By Maxim Integrated 167
Maxim's MAX7360 I2C-interfaced peripheral provides microprocessors with management of up to 64 key switches, with an additional eight LED drivers/GPIOs that feature constant-current, PWM intensity control, and rotary switch control options.
The key-switch drivers interface with metallic or resistive switches with on-resistances up to 5 kΩ. Key inputs are monitored statically, not dynamically, to ensure low-EMI operation. The MAX7360 features autosleep and autowake modes to further minimize the power consumption of the device. The autosleep feature puts the device in a low-power state (1 µA typ) after a sleep timeout period. The autowake feature configures the MAX7360 to return to normal operating mode from sleep upon a key press.
The key controller debounces and maintains a FIFO of keypress and release events (including autorepeat, if enabled). An interrupt (active-low INTK) output can be configured to alert keypresses, as they occur, or at maximum rate.
There are eight open-drain I/O ports, which can be used to drive LEDs. The maximum constant-current level for each open-drain port is 20 mA. The intensity of the LED on each open-drain port can be individually adjusted through a 256-step PWM control. An input port pair (PORT6, PORT7) can be configured to accept 2-bit gray code inputs from a rotary switch. In addition, if not used for key-switch control, up to six column pins can be used as general-purpose open-drain outputs (GPOs) for LED drive or logic control.
The MAX7360 is offered in a 40-pin (5 mm x 5 mm), thin QFN package with an exposed pad, and a small 36-bump wafer level package (WLP) for cell phones, pocket PCs, and other portable consumer electronic applications. The MAX7360 operates over the -40°C to +85°C extended temperature range.