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参数资料
| 型号： | ISL97634IRT14Z-TK |
| 厂商： | Intersil |
| 文件页数： | 8/12页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVR WHITE BCKLGT 8-TDFN |
| 标准包装： | 1,000 |
| 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
TABLE 1.
Applications
PART NO.
ISL97634IRT14Z
ISL97634IRT18Z
ISL97634IRT26Z
OVP
14V
18V
26V
MAX ILED
70mA
50mA
30mA
Analog Dimming
Analog dimming is usually not recommended because of the
brightness non-linearity at low levels dimming. However, some
systems are EMI or noise sensitive that analog dimming may be
more suitable than PWM dimming under those situations. The
Shutdown
When PWM/EN is taken low the ISL97634 enters into the
power-down mode where the supply current is reduced to less
than 1μA. The device resumes normal when the PWM/EN goes
high.
Components Selection
ISL97632 is part of the same family as the ISL97634 and has
been designed with a serial interface to give access to 32
separate dimming levels. Alternatively analog dimming can be
achieved by applying a variable DC voltage (V Dim ) at the FB pin
(see Figure 15) to adjust the LED current. As the DC dimming
signal voltage increases above VFB, the voltage drop on R 1 and
R 2 increases and the voltage drop on RSET decreases. Thus, the
LED current decreases as shown in Equation 6:
R 2 ? R
The input capacitance is typically 0.22μF. The output capacitor
should be in the range of 0.22μF to 1μF. X5R or X7R type of
ceramic capacitors of the appropriate voltage rating are
V FB ? ( R 1 + R 2 ) – V Dim ? R 1
I LED = --------------------------------------------------------------------------
SET
(EQ. 6)
recommended.
When choosing an inductor, make sure the average and peak
current ratings are adequate by using Equations 3, 4 and 5 (80%
efficiency assumed):
If V DIM is taken below FB, the inverse will happen and the
brightness will increase.
The DC dimming signal voltage can be a variable DC voltage from
a POT, a DCP (Digitally Controlled Potentiometer), or a DC voltage
0.8 ? V IN
I LED ? V OUT
I LAVG = ---------------------------------
(EQ. 3)
generated by filtering a high frequency PWM control signal.
L1
22μH
I LPK = I LAVG + --- ? Δ I L
(EQ. 4)
Δ I L = ---------------------------------------------------
L ? V OUT ? f OSC
1
2
V IN ? ( V OUT – V IN )
(EQ. 5)
Where:
? Δ I L is the peak-to-peak inductor current ripple in Amps
V IN
3.3V
C1
1μF
V IN LX
V OUT
ISL97634
PWM FB
GND R2
R1
3.3k
LEDs
R SET
4.75 Ω
C2
0.22μF
R 2 ? R 1 ?
V Dim = ------- ? V FB ? ? 1 + ------- – F ?
[ ( V Dim_max – V FB ) ? R 1 ]
R 2 = -------------------------------------------------------------------
[ V FB ? ( 1 – F min ) ]
? L is the inductance in H
? f OSC is the switching frequency, typically 1.45MHz
The ISL97634 supports a wide range of inductance values (10μH
to ~82μH). For lower inductor values or lighter loads, the boost
inductor current may become discontinuous. For high boost
inductor values, the boost inductor current will be in continuous
mode.
In addition to the inductor value and switching frequency, the
input voltage, number of LEDs and the LED current also affects
whether the converter operates in continuous conduction or
discontinuous conduction mode. Both operating modes are
allowed and normal. The discontinuous conduction mode yields
lower efficiency due to higher peak current.
Compensation
The product of the output capacitor and the load create a pole
while the inductor creates a right half plane zero. Both of these
attributes degrade the phase margin but the ISL97634 has
internal compensation network that ensures the device operates
reliably under the specified conditions. The internal
compensation and the highly integrated functions of the
ISL97634 make it a design friendly device to be used in high
volume, high reliability applications.
8
V Dim
FIGURE 15. ANALOG DIMMING CONTROL APPLICATION CIRCUIT
As brightness is directly proportional to LED currents, V Dim may
be calculated for any desired “relative brightness” (F) using
Equation 7:
(EQ. 7)
R 1 ? R 2 ?
Where F = I LED (dimmed)/I LED (undimmed).
These equations are valid for values of R 1 and R 2 such that both
R 1 >>RSET and R 2 >>RSET.
The analog dimming circuit can be tailored to a desired relative
brightness for different V Dim ranges using Equation 8.
(EQ. 8)
Where V Dim_max is the maximum V Dim voltage and F min is the
minimum relative brightness (i.e., the brightness with V Dim_max
applied).
i.e., V Dim_max = 5V, F min = 10% (i.e., 0.1), R 2 = 189k
i.e., V Dim_max = 1V, F min = 10% (i.e., 0.1), R 2 = 35k
FN6264.4
August 27, 2013
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL97634IRT18Z | 制造商:Intersil 功能描述:White LED Driver with PWM Dimming(4 LED) |
| ISL97634IRT18Z-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 |
| 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 |
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