收藏本站

ADM8843
THEORY OF OPERATION
The ADM8843 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 2.6 V to 5.5 V (Li-Ion) input supply voltage. The charge pump
automatically switches among 1×/1.5×/2× modes, based on the
input voltage, to maintain sufficient drive for the LED anodes,
with V CC input voltages as low as 2.6 V. It also includes regulation
of the charge pump output voltage for supply voltages up to 5.5 V.
The ADM8843’s four LEDs are arranged into two groups, main
and sub. The main display can have up to three LEDs (FB1 to
FB3), and the sub display has one LED (FB4) (see Figure 18).
The CTRL1 and CTRL2 digital input control pins control the
shutdown operation and the brightness of the main and sub
displays (see Table 4).
Table 4. Shutdown Truth Table
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
internally gained up by 120 within the ADM8843 to produce
I LED currents of up to 20 mA/LED (I LED = I SET × 120 and I SET =
1.18 V/R SET ). The ADM8843 uses four separate current sinks to
sense each LED current individually with a typical matching
performance of 0.3%. This current matching performance
ensures uniform brightness across a color display.
The ADM8843 lets the user 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 ADM8843 also allows the brightness of the white
LEDs to be controlled using a dc voltage (see Figure 17). Soft
start circuitry limits the in-rush current flow at power-up. The
CTRL1
0
0
1
1
CTRL2
0
1
0
1
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
ADM8843 is fabricated using CMOS technology for minimal
power consumption and is packaged in a 16-lead lead frame
chip scale package.
ADM8843
I SET
V BRIGHT
0V–2.5V
R = 15k Ω
R SET = 13.4k Ω
Figure 17. PWM Brightness Control Using a DC Voltage Applied to V BRIGHT
C1
1 μ F
C2
1 μ F
V CC
ADM8843
V OUT
C4
4.7 μ F
CHARGE PUMP
1 × /1.5 × /2 × MODE
C3
2.2 μ F
MAIN
SUB
OSC
CTRL1
CONTROL
CTRL2
I SET
R SET
LOGIC
LED
CURRENT
CONTROL
CIRCUIT
V REF
FB1
FB2
FB3
FB4
CURRENT CONTROLLED SINKS
GND
Figure 18. Functional Block Diagram
Rev. C | Page 9 of 16
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
ADP1653ACPZ-R7 IC LED DRVR PHOTO FLASH 16-LFCSP
ADP1712-EVALZ BOARD EVALUATION ADP1712
ADP1720-EVALZ BOARD EVAL FOR ADP1720-ADJ
ADP2140CPZ-REDYKIT REDYKIT 2 BOARDS ADP2140ACPZ
ADP3110AKRZ-RL IC MOSFET DRIVER DUAL 12V 8SOIC
ADP3120AJCPZ-RL IC MOSFET DRIVER DUAL 12V 8-DFN
ADP3121JRZ-RL IC MOSFET DRIVER DUAL 12V 8SOIC
ADP3415LRMZ-REEL IC MOSFET DVR DUAL BOOTST 10MSOP
相关代理商/技术参数
ADM8843ACUZ-REEL7 制造商:Analog Devices 功能描述:
ADM8843EB-EVALZ 功能描述:BOARD EVAL ADM8843 RoHS:是 类别:编程器，开发系统 >> 评估板 - LED 驱动器 系列:- 标准包装:1 系列:PowerWise® 电流 - 输出 / 通道:20mA 输出及类型:1，非隔离 输出电压:17V 特点:可调光 输入电压:2.7 ~ 5.5 V 已供物品:板 已用 IC / 零件:LM3508 相关产品:LM3508TLX-ND - IC LED DRVR WHT BCKLGT 9USMDLM3508TLDKR-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLCT-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLTR-ND - IC LED DRVR WHT BCKLGT 9MICROSMD
ADM8845 制造商:AD 制造商全称:Analog Devices 功能描述:Charge Pump Driver for LCD White LED Backlights
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 制造商全称: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 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:6,000 系列:- 恒定电流:- 恒定电压:- 拓扑:开路漏极，PWM 输出数:4 内部驱动器:是 类型 - 主要:LED 闪烁器 类型 - 次要:- 频率:400kHz 电源电压:2.3 V ~ 5.5 V 输出电压:- 安装类型:表面贴装 封装/外壳:8-VFDFN 裸露焊盘 供应商设备封装:8-HVSON 包装:带卷 (TR) 工作温度:-40°C ~ 85°C 其它名称:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND