10-Port, Constant-Current LED Driver and I/O Expander with PWM Intensity Control

The MAX6946/MAX6947 I²C-/SMBus™-compatible, serial-interfaced peripherals provide microprocessors with 10 I/O ports rated to 7V.

Each port can be configured as a 2.5mA to 20mA constant-current LED driver (static or PWM), a 1.25mA to 10mA constant-current LED driver (static or PWM), an open-drain logic output, or an overvoltage-protected Schmitt logic input.

Analog and switching LED intensity control includes individual 8-bit PWM control per output, individual 1-bit analog current control (half/full scale) per output, and a global 3-bit DAC current control that applies to all LED outputs.

The MAX6946/MAX6947 can stagger the PWM timing of the 10-port outputs in consecutively phased 45° increments. Staggering the outputs spreads the PWM load currents over time in eight steps, helping to even out the power-supply current and reduce the RMS current.

For a similar part with an SPI™-/QSPI™-/ or MICROWIRE™-compatible interface, refer to the MAX6966/MAX6967 data sheet.

Applications

* Cellular Phones * Keypad Backlights * LCD Backlights * LED Status Indicators * Portable Equipment * RGB LED Drivers

* 2.25V to 3.6V Operation

* I/O Ports Default to High Impedance (LEDs Off) on Power-Up

* I/O Port Inputs Are Overvoltage Protected to 7V

* I/O Port Outputs Are 7V-Rated Open-Drain, 10mA or 20mA Constant-Current Static/PWM LED Drivers, or Open-Drain Logic Outputs

* I/O Ports Support Hot Insertion

* Individual 8-Bit PWM Intensity Control for Each LED

* Active-Low RST Input Clears Serial Interface and Can Exit Shutdown (Warm Start)

* MAX6946 OSC Input Allows for External PWM Clock Input

* MAX6947 AD0 Input Selects from Two Slave Addresses

* Auto Ramp-Up Out of Shutdown, and Up to 4s Hold-Off Before Ramp-Down into Shutdown

* 0.8µA (typ) Shutdown Current

* -40°C to +125°C Temperature Range

* Tiny WLP Package (4 x 4 Grid)