OVERVIEW

The SM8133B is a charge pump type white LED driver. It can drive 1 to 6 backlight white LED connected in parallel and 1 flash white LED. The output voltage circuit has a 3.0V LDO (Low Dropout Regulator), making the device ideal for camera-equipped cellular phones. The charge pump switches between ×1 to ×1.5 boost mode in response to LED drive current requirements to extend battery life to the maximum. The boost switching occurs in response to the drive current of all the connected LED and thus supports variations in LED for ward-bias voltage drop (VF). Each LED drive current is controlled by a 7-channel LED drive current control circuit. The 6 backlight channels can be subdivided into 2 groups, with each group having independent dimming and lighting control. The backlight grouping, backlight LED drive current and ON/OFF control, flash

LED drive current and ON/OFF control, and LDO output ON/OFF control are all set by 3-wire serial interface data input. Also, the RESETB pin can be connected to the microcontroller supply for a system-wide shutdown function.

FEATURES

■ Noise reduction due to charge pump boost circuit

■ Automatic charge pump switching to conserve power

■ Drives 1 to 6 backlight white LED(30mA/ch at maximum setting)

■ Drives a flash white LED (150mA at maximum setting)

■ Backlight and flash white LED brightness adjustment

■ Group settings for 2-group backlight lighting control

■ 3-wire serial input interface for all setting and control

■ 3.0V output LDO circuit built-in

■ Shutdown function by RESETB pin

■ Soft start circuit built-in

■ Thermal protection circuit built-in

■ Input voltage range

• No-load current (IOUT= 0mA): 2.7 to 4.6V

• Load current (IOUT= 80mA): 3.0 to 4.6V

• Load current (IOUT= 200mA): 3.3 to 4.6V

■ Quiescent current

• LDO only: 0.3mA (typ)

• Not -switching (×1.0 mode): 0.5mA (typ)

• Switching (×1.5 mode): 2.5mA (typ)

■ Standby current: 0.01µA (typ)

■ Operating frequency: 750kHz (typ)

■ Backlight LED current: 30mA/ch (typ)

■ Flash LED current: 150mA (typ)

■ All LED total maximum current: 200mA (typ)

■ Backlight LED current matching (ILED= 30mA) : ±3

■ Flash LED current accuracy (ILED= 150mA) : ±5

■ LDO (Low Dropout Regulator) output voltage : 3.0V±2

■ Packages:20-pin QFN WL-CSP (under development)

APPLICATIONS

■ Cellular phone

■ Digital still camera

■ PDA

■ Portable games