The A8503 is a multi-output WLED/RGB LED for midsize LCD backlightingdrive。 It incorporates a current modeBoost converterWith internal power switch and six current converters. The boost converter provides output voltages up to 47 V. The boost converter drives 72 LEDs with a battery voltage drop of 5 V, each with a current of 20 mA. LED converters can draw 32 mA each and can be paralleled to provide higher LED current. The A8503 provides protection against overvoltage, open-diode, LED string break or short, and overtemperature. Two-stage wave-by-wave current limit gives you soft-start and overload protection. Provides soft-start stale monitoring for enhanced boot fault protection.
When the MODE pin is set low, the A8503 locks the fault and can only be re-enabled by disconnecting and reconnecting the input voltage, VIN, or switching the EN pin. Placing the MODE pin high provides automatic restart after a fault. The A8503 has EN (Enable) and PWM (Light and Dark Control) pins to meet the requirements of today's popular laptop backlight control interfaces.
The device is available in a 26-contact, 4 mm× 4 mm, 0.75 mm nominal total height QFN package with exposed heatsink plate for enhanced thermal dissipation. The package is lead-free and the leadframes are 100% matte tin.
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- Laptop and PDA displays
- LCD monitor
- LCD panel
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- Active current sharing between LED strings achieves ±0.6% accuracy and matching
- Drives up to 12 serial × 6 parallel = 72 LEDs (Vf = 3.2 V, If = 20 mA) at 5 V
- Each channel draws 32 mA
- Adjustable Overvoltage Protection (OVP)
- 600 kHz to 2 MHz adjustable switching frequency
- Open or short LED string protection
- Open Schottky diode protection
- Overtemperature, wave-by-wave current limit, undervoltage, and soft-start outdated protection
- Optional latch/auto-restart protection mode
- There is no audible ceramic capacitor noise during PWM dimming control
- LED modules using ESD capacitors do not require pull-up resistors
- Extend battery life
- Optimized efficiency for three-cell laptops
- 0.1 μA shutdown current
- Unique architecture eliminates the need for an external voltage divider and associated battery discharge
- Robust and small solution
- The 55 V, 2 A DMOS switch in a 4 mm × 4 mm package allows for IPC-2221/2 / IPC-D-275 compatible PCB layouts