- 您现在的位置：买卖IC网 > PDF目录20781 > ISL97686IRTZ-T (Intersil)IC LED DRVR BACKLIGHT 28TQFN PDF资料下载
参数资料
| 型号： | ISL97686IRTZ-T |
| 厂商： | Intersil |
| 文件页数： | 16/23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
Inductor
The selection of the inductor should be based on its maximum
current (I SAT ) characteristics, power dissipation, EMI
susceptibility (shielded vs unshielded), and size. Inductor type
and value influence many key parameters, including the inductor
ripple current, current limit, efficiency, transient performance
and stability.
The inductor’s maximum current capability must be large enough
to handle the peak current at the worst case condition. If an
inductor core is chosen with a lower current rating, saturation in
the core will cause the effective inductor value to fall, leading to
an increase in peak to average current level, poor efficiency and
overheating in the core. The series resistance, DCR, within the
inductor causes conduction loss and heat dissipation. A shielded
inductor is usually more suitable for EMI susceptible
applications, such as LED backlighting.
The peak current can be derived from the voltage across the
inductor during the off period, as expressed in Equation 10:
IL peak = ( V O × I O ) ? ( 85% × V I ) + 1 ? 2 [ V I × ( V O – V I ) ? ( L × V O × f SW ) ]
(EQ. 10)
The choice of 85% is just an average term for the efficiency
approximation. The first term is the average current, which is
inversely proportional to the input voltage. The second term is
the inductor current change, which is inversely proportional to L
and f SW . As a result, for a given switching frequency, minimum
input voltage must be used to calculate the input/inductor
current as shown in Equation 10. For a given inductor size, the
larger the inductance value, the higher the series resistance
because of the extra number of turns required, thus, higher
conductive losses. The ISL97686 current limit should be less
than the inductor saturation current.
Output Capacitors
The output capacitor acts to smooth the output voltage and
supplies load current directly during the conduction phase of the
power switch. Output ripple voltage consists of the discharge of
the output capacitor during the FET turn-on period and the
voltage drop due to load current flowing through the ESR of the
output capacitor. The ripple voltage is shown in Equation 11:
to capacitance change overvoltage. Y5V’s absolute capacitance
can be reduced to 10%~20% of its rated capacitance at the
maximum voltage. In any case, Y5V type ceramic capacitors
should be avoided.
A larger output capacitor will also ease the driver response
during PWM dimming off period due to the longer sample and
hold effect of the output drooping. The driver does not need to
boost as much on the next on period, which minimizes transient
current. The output capacitor also plays an important role for
system compensation.
Channel Capacitor
It is recommended to use at least 1nF capacitors from CH pins to
V OUT . Larger capacitors will reduce LED current ripple at boost
frequency, but will degrade transient performance at high PWM
frequencies. The best value is dependant on PCB layout. Up to
4.7nF is sufficient for most configurations.
Schottky Diode
A high speed rectifier diode is necessary to prevent excessive
voltage overshoot, especially in the boost configuration. Low
forward voltage and reverse leakage current will minimize
losses, making Schottky diodes the preferred choice. Although
the Schottky diode turns on only during the boost switch off
period, it carries the same peak current as the inductor,
therefore, a suitable current rated Schottky diode must be used.
High Current Applications
Each channel of the ISL97686 can support up to 160mA. For
applications that need higher current, multiple channels can be
grouped to achieve the desirable current. For example, in
Figure 21, the cathodes of the last LEDs can be connected to
CH1/CH2 and CH3/CH4, this configuration can be treated as a
single string with up to 350mA current driving capability.
BOOST OUTPUT
Δ V CO = ( I O ? C O × D ? f Sw ) + ( I O × ESR )
(EQ. 11)
where I O represents the output current, C O is the output
capacitance, D is the duty ratio as described in Equation 9. ESR
is the equivalent series resistance of the output capacitance and
f sw is the switching frequency of the converter. Equation 11
shows the importance of using a low ESR output capacitor for
minimizing output ripple.
As shown in Equation 11, the output ripple voltage, Δ V Co , can be
reduced by increasing the output capacitance, C O or the
switching frequency, f SW , or using output capacitors with small
ESR. In general, ceramic capacitors are the best choice for
output capacitors in small to medium sized LCD backlight
applications due to their cost, form factor, and low ESR.
The choice of X7R over Y5V ceramic capacitors is highly
recommended because the X7R type capacitor is less sensitive
16
CH1
CH2
CH3
CH4
FIGURE 21. GROUPING MULTIPLE CHANNELS FOR HIGH CURRENT
APPLICATIONS
FN7953.0
April 23, 2012
相关PDF资料 |
PDF描述 |
|---|---|
| MAX6964AEG+ | IC LED DRIVER LINEAR 24-QSOP |
| MAX6968APE+ | IC LED DRIVER LINEAR 16-DIP |
| MAX6971ANG+ | IC LED DRIVER LINEAR 24-DIP |
| ECC08DRES | CONN EDGECARD 16POS .100 EYELET |
| MAX16832CASA+ | IC LED DRIVER HIGH BRIGHT 8-SOIC |
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 |
发布紧急采购，3分钟左右您将得到回复。