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参数资料
| 型号： | ZXLD1321DCATC |
| 厂商： | Diodes Inc |
| 文件页数： | 18/20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
Additional notes which apply to all operational modes
Note with all these circuits that the ON time is set by the time it takes the coil to reach the peak
current. This peak value is reduced by the control loop to give the desired LED power, so the ON
time can vary over a wide range. The minimum coil current can be zero (discontinuous operation)
or finite (continuous operation) depending on the supply voltage, LED current and the LED
voltage. The OFF time is set by an internal timer and is nominally 1.2μs at 100% LED power (V ADJ
= 500mV), increasing to about 8μs at 10% LED power (V ADJ = 50mV). The longer OFF time and
variable peak current enables the circuit to dim the LED whilst maintaining continuous switching,
rather than "skipping" or stalling and continuous running is better for reducing electrical noise
and also for eliminating audible noise from the coil core.
Layout considerations
As with all switching DC to DC converters, the currents can be large. Using small inductors with
a reasonably high supply voltage will cause currents to change quickly. High dI/dt can cause
inductively-coupled spikes into adjacent tracks. At the transition from of the ON phase to the OFF
phase and back, where the power transistor switches, the voltage at the collector rises and falls
quickly. High dV/dt can cause capacitively coupled spikes into adjacent tracks, especially if they
have a high impedance. For this reason, all tracks on the PCB should be thick, to minimise drops,
and short to keep all the components coupled tightly together.
A double-sided board should be used with a ground plane to screen the tracks and provide a good
ground return for the various functions and the rear exposed pad on the package should have an
appropriately-sized land with good ground connections, both to reduce electrical noise due to
ground drops and to improve thermal conductivity.
The input decoupling capacitor C1 should be very close to the chip pins and the LED sense
resistor R3 should have Kelvin tracks to M_VIN and M_LOAD to achieve LED current
measurement accuracy, as the PCB tracks will have comparable resistance to the 100m ? resistor,
so taking sense tracks to the current monitor which are not connected close to the ends of R3 will
cause a measurement error.
The peak current sense resistor R1 should have short tracks to the ground at the bottom end and
Kelvin tracks to ISENSE at the top end. This resistor might need to be only 25m ? and PCB track
resistance becomes comparable if the tracks are not very short. ISENSE is a high impedance
input, so a thin track from this pin directly to the top of R SENSE resistor R1 will still give an accurate
measurement.
The ADJ pin should have short tracks, as this is a fairly low-level signal controlling the power of
the system. As it needs to be less than 28mV for shutdown, a close ground connection is needed
for the pull-down device, as any ground drops could raise the potential. In particular, if a bipolar
transistor is used as a pull-down device, this will have an appreciable V SAT , which could perhaps
be half the shutdown potential.
The bottom of the thermistor must be coupled very closely to ground, as the TADJ pin varies the
LED current from 100% to 0% for a voltage change of only 25mV, so any noise on the bottom of
the thermistor will seriously affect the accuracy of the Thermal Protection circuit.
Issue 1 - January 2008
? Zetex Semiconductors plc 2008
18
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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