Features and Benefits
- ADM8845 drives 6 white LEDs from a 2.6V to 5.5V (li-ion) input supply
- 1x/1.5x/2x Fractional Charge Pump to maximize power efficiency
- 1% LED Current Matching
- Power Sub and main Display LEDs
- Low Power Shutdown Mode
- Package footprint only 9mm2 (3mm x 3mm)
- Package height only 0.9mm
- Shutdown Function
- Soft-start limiting inrush current
Product DetailsThe evaluation system contains the following items:
- ADM8845 Evaluation Board
- PC Parallel to Serial Cable
- CD containing evaluation board software
The ADM8845 evaluation board contains the following main components, which can be identified from the block diagram, the schematic diagram and the printed circuit board.
- 13 jumper points to facilitate the connection of external inputs and internal circuitry.
- 21 test points for signal connection and measurement
- A patchwork area to facilitate the connection up the ADM8845 Eval Board to external components.
The ADM8845 provides the power required to drive up to 6 white LEDs, using charge pump technology. The LEDs are used for backlighting a color LCD display. To maximize power efficiency, a charge pump that can operate in either a 1x, 1.5x or 2x mode is used. The charge pump automatically switches between 1x/1.5x/2x modes based on the input voltage, to maintain correct output levels at a high power efficiency. Improved brightness matching of the LEDs is achieved by the use of a feedback pin to sense individual LED current with a maximum ILED to ILED matching accuracy of 1% and ILED to ISET maximum matching of 1%.
The ADM8845 provides two digital input control pins, CTRL1 and CTRL2, which control the operation and the brightness of the LEDs. The ADM8845 is configured with a sub and main display, the main display refers to 4 of the 6 LEDs (FB1 - FB4) and the sub display refers to the remaining 2 LEDs (FB5 – FB6).
The ADM8845 provides the option to control the brightness of the LEDs with a digital PWM signal. The duty cycle of the PWM signal determines the brightness of the backlight LEDs. Brightness control of the LEDs can also be controlled by a DC voltage. The ADM8845 has soft-start circuitry to limit inrush current flow at power up.
The ADM8845 is fabricated using CMOS technology for minimal power consumption. The part is packaged in a 16-lead LFCSP (Lead Frame Chip Scale Package).
Documentation & Resources
Pricing displayed is based on 1-piece.
Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.