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參數(shù)資料
| 型號： | ADM8845 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Charge Pump Driver for LCD White LED Backlights |
| 中文描述： | 電荷泵驅(qū)動器的液晶顯示白色LED背光源 |
| 文件頁數(shù)： | 14/18頁 |
| 文件大?。?/td> | 341K |
| 代理商： | ADM8845 |
ADM8845
Preliminary Technical Data
ADM8845 LED BRIGHTNESS CONTROL USING A
PWM SIGNAL APPLIED TO V
PWM
Adding two external resistors and a capacitor as shown on
Figure 26, can also be used to achieve PWM brightness control.
This PWM brightness control method can be used instead of
CTRL1 and/or CTRL2 digital PWM brightness control. With
this configuration, CTRL1 and CTRL2 digital logic pins can be
used to control shutdown of the white LEDs, while V
PWM
can be
used to control the brightness of all the white LEDs. By applying
a high-frequency PWM signal (Amplitude 0V to 2.5V) to drive
an R-C-R filter on the I
SET
pin of the ADM8845. A 0% PWM
duty cycle corresponds to 20mA/LED, while a 100% PWM duty
cycle corresponds to a 0mA/LED. At PWM frequencies above
5kHz, C5 may be reduced. Refer to Figure 26, ADM8845 PWM
Brightness Control Using Filtered-PWM Signal. The amplitude
of the PWM signal must be 0 V and 2.5 V only, in order to have
20mA flowing in each LED.
Rev. PrJ 06/04 | Page 14 of 18
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#######:#
#########
-#8#
#8#
####-#8#
#8#
6
;<6
##.
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#8#".>
#8#".>#
#8#.>
Figure 26. ADM8845 PWM Brightness Control Using Filtered-
PWM Signal
ADM8845 LED BRIGHTNESS CONTROL USING A
DC VOLTAGE APPLIED TO V
BRIGHT
Adding one resistor as shown in figure 27 , this configuration
can also be used to achieve brightness control of the white LEDs
using a DC voltage applied to the V
BRIGHT
node. Figure 28 shows
an application example of LED Brightness control using a DC
Voltage with a amplitude of 0V to 2.5V, applied to V
BRIGHT
.
6
7
#8#>
#8#.>
##.
Figure 27. ADM8845 PWM Brightness Control Using a DC
Voltage applied to VBRIGHT
The equation for I
LED
is:
I
SET
= [(1/R
SET
+ 1/R)(V
SET
)] – [(1/R)(V
BRIGHT
)]
I
LED
= 120*I
SET
Where R = 15k Ohm, V
SET
= voltage at I
SET
pin (1.18V)
7
.
.
.
".
.
Figure 28. ADM8845 PWM Brightness Control Application
Diagram Using a DC Voltage applied to V
BRIGHT
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|---|---|
| ADM8845ACP | Charge Pump Driver for LCD White LED Backlights |
| ADM8845ACP-REEL7 | Charge Pump Driver for LCD White LED Backlights |
| ADM8845ACPZ | Charge Pump Driver for LCD White LED Backlights |
| ADM8845ACPZ-REEL7 | 20-21 (9 Contact) Pin Insert; For Use With:Amphenol MIL-C-5015 97 Series Circular Connectors; No. of Contacts:9; Gender:Male; Operating Voltage:700V |
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ADM8845ACP | 制造商:Analog Devices 功能描述:CHG PUMP STPUP 30MA 16LFCSP - Bulk |
| ADM8845ACP-REEL | 制造商:Analog Devices 功能描述:Charge Pump STPUP 30mA 16-Pin LFCSP EP T/R |
| ADM8845ACP-REEL7 | 制造商:Analog Devices 功能描述:Charge Pump STPUP 30mA 16-Pin LFCSP EP T/R |
| ADM8845ACPZ | 制造商:AD 制造商全稱:Analog Devices 功能描述:Charge Pump Driver for LCD White LED Backlights |
| ADM8845ACPZ-REEL | 功能描述:IC LED DRVR WHITE BCKLGT 16LFCSP RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動器 系列:- 標準包裝:6,000 系列:- 恒定電流:- 恒定電壓:- 拓撲:開路漏極，PWM 輸出數(shù):4 內(nèi)部驅(qū)動器:是 類型 - 主要:LED 閃爍器 類型 - 次要:- 頻率:400kHz 電源電壓:2.3 V ~ 5.5 V 輸出電壓:- 安裝類型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤 供應商設備封裝:8-HVSON 包裝:帶卷 (TR) 工作溫度:-40°C ~ 85°C 其它名稱:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
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