Chip cards are also plastic cards as magnetic stripe cards, but where the data is stored into a memory included on the card instead of the magnetic stripe. This technology offer more flexibility and security as magnetic card technology. There are two types of chip cards, asynchronous and synchronous.
Synchronous also called “Memory Cards” have no CPU incorporated in the card. Synchronous chip cards are composed by EEPROM, ROM, LOGIC, I/O block and the Chip Card Interface (see Figure 1). The logic consists of four different parts:
- Address counter logic - converts the serial clock into the corresponding memory address;
- Address counter reset logic – detects a regular reset of the address counter;
- Programmer logic – detects a regular change of the memory content;
Security logic – integrated with check for valid chip access.
Figure 1. Synchronous chip card
This type of card is used by the applications which have to save only a few data information and use the synchronous protocol. This means that the memory address counter is counted up and the memory read-out synchronously with the clock.
Asynchronous cards include microcontroller with a system clock ranging from 1 to 5 MHz and they are qualified for specific applications providing higher security level (see Figure 2).
Figure 2. Asynchronous chip card
These cards have a chip interface with 8 pins. An example for the pin-out of the chip interface is presented Figure 3, where:
- C1 is the power supply of the chip;
- C2 is the reset signal of the address counter;
- C3 is the chip clock signal;
- C4 is reserved;
- C5 is the GND pin;
- C6 is the VPP pin;
- C7 is the I/O pin;
- C8 is reserved.
Figure 3. Example of chip card PIN layout
Associated card readers are available in Serial and USB (or both) interfaces.
Figure 4. Many different pad layouts can be found on a contact Smart card