- 您现在的位置：买卖IC网 > PDF目录20766 > ISL97631IHTZ-T7A (Intersil)IC LED DRIVR WHITE BCKLGT TSOT-6 PDF资料下载
参数资料
| 型号： | ISL97631IHTZ-T7A |
| 厂商： | Intersil |
| 文件页数： | 5/8页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVR WHITE BCKLGT TSOT-6 |
| 标准包装： | 250 |
| 拓扑： | PWM，升压（升压） |
| 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： | 800kHz ~ 1.8MHz |
| 电源电压： | 2.7 V ~ 5.5 V |
| 输出电压： | 27V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-6 细型，TSOT-23-6 |
| 供应商设备封装： | TSOT-23-6 |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
ISL97631
The magnitude of the PWM signal should be higher than the
minimum ENAB voltage high. The bench PWM dimming test
results are shown in Figure 8. In the test, two PWM
L1
22μH
frequencies 400Hz and 1kHz are chosen to compare the
linear dimming range. It is clear that there is a wider linear
dimming range for the lower PWM frequency than for the
higher one, due to the self discharge of the output capacitor
through the LEDs during the low ENAB periods. To achieve
a better linearity with high frequencies an NMOS FET can be
placed between the FB pin and the LED stack, with its gate
V IN
2.7V~5.5V
C1
1μF
OFF/ON
V IN LX
V OUT
ISL97631
ENAB FB
GND R2
R1
3.3k
LEDs
R SET
4.75 ?
C2
0.22μF
driven by the same signal as ENAB. This acts to prevent self
discharge of the output capacitor during the off periods. In
the PWM dimming test, the output capacitor is 0.22μF.
V Dim
FIGURE 9. ANALOG DIMMING CONTROL APPLICATION
CIRCUIT
20
18
16
14
12
The analog dimming circuit can be tailored to a desired
relative brightness for different V Dim ranges using
Equation 5.
[ ( V Dim_max – V FB ) ? R 1 ]
[ V FB ? ( 1 – F min ) ]
10
8
6
1kHz
400Hz
R 2 = -------------------------------------------------------------------
(EQ. 5)
4
2
0
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).
0
20
40 60
DUTY-CYCLE (%)
80
100
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
FIGURE 8. PWM DIMMING LINEAR RANGE (FOR 400Hz AND
1kHz PWM FREQUENCIES CONDITION,
C OUT = 0.22μF)
ANALOG DIMMING
The second dimming method applies a variable DC voltage
(V Dim ) at FB pin (see Figure 9) to adjust the LED current. As
the DC dimming signal voltage increases above V FB , the
voltages drop on R 1 and R 2 increase and the voltage drop
on R SET decreases. Thus, the LED current decreases.
Open-Voltage Protection
In some applications, it is possible that the output is
opened, e.g. when the LEDs are disconnected from the
circuit or the LEDs fail. In this case the feedback voltage
will be zero. The ISL97631 will then switch to a high duty
cycle resulting in a high output voltage, which may cause
the LX pin voltage to exceed its maximum 27V rating. To
implement overvoltage protection, a zener diode Dz and a
resistor R 1 can be used at the output and FB pin to limit the
voltage on the LX pin as shown in Figure 10. It is clear that
I LED = ------------------------------------------------------------------------- 1 -
V FB ? ( R 1 + R 2 ) – V Dim ? R
R 2 ? R SET
(EQ. 3)
as the zener is turned on, due to the overvoltage, the zener
diode’s current will set up a voltage on R 1 and R SET and this
voltage is applied on FB pin as the feedback node. This
The DC dimming signal voltage can be a variable DC voltage
or a DC voltage generated by filtering a high frequency PWM
control signal.
As brightness is directly proportional to LED currents, V Dim
may be calculated for any desired “relative brightness” (F)
using Equation 4.
feedback will prevent the output from reaching the
overvoltage condition. In the overvoltage protection circuit
design, the zener voltage should be larger than the
maximum forward voltage of the LED string.
R 2 ? ?
1 + ------ 1 - – F
V Dim = ------- ? V FB ? ? ?
R 1 ? R 2 ?
R
(EQ. 4)
Where F = I LED (dimmed)/I LED (undimmed).
These equations are valid for values of R1 and R2 such that
both R1>>RSET and R2>>RSET.
5
FN7370.1
December 21, 2005
相关PDF资料 |
PDF描述 |
|---|---|
| TPSD337M006R0070 | CAP TANT 330UF 6.3V 20% 2917 |
| LQP03TN1N8C04D | INDUCTOR 1.8NH 280MA 0201 |
| TPSD226K035H0125 | CAP TANT 22UF 35V 10% 2917 |
| NCP3985SN30T1G | IC REG LDO 3V .15A 5TSOP |
| AP431YL-13 | IC VREF SHUNT PREC ADJ SOT-89-3 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL97632IRT14Z | 制造商:Intersil 功能描述:LED Driver with 1-Wire Dimming(3 LED) |
| ISL97632IRT14Z-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 |
| ISL97632IRT14Z-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 |
| ISL97632IRT18Z | 制造商:Intersil 功能描述:LED Driver with 1-Wire Dimming(4 LED) |
| ISL97632IRT18Z-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 |
发布紧急采购，3分钟左右您将得到回复。