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参数资料
| 型号： | ZXLD1321DCATC |
| 厂商： | Diodes Inc |
| 文件页数： | 16/20页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WHITE BCKLGT 14-TDFN |
| 特色产品： | LED Driver Solutions |
| 标准包装： | 1 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 1 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 闪灯/白光 |
| 类型 - 次要： | 高亮度 LED（HBLED），白色 LED |
| 频率： | 600kHz |
| 电源电压： | 2 V ~ 12 V |
| 输出电压： | 18V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 14-TDFN 裸露焊盘 |
| 供应商设备封装： | 14-DFN-EP（4x3） |
| 包装： | 标准包装 |
| 工作温度： | -40°C ~ 125°C |
| 产品目录页面： | 1478 (CN2011-ZH PDF) |
| 其它名称： | ZXLD1321DCADKR |
ZXLD1321
Operation in bootstrap mode
Diagram B : Bootstrap mode
Operation of bootstrap LED driver
This is used when the input voltage is less than 2 volts. Note that the chip VIN now goes to the
cathode of the Schottky diode D1. The control loop can not operate at this low voltage, so the
chip goes into a start-up mode, where the output transistor is switched on and off at nominally
50kHz with a 50:50 duty cycle with about 10mA of base current into the power transistor (20% of
nominal). The emitter current is still sensed by R1 and the "ON" part of the duty cycle will be
terminated either when the emitter sense voltage reaches 10mV (corresponding to 20% of the set
peak current) or the ON part of the duty cycle finishes after 10μs. There is no control of the LED
current yet, the circuit just operates in Boost mode. Eventually, the reservoir capacitor C3 charges
up to 2V and the chip goes into "Normal" mode, where it delivers 50mA to the base of the power
transistor and the control loop works normally. It will continue to charge C3 until the LED current
is correctly established, with the chip now running from a voltage equal to the LED forward drop
(around 3.6V for one LED) even though the supply is still below 2 volts. Once the circuit has
reached this condition, the rest of the description of the operation is the same as for the Boost
operation.
Like the Boost circuit, this circuit has an ON phase, where the coil is connected from the supply
to ground and an OFF phase, where the coil current flows through the LED via the Schottky diode
D1. The current therefore only flows into the LED circuit during the OFF phase, although the
reservoir capacitor C2 should keep current flowing in the LED(s) continuously.
ADJ is set between 50mV and 500mV to give between 10% and 100% power respectively. Making
R2 = zero gives a base current to the output transistor of 50mA nominal and making R2 = 1.68k ?
gives 10mA nominal. The reduced base current will lower supply current and hence improve
efficiency in lower power applications. Making R1 = 50m ? gives a peak coil current of 1 Amps.
The internal power transistor turns on until the coil current builds up to the peak. At this point
the transistor switches off and the coil current continues to flow in the LED(s) via Schottky diode
D1.
Issue 1 - January 2008
? Zetex Semiconductors plc 2008
16
www.zetex.com
相关PDF资料 |
PDF描述 |
|---|---|
| ZXLD1322DCCTC | IC LED DRIVR WHITE BCKLGT 14-DFN |
| ZXLD1350ET5TA | IC LED DRIVR WHITE BCKLGT TSOT-5 |
| ZXLD1352ET5TA | IC LED DRIVER HIGH BRIGHT TSOT-5 |
| ZXLD1356DACTC | IC LED DRIVER WHITE BCKLGT 6-DFN |
| ZXLD1360ET5TA | IC LED DRIVR WHITE BCKLGT TSOT-5 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ZXLD1322 | 制造商:DIODES 制造商全称:Diodes Incorporated 功能描述:BUCK/BOOST MODE DC-DC CONVERTER |
| ZXLD1322DCCTC | 功能描述:直流/直流开关转换器 Buck-Boost DC-DC Con 0.7A output 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 |
| ZXLD1322DCCTC-CUT TAPE | 制造商:DIODES 功能描述:ZXLD1322 Series 15 V 600 kHz 700 mA Buck/Boost Mode DC-DC Converter - DFN-14 |
| ZXLD1322DCTC | 制造商:ZETEX 制造商全称:ZETEX 功能描述:Buck/boost mode DC-DC converter for LED driving with 700mA output and current control |
| ZXLD1350 | 制造商:ZETEX 制造商全称:ZETEX 功能描述:350mA LED driver with internal switch |
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