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参数资料
| 型号： | ISL97801ARZ |
| 厂商： | Intersil |
| 文件页数： | 11/19页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVER AUTOMOTIVE 20-QFN |
| 标准包装： | 75 |
| 拓扑： | PWM，降压（降压），升压（升压） |
| 输出数： | 1 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 车载，背光 |
| 频率： | 850kHz ~ 1.15MHz |
| 电源电压： | 2.7 V ~ 16 V |
| 输出电压： | 32V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-VFQFN 裸露焊盘 |
| 供应商设备封装： | 20-QFN（4x4） |
| 包装： | 管件 |
| 工作温度： | -40°C ~ 105°C |
ISL97801
Theory of Operation
General Description
The ISL97801 is a flexible, highly integrated high-power LED
VIN
FB
driver consisting of a PWM switching controller and
integrated 36V NDMOS power FET. The device can drive up
to 8 series high-power LED's at currents up to 1A at 16V
input or 5 LEDs at current up to 350mA at 2.7V input. The
control loop can be configured as either as a boost or buck
Voltage
Feedback
LEVEL
SHIFT
+
-
GND
regulator with the configuration of the buck/boostn pin,
providing an output voltage above or below the input supply
EL7801
VDC /2
voltage, depending on the number of stacked LED's. The
controller operates from 2.7V to 16V depending on the
numbers of LEDs and current required and can be powered
by a single lithium ion battery, 5V or 12V regulated supplies
or automotive electrical systems. LED current is sensed
through a low value resistor in series with the LED. A
thermistor can be used to implement a thermal protection
scheme to limit the maximum LED temperature to a preset
desirable level.
Switching Regulator
The ISL97801 employs a current mode PWM control
FIGURE 29. FB REFERENCE AUTO SWITCH
Start-up
To maximize external PWM switching speed, the ISL97801
does not include an internal soft-start circuit. When VDC
exceeds the power on reset threshold, switching is delayed
for 1ms (T DELAY ) allowing the output capacitor to charge
through the inductor. If soft-start control is required, a
suitable application circuit is shown in Figure 30.
VBAT
scheme with a nominal switching frequency of 1MHz. This
provides fast transient response and enables the use of low
profile inductors and compact multilayer ceramic capacitors.
Settling time is optimized by the use of a simple control loop
without an error amplifier, relying instead on intrinsic gain
VBAT FAULT
ISL97801 VIN
SWD1
SWD2
10μH
L1
C1
4.7nF
VOUT
COUT
20μF
within the direct summing path. Due to the lower loop gain,
R1
offset must be accounted for when setting up initial LED bias
current. Refer to the applications section of the datasheet for
FB
SWS1 SWS2
R2
2k
100
0.5
RSENSE
further information. Figure 28 shows a block diagram of the
system.
Application Configurations
Operating Modes
The ISL97801 can operate as either a buck or boost
regulator. Hardwire BUCK/BOOSTN to GND for boost mode
or to VDC for buck mode. In buck mode the power NDMOS
drive circuit is "floated" (boot-strapped) allowing the NDMOS
gate to be driven above VIN to fully enhance the power
NDMOS. An internal Schottky diode between VDC (5V) and
VHI reduces external component count. Use a ceramic
capacitor of at least 50nF between VHI and SWS1/2 to
bootstrap VHI.
LED Load Connection
ISL97801 includes an auto-sensing FB level shift circuit that
enables the LED load to be connected to either GND or VIN.
An internal sense circuit monitors the FB pin voltage. When
the level exceeds VDC/2, the feedback reference voltage is
switched from GND to VIN. Refer to the application section
of the datasheet for typical application schematics.
11
FIGURE 30. EXTERNAL SOFT-START CIRCUIT
Light Level Control
Two light control schemes are provided:
1. An external PWM signal via the EN/PWM pin, providing
low frequency PWM dimming.
2. Bias current level adjustment via the LEVEL input or fixed
internal bias.
PWM Dimming
LED color temperature varies with bias current. In
backlighting applications PWM dimming offers better control
of color temperature because current through the LED's is
kept constant. A 5V gate driver (ENL) synchronized to
EN/PWM can be used to control an external N-Ch FET and
disconnect the LED stack during the PWM off period. The
switch prevents discharge of the output capacitor by the LED
load, maintaining a constant bias independent of PWM duty
cycle. Operation at 1kHz PWM rate is shown in Figure 31
and Figure 32. The load disconnect switch improves PWM
dynamic range, linearity and color temperature control. To
FN6428.1
April 2, 2007
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL97801ARZ-T | 功能描述:IC LED DRIVER AUTOMOTIVE 20-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 恒定电流:- 恒定电压:- 拓扑:升压（升压），切换式电容器（充电泵） 输出数:1 内部驱动器:是 类型 - 主要:背光 类型 - 次要:白色 LED 频率:625kHz ~ 875kHz 电源电压:2.7 V ~ 5.3 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-µMAX 包装:带卷 (TR) 工作温度:-40°C ~ 85°C |
| ISL97801ARZ-TK | 功能描述:IC LED DRIVER AUTOMOTIVE 20-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:60 系列:- 恒定电流:- 恒定电压:- 拓扑:线性（LDO），PWM，升压（升压） 输出数:8 内部驱动器:是 类型 - 主要:背光 类型 - 次要:RGB，白色 LED 频率:500kHz ~ 1.5MHz 电源电压:4.75 V ~ 26 V 输出电压:45V 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* 工作温度:-40°C ~ 85°C |
| ISL97801BOOSTEVALZ | 功能描述:EVAL BOARD FOR ISL97801 RoHS:是 类别:编程器，开发系统 >> 评估板 - LED 驱动器 系列:* 标准包装:1 系列:PowerWise® 电流 - 输出 / 通道:20mA 输出及类型:1，非隔离 输出电压:17V 特点:可调光 输入电压:2.7 ~ 5.5 V 已供物品:板 已用 IC / 零件:LM3508 相关产品:LM3508TLX-ND - IC LED DRVR WHT BCKLGT 9USMDLM3508TLDKR-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLCT-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLTR-ND - IC LED DRVR WHT BCKLGT 9MICROSMD |
| ISL97900CRZ | 功能描述:LED照明驱动器 High Current RGB Driver/Controller, 28L 4x5 QFN, Commercial 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 |
| ISL97900CRZ-T | 功能描述:LED照明驱动器 High Current RGB Driver/Controller, 28L 4x5 QFN, Commercial 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 |
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