Supertex公司的HV9957是帶故障保護(hù)六路LED驅(qū)動(dòng)器,包括一個(gè)開(kāi)關(guān)模式升壓轉(zhuǎn)換器和六個(gè)低壓降線性穩(wěn)流器,提供了高效率和精密的電流控制,電流精度達(dá)±1.5%,占空比精度達(dá)0.5%.每路電流高達(dá)30mA,采用相位PWM調(diào)光,輸出電壓額定值56V.保護(hù)功能包括欠壓,過(guò)壓,開(kāi)路/短路,過(guò)流和超溫等.主要用在多串固態(tài)照明和手持LED背光照明.本文介紹了HV9957主要特性, 簡(jiǎn)化框圖,故障保護(hù)框圖, 典型應(yīng)用電路以及六路LED驅(qū)動(dòng)器演示板主要特性和指標(biāo),電路圖, 布局圖和連接圖.

Six-Channel LED Driver with Integrated Fault Protection

The HV9957 LED driver combines a switch-mode boost converter and six low-dropout linear current regulators to provide the advantages of high efficiency with precise current control.

It may be configured for many applications, and is especially suited for one to three cell lithium-ion powered devices. An internal boost controller with an integrated switch eliminates the need for an external MOSFET.

Phased PWM dimming eliminates audible noise, reduces transient load on the boost converter, and minimizes supply current ripple. PWM dimming may be synchronized to an
external signal such as the display refresh rate or, internally generated by a resistor or crystal oscillator.

Fault protection is provided against open/shorted LEDs, over voltage, under voltage, over current, and over temperature conditions. When a string fails, either shorted or open, the
affected channel is removed from feedback and the rest continue operating normally.

HV9957主要特性:

Drives six strings of LEDs, up to 30mA each

Phased PWM dimming

Pin-programmable dimming frequency or synchronizable to an external signal

PWM dimming to very low duty cycles

±1.5% typical current and 0.5% duty cycle matching

Optional crystal oscillator for precision dimming frequency

Outputs rated to 56V

Robust protection against under voltage, over voltage, open/shorted strings, over current, and over temperature. Good strings remain lit.

Programmable boost converter frequency

10μA maximum input current in shutdown state

Resistor-programmable full-scale LED current

24-Lead 4×4 QFN package

HV9957應(yīng)用:

Multi-string solid-state lighting applications

Portable LED backlighting applications

圖1.HV9957簡(jiǎn)化框圖

圖2.HV9957故障保護(hù)框圖

圖3.HV9957典型應(yīng)用電路

六路LED驅(qū)動(dòng)器演示板

The HV9957 LED driver combines a switch-mode boost converter and six low-dropout linear current regulators to provide the advantages of high efficiency with precise current control.

六路LED驅(qū)動(dòng)器演示板主要特性:

?? Phased dimming

?? Temperature-triggered faulty LED protection

?? Smart ‘outlier’ faulty string discrimination

?? Overcurrent protection

?? Precise dimming frequency

?? Accurate channel matching

六路LED驅(qū)動(dòng)器演示板指標(biāo):


圖4.六路LED驅(qū)動(dòng)器演示板電路圖
六路LED驅(qū)動(dòng)器演示板材料清單:


圖5.六路LED驅(qū)動(dòng)器演示板布局圖和連接圖
詳情請(qǐng)見(jiàn):
http://www.supertex.com/pdf/datasheets/HV9957.pdf
和
http://www.supertex.com/pdf/misc/HV9957DB1.pdf