- 您现在的位置：买卖IC网 > PDF目录20789 > ISL97672AIRZ-T (Intersil)IC LED DRVR LOW DIMMING 20QFN PDF资料下载
参数资料
| 型号： | ISL97672AIRZ-T |
| 厂商： | Intersil |
| 文件页数： | 13/16页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR LOW DIMMING 20QFN |
| 标准包装： | 6,000 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 6 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 背光 |
| 频率： | 200kHz ~ 1.5MHz |
| 电源电压： | 4.5 V ~ 26.5 V |
| 输出电压： | 45V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-VFQFN 裸露焊盘 |
| 供应商设备封装： | 20-QFN（3x4） |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
ISL97672A
Input Capacitor
Switching regulators require input capacitors to deliver peak
charging current and to reduce the impedance of the input
supply. The capacitors reduce interaction between the regulator
and input supply, thus improving system stability. The high
switching frequency of the loop causes almost all ripple current
to flow into the input capacitor, which must be rated accordingly.
A capacitor with low internal series resistance should be chosen
to minimize heating effects and to improve system efficiency.
The X5R and X7R ceramic capacitors offer small size and a lower
value for temperature and voltage coefficient compared to other
ceramic capacitors.
An input capacitor of 10μF is recommended. Ensure that the
voltage rating of the input capacitor is able to handle the full
supply range.
Inductor
Inductor selection should be based on its maximum current (I SAT )
characteristics, power dissipation (DCR), EMI susceptibility
(shielded vs unshielded), and size. Inductor type and value
influence many key parameters, including ripple current, current
limit, efficiency, transient performance, and stability.
Inductor maximum current capability must be adequate to
handle the peak current in the worst-case condition. If an
inductor core with too low a current rating is chosen, 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 shown in Equation 10:
IL peak = ( V O × I O ) ? ( 85% × V I ) + 1 ? 2 [ V I × ( V O – V I ) ? ( L × V O × f S ) ]
(EQ. 10)
The value of 85% is an average term for the efficiency
approximation. The first term is average current that is inversely
proportional to the input voltage. The second term is inductor
current change that is inversely proportional to L and f S . As a
result, for a given switching frequency and minimum input
voltage at which the system operates, the inductor I SAT must be
chosen carefully.
Output Capacitors
The output capacitor smooths the output voltage and supplies
load current directly during the conduction phase of the power
switch. Output ripple voltage consists of discharge and charge of
the output capacitor during FET On and OFF time and the voltage
drop due to flow through the ESR of the output capacitor. The
ripple voltage can be shown as Equation 11:
user must select an output capacitor with low ESR and adequate
input ripple current capability.
Note: Capacitors have a voltage coefficient that makes their
effective capacitance drop as the voltage across them increases.
C OUT in Equation 11 assumes the effective value of the capacitor
at a particular voltage and not the manufacturer’s stated value,
measured at 0V.
The value of Δ V Co can be reduced by increasing C O or f S , or by
using small ESR capacitors. 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.
A larger output capacitor also eases driver response during the
PWM dimming Off period, due to the longer sample and hold
effect of the output drooping. The driver does not need to boost
harder in the next On period that minimizes transient current.
The output capacitor is also needed for compensation, and in
general, 2x4.7μF/50V ceramic capacitors are suitable for
notebook display backlight applications.
Schottky Diode
A high-speed rectifier diode is necessary to prevent excessive
voltage overshoot. Schottky diodes are recommended because
of their fast recovery time, low forward voltage and reverse
leakage current, which minimize losses. The reverse voltage
rating of the selected Schottky diode must be higher than the
maximum output voltage. Also the average/peak current rating
of the Schottky diode must meet the output current and peak
inductor current requirements.
Applications
High-Current Applications
Each channel of the ISL97672A can support up to 30mA
(50mA @ V IN = 12V). For applications that need higher current,
multiple channels can be grouped to achieve the desired current
(Figure 21). For example, the cathode of the last LED can be
connected to CH0 through CH2; this configuration can be treated
as a single string with 90mA current driving capability.
V OUT
CH0
CH1
CH2
Δ V CO = ( I O ? C O × D ? f S ) + ( ( I O × ESR )
(EQ. 11)
The conservation of charge principle shown in Equation 9 also
indicates that, during the boost switch Off period, the output
capacitor is charged with the inductor ripple current, minus a
relatively small output current in boost topology. As a result, the
13
FIGURE 21. GROUPING MULTIPLE CHANNELS FOR HIGH CURRENT
APPLICATIONS
FN7710.3
November 22, 2013
相关PDF资料 |
PDF描述 |
|---|---|
| JWS7515/A | PWR SUP 15.0V 5A SNG OUTPUT |
| JWS7548/A | POWER SUPL 75W 48V 1.6A ENCLOSED |
| USR 2-0808 14K OHM D 0.01% 1PPM | RES 14K OHM .6W .01% FOIL RADIAL |
| USR 2-0808 12K OHM D 0.01% 1PPM | RES 12K OHM .6W .01% FOIL RADIAL |
| USR 2-T220B 22000.00 OHM D 0.1% 3PPM | RES 22K OHM 6W .1% FOIL TO-220 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL97672AIRZ-TK | 功能描述:IC LED DRVR LOW DIMMING 20QFN 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 |
| ISL97672BIRZ | 功能描述:IC LED DRVR BACKLIGHT 20QFN 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 |
| ISL97672BIRZ-T | 功能描述:IC LED DRVR BACKLIGHT 20QFN 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 |
| ISL97672IRZ | 制造商:Intersil Corporation 功能描述:6-CH LED DRIVER WITH PWM DIMMING - Rail/Tube 制造商:Intersil 功能描述:6-CH LED DRVR W/PWM DIM |
| ISL97672IRZ-T | 制造商:Intersil Corporation 功能描述:6-CH LED DRIVER WITH PWM DIMMING, T&R - Tape and Reel 制造商:Intersil 功能描述:6-CH LED DRVR W/PWM DIM |
发布紧急采购，3分钟左右您将得到回复。