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参数资料
| 型号： | ISL97684IRTZ-TK |
| 厂商： | Intersil |
| 文件页数： | 15/17页 |
| 文件大小： | 0K |
| 描述： | IC LED DVR PWM CTRL 4CH 16TQFN |
| 标准包装： | 1 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 4 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 背光 |
| 频率： | 500kHz ~ 650kHz，900kHz ~ 1.1MHz |
| 电源电压： | 4 V ~ 26.5 V |
| 输出电压： | 45V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 供应商设备封装： | 16-TQFN（3x3） |
| 包装： | 标准包装 |
| 工作温度： | -40°C ~ 85°C |
| 其它名称： | ISL97684IRTZ-TKDKR |
ISL97682, ISL97683, ISL97684
Components Selections
According to the inductor Voltage-Second Balance principle, the
change of inductor current during the switching regulator
On-time is equal to the change of inductor current during the
switching regulator Off-time. Since the voltage across an inductor
is as shown in Equation 10:
including ripple current, current limit, efficiency, transient
performance and stability.
The inductor’s maximum current capability must be adequate
enough to handle the peak current at the worst case condition.
Additionally if an inductor core is chosen with too low a current
rating, saturation in the core will cause the effective inductor
V L = L × Δ I L ? Δ t
and Δ I L @ On = Δ I L @ Off, therefore:
( V I – 0 ) ? L × D × t S = ( V O – V D – V I ) ? L × ( 1 – D ) × t S
(EQ. 10)
(EQ. 11)
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.
V O ? V I = 1 ? ( 1 – D )
where D is the switching duty cycle defined by the turn-on time
over the switching periods. V D is a Schottky diode forward
voltage that can be neglected for approximation.
Rearranging the terms without accounting for V D gives the boost
ratio and duty cycle as Equations 12 and 13:
(EQ. 12)
The peak current can be derived from the voltage across the
inductor during the Off-period, expressed in Equation 14:
IL peak = ( V O × I O ) ? ( 85% × V I ) + 1 ? 2 [ V I × ( V O – V I ) ? ( L × V O × f SW ) ]
(EQ. 14)
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
D = ( V O – V I ) ? V O
(EQ. 13)
the inductor current change, which is inversely proportional to L
and F SW as a result, for a given switching.
Input Capacitor
Switching regulators require input capacitors to deliver peak
charging current and to reduce the impedance of the input
supply. This reduces interaction between the regulator and input
supply, thereby improving system stability. The high switching
frequency of the loop causes almost all ripple current to flow in
the input capacitor, which must be rated accordingly.
A capacitor with low internal series resistance should be chosen
to minimize heating effects and improve system efficiency, such
as X5R or X7R ceramic capacitors, which offer small size and a
lower value of temperature and voltage coefficient compared to
other ceramic capacitors.
It is recommended that an input capacitor of at least 10μF be
used. Ensure the voltage rating of the input capacitor is suitable
to handle the full supply range.
Inductor
The selection of the inductor should be based on its maximum
and saturation current (I SAT ) characteristics, power dissipation
(DCR), EMI susceptibility (shielded vs unshielded), and size.
Inductor type and value influence many key parameters,
15
Applications
Low Voltage Operations
The ISL97682, ISL97683, ISL97684 VIN pin can be separately
biased from the LEDs power input to allow low voltage operation.
For systems that have only single supply, VOUT can be tied to the
driver VIN pin to allow initial start-up; see Figure 26. The circuit
works as follows; when the input voltage is available and the
device is not enabled, the V OUT follows V IN with a Schottky diode
voltage drop. The V OUT bootstrapped to VIN pin allows an initial
start-up once the part is enabled. Once the driver starts up with
V OUT regulating to the target, the VIN pin voltage also increases.
As long as the V OUT does not exceed 26.5V and the extra power
loss on VIN is acceptable, this configuration can be used for input
voltage as low as 3.0V. For systems where a single input supply
of 4V to 5.5V is available, the VIN pin can be shorted to VDC,
allowing a slight gain in efficiency due to bypassing the internal
LDO.
For systems that have dual supplies, the VIN pin can be biased
from 5V to 12V. The input voltage can be as low as 2.7V without
the limitations previously mentioned; see Figure 27.
FN7689.1
May 16, 2012
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL97686IBZ | 功能描述:IC LED DRVR BACKLIGHT 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 |
| ISL97686IBZ-T | 功能描述:IC LED DRVR BACKLIGHT 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 |
| ISL97686IRTZ | 功能描述:IC LED DRVR BACKLIGHT 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 |
| ISL97686IRTZ-T | 功能描述:IC LED DRVR BACKLIGHT 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 |
| 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 |
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