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| 型号： | MAX8550ETI+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 23/29页 |
| 文件大小： | 0K |
| 描述： | IC PWR SUP DDR INTEG 28TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 应用： | 控制器，DDR |
| 输入电压： | 2 V ~ 28 V |
| 输出数： | 2 |
| 输出电压： | 1.8V，2.5V，0.7 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 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（5x5） |
| 包装： | 管件 |
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MAX8550/MAX8551
Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
a divider current of approximately 10μA to prevent signifi-
cant inaccuracy in the valley current-limit tolerance.
Foldback Current Limit
Alternately, foldback current limit can be implemented
V ILIM ( 0 V ) = P FB × V ILIM ( NOM )
4) The value for R4 can be calculated as:
if the UVP latch option is not available. Foldback cur-
rent limit reduces the power dissipation of external
components so they can withstand indefinite overload
and short circuit, with automatic recovery after the over-
R 4 =
2V - V ILIM( 0 V )
10 μ A
R 56 = ?
? 10 μ A ?
V ILIM ( NOM ) = 10 × I LOAD ( MAX ) × ? 1 - ?
V OUT × R 4 × R 5 6
(
) )
(
? V - V - V ILIM ( 0 V ) × R 4 - ?
( (
)
)
? V ILIM ( NOM ) ? V ILIM ( 0 V ) × R 56
?
?
load or short circuit is removed. To implement foldback
current limit, connect a resistor from V OUT to ILIM (R6
in Figure 7 and the Typical Applications Circuit), in
addition to the resistor-divider network (R4 and R5)
used for setting the adjustable current limit as shown in
Figure 7.
The following is a procedure for calculating the value of
R4, R5, and R6:
1) Calculate the voltage, V ILIM(NOM) , required at ILIM
when the output voltage is at nominal:
? LIR ?
? 2 ?
× R DS ( ON ) Q 2
5) The parallel combination of R5 and R6, denoted
R56, is calculated as:
? 2 V ?
? - R 4
6) Then R6 can be calculated as:
R 6 =
? OUT ILIM ( NOM ) ?
? ?
?
7) Then R5 is calculated as:
2) Pick a percentage of foldback, PFB, from 15%
to 40%.
3) Calculate the voltage, V ILIM(0V) , when the output is
shorted (0V):
R 5 =
R6 × R56
R 6 - R 56
Boost-Supply Diode and
Capacitor Selection (Buck)
A low-current Schottky diode, such as the CMDSH-3
from Central Semiconductor, works well for most appli-
V OUT
cations. Do not use large-power diodes, because high-
er junction capacitance can charge up the voltage at
MAX8550/
MAX8551
REF
C REF
R4
R5
BST to the LX voltage and this exceeds the absolute
maximum rating of 6V. The boost capacitor should be
0.1μF to 4.7μF, depending on the input and output volt-
ages, external components, and PC board layout. The
ILIM
GND
R6
boost capacitance should be as large as possible to
prevent it from charging to excessive voltage, but small
enough to adequately charge during the minimum low-
side MOSFET conduction time, which happens at maxi-
mum operating duty cycle (this occurs at minimum
input voltage). In addition, ensure that the boost capac-
itor does not discharge to below the minimum gate-to-
source voltage required to keep the high-side MOSFET
Figure 7. Foldback Current Limit
Maxim Integrated
23
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8550ETI+ | 功能描述:电压模式 PWM 控制器 Integrated DDR Power Supply Solution RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX8550ETI+T | 功能描述:电压模式 PWM 控制器 Integrated DDR Power Supply Solution RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX8550ETI-T | 功能描述:PMIC 解决方案 RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8550EVKIT | 功能描述:电源管理IC开发工具 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 |
| MAX8551ETI | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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