ADM8845:  Charge Pump Driver for 6 White LED LCD Backlights

The ADM8845 provides the power required to drive up to 6 white LEDs from a 2.6 V to 5.5 V (li-ion) input supply, using charge pump technology. The white LEDs are used for backlighting a color LCD ...More

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ADM8845:  Charge Pump Driver for 6 White LED LCD Backlights

Product Description

The ADM8845 provides the power required to drive up to 6 white LEDs from a 2.6 V to 5.5 V (li-ion) input supply, using charge pump technology. The white LEDs are used for backlighting a color LCD display. To maximize power efficiency, a charge pump that can operate in either of 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 white LEDs is achieved by the use of a feedback pin to sense each individual LED current with a maximum matching accuracy of 1% and ISET to ILED maximum matching of 1%.

The ADM8845 provides two digital input control pins, CTRL1 and CTRL2, which control the shutdown operation and the brightness of the LEDs. The LEDs are arranged into two groups, main and sub display options, the main display refers to 4 of the 6 LEDs (FB1 -FB4) and the sub display refers to the remaining 2 LEDs (FB5 - FB6). Brightness control of the white LEDs can be achieved with a digital PWM signal applied to CTRL1 and/or CTRL2 to provide brightness control on the main and/or sub displays. The duty cycle of the applied digital PWM signal determines the brightness of the backlight white LEDs. Also brightness control of the white LEDs can be controlled using a DC voltage or a PWM signal applied to the ISET pin with a few external components added.

The ADM8845 also 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-pin LFCSP package.

Features

  • Drives 6 White LEDs from a 2.6 V to 5.5 V (li-ion) Input Supply
  • 1x/1.5x/2x Fractional Charge Pump to Maximise Power Efficiency
  • 1% LED Current Matching (Max Error)
  • Up to 88% Power Efficiency
  • Powers Main and Sub Displays LEDs
  • Package Footprint only 9mm2 (3mm x 3mm)
  • Package Height only 0.9mm
  • Low Power Shutdown Mode
  • Shutdown Function
  • Soft-start limiting inrush current

Diagrams

ADM8845 Diagram
Functional Block Diagram for ADM8845

Specifications

Product Description Charge Pump Driver for 6 White LED LCD Backlights
Input Voltage Range (Vcc) 2.6 to 5.5V
Base Drive (mA) n/a
Efficency (%) 88%
LED # 6
Frequency Range 0.1 to 200 kHZ
Package 16-LFCSP

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Part# Input Voltage Range (Vcc) Vout Adjust Options Iout (max) (mA) Switching Frequency (MHz) Package Price* (1000-4999)
ADM8843 2.6 to 5.5V - 20 1.5 16-LFCSP $0.50
ADM8845 2.6 to 5.5V - 30 - 16-LFCSP $0.71
ADP1610 2.5 to 5.5 V Vin to 12 V 1.2 1.2 8-MSOP $1.12
ADP1611 2.5 to 5.5 V Vin to 20 V 1.2 1.2 8-MSOP $1.20
ADP1653 2.75 to 5.5 V - 500 1.2 16-LFCSP $1.47
ADP5520 2.27 to 5.5 V - 30 1 - $1.66

* The pricing listed here is provided only for budgetary purposes as recommended list price in U.S. Dollars in the United States ex factor per unit for the stated volume. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
** Pricing is currently unavailable. Click on the product number to see the Product Page for additional information.

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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.

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*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.
**Sample availability may be better than production availability. Please enter samples iinto your cart to check sample availability.

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