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参数资料
| 型号： | ISL97636IRZ-T |
| 厂商： | Intersil |
| 文件页数： | 11/18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
For example, if the maximum required LED current
(I LED(max) ) is 20mA, rearranging Equation 1
yields Equation 3:
charged to the required value at a low current limit and
prevents high input current for systems that have only a low
to medium output current requirement.
R SET = 733 ? 0.02 = 36.6k Ω
(EQ. 2)
For systems with no master fault protection FET, the inrush
current will flow towards C OUT when VIN is applied and it is
PWM CURRENT CONTROL
The average LED current of each channel can be controlled by
an external PWMI signal, as shown in Equation 3:
determined by the ramp rate of VIN and the values of C OUT
and L.
Fault Protection and Monitoring
I LED ( ave ) = I LED × PWMI
(EQ. 3)
The ISL97636 features extensive protection functions to
cover all the perceivable failure conditions. The failure mode
of a LED can be either open circuit or as a short. The
The PWM dimming frequency can be, for example, 20kHz,
but there are minimum on and off time requirements such
that the dimming will be in the range of 10% to 99.5%. If the
dimming frequency is below 5kHz, the dimming range can
be 1% to 99.5%.
The PWM dimming off time cannot be longer than 28ms or
else the driver will enter shutdown.
5V Low Dropout Regulator
A 5.2V LDO regulator is present at the VDC pin to develop
the necessary low voltage supply which is used by the chips
internal control circuitry. Because VDC is an LDO pin, it
requires a bypass capacitor of 1μF or more for the
regulation. For applications with an input voltage ≤ 5.5V, the
VIN and VDC pins can be connected together. The VDC pin
can be used as a coarse reference with few mA sourcing
capability.
Inrush Control and Soft-start
The ISL97636 has separately built-in independent inrush
control and soft-start functions. The inrush control function is
built around the short circuit protection FET, and is only
available in applications which include this device. At
start-up, the fault protection FET is turned on slowly due to a
30μA pull-down current output from the FAULT pin. This
discharges the fault FET's gate-source capacitance, turning
on the FET in a controlled fashion. As this happens, the
output capacitor is charged slowly through the weakly turned
on FET before it becomes fully enhanced. This results in a
low inrush current. This current can be further reduced by
adding a capacitor (in the 1nF to 5nF range) across the gate
source terminals of the FET.
Once the chip detects that the fault protection FET is turned
on hard, it is assumed that inrush is complete. At this point,
the boost regulator will begin to switch and the current in the
inductor will ramp-up. The current in the boost power switch
is monitored and the switching terminated in any cycle
where the current exceeds the current limit. The ISL97636
includes a soft-start feature where this current limit starts at a
low value (375mA). This is stepped up to the final 3A current
limit in seven further steps of 375mA. These steps will
happen over a 1ms total time, such that after 1ms the final
limit will be reached. This allows the output capacitor to be
11
behavior of an open circuited LED can additionally take the
form of either infinite resistance or, for some LEDs, a zener
diode, which is integrated into the device in parallel with the
now opened LED.
For basic LEDs (which do not have built-in zener diodes), an
open circuit failure of an LED will only result in the loss of
one channel of LEDs without affecting other channels.
Similarly, a short circuit condition on a channel that results in
that channel being turned off does not affect other channels
unless a similar fault is occurring.
Due to the lag in boost response to any load change at its
output, certain transient events (such as LED current steps
or significant step changes in LED duty cycle) can transiently
look like LED fault modes. The ISL97636 uses feedback
from the LEDs to determine when it is in a stable operating
region and prevents apparent faults during these transient
events from allowing any of the LED stacks to fault out. See
Table 1 for more details.
A fault condition that results in an input current that exceeds
the devices electrical limits will result in a shutdown of all
output channels.
Short Circuit Protection (SCP)
The short circuit detection circuit monitors the voltage on
each channel and disables faulty channels which are
detected above 8V (the action taken is described in Table 1.)
Open Circuit Protection (OCP)
When one of the LEDs becomes open circuit, it can behave
as either an infinite resistance or a gradually increasing finite
resistance. The ISL97636 monitors the current in each
channel such that any string which reaches at least 75% of
the intended output current is considered “good”. Should the
current subsequently fall below 50% of the target, the channel
will be considered an “open circuit”. Furthermore, should the
boost output of the ISL97636 reach the OVP limit or should
the lower over-temperature threshold be reached, all
channels which are not “good” will immediately be considered
as “open circuit”. Detection of an “open circuit” channel will
result in a time-out before disabling of the affected channel.
This time-out is sped up when the device is above the lower
over-temperature threshold in an attempt to prevent the upper
over-temperature trip point from being reached.
FN6570.0
May 9, 2008
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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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