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Dual Smart Card Interface with Serial Control Fits in a 5x5mm QFN Package
| The manufacturer says . . . | ChipCenter's Paul O'Shea says . . . |
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Linear Technology announces the LTC1955, a dual smart card interface that provides all of the necessary supervisory, level shifting and power control functions for two smart cards in a single QFN-32 package. The LTC1955 can also interface with two Security Access Module (S.A.M.) cards or a combination of one S.A.M. card and one smart card. It meets all of the provisions of ISO7816-3, is EMV compatible and offers greater than 10KV ESD protection on all of its pins. Its integrated control/status serial port allows it to be easily daisy chained in applications that require multiple cards. A low operating current of 250 microA (shutdown current < 1 microA) and the tiny (5x5x0.75mm) QFN package makes the LTC1955 ideal for space-constrained hand held applications. The LTC1955 contains a buck-boost charge pump enabling it to generate voltages of 5V/3V/1.8V from an input voltage of 2.7V to 5.5V making it optimal for single cell Li-Ion, or multi-cell NiMH/alkaline battery applications. Its integrated level translation is automatic for optimum data transfer while supervisory functions prevent smart card faults, automatically shutting down when electrical faults are detected. The card voltages can be independently set to 1.8V, 3V or 5V. Both interfaces include a card detection channel with automatic debounce circuitry. To reduce wiring costs, the LTC1955 interfaces with the microcontroller via a simple 4-wire serial interface. Multiple devices may be connected in daisy-chain fashion to accommodate a larger number of smart cards. |
Smart Card technology is picking up steam as a preferred way to do business. Designers are adding to the circuitry stockpile with designs that make it cheaper and smaller to implement, as well as offering lower power designs. This introduction has several features worth noting including power management and control for two Smart Cards. Also worth noting ý it is compatible with ISO7816-3 (cards with contacts ý part 3 electronic signals and transmission protocols) and with the European MasterCard and Visa (EMV) standards for how online purchases are made. The LTC 1955 focuses on the Smart Card interface and does it well. It uses a slick buck-boost charge pump to provide all the typical voltages from 1.8 V to 5V for various Smart Card classes. The four-wire serial interface connecting the LTC1955 to the smart card microcontroller makes this a clean design worth looking at. The low supply current and shutdown current are important as is the small packaging make this just right for space and power constrained applications. The LTC1955 is available from stock in a 32-lead QFN package. Pricing starts at $2.45 each for 1,000-piece quantities. |
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