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参数资料
| 型号： | ISL97636IRZ-T |
| 厂商： | Intersil |
| 文件页数： | 10/18页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVR WHITE BCKLGT 24-QFN |
| 标准包装： | 6,000 |
| 拓扑： | 线性（LDO），PWM，升压（升压） |
| 输出数： | 8 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 车载，背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 1MHz ~ 1.3MHz |
| 电源电压： | 6 V ~ 24 V |
| 输出电压： | 34.5V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-VFQFN 裸露焊盘 |
| 供应商设备封装： | 24-QFN 裸露焊盘（4x4） |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
ISL97636
Theory of Operation
PWM Boost Converter
The current mode PWM boost converter produces the
minimal voltage needed to enable the LED stack with the
highest forward voltage drop to run at the programmed
current. The ISL97636 employes current mode control boost
architecture that has a fast current sense loop and a slow
voltage feedback loop. Such architecture achieves a fast
transient response that is essential for the notebook
+
-
REF
+
-
backlight application where the power can be a series of
drained batteries or instantly changed to an AC/DC adapter
without rendering a noticeable visual nuisance. The number
of LEDs that can be driven by ISL97636 depends on the
type of LED chosen in the application. The ISL97636 is
capable of boosting up to 34.5V and typically driving 9 LEDs
in series for each of the 8 channels, enabling a total of 72
pieces of the 3.5V/30mA type of LEDs.
Enable and PWMI
The EN/PWMI pin serves dual purposes; it is used as an
enable signal and can be used for PWM input signal for
dimming. If a PWM signal is applied to this pin, the first pulse of
minimum 40μs will be used as an Enable signal. If there is no
signal for longer than 28ms, the device will enter shutdown.
The EN/PWMI pin cannot be floating, thus a 10k Ω pull-down
resistor may need to be added.
Current Matching and Current Accuracy
Each channel of the LED current is regulated by the current
source circuit, as shown in Figure 17.
The LED peak current is set by translating the R SET current
to the output with a scaling factor of 733/R SET . The source
terminals of the current source MOSFETs are designed as
100mV to minimize the power loss. The sources of errors of
the channel-to-channel current matching come from the
op amp’s offset, internal layout and reference and these
parameters are optimized for current matching and absolute
current accuracy. The absolute accuracy is also determined
by the external R SET , and therefore a 1% tolerance resistor
should be used.
RSET
+
-
PWM DIMMING
FIGURE 17. SIMPLIFIED CURRENT SOURCE CIRCUIT
Dynamic Headroom Control
The ISL97636 features a proprietary Dynamic Headroom
Control circuit that detects the highest forward voltage string
or effectively the lowest voltage from any of the IIN pins.
When this lowest I IN voltage is lower than the short circuit
threshold, V SC , such voltage will be used as the feedback
signal for the boost regulator. The boost makes the output to
the correct level such that the lowest IIN pin is at the target
headroom voltage. Since all LED stacks are connected to
the same output voltage, the other IIN pins will have a higher
voltage, but the regulated current source circuit on each
channel will ensure that each channel has the same current.
The output voltage will regulate cycle by cycle and it is
always referenced to the highest forward voltage string in the
architecture.
Dimming Controls
The ISL97636 allows two ways of controlling the LED
current, and therefore, the brightness. They are:
1. DC current adjustment
2. PWM chopping of the LED current defined in Step 1.
MAXIMUM DC CURRENT SETTING
The initial brightness should be set by choosing an
appropriate value for R SET . This should be chosen to fix the
maximum possible LED current:
I LEDmax = ---------------
733
R SET
(EQ. 1)
DC CURRENT ADJUSTMENT
R SET can be a DCP (Digitally Controlled Potentiometer) for
DC current adjustment but minimum resistance should not
be lower than 21k Ω for a maximum of 35mA.
10
FN6570.0
May 9, 2008
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相关代理商/技术参数 |
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| ISL97636IRZ-TK | 功能描述:IC LED DRIVR WHITE BCKLGT 24-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 |
| ISL97642IRTZ | 功能描述:IC REG TFT-LCD DC/DC 32-TQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 应用说明:Ultrasound Imaging Systems Application Note 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:37 系列:- 应用:医疗用超声波成像，声纳 电流 - 电源:- 电源电压:2.37 V ~ 6 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:56-WFQFN 裸露焊盘 供应商设备封装:56-TQFN-EP（8x8） 包装:管件 |
| ISL97642IRTZ-T | 功能描述:IC REG TFT-LCD DC/DC 32-TQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 应用说明:Ultrasound Imaging Systems Application Note 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:37 系列:- 应用:医疗用超声波成像，声纳 电流 - 电源:- 电源电压:2.37 V ~ 6 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:56-WFQFN 裸露焊盘 供应商设备封装:56-TQFN-EP（8x8） 包装:管件 |
| ISL97642IRTZ-TK | 功能描述:IC REG TFT-LCD DC/DC 32-TQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 应用说明:Ultrasound Imaging Systems Application Note 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:37 系列:- 应用:医疗用超声波成像，声纳 电流 - 电源:- 电源电压:2.37 V ~ 6 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:56-WFQFN 裸露焊盘 供应商设备封装:56-TQFN-EP（8x8） 包装:管件 |
| ISL97644IRZ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Intersil Corporation 功能描述: |
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