LED drive technology with charge pump drive based on ADP8863

The ADP8863 combines a powerful charge pump driver with advanced autonomous LED lighting features. It allows as many as seven LEDs to be independently driven up to 30 mA (maximum). The seventh LED can also be driven to 60 mA (maximum). All LEDs are programmable for maximum current and fade in/

fade out times via the I2C interface.

Additionally, automated blinking routines can be independently programmed and enabled for all seven LED channels. These LEDs can also be combined into groups to reduce the processor instructions.

This entire configuration is driven by a two-capacitor charge pump with gains of 1×, 1.5×, and 2×. The charge pump is capable of driving a maximum IOUT of 240 mA from a supply of 2.5 V to 5.5 V. The device includes a variety of safety features including short-circuit, overvoltage, and overtemperature protection. These features allow 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.

The ADP8863 is available in a compact lead frame chip scale package (LFCSP).

ADP8863 key features:

Automated blinking and funlight timing for each LED driver

16 programmable fade in and fade out times

0.1 sec to 5.5 sec

Selectable linear, square, or cubic fade rates

7 independent and programmable LED drivers

7 drivers capable of 30 mA

1 driver also capable of 60 mA (maximum)

Programmable maximum current limit (128 levels)

Separate and independent controls for backlight LEDs

Backlight fade override

Up to two built-in comparator inputs with programmable modes for ambient light sensing

Charge pump with automatic gain selection of 1×, 1.5×, and 2× for maximum efficiency

Standby mode for <1 μA current consumption

I2C-compatible interface for all programming

Dedicated reset pin and built-in power-on reset (POR)

Short-circuit uit, overvoltage, and overtemperature protection

Internal soft start to limit inrush currents

Input-to-output isolation during faults or shutdown

Operation down to VIN = 2.5 V with undervoltage lockout (UVLO) at VIN = 2.0 V

Small lead frame chip scale package (LFCSP)

ADP8863 Application:

LED indication

Funlight indicator lighting

Keypad backlighting

RGB LED color generation and mixing

General backlighting of small format displays

Figure 1. ADP8863 detailed block diagram

Figure 2. ADP8863 typical operating circuit block diagram

Figure 3. ADP8863 uses ballast resistors to power LEDs

Figure 4. ADP8863 connected to ADP8861 to power more LEDs.

Figure 5. Another application circuit for low Vf LEDs