| Number of channels (#) | 6 |
| Vin (Min) (V) | 5.5 |
| Vin (Max) (V) | 22 |
| Vout (Min) (V) | 10 |
| Vout (Max) (V) | 40 |
| Type | Inductive |
| Switching frequency (Max) (kHz) | 1250 |
| LED current per channel (mA) | 50 |
| Peak efficiency (%) | 91 |
| Topology | Boost |
| Features | Adjustable Switch Frequency, Enable/Shutdown, I2C Control, PWM Control |
| Operating temperature range (C) | -30 to 85 |
- High-Voltage DC/DC Boost Converter with Integrated FET
with Four Switching Frequency Options: 156/312/625/1250 kHz - 2.7-V to 22-V Input Voltage Range to Support 1x to 5x Cell Li-Ion
Batteries - Programmable PWM Resolution
- 8 to 13 True Bits (Steady State)
- Additional 1 to 3 Bits Using Dithering During Brightness
Changes
- I2C and PWM Brightness Control
- Automatic PWM & Current Dimming for Improved Efficiency
- PWM output frequency and LED Current set through Resistors
- Optional Synchronization to Display VSYNC Signal
- Six LED Outputs with LED Fault (Short/Open) Detection
- Low Input Voltage, Overtemperature, Overcurrent Detection,
and Shutdown - Minimum Number of External Components
The LP8550 is a white-LED driver with integrated boost converter. It has six adjustable current sinks which can be controlled by PWM input or with I2C-compatible serial interface. The boost converter has adaptive output voltage control based on the LED driver voltages. This feature minimizes the power consumption by adjusting the voltage to lowest sufficient level in all conditions.
LED outputs have 8-bit current resolution and up to 13-bit PWM resolution with additional 1- to 3-bit dithering to achieve smooth and precise brightness control. Proprietary Phase Shift PWM control is used for LED outputs to reduce peak current from the boost converter, thus making the boost capacitors smaller. The Phase Shifting scheme also eliminates audible noise.
Automatic PWM dimming at lower brightness values and current dimming at higher brightness values can be used to improve the optical efficiency. Internal EEPROM is used for storing the configuration data. This makes it possible to have minimum external component count and make the solution very small.
The LP8550 has safety features which make it possible to detect LED outputs with open or short fault — low input voltage and boost overcurrent conditions are monitored, and chip is turned off in case of these events. Thermal de-rating function prevents overheating of the device by reducing backlight brightness when set temperature has been reached.
