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| 型号： | MAX17112ETB+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 10/12页 |
| 文件大小： | 0K |
| 描述： | IC CONV DC-DC STEP UP 10TDFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| 应用： | LCD 监视器，笔记本电脑显示器 |
| 电源电压： | 2.6 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 供应商设备封装： | 10-TDFN-EP（3x3） |
| 包装： | 标准包装 |
| 产品目录页面： | 1412 (CN2011-ZH PDF) |
| 其它名称： | MAX17112ETB+TDKR |
High-Performance, Step-Up, DC-DC Converter
The maximum output current, input voltage, output volt-
age, and switching frequency determine the inductor
Calculate the ripple current at that operating point and
the peak current required for the inductor:
V IN ( MIN ) × ( V MAIN IN ( MIN )
value. Very high inductance values minimize the current
ripple, and therefore, reduce the peak current, which
decreases core losses in the inductor and I 2 R losses in
the entire power path. However, large inductor values
I RIPPLE =
- V
L × V MAIN × f O S C
)
I PEAK IN ( DC , MAX ) + RIPPLE
= I
also require more energy storage and more turns of
wire, which increase physical size and can increase I 2 R
losses in the inductor. Low inductance values decrease
the physical size, but increase the current ripple and
peak current. Finding the best inductor involves choos-
ing the best compromise between circuit efficiency,
inductor size, and cost.
The equations used here include a constant called LIR,
which is the ratio of the inductor peak-to-peak ripple
current to the average DC inductor current at the full
load current. The best trade-off between inductor size
and circuit efficiency for step-up regulators generally
has an LIR between 0.3 and 0.5. However, depending
I
2
The inductor ’s saturation current rating and the
MAX17112’s LX current limit (I LIM ) should exceed 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.
Considering the typical operating circuit, the maximum
load current (I MAIN(MAX )) is 600mA with a 15V output
and a typical input voltage of 5V. Choosing an LIR of 0.5
and estimating 85% efficiency at this operating point:
? 5 V ? ?
? ? ? ?
L = ?
? ≈ 2 . 7 μH
0 . 6 A × 1 . 2 MHz ? ? 0 .55 ?
on the AC characteristics of the inductor core material
and ratio of inductor resistance to other power-path
resistances, the best LIR can shift up or down. If the
inductor resistance is relatively high, more ripple is
? 15 V
2
15 V - 5 V ? ? 0.85 ?
? ?
acceptable to reduce the number of turns required, and
to increase the wire diameter. If the inductor resistance
Using the circuit’s minimum input voltage (4.5V) and
estimating 85% efficiency at this operating point:
is relatively low, increasing inductance to lower the
peak current can decrease losses through the power
path. If extremely thin high-resistance inductors are
used, as is common for LCD panel applications, the
I IN ( DC , MAX ) =
0.6 A × 15 V
4 . 5 V × 0 . 85
≈ 2 . 35 A
best LIR can increase to between 0.5 and 1.0.
Once a physical inductor is chosen, higher and lower
The ripple current and the peak current at that input
voltage are:
values of the inductor should be evaluated for efficien-
cy improvements in typical operating regions.
Calculate the approximate inductor value using the typ-
I RIPPLE =
4 . 5 V × ( 15 V - 4 . 5 V )
2 . 7 μH × 15 V × 1 . 2 MHz
≈ 0 . 9 7 A
ical input voltage (V IN ), the maximum output current
(I MAIN(EFF) ), the expected efficiency ( η TYP ) taken from
an appropriate curve in the Typical Operating
Characteristics, and an estimate of LIR based on the
I PEAK = 2 . 35 A +
0.97 A
2
= 2 . 84 A
? ? η
? V IN ? ?
TYP ?
V MAIN IN
L = ?
? ? I ? ?
LIR ?
? MAIN ( EFF ) × f OSC ?
? V OUT
I IN ( DC , MAX ) =
V RIPPLE ( C ) ≈ MAIN ? MAIN IN ?
above discussion:
2
- V
?
Choose an available inductor value from an appropriate
inductor family. Calculate the maximum DC input cur-
rent at the minimum input voltage, V IN(MIN) , using con-
servation of energy and the expected efficiency at that
operating point ( η MIN ) taken from an appropriate curve
in the Typical Operating Characteristics:
I MAIN(EFF ) × V OUT
V IN ( MIN ) × η MIN
Output Capacitor Selection
The total output voltage ripple has two components: the
capacitive ripple caused by the charging and discharg-
ing of the output capacitance, and the ohmic ripple due
to the capacitor’s equivalent series resistance (ESR):
V RIPPLE = V RIPPLE ( C ) + V RIPPLE ( ESR )
I ? V - V ?
C OUT ? V MAIN f OSC ?
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17112EVKIT+ | 功能描述:电源管理IC开发工具 MAX17112 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX17113ETL+ | 功能描述:其他电源管理 Power-Supply Controller RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
| MAX17113ETL+T | 功能描述:LCD 驱动器 Power-Supply Controller RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| MAX17113EVKIT+ | 功能描述:电源管理IC开发工具 MAX17113 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX17114ETM | 制造商:MAXIM 功能描述:Pb Free |
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