DS_8024RN_020
73S8024RN Data Sheet
4 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.
Choice of the VCC Capacitor:
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. Table 1 shows the recommended capacitors for each VPC
power supply configuration and applicable specification.
Table 1: Choice of VCC Pin Capacitor
Specification Requirements
System Requirements
Max
Min VPC
Power
Supply
Required
Min VCC Voltage
Allowed During
Transient Current
Transient
Current
Charge
Capacitor
Specification
Capacitor Value
Type
X5R/X7R
w/
ESR <
EMV 4.0
ISO-7816-3
NDS
4.6V
4.5V
4.6V
30nA.s
20nA.s
40nA.s
4.75V
4.75V
4.85V
3.3 μF
1 μF
1 μF
100mΩ
Note: Capacitor value for NDS implementation is also defined by the deactivation time requirement.
5 Over-Temperature Monitor
A built-in detector monitors die temperature. Upon an over-temperature condition, a card deactivation
sequence is initiated, and an error or fault condition is reported to the system controller.
6 On-Chip Oscillator and Card Clock
The 73S8024RN device has an on-chip oscillator that can generate the smart card clock using an
external crystal (connected between the pins XTALIN and XTALOUT) to set the oscillator frequency.
When the clock signal is available from another source, it can be connected to the pin XTALIN, and the
pin XTALOUT should be left unconnected.
The card clock frequency may be chosen between four different division rates, defined by digital inputs
CLKDIV 1 and CLKDIV 2, as per Table 2.
Table 2: Card Clock Frequency
CLKDIV1
CLKDIV2
CLK
0
0
1
1
0
1
0
1
⅛ XTALIN
¼ XTALIN
XTALIN
½ XTALIN
Card power down mode (card clock STOP) is supported and is controllable through the dedicated digital
inputs CLKSTOP and CLKLEV (not supported in the 20QFN package).
Rev. 1.8
9
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
