Supertex公司的HV9967是開環平均模式電流控制LED驅動器,集成了60V 0.8Ω MOSFET,可用作單獨使用的降壓轉換器開關,LED電流精度3%,單個電阻設定LED電流,能和500V耗盡型MOSFET級聯,主要應用在DC/DC或AC/DC LED驅動器,平板顯示器的RGB背光,通用恒流源,信號和裝飾LED照明以及充電器.本文介紹了HV9967主要特性,功能方框圖, 典型應用電路圖以及4W LED驅動器演示板主要指標, 電路圖和材料清單.
4W LED Driver Demoboard with Accurate Average-Mode Constant Current Control
The HV9967 is an open loop average-mode current control LED driver IC operating in a constant off-time mode.
The IC features an integrated 60V 0.8Ω MOSFET that can be used as a stand-alone buck converter switch, or connected as a source driver output for driving an external high-voltage depletionmode MOSFET. The HV9967 is powered through its switching output when the integrated switch is off. Hence, the same external MOSFET can be used as a high-voltage linear regulator deriving the power supply voltage for powering the IC.
The LED current is programmed with one external resistor. The average-mode current control does not produce a peakto- average error, and therefore greatly improves accuracy, line and load regulation of the LED current without any need for loop compensation or direct sensing the LED current at a high-voltage potential. The auto-zero circuit allows the IC to cancel the effect of both the input offset voltage and the propagation delay in the current sense comparator.
The HV9967 features hiccup-mode short circuit protection and the over-temperature protection. A PWM dimming input is provided.
HV9967主要特性:
3% accurate LED current
Integrated 60V 0.8Ω MOSFET
Small outline MSOP-8 package
Low sensitivity to external component variation
Cascode connection with a 500V depletion-mode MOSFET
Single resistor LED current setting
Fixed off-time control
PWM dimming input
Output short circuit protection with skip mode
Over-temperature protection
HV9967應用:
DC/DC or AC/DC LED driver applications
RGB backlighting of flat panel displays
General purpose constant current source
Signage and decorative LED lighting
Chargers
圖1.HV9967功能方框圖
圖2.HV9967典型應用電路圖
圖3.HV9967低壓DC輸入的典型應用電路圖
4W LED驅動器演示板
4W LED Driver Demoboard with Accurate Average-Mode Constant Current Control
The HV9967DB1 demoboard is a high-brightness LED driver designed to drive 4 LEDs in series at currents up to 350mA from a 20 - 60V DC input. The demoboard uses the Supertex’s HV9967 in a buck configuration in a constant offtime mode.
The HV9967DB1 LED driver features tight regulation of the LED current within a few milliamps over the entire range of the input voltage (i.e. 20 - 60VDC). The LED current accuracy is almost insensitive to the passive component tolerances, such as the output filter inductance or the timing resistor.
PWM dimming can be achieved by applying a pulse-widthmodulated square wave signal between the PWMD and GND pins.
4W LED驅動器演示板指標:
圖4.4W LED驅動器演示板外形圖
圖5.4W LED驅動器演示板電路圖
4W LED驅動器演示板材料清單(BOM):
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