Features and Benefits
- Drives 6 LEDs from 2.6 V to 5.5 V (Li-Ion) input supply
- 1×/1.5×/2× fractional charge pump to maximize power efficiency
- 1% max LED current matching
- Up to 88% power efficiency over Li-Ion range
- Powers main and sub display LEDs with individual shutdown
- Package footprint only 9 mm2 (3 mm × 3 mm)
- Package height only 0.9 mm
- Low power shutdown mode
- Shutdown function
- Soft-start limiting in-rush current
Product DetailsThe ADM8845 uses charge pump technology to provide the power required to drive up to six LEDs. The LEDs are used for backlighting a color LCD display, having regulated constant current for uniform brightness intensity. The main display can have up to four LEDs, and the sub display can have one or two LEDs. The digital CTRL1 and CTRL2 input control pins control the shutdown operation and the brightness of the main and sub displays.
To maximize power efficiency, the charge pump can operate in a 1×, 1.5×, or 2× mode. The charge pump automatically switches between 1×/1.5×/2× modes, based on the input voltage, to maintain sufficient drive for the LED anodes at the highest power efficiency
Improved brightness matching of the LEDs is achieved by a feedback pin to sense individual LED current with a maximum matching accuracy of 1%.
- Cellular phones with main and sub displays
- White LED backlighting
- Camera flash/strobes and movie lights
- Micro TFT color displays
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
The 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).
Features & 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
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.