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| 型号： | MAX8550AETI+ |
| 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： | 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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Integrated DDR Power-Supply Solution for
Desktops, Notebooks, and Graphic Cards
? 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
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.
? Inductor Operating Point. This choice provides trade-
offs: size vs. efficiency and transient response vs. out-
put ripple. Low inductor values provide better
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 divider
from VTT to VTTS. The maximum value for VTT is V VTTI -
V DROPOUT where V DROPOUT = I VTT × 0.3 Ω (max) at T A
= +85°C.
The termination reference voltage (VTTR) tracks 1/2
V REFIN .
Inductor Selection (Buck)
The switching frequency and inductor operating point
determine the inductor value as follows:
V OUT ( V IN OUT )
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
L =
- V
V IN × f SW × I LOAD ( MAX ) × LIR
at the edge of critical conduction (where the inductor
current just touches zero with every cycle at maximum
For example: I LOAD(MAX) = 12A, V IN = 12V, V OUT =
2.5V, f SW = 600kHz, 30% ripple current or LIR = 0.3:
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
L =
2 . 5 V ( 12 V - 2.5V)
12 V × 600 kHz × 12 A × 0 . 3
≈ 1 μ H
inductor value also determines the load-current value
at which PFM/PWM switchover occurs.
Setting the Output Voltage (Buck)
Preset Output Voltages
The MAX8550A dual-mode operation allows the selec-
tion of common voltages without requiring external
components (Figure 5). Connect FB to GND for a fixed
FB
TO
ERROR
AMPLIFIER
MAX8550A
OUT
1.8V
(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 MAX8550A regulates FB to a fixed reference volt-
age (0.7V). The adjusted output voltage is:
REF (2.0V)
2.5V
(FIXED)
V OUT FB ? 1 +
= V
?
?
R C ?
R D ? ?
+
V RIPPLE
2
0.1V
Figure 5. Dual-Mode Feedback Decoder
18
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8550AETI+ | 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 |
| MAX8550AETI+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 |
| MAX8550AETI-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 |
| MAX8550ETI | 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 |
| 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 |
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