCC. A card deactivation sequence is forced upon fault of any of these voltage supervisors. The two voltage
supervisors for VPC and VCC are linked so that a fault is generated to activate a deactivation sequence when the
voltage VPC becomes lower than VCC. It allows the 73S8004R to operate at lower VPC voltage when using 3V
cards only.
The voltage regulator can provide a current of at least 65mA on VCC to comply with EMV 4.0 specification. The
VPC voltage supervisor threshold values are also defined from the EMV 4.0 specification. Digital circuitry is
powered by the power supply applied on the VDD pin. VDD also defines the voltage range to interface with the
system controller. A third voltage supervisor monitors the VDD voltage. It is used to initialize the ISO-7816-3
sequencer at power-on, and to deactivate the card at power-off or upon fault. The voltage threshold of the VDD
voltage supervisor is internally set by default to 2.3V nominal. However, it may be desirable, in some applications,
to modify this threshold value. The pin VDDF_ADJ (pin 18 in the SO package, pin 17 in the MLF package) is used
to connect an external resistor REXT to ground to raise the VDD fault voltage to another value VDDF. The resistor
value is defined as follows:
R
EXT= 56kΩ /(VDDF - 2.33)
When this capability is not used, the VDDF_ADJ must be left open.
CARD POWER SUPPLY
The card power supply is internally provided by the LDO regulator, and controlled by the digital ISO-7816-3
sequencer. Card voltage selection is carried out by the digital input 5V/#V.
Depending on the applications, the requirements in terms of both VCC minimum voltage and transient currents that
the interface must be able to provide to the card are different. An external capacitor must be connected between
the VCC pin and to the card ground in order to guarantee stability of the LDO regulator, and to handle the
transient requirements. The type and value of this capacitor can be optimized to meet the desired specification.
The table below shows the recommended capacitors for each VPC power supply configuration and applicable
specification.
Specification Requirement
Application
Max
Min VCC Voltage allowed
During transient current
Min VPC Power
Supply
transient
current
charge
Specification
Capacitor Type
Capacitor Value
required
X7R
w/
EMV 4.0
ISO-7816-3
4.6V
4.5V
30nA.s
4.75V
4.75V
3.3 µF
1 µF
20nA.s
ESR < 100mΩ
Table 1: Choice of VCC pin capacitor
Page 5
© 2002-2003 TDK Semiconductor Corporation
Proprietary and Confidential
Rev 1.1
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
