ADM8845EB-EVALZ Analog Devices Inc, ADM8845EB-EVALZ Datasheet
ADM8845EB-EVALZ
Specifications of ADM8845EB-EVALZ
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ADM8845EB-EVALZ Summary of contents
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FEATURES Drives 6 LEDs from 2 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 ...
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ADM8845 TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Revision History ............................................................................... 2 Specifications ..................................................................................... 3 Absolute Maximum Ratings ............................................................ 4 Thermal Characteristics .............................................................. 4 ESD Caution .................................................................................. 4 Pin ...
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SPECIFICATIONS −40°C to +85°C, unless otherwise noted; C1 1.0 µ 2.2 µ 4.7 µ Table 1. Parameter Min INPUT VOLTAGE, V 2.6 CC ...
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ADM8845 ABSOLUTE MAXIMUM RATINGS T = 25°C, unless otherwise noted. A Table 2. Parameter Supply Voltage SET CTRL1, CTRL2 V Shorted 1 OUT Feedback Pins FB1 to FB6 Operating Temperature Range 2 Six LEDs Enabled with 30 ...
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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Table 3. Pin Function Descriptions Pin No. Mnemonic Function 1 V Charge Pump Output. A 2.2 µF capacitor to ground is required on this pin. Connect V OUT the LEDs. 2 C2+ Flying Capacitor 2 ...
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ADM8845 TYPICAL PERFORMANCE CHARACTERISTICS 4.75 6.75 8.75 10.75 R (k) SET Figure 3. I (mA) Current vs. R LED 20.35 20.30 –40C 20.25 20.20 20.15 20.10 20.05 20.00 2.6 3.1 3.6 4.1 SUPPLY ...
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DUTY CYCLE (%) Figure 9. I (mA) vs. PWM Dimming (Varying Duty Cycle), LED Six LEDs Enabled, Frequency = 1 kHz 300 250 200 20mA/LED 150 15mA/LED 100 50 0 ...
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ADM8845 OUT CH1 20.0mV B CH2 20.0mV B M 400ns CH1 W W Figure 15. 1× Mode Operating Waveforms 3. 3.2V ...
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Figure 21. Maximum I (mA) vs. Ambient Temperature, LED Six LEDs Connected 85°C Rev Page ADM8845 ...
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ADM8845 THEORY OF OPERATION The ADM8845 charge pump driver for LCD white LED back- lights implements a multiple gain charge pump (1×, 1.5×, 2×) to maintain the correct voltage on the anodes of the LEDs over a 2 ...
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OUTPUT CURRENT CAPABILITY The ADM8845 can drive current to each of the six LEDs given an input voltage of 2 5.5 V. The LED currents have a maximum current matching of 1% between ...
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ADM8845 The main and sub display brightness of the ADM8845 can be controlled together or separately by applying a digital PWM signal to both CTRL1 and CTRL2 pins. The duty cycle of the applied digital PWM signal determines the brightness ...
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FULL ON LED CONFIG. CTRL1 CTRL2 V OUT I LED (SUB) I LED (MAIN) 100% SUB DISPLAY BRIGHTNESS 100% MAIN DISPLAY BRIGHTNESS LED BRIGHTNESS CONTROL USING A PWM SIGNAL APPLIED TO V PWM Adding two external resistors and a capacitor, ...
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ADM8845 APPLICATIONS LAYOUT CONSIDERATIONS AND NOISE Because of the s switching behavior of the ADM8845, PCB trace layout is an important consideration. To ensure optimum performance, a ground plane should be used, and all capacitors (C1, C2, C3, C4) must ...
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DRIVING FLASH LEDs The ADM8845 can be operated with any two FBx pins used in parallel to double the combined LED current supplied by the ADM8845. For example, if three flash LEDs need to be driven with 60 mA/LED, the ...
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ADM8845 DRIVING FOUR BACKLIGHT WHITE LEDs AND FLASH LEDs The ADM8845 can be configured to power four backlight white LEDs and a camera flash, bundled into one package. FB1 to FB4 power the backlight light, FB5 and FB6 power two ...
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POWER EFFICIENCY The ADM8845 power efficiency (η) equations are η OUT ((V × I × Gain × LOAD × (V × OUT F ...
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... OUTLINE DIMENSIONS PIN 1 INDICATOR 12° MAX 1.00 0.85 0.80 SEATING PLANE ORDERING GUIDE Model 1 Temperature Range ADM8845ACPZ-REEL −40° 85°C ADM8845ACPZ-REEL7 −40° 85°C ADM8845EB-EVALZ RoHS Compliant Part. 3.00 0.60 MAX BSC SQ 0. (BOTTOM VIEW) 2.75 TOP BSC SQ EXPOSED VIEW 9 0.50 ...
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NOTES Rev Page ADM8845 ...
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ADM8845 NOTES ©2004–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D04867-0-1/11(C) Rev Page ...