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參數資料
| 型號： | ADM8845ACP |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 顯示驅動器 |
| 英文描述： | Charge Pump Driver for LCD White LED Backlights |
| 中文描述： | LED DISPLAY DRIVER, QCC16 |
| 封裝： | 3 X 3 MM, 0.90 MM HEIGHT, LFCSP-16 |
| 文件頁數： | 10/18頁 |
| 文件大小： | 341K |
| 代理商： | ADM8845ACP |
ADM8845
Preliminary Technical Data
ADM8845 OPERATION
The ADM8845 charge pump driver for LCD white LED backlights implements a multiple gain charge pump (1x, 1.5x, 2x)to maintain the
correct voltage on the anodes of the LEDs over a 2.6V to 5.5V (li-ion) input supply voltage. The charge pump automatically switches
between 1x/1.5x/2x modes based on the input voltage, to maintain sufficient drive for the LED anodes, with V
CC
input voltages as low as
2.6V. It also includes regulation of the charge pump output voltage for supply voltages up to 5.5V. The ADM8845 six LEDs are arranged
into two groups; main and sub. The main display can be up to four LEDs (FB1 to FB4) and the sub display can be up to two LEDs (FB5
and FB6), see Figure 23. Two digital input control pins, CTRL1 and CTRL2, control the shutdown operation and the brightness of the
main and sub displays, see Table 4.
Rev. PrJ 06/04 | Page 10 of 18
CTRL1
0
0
1
1
CTRL2
0
1
0
1
Table 4. ADM8845 Digital Inputs Truth Table
LED Shutdown Operation
Sub Display Off / Main Display Off
Sub Display Off / Main Display On
Sub Display On / Main Display Off
Sub Display On / Main Display On
An external resistor R
SET
is connected between the I
SET
pin and GND, this resistor sets up a reference current I
SET
which is gained up by 120
internally within the ADM8845 to produce the I
LED
currents of up to 30mA/LED, (I
LED
= I
SET
* 120 and I
SET
= 1.18V /R
SET
). The ADM8845
uses six individual current sinks to individually sense each LED current with a maximum matching performance of 1%. This current
matching performance ensures uniform brightness across a color display.
The ADM8845 provides the option to control the brightness of the white LEDs with a digital PWM signal applied to CTRL1 and/or
CTRL2. The duty cycle of the applied PWM signal determines the brightness of the main and/or sub display backlight white LEDs. The
ADM8845 also allows the brightness of the white LEDs to be controlled using a DC voltage, refer to page 14, Figure 27Figure . Soft-start
circuitry limits the inrush current flow at power up. The ADM8845 is fabricated using CMOS technology for minimal power
consumption and is packaged in a 16-Lead Frame Chip Scale Package.
Charge Pump
1x/1.5x/2x mode
Control
Logic
VCC
C4
Osc
Vref
+
-
LED Current
Control
Circuit
Current Controlled Sinks
Iset
GND
ADM8845
Vout
FB2
FB3
FB4
FB5
FB6
FB1
C3
C1
C2
Rset
Current
Co1
Current
2
Current
3
Current
Control
4
Current
5
Current
Control
6
CTRL1
CTRL2
SUB
MAIN
Figure 23. ADM8845 FUNCTIONAL BLOCK DIAGRAM
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| 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 |
| ADM8845ACPZ-REEL1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Charge Pump Driver for LCD White LED Backlights |
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