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参数资料
| 型号： | ISL97635IRZ-T |
| 厂商： | Intersil |
| 文件页数： | 11/28页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WHT/RGB BCKLGT 24QFN |
| 标准包装： | 6,000 |
| 拓扑： | 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： | RGB，白色 LED |
| 频率： | 600kHz，1.2MHz |
| 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 |
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ISL97635
Pin Descriptions (I = Input, O = Output, S = Supply) (Continued)
PIN
22
23
24
NAME
COMP
VIN
VDC
TYPE
O
S
S
DESCRIPTION
Boost compensation pin
Input voltage for the device and LED power
De-couple capacitor for internally generated supply rail. If 2.7V < VBL+ < 5.5V, apply VDC directly with
a supply voltage of 2.7V to 5.5V
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 ISL97635 employs 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
backlight application where the power can be a series of
+
-
REF
+
-
drained batteries or instantly change to an AC/DC adapter
without rendering a noticable visual nuisance. The number
of LEDs that can be driven by ISL97635 depends on the
type of LED chosen in the application. The ISL97635 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 as a 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, reference, and current
source resistors. These parameters are optimized for current
matching and absolute current accuracy. On the other hand,
the absolute accuracy is additionally determined by the
external R SET , and therefore, additional tolerance will be
contributed by the current setting resistor. A 1% tolerance
resistor is therefore recommended.
11
RSET
+
-
PWM DIMMING
DC DIMMING
FIGURE 17. SIMPLIFIED CURRENT SOURCE CIRCUIT
Dynamic Headroom Control
The ISL97635 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
programmed current. The output voltage will regulate
cycle-by-cycle and is always referenced to the highest
forward voltage string in the architecture.
Dimming Controls
The ISL97635 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.
There are various ways to achieve DC or PWM current
control, which will be described in the following.
FN6434.2
December 22, 2008
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相关代理商/技术参数 |
参数描述 |
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| ISL97635IRZ-TK | 功能描述:IC LED DRVR WHT/RGB BCKLGT 24QFN 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 |
| ISL97636AIRZ | 功能描述:LED照明驱动器 6-CH LED DRVR 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 |
| ISL97636AIRZ-T | 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 |
| ISL97636AIRZ-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 |
| ISL97636IRZ | 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:- 标准包装:6,000 系列:- 恒定电流:- 恒定电压:- 拓扑:开路漏极，PWM 输出数:4 内部驱动器:是 类型 - 主要:LED 闪烁器 类型 - 次要:- 频率:400kHz 电源电压:2.3 V ~ 5.5 V 输出电压:- 安装类型:表面贴装 封装/外壳:8-VFDFN 裸露焊盘 供应商设备封装:8-HVSON 包装:带卷 (TR) 工作温度:-40°C ~ 85°C 其它名称:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
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