Charge Pump Parallel Backlight Driver with Image Content PWM Input
The ADP8870 combines a programmable backlight LED charge-pump driver with automatic phototransistor control of the brightness (LED current) and a PWM input to control the scale of the output current. This combination allows significant power savings because it automatically changes the current intensity based on the sensed ambient lighting levels and the display image content. It performs this function automatically, eliminating the need for a processor to monitor the phototransistor. The light intensity thresholds are fully programmable via the I2C interface.
The ADP8870 allows up to six LEDs to be independently driven up to 30 mA (maximum). An additional seventh LED can be driven to 60 mA (maximum). All LEDs are individually programmable for minimum/maximum current and fade-in/fade-out times through an I2C interface. These LEDs can also be combined into groups to reduce the processor instructions during fade-in and fade-out.
Driving these components is a two-capacitor charge pump with gains of 1×, 1.5×, and 2×. This setup is capable of driving a maximum IOUT of 240 mA from a supply of 2.5 V to 5.5 V. A full suite of safety features, including short-circuit, overvoltage, and overtemperature protection, allows easy implementation of a safe and robust design. Additionally, input inrush currents are limited via an integrated soft start combined with controlled input-to-output isolation.
- Mobile display backlighting
- Mobile phone keypad backlighting
- RGB LED lighting
- LED indication
- General backlighting of small format displays
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
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