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参数资料
| 型号： | ISL97634IRT18Z-T |
| 厂商： | Intersil |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVR WHITE BCKLGT 8-TDFN |
| 标准包装： | 6,000 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 1 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 车载，背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 1.3MHz ~ 1.6MHz |
| 电源电压： | 2.4 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-WFDFN 裸露焊盘 |
| 供应商设备封装： | 8-TDFN（2x3） |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
ISL97634
Efficiency Improvement
Figure 2 shows the efficiency measurements during PWM
operation. The choice of the inductor has a significant impact on
the power efficiency. Equation 4 shows the higher the inductance,
the lower the peak current, therefore, the lower the conduction
and switching losses. On the other hand, it has also a higher series
resistance. Nevertheless, the efficiency improvement effect by
lowering the peak current is greater than the resistance increases
with larger value of inductor. Efficiency can also be improved for
systems that have high supply voltages. Since the ISL97634 can
only supply from 2.4V to 5.5V, V IN must be separated from the
high supply voltage for the boost circuit as shown in Figure 16 and
the efficiency improvement is shown in Figure 17.
follower action of M1, limiting the maximum voltage on the
ISL97634 LX pin to below V IN , but allowing the output voltage to go
much higher than the breakdown limit on the LX pin. The switch
current limit and maximum duty cycle will not be changed by this
setup, so input voltage will need to be carefully considered to make
sure that the required output voltage and current levels are
achievable. Because the source of M1 is effectively floating when
the internal LX switch is off, the drain-to-source capacitance of M1
may be sufficient to capacitively pull the node high enough to break
down the gate oxide of M1. To prevent this, V OUT should be
connected to V IN , allowing the internal Schottky diode to limit the
peak voltage. This will also hold the VOUT pin at a known low
voltage, preventing the built in OVP function from causing problems.
This OVP function is effectively useless in this mode as the real
C3 0.22μF
D1
output voltage is outside its intended range. If the user wants to
implement their own OVP protection (to prevent damage to the
output capacitor), they should insert a zener diode from VOUT to the
Vs = 12V
C1
1μF
1
L1
22μH
2
D2
D3
FB pin. In this setup, it would be wise not to use the FBSW to FB
switch, as otherwise, the zener diode will have to be a high power
one capable of dissipating the entire LED load power. Then the LED
V IN = 2.7V TO 5.5V
C2 0.1μF
VIN LX
VOUT
ISL97634
FBSW
D4
D5
D6
stack can then be connected directly to the sense resistor via a
10k Ω resistor to FB. A zener can be placed from VOUT to the FB pin
allowing an overvoltage event to pull-up on FB with a low
breakdown current (and thus low power zener diode) as a result
of the 10k Ω resistor.
PWM / EN
FB
GND
R1
4 Ω
V IN = 2.7V TO 5.5V
C1
1μF
L1
1 2
10μH or 22μH
M1
D0
10BQ100
C3 4.7μF
FQT13N06L
FIGURE 16. SEPARATE HIGH INPUT VOLTAGE FOR HIGHER
EFFICIENCY OPERATION
C2
0.1μF
VIN VOUT
LX
ISL97634
SK011C226KAR
FBSW
.
90
V S = 12V
FB
PWM/EN
GND
R1
6.3 Ω
85
V S = 9V
80
V IN = 4V
75
7 LEDs
L1 = 22μH
R1 = 4 Ω
f PWM
FIGURE 18. HIGH VOLTAGE LED DRIVER USING A CASCODE
70
0
5
10
15
20
25
30
SEPIC Operation
ILED (mA)
FIGURE 17. EFFICIENCY IMPROVEMENT WITH 9 AND 12V INPUTS
Operation with VOUT above 26V
For LED backlighting applications that need an output voltage above
26V, the voltage range of the ISL97634 is not sufficient. However,
the ISL97634 can be used as an LED controller with an external
protection MOSFET connected in cascode fashion to achieve higher
output voltage as shown in Figure 18. A 60V logic level N-Channel
MOSFET is configured such that its drain ties between the inductor
and the anode of Schottky diode, its gate ties to the input, and its
source ties to the ISL97634 LX node connecting to the drain of the
internal switch. When the internal switch turns on, it pulls the source
of M1 down to ground and LX conducts as normal. When the
internal switch turns off, the source of M1 will be pulled up by the
9
For applications where the output voltage is not always above the
input voltage, a buck or boost regulation is needed. A SEPIC
(Single-Ended Primary Inductance Converter) topology, shown in
Figure 19, can be considered for such an application. A single
cell Li-ion battery operating a cellular phone backlight or
flashlight is one example. The battery voltage is between 2.5V
and 4.2V, depending on the state of charge. On the other hand,
the output may require only one 3V to 4V medium power LED for
illumination because the light guard of the backlight assembly is
optimized for cost efficiency trade-off reason.
In fact, a SEPIC configured LED driver is flexible enough to allow
the output to be well above or below the input voltage, unlike the
previous example. Another example is when the number of LEDs
and input requirements are different from platform to platform, a
common circuit and PCB that fit all the platforms in some cases
FN6264.4
August 27, 2013
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL97634IRT18Z-TK | 功能描述:IC LED DRIVR WHITE BCKLGT 8-TDFN 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 |
| ISL97634IRT26Z-T | 功能描述:IC LED DRIVR WHITE BCKLGT 8-TDFN 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 |
| ISL97634IRT26Z-TK | 功能描述:IC LED DRIVR WHITE BCKLGT 8-TDFN 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 |
| ISL97635AIRZ | 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:- 标准包装:1 系列:- 恒定电流:- 恒定电压:- 拓扑:PWM，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:642kHz 电源电压:2.7 V ~ 5.5 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-VFDFN 裸露焊盘 供应商设备封装:10-VSON 包装:剪切带 (CT) 工作温度:-30°C ~ 85°C 产品目录页面:1371 (CN2011-ZH PDF) 其它名称:BD1603NUV-E2CT |
| ISL97635AIRZ-T | 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 |
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