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| 型号： | MAX8550ETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 18/29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： | 2,500 |
| 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： | 带卷 (TR) |
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MAX8550/MAX8551
Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
shut off, go high impedance, and restart after the die
portion of the IC cools by 15 ° C. Both thermal faults are
independent. For example, if the VTT output is over-
loaded to the point that it triggers its thermal fault, the
buck regulator continues to function.
Design Procedure
Firmly establish the input voltage range (V IN ) and maxi-
mum load current (I LOAD ) in the buck regulator before
choosing a switching frequency and inductor operating
point (ripple current ratio or LIR). The primary design
trade-off lies in choosing a good switching frequency
and inductor operating point, and the following four fac-
tors dictate the rest of the design:
Setting the Output Voltage (Buck)
Preset Output Voltages
The MAX8550/MAX8551s’ Dual-Mode operation allows
the selection of common voltages without requiring
external components (Figure 5). Connect FB to GND for
a fixed 2.5V output, to AV DD for a fixed 1.8V output, or
connect FB directly to OUT for a fixed 0.7V output.
Setting the Buck Regulator Output (V OUT ) with a
Resistive Voltage-Divider at FB
The buck-regulator output voltage can be adjusted from
0.7V to 5.5V using a resistive voltage-divider (Figure 6).
The MAX8550/MAX8551 regulate FB to a fixed refer-
ence voltage (0.7V). The adjusted output voltage is:
V OUT FB ? 1 +
= V
? Input Voltage Range. The maximum value (V IN(MAX) )
must accommodate the worst-case voltage. The mini-
mum value (V IN(MIN) ) must account for the lowest
voltage after drops due to connectors and fuses. If
?
?
R C ?
R D ? ?
+
V RIPPLE
2
there is a choice, lower input voltages result in better
efficiency.
? Maximum Load Current. There are two values to con-
sider. The peak load current (I PEAK ) determines the
instantaneous component stresses and filtering
requirements and thus drives output capacitor selec-
tion, inductor saturation rating, and the design of the
current-limit circuit. The continuous load current
(I LOAD ) determines the thermal stresses and thus
drives the selection of input capacitors, MOSFETs,
and other critical heat-contributing components.
? Switching Frequency. This choice determines the
basic trade-off between size and efficiency. The opti-
mal frequency is largely a function of maximum input
where V FB is 0.7V, R C and R D are shown in Figure 6,
and V RIPPLE is:
V RIPPLE = LIR × I LOAD ( MAX ) × R ESR
Setting the VTT and VTTR Voltages (LDO)
The termination power-supply output (VTT) can be set by
two different methods. First, the VTT output can be con-
nected directly to the VTTS input to force VTT to regulate
to V REFIN / 2. Secondly, VTT can be forced to regulate
higher than V REFIN / 2 by connecting a resistive
voltage, due to MOSFET switching losses proportion-
al to frequency and V IN 2 . The optimum frequency is
also a moving target, due to rapid improvements in
MOSFET technology that are making higher frequen-
cies more practical.
FB
TO
ERROR
AMPLIFIER
MAX8550/
MAX8551
OUT
1.8V
(FIXED)
? Inductor Operating Point. This choice provides trade-
offs: size vs. efficiency and transient response vs. out-
put ripple. Low inductor values provide better
transient response and smaller physical size but also
result in lower efficiency and higher output ripple due
to increased ripple currents. The minimum practical
inductor value is one that causes the circuit to operate
at the edge of critical conduction (where the inductor
current just touches zero with every cycle at maximum
load). Inductor values lower than this grant no further
size-reduction benefit. The optimum operating point is
usually found between 20% and 50% ripple current.
When pulse skipping ( SKIP = low at light loads), the
inductor value also determines the load-current value
REF (2.0V)
0.1V
2.5V
(FIXED)
18
at which PFM/PWM switchover occurs.
Figure 5. Dual-Mode Feedback Decoder
Maxim Integrated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| MAX8551ETI+ | 制造商:Maxim Integrated Products 功能描述:INTEGRATED DDR POWER-SUPPLY SOLUTIONS FOR DESKTOPS, NOTEBOOK - Rail/Tube |
| MAX8551ETI+T | 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 |
| MAX8551ETI-T | 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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