STMicroelectronics’ Xpander Logic family overcomes the limited number of I/O ports in microcontroller- and microprocessor-based embedded systems. Any existing or additional I/O-intensive tasks on the CPU can be now reassigned to the Xpander Logic IC that operates with ultra-low power and comes in a very small package, making it suitable for portable multimedia devices such as mobile phones, smartphones, and personal digital assistants.

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The Xpander Logic family allows the existing system processor to use a wide range of intelligent functions through a standard and high-speed I²C serial peripheral interface. These intelligent features include a keypad controller, supporting 96 keys maximum, and a PWM controller, able to adjust the brightness of the LEDs in addition to performing sophisticated brightness patterns. The logic family also offers a 3-wire rotating-wheel controller, which supports the increasingly popular rotating wheel interface in portable electronics by detecting the motion of the wheel and providing monitoring/buffering features.

The family also integrates an ADC and a DAC, allowing the host system to implement a wide range of mixed-signal features while providing an automatic dimming unit that lets the ambient light sensor control a backlight unit without CPU intervention. In production now, the devices are housed in QFN16, microTFBGA25 and microTFBGA36 packages. The Xpander Logic STMPE2401 provides all the above-mentioned intelligent functions in a microTFBGA36 package, while the STMPE801 performs the basic I/O expander function in a QFN16 package. The STMPE2401 and STMPE801 cost $1.50 and $0.80, respectively, in 100,000 unit quantities.

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