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Microchip adds stand-alone analog front end for wireless authentication

Microchip Technology Inc. has introduced the MCP2030, a three-channel transponder designed to serve as a stand-alone analog front end (AFE) in smart, low-frequency (125 kHz typical) wireless authentication applications such as passive-keyless-entry and tire pressure monitoring systems (TPMS).

Art Eck, a senior product marketing engineer in Microchip's analog and interface products division, said the MCP2030 provides programmable antenna tuning and modulation depth that is adjustable to as low as 8% compared with a more typical 50%.

Eck said the front end was originally developed for use in the PIC16F639, a microcontroller that targets remote passive keyless entry among other low-frequency sensing applications. “The MCP2030 makes the same front-end functionality available on other microcontrollers in addition to those from Microchip,” he said. “It expands the choices available to designers.”

The AFE outputs demodulated data, a carrier clock, or a received signal strength indicator (RSSI). When the RSSI output is selected, the device outputs analog current proportional to the input signal strength. Eck said the RSSI feature can be used for antenna tuning, and for measuring distance from the signal source. “In a keyless entry application, it can tell you whether the fob is inside or outside the car, and if it’s inside, where it is.”

The MCP2030 AFE offers adjustable, high input sensitivity of 3 mVpp typical. Its threee-input channel design enables three-axis reception for improved performance independent of range, antenna orientation and environmental “noise.” Each channel is equipped with dynamically selectable tuning capacitors up to 63 pF in 1pF steps to allow firmware-driven antenna tuning for better signal matching without hand tuning.

An intelligent wake-up filter extends battery life by allowing the external microcontroller to stay in low-power mode until it detects recognized input signals.

The MCP2030 AFE communicates with a microcontroller over an SPI bus, and its features are dynamically controllable by the external microcontroller, depending upon field application.

The AFE is available in 14-pin TSSOP, SOIC, and PDIP packages.

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