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| 型号： | MAX17061AETI+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 21/24页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WHITE BCKLGT 28-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 8 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 车载，背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 1MHz |
| 电源电压： | 4.5 V ~ 26 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
8-String White LED Driver with
SMBus for LCD Panel Applications
( V OUT ( MAX ) + V DIODE ? 2 × V IN ( MIN ) ) × R S
2 × 24 . 7 mV × f OSC ( MIN )
35 . 9 V ? 7 V ? ? 0 . 85 ?
? 7 V ? ?
L = ? ? ? ? ? ? = 9 . 44 μ H
I OUT ( MAX ) × V OUT
V IN ( MIN ) × η MIN
L CCM ( MIN ) = ( 35 . 9 V + 0 . 4 V ? 2 × 7 V ) × 12 m Ω = 6 . 0 μ H
V IN ( MIN ) × ( V OUT ( MAX ) ? V IN ( MIN ) )
L × V OUT ( MAX ) × f OSC
I PEAK =
7 V × ( 35 . 9 V ? 7 V )
2 × 10 μ H × 35 . 9 V × 0 . 9 MHz
L DCM ( MAX ) = ? 1 ?
?
The MAX17061A has a minimum inductor value limita-
tion for a stable operation in CCM mode at low input
voltage because of the internal fixed-slope compensa-
tion. The minimum inductor value for stability is calcu-
lated with the following equation:
L CCM ( MIN ) =
where 24.7mV is a scale factor from slope compensa-
tion, and the R S is the equivalent current-sensing scale
factor (12m Ω typ):
1) Choose an available inductor value from an appropri-
ate inductor family. Calculate the maximum DC input
current at the minimum input voltage V IN(MIN), using
conservation of energy and the expected efficiency
at that operating point ( η MIN ) taken from an appropri-
ate curve in the Typical Operating Characteristics:
,
I IN ( DCMAX ) =
2) Calculate the ripple current at that operating point
and the peak current required for the inductor:
I RIPPLE =
Inductor Selection in DCM Operation
When DCM operating mode is chosen to minimize the
inductor value, the calculations are different from those
Inductor Selection Design
Examples:
Considering the Typical Operating Circuit with four
10-LED strings and 25mA LED full-scale current, the
maximum load current (I OUT(MAX) ) is 100mA with a
35.9V output and a minimal input voltage of 7V.
Choosing a CCM operating mode with LIR = 1 at 1MHz
and estimating efficiency of 85% at this operating point:
2
? 35 . 9 V ? ? 100 mA × 1 MHz ? ? 1 ?
In CCM, the inductor has to be higher than L CCM(MIN):
2 × 24 . 7 mV × 0 . 9 MHz
A10μH inductor is chosen, which is higher than the
minimum L that guarantees stability in CCM.
The peak-inductor current at minimum input voltage is
calculated as follows:
100mA × 35.9V
7 V × 0 . 85
+ = 0 . 92 A
Alternatively, choosing a DCM operating mode at 750kHz
and estimating efficiency of 85% at this operating point:
? 7 V ?
? 35 . 9 V + 0 . 4 V ?
above in CCM mode. The maximum inductor value for
DCM mode is calculated with the following equation:
The peak-inductor current in DCM is calculated with fol-
×
( 7 V ) 2 × 0 . 85
2 × 0 . 825 MHz × 35 . 9 V × 100 mA
= 5 . 6 μ H
L DCM ( MAX ) = ? 1 ? ?
V IN ( MIN ) 2 × η
2 × f OSC ( MAX ) × V OUT ( MAX ) × I OUT ( MAX )
100 mA × 2 × 35 . 9 V × ( 35 . 9 V + 0 . 4 V ? 7 V )
4 . 7 uH × 0 . 675 MHz × 0 . 85 × ( 35 . 9 V + 0 . 4 V )
I PEAK IN ( DCMAX ) + RIPPLE
= I
2
lowing equation:
? V IN ( MIN ) ?
? V OUT ( MAX ) + V DIODE ?
×
I
,
The inductor’s saturation current rating should exceed
A 4.7μH inductor is chosen. The peak inductor current
at minimum input voltage is calculated as follows:
I PEAK = = 1 . 47 A
Output Capacitor Selection
The total output voltage ripple has two components: the
capacitive ripple caused by the charging and discharging
on the output capacitor, and the ohmic ripple due to the
capacitor’s equivalent series resistance (ESR):
V RIPPLE = V RIPPLE ( C ) + V RIPPLE ( ESR )
? ?
I PEAK and the inductor’s DC current rating should
exceed I IN(DC,MAX) . For good efficiency, choose an
inductor with less than 0.1 Ω series resistance.
and:
V RIPPLE ( C ) ≈
I OUT(MAX ) ? V OUT(MAX ) ? V IN(MIN) ?
C OUT ? V OUT ( MAX ) f OSC ?
______________________________________________________________________________________
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相关代理商/技术参数 |
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| MAX17061AEVCMAXQU+ | 功能描述:LED 照明开发工具 Evaluation Kit/Evaluation system for MAX17061A RoHS:否 制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装: |
| MAX17061AEVKIT+ | 功能描述:LED 照明开发工具 MAX17061A Eval Kit RoHS:否 制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装: |
| MAX17061ETI+ | 功能描述:LED照明驱动器 8-String White LED Driver w/SMBus RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX17061ETI+T | 功能描述:LED照明驱动器 8-String White LED Driver w/SMBus RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX17061EVCMAXQU+ | 功能描述:LED 照明开发工具 Evaluation Kit/Evaluation System for the MAX17061 RoHS:否 制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装: |
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