Analog Devices ADM8843 Evaluation Tools ADM8843EB-EVALZ ADM8843EB-EVALZ データシート
製品コード
ADM8843EB-EVALZ
Evaluation Board for Charge Pump Driver for
LCD White LED Backlights
Preliminary Technical Data
EVAL-ADM8843
Rev. PrC
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703
© 2005 Analog Devices, Inc. All rights reserved.
FEATURES
ADM8843 drives 4 white LEDs from a 2.6V to 5.5V (li-ion)
input supply
1x/1.5x/2x Fractional Charge Pump to maximize power
efficiency
0.3% Typ LED Current Matching
Power Sub and main Display LEDs
Low Power Shutdown Mode
Package footprint only 9mm
input supply
1x/1.5x/2x Fractional Charge Pump to maximize power
efficiency
0.3% Typ LED Current Matching
Power Sub and main Display LEDs
Low Power Shutdown Mode
Package footprint only 9mm
2
(3mm x 3mm)
Package height only 0.9mm
Shutdown Function
Soft-start limiting inrush current
Shutdown Function
Soft-start limiting inrush current
APPLICATIONS
White LED Backlighting
Micro TFT Color displays
Mobile Phones with Main and Sub Displays
DSC
PDAs
Micro TFT Color displays
Mobile Phones with Main and Sub Displays
DSC
PDAs
INTRODUCTION
The ADM8843 Evaluation Board allows the ADM8843 Charge
Pump Driver for LCD white LED backlights to be quickly and
easily evaluated.
Pump Driver for LCD white LED backlights to be quickly and
easily evaluated.
The evaluation board allows all of the input and output
functions to be exercised without the need for external
components.
functions to be exercised without the need for external
components.
ADM8843 GENERAL DESCRIPTION
The following gives a brief description of the ADM8843 and the
evaluation board hardware overview. Further information can
be found in the data sheet for the device.
evaluation board hardware overview. Further information can
be found in the data sheet for the device.
The ADM8843 provides the power required to drive up to 4
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.
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
typical I
use of a feedback pin to sense individual LED current with a
typical I
LED
to I
LED
matching accuracy of 0.3%.
The ADM8843 provides two digital input control pins, CTRL1
and CTRL2, which control the operation and the brightness of
the LEDs. The ADM8843 is configured with a sub and main
display, the main display refers to 3 of the 6 LEDs (FB1 – FB3)
and the sub display refers to the remaining LED (FB54).
and CTRL2, which control the operation and the brightness of
the LEDs. The ADM8843 is configured with a sub and main
display, the main display refers to 3 of the 6 LEDs (FB1 – FB3)
and the sub display refers to the remaining LED (FB54).
The ADM8843 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 ADM8843 has soft-start circuitry to limit inrush
current flow at power up.
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 ADM8843 has soft-start circuitry to limit inrush
current flow at power up.
The ADM8843 is fabricated using CMOS technology for
minimal power consumption. The part is packaged in a 16-lead
LFCSP (Lead Frame Chip Scale Package).
minimal power consumption. The part is packaged in a 16-lead
LFCSP (Lead Frame Chip Scale Package).
EVALUATION SYSTEM PACKAGE CONTENTS
The evaluation system contains the following items:
• ADM8843 Evaluation Board
• PC Parallel to Serial Cable
• CD containing evaluation board software
EVALUATION BOARD HARDWARE
The ADM8843 evaluation board contains the following main
components, which can be identified from the block diagram,
the schematic diagram and the printed circuit board silkscreen
of figures 1,3 and 4 overleaf.
components, which can be identified from the block diagram,
the schematic diagram and the printed circuit board silkscreen
of figures 1,3 and 4 overleaf.
• 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
ADM8843 Eval Board to external components.