The LM3533 is a complete power source for backlight, keypad, and indicator LEDs in smartphone handsets. The high-voltage inductive boost converter provides the power for two series LED strings for display backlight and keypad functions (HVLED1 and HVLED2). The integrated charge pump provides the bias for the five low-voltage indicator LED current sinks (LVLED1 to LVLED5). All low-voltage current sinks can have a programmable pattern modulated onto their output current for a wide variety of blinking patterns.
Additional features include a pulse width modulation (PWM) control input for content adjustable backlight control (CABC), and an ambient light sensor interface (ALS) with an internal 8-bit ADC to provide automatic current adjustment based upon ambient light conditions. Both the PWM and ALS inputs can be used to control any high- or low-voltage current sink.
The LM3533 is fully programmable via an I2C-compatible interface. The device is available in a 20-pin DSBGA and operates over a 2.7-V to 5.5-V input voltage range and a −40°C to +85°C temperature range.
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|Vin (Max) (V)|
|Vout (Max) (V)|
|Switching Frequency (Max) (kHz)|
|LED Current Per Channel (mA)|
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|Operating Temperature Range (C)|
|Approx. Price (US$)|
|-40 to 125|
|0.70 | 1ku|