基于ADP8863設計的帶電荷泵驅動的LED驅動技術
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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主要特性:
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 (maximum)
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, 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應用:
LED indication
Funlight indicator lighting
Keypad backlighting
RGB LED color generation and mixing
General backlighting of small format displays
圖1.ADP8863詳細方框圖
圖2.ADP8863典型工作電路框圖
圖3.ADP8863采用鎮流電阻給LED供電方框圖
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