IC takes charge of clamshell handset I/O

A new IC aims to simplify the design, lower the power consumption and improve the reliability of "clamshell" style mobile phones.

Toshiba Electronics Europe has launched an IC that will simplify the design, lower the power consumption and improve the reliability of "clamshell" style mobile phones.

The low-power TC35890XBG Flexpander IC addresses the mechanical and electrical challenges that face designers of high-end clamshell designs by delivering key phone functionality while significantly reducing the number of I/O connections made through the phone's hinge to the baseband application processor.

Toshiba's Flexpander IC Flexpander combines 24 general purpose and configurable input/output pins with built-in functionality for managing the phone keypad, PWM signal generation for LED and vibrator control, and a rotator wheel interface.

The device operates from a 32kHz clock and is designed for use in the upper part of the clamshell design.

Connection to a baseband or application processor in the lower part of the shell is via a two-wire I2C serial interface.

Typically, such baseband and application processors are implemented with a minimum pin count.

Now, by using the Flexpander IC, designers can effectively expand the I/O capabilities of the baseband or application processor while limiting the connections over the hinge to just the serial interface and the clock signal.

Toshiba's new IC offers the flexibility to handle keyboard configurations with as many as 96 keys.

The device monitors for key presses and releases, can detect up to four simultaneous key depressions, and incorporates integral debouncing algorithms in hardware.

PWM functionality is based on three versatile, cascadable timers that can be programmed to generate modulated PWM signals without the need for interaction of an external processor.

The rotator wheel state machine counts up or down the rotations of an external rotator wheel and can handle rotator devices with up to three dedicated click positions.

Operating from a low frequency 32kHz (optional up to 20MHz) clock source running on a supply voltage from 1.7 to 3.6V, Flexpander is optimised for low power operation.

Three different power modes ensure power consumption is kept low across a wide variety of operating conditions.

Flexpander can be powered down completely without affecting the connected system.

The Flexpander is supplied in a miniature 36-pin P-TFBGA package with a footprint of just 5 x 5mm and a low profile of only 1.2mm.

The device's flexible expansion capabilities allow designers to select the IC as a standard platform across a variety of different mobile phone variants.

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