Description
The A8503 is a multi-output WLED/RGB LED driver for medium-size LCD backlighting. It integrates a current-mode boost converter with internal power switch and six current sinks. The boost converter can provide output voltages up to 47 V. The boost converter can drive up to 72 LEDs at 20 mA per LED with a battery voltage down to 5 V. The LED sinks are capable of sinking up to 32 mA each, and can also be paralleled together to achieve even higher LED currents. The A8503 provides protection against overvoltage, open diode, open or shorted LED string, and overtemperature. A dual level cycle-by-cycle current limit function provides soft start and protects against overloads. A soft start timeout monitor is provided to enhance protection when starting up into a fault condition.
When the MODE pin is set low, the A8503 latches on a fault, and can be re-enabled only by cycling the input voltage, VIN, or by toggling the EN pin. Connecting the MODE pin high provides auto-restart after fault events. The A8503 features EN (enable) and PWM (dimming) pins to comply with popular notebook backlight control interfaces.
The device package is a 26-contact, 4 mm × 4 mm, 0.75 mm nominal overall height QFN, with exposed pad for enhanced thermal dissipation. It is lead (Pb) free, with 100% matte tin leadframe plating.
Functional Block Diagram
Features
- Active current sharing between LED strings for ±0.6% accuracy and matching
- Drives up to 12 series × 6 parallel = 72 LEDs (Vf = 3.2 V, If = 20 mA) at 5 V
- Each individual current sink is capable of 32 mA
- Adjustable overvoltage protection (OVP)
- 600 kHz to 2 MHz adjustable switching frequency
- Open or shorted LED string protection
- Open Schottky diode protection
- Overtemperature, cycle-by-cycle current limit, undervoltage, and soft start time-out protections
- Selectable latched/auto-restart protection modes
- No audible MLCC noise during PWM dimming
- No pull-up resistors required for LED modules that use ESD capacitors
- Extends battery life
- Efficiency optimized for 3-cell notebooks
- 0.1 µA shutdown current
- Unique architecture eliminates external voltage divider and associated battery drain
- Rugged and small footprint solution
- 55 V, 2 A DMOS switch in 4 mm × 4 mm package—allows IPC-2221/2 / IPC-D-275 compliant PCB layout
Applications
- Notebook and sub-notebook displays
- LCD monitors
- LCD panels
source：ShenZhen henlito electronic co.,ltd.
web:www.henlito.com
