MAX17061AETI+T【PDF 15/24 页】IC LED DRVR WHITE BCKLGT 28-TQFN

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8-String White LED Driver with

SMBus for LCD Panel Applications

Current-Source Fault Protection

The MAX17061A performs a diagnostic test at startup.

Open/short strings are disabled. LED fault open/short is

also detected after startup. When one or more strings

fails after startup, the corresponding current sources

are disabled. The remaining LED strings still operate

normally. When a fault is detected, bit 4 or/and bit 5, as

well as bit 0 of the fault/status resister are set (see the

Fault/Status Register section).

Open-Current Source Protection

The MAX17061A step-up converter output voltage is

regulated according to the minimum FB_ voltages on

all the strings in use. If one or more strings are open,

the respective FB_ pins are pulled to ground. For any

FB_ lower than 175mV, the corresponding current

source is disabled. The unaffected LED strings still

operate normally. If all strings in use are open, the

MAX17061A shuts down the step-up converter.

Dimming Control

The MAX17061A internally generates a DPWM signal

for accurate WLED brightness dimming control. The

DPWM frequency is adjustable through an external set-

ting resistor and has 1.5% accuracy for R FSET = 464k Ω .

The duty cycle of this DPWM signal can be controlled

externally through two interfaces: PWM and SMBus. The

ISET pin sets the amplitude of the current sources for

each LED string (Figure 3). The internal DPWM signal

directly controls the duty cycle of these current sources.

The resulting current is chopped and synchronized to

the DPWM signal. When filtered by the slow response

time of the human eye, the overall brightness is modu-

lated in a consistent flicker-free manner.

Full-Scale LED Brightness

in DPWM Dimming Control

The full-scale LED current in the DPWM dimming is

determined by resistance from the ISET pin to ground:

The MAX17061A can tolerate A slight mismatch (4.4V)

between LED strings. When severe mismatches

(> 4.4V) or WLED shorts occur, the FB_ voltages will be

I LEDMAX =

20mA × 200k Ω

R ISET

uneven because mismatched voltage drops across

strings. If a given FB_ voltage is higher than 5.6V (typ)

after 24μs blanking time when LEDs are turned on, an

LED short condition is detected on the respective

string. When the short continues for greater than 2ms,

the string is disabled. The controller allows the unaf-

fected LED strings to operate normally. When only one

string is in operation and there are shorts on some

LEDs, then the converter does not shut down. Instead,

the output voltage is adjusted accordingly. The LED

short-protection feature is disabled during the soft-start

phase of the step-up converter.

The acceptable resistance range is 133k Ω < R ISET <

266k Ω , which corresponds to full-scale LED current of

30mA > I LEDMAX > 15mA. Connect ISET to V CC for a

default full-scale LED current of 25mA.

The current source output is pulse-width modulated

and synchronized with a DPWM signal to reduce jitter

and flicker noise in the display.

D=

t ON

t DPWM

DPWM DIMMING MODE

DPWM

D = 50%

t ON

D = 30%

D = 12.5%

D = 6.25%

t DPWM

I LEDMAX

I LED

0A

Figure 3. LED Current Control by DPWM Signal in Dimming

______________________________________________________________________________________

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相关代理商/技术参数

MAX17061AEVCMAXQU+ 功能描述:LED 照明开发工具 Evaluation Kit/Evaluation system for MAX17061A RoHS:否制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装:

MAX17061AEVKIT+ 功能描述:LED 照明开发工具 MAX17061A Eval Kit RoHS:否制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装:

MAX17061ETI+ 功能描述:LED照明驱动器 8-String White LED Driver w/SMBus RoHS:否制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N

MAX17061ETI+T 功能描述:LED照明驱动器 8-String White LED Driver w/SMBus RoHS:否制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N

MAX17061EVCMAXQU+ 功能描述:LED 照明开发工具 Evaluation Kit/Evaluation System for the MAX17061 RoHS:否制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装:

MAX17061EVKIT+ 功能描述:LED 照明开发工具 MAX17061 Eval Kit RoHS:否制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装:

MAX17062ETB+ 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:TFT-LCD STEP-UP DC-DC CONVERTER - Rail/Tube

MAX17062ETB+T 功能描述:直流/直流开关转换器 TFT-LCD Step-Up DC/DC Converter RoHS:否制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT