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The DS8007 and smart card interface fundamentals

Posted: 11 Mar 2008 ?? ?Print Version ?Bookmark and Share

Keywords:DS8007? smart card? MCU? secure MCU?

What is a smart card? A smart card is generally defined as any pocket-sized card containing an embedded IC. Because of the embedded integrated circuit, smart cards are sometimes referred to as

Integrated Circuit Cards, or ICCs. Used in widely varying applications, these cards replace the familiar payment (debit or credit) cards that use a magnetic stripe to store information about the card account. The transition to smart cards in payment applications is occurring primarily because of increased functionality, and especially because of the improved security possible with this technology. These latter capabilities must, however, be evaluated against the smart card's higher cost.

The ICs embedded in smart cards can be either simple, non-volatile memory devices or something as sophisticated as a MCU capable of performing complex operations. A simple non-volatile memory device in a payment card can replace the magnetic stripe for storing data. In many such devices, the memory is combined with additional logic to restrict access to some, or all of the memory. However, the real power of smart cards lies in the ability of an embedded MCU to perform data processing and/or encryption functions.

This processing ability allows enhanced security capabilities. Yet as complexity rises, so does the cost of the card. The cost of a smart card with an embedded processor ranges between $7.00 to $15.00, while a payment card with a magnetic stripe can cost as little as $0.75. This higher cost of smart cards has slowed the universal conversion from simpler technology, but as the requirements for security increase, so will the need for smart cards.

The DS8007 provides all electrical signals necessary to physically interface a MCU with two separate smart cards. The device contains a dedicated internal sequencer that controls automatic card activation and deactivation, and an ISO UART for data communication. Charge pumps and voltage regulators allow the device to operate from a 2.7V to 6.0V supply voltage, and to produce two independent smart card supply voltages, either of which can be 1.8V, 3.0V, or 5V. Communication with the microcontroller is provided by a standard, parallel 8-bit bus that carries either data in a non-multiplexed configuration or data and address in multiplexed configuration.

This application note describes some of the fundamentals of smart cards and how to communicate with them. Software is provided that uses the DS8007 to interface a smart card with a DS5002 secure microprocessor.

View the PDF document for more information.

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