The ADP5587 is an I/O port expander and keypad matrix designed for QWERTY type phones that require a large keypad matrix and expanded I/O lines. I/O expander ICs are used in mobile platforms as a solution to the limited number of GPIOs available in the main processor.
In its small 2 mm × 2 mm package, the ADP5587 contains enough power to handle all key scanning and decoding and to flag the processor of key presses and releases via the I2C interface and interrupt. The ADP5587 frees the main microprocessor from the need to monitor the keypad, thereby minimizing current drain and increasing processor bandwidth. The ADP5587 is also equipped with a buffer/FIFO and key event counter to handle and keep track of up to 10 unprocessed key or GPI events with overflow wrap and interrupt capability.
The ADP5587 has keypad lock capability with an option to trigger or not trigger an interrupt at key presses and releases. All communication to the main processor is done using one interrupt line and two I2C-compatible interface lines. The ADP5587 can be configured as a keypad matrix of up to 8 rows × 10 columns (a maximum of 80 keys).
When the ADP5587 is used for smaller keypad matrices, unused row and column pins can be reconfigured to act as general-purpose inputs or outputs. R0 to R7 denote the row pins of the matrix, whereas C0 to C9 denote the column pins. At power-up, all rows and columns default to GPIs and must be programmed to function as part of the keypad matrix or as GPOs.
Two options for I2C addresses exist for the LFCSP package to reduce the chance of port contention and allow up to two ADP5587 ICs to operate on the same I2C bus (see the Ordering Guide).
Applications
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Keypad and I/O expander designed for QWERTY type phones that require a large keypad matrix
