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参数资料
| 型号： | ISL97686IRTZ-T |
| 厂商： | Intersil |
| 文件页数： | 13/23页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR BACKLIGHT 28TQFN |
| 标准包装： | 6,000 |
| 拓扑： | 线性（LDO），PWM，升压（升压） |
| 输出数： | 4 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 汽车，背光，通用型 |
| 频率： | 200kHz ~ 1.2MHz |
| 电源电压： | 9 V ~ 32 V |
| 输出电压： | 75V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 105°C |
ISL97686
It is important that PGND pin 14 (TQFN)/18 (SOIC) is connected
directly to the base of the sense resistor, with no other
connection to the ground system, except via this path. This is
because this pin is used as a ground reference for the CS pin.
Connecting it here gives the maximum noise immunity and the
best stability characteristics.
The ISL97686 uses a digital current limit based soft-start. The
initial limit level is set to one ninth of the full current limit, with
eight subsequent steps increasing this by a ninth of the final
value every 2ms until it reaches the full limit. In the event that no
LEDs have been conducting during the interval since the last step
(for example if the LEDs are running at low duty cycle at low
PWM frequency), the step will be delayed until the LEDs are
conducting again.
If the LEDs are off for more than 120ms, making the converter
go into sleep mode, soft-start will be restarted when the LEDs are
re-enabled.
Fault Protection and Monitoring
The ISL97686 features extensive protection functions to cover all
perceivable failure conditions. The failure mode of an LED can be
either open or short circuit. The behavior of an open circuit LED
can additionally take the form of either infinite or very high
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 LED failure 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 significant step changes in LED
duty cycle, or a change in LED current caused by CSEL switching)
can transiently look like LED fault modes. The ISL97686 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 strings to fault out.
See Figure 20 and Table 2 for more details.
Unused CH pins should be grounded, which will disable them
from start-up. This will prevent V OUT having to ramp to OVP at
start-up, in order to determine that they are open.
Undervoltage Lock-out
If the input voltage falls below the UVLO level of 2.8V, the device
will stop switching and reset. Operation will restart, with all
digital settings will be returned to their default states, once the
input voltage is back in the normal operating range.
Over-Temperature Protection (OTP)
The OTP threshold is set to +150°C. When this is reached, the
boost will stop switching and the output current sources will be
switched off and stay off until power or EN is cycled. For the
extensive fault protection conditions, please refer to Figure 20
and Table 2.
VIN OVP
If VIN exceeds 35V, the part will be shut down until power or EN is
cycled. At this point, all digital settings will be reset to their
default states.
Shutdown
When the EN pin is low the entire chip is shut down to give close
to zero shutdown current. The digital interfaces will not be active
during this time. The EN can be high before VIN.
COMPENSATION
The ISL97686 boost regulator uses a current mode control
architecture, with an external compensation network connected
to the COMP pin. The component values shown in Figure 19
should be used. The network comprises a 47pF capacitor from
COMP to AGND, in parallel with a series RC of 25k ? and 2.2nF,
also from COMP to AGND.
COM P
Short Circuit Protection (SCP)
The short circuit detection circuit monitors the voltage on each
channel and disables faulty channels which are detected to be
more than the short circuit threshold, 8V above the lowest CH
2.2nF
25k
47pF
pin, following a timeout period.
Open Circuit Protection (OCP)
When any of the LEDs become open circuit during the operation,
that channel will be disabled after a timeout period, and the part
will continue to drive the other channels. The ISL97686 monitors
the current in each channel such that any string which reaches
the intended output current is considered “good”. Should the
current subsequently fall below the target, the channel will be
considered an “open circuit”. Furthermore, should the boost
output of the ISL97686 reach the OVP limit, all channels which
are not “good” will be timed out.
13
FIGURE 19. COMPENSATION NETWORK
FN7953.0
April 23, 2012
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL97687IBZ | 功能描述:IC LED DRVR 4 CHAN PWM 28SOIC 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 |
| ISL97687IBZEV1Z | 制造商:Intersil 功能描述:ISL97687 EVAL |
| ISL97687IBZ-T | 功能描述:IC LED DRVR 4 CHAN PWM 28SOIC 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 |
| ISL97687IRTZ | 功能描述:IC LED DRVR 4 CHAN PWM 28TQFN 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 |
| ISL97687IRTZ-T | 功能描述:IC LED DRVR 4 CHAN PWM 28TQFN 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 |
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