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參數資料
| 型號： | ADM8845 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Charge Pump Driver for LCD White LED Backlights |
| 中文描述： | 電荷泵驅動器的液晶顯示白色LED背光源 |
| 文件頁數： | 15/18頁 |
| 文件大?。?/td> | 341K |
| 代理商： | ADM8845 |
Preliminary Technical Data
ADM8845
ADM8845 APPLICATIONS
Rev. PrJ 06/04| Page 15 of 18
LAYOUT CONSIDERATIONS AND NOISE
Because of the ADM8845 switching behavior, PCB trace layout
is an important consideration. To ensure optimum performance
a ground plane should be used, all capacitors (C1,C2,C3,C4)
should be located with minimal track lengths to the pins of the
ADM8845.
WHITE LED SHORTING
If a LED is shorted, the ADM8845 will continue to drive the
remaining LEDs with I
LED
per LED (I
LED
= I
SET
* 120). This is
because the ADM8845 uses six internal currents sinks to
produce the LED current. If a LED is shorted, then the
ADM8845 will continue to sink (I
SET
* 120)mA as programmed
by the R
SET
resistor through the shorted LED.
DRIVING FEWER THAN SIX LEDS
The ADM8845 can be operated with less than 6 LEDs in
parallel, simply leave the un-used FBx pins floating. For
example Figure 29, shows five LEDs being powered by the
ADM8845 or Figure 30 shows three main LEDs + one sub LED.
VOUT
FB1
FB2
FB3
FB4
FB5
FB6
Vcc
2.6V - 5.5V
CTRL1
CTRL2
GND
ADM8845
LCD
Figure 29. ADM8845 Driving Five White LEDs
Main Display
Sub Display
VOUT
FB1
FB2
FB3
FB4
FB5
FB6
2.6Vcc
CTRL1
CTRL2
GND
ADM8845
R
SET
I
SET
Figure 30. ADM8845 Driving 3three Main and one Sub
DRIVING FLASH LEDS
The ADM8845 can be operated with any two FBx pins operated
in parallel to double the combined LED current supplied by the
ADM8845. For example if three Flash LEDs are required to be
driven with 60mA/LED. Then the ADM8845 can be configured
as follows, see Figure 31, see also Figure 22, Max LED Current
vs. Ambient Temperature.
VOUT
FB1
FB2
FB3
FB4
FB5
FB6
Vcc
2.6V - 5.5V
CTRL1
CTRL2
GND
ADM8845
Rset
4.72k
60mA
60mA
60mA
Figure 31. ADM8845 Driving three flash LEDs
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相關代理商/技術參數 |
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|---|---|
| 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:4 內部驅動器: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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