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| 型号： | MAX1791EUB+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 18/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 10-UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 300kHz |
| 电源电压： | 5 V ~ 20 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1410 (CN2011-ZH PDF) |
High-Efficiency, 10-Pin μMAX, Step-Down
Controllers for Notebooks
(Figure 10). Refer to the MAX1791 EV kit manual for a
OUT
specific layout example.
FIXED
1.8V
FIXED
3.3V
TO ERROR
AMP
If possible, mount all of the power components on the
top side of the board, with their ground terminals flush
against one another. Follow these guidelines for good
PC board layout:
FB
?
Isolate the power components on the top side from
the sensitive analog components on the bottom
side with a ground shield. Use a separate GND
0.150V
2.5V
MAX1762
?
plane under OUT. Avoid the introduction of AC cur-
rents into the GND ground planes. Run the power
plane ground currents on the top side only, if possi-
ble.
Keep the high-current paths short, especially at the
Figure 9. Feedback MUX
a fixed +1.8V (MAX1762) or 3.3V (MAX1791) output.
Connect FB to VL for a fixed 2.5V (MAX1762) or 5.0V
(MAX1791) output. Otherwise, connect FB to a resistive
voltage-divider for an adjustable output.
?
ground terminals. This practice is essential for sta-
ble, jitter-free operation.
Keep the power traces and load connections short.
This practice is essential for high efficiency. Using
thick copper PC boards (2oz vs. 1oz) can enhance
full-load efficiency by 1% or more. Correctly routing
PC board traces is a difficult task that must be
Setting the Output Voltage
Select V OUT > 1.25V for the MAX1762/MAX1791 by
connecting FB to a resistive voltage-divider between
V OUT and GND (Figure 2). Choose R2 to be about
10k ? , and solve for R1 using the equation:
?
approached in terms of fractions of centimeters,
where a single milliohm of excess trace resistance
causes a measurable efficiency penalty.
Inductor and GND connections to the synchronous
rectifiers for current limiting must be made using
Kelvin sensed connections to guarantee the cur-
V OUT FB × ? 1 +
= V ?
?
?
?
R1 ?
R2 ?
rent-limit accuracy. With 8-pin SO MOSFETs, this is
best done by routing power to the MOSFETs from
outside using the top copper layer, while connect-
R2 = ? OUT FB ? × R1
V FB REF ?
?
where V FB = 1.25V. For a V OUT = 3.0V, R2 = 10k ? and
R1 = 14k ? .
For a desired V OUT < 1.25V, connect FB to a resistive
voltage-divider between REF and OUT (Figure 3).
Choose R1 to be about 50k ? , and solve for R2 using
the equation:
? V -V ?
-V
where V FB = 1.25V and V REF = 2.0V. For a V OUT =
1.0V, R1 = 50k ? and R2 = 16.5k ? . Under these condi-
tions, a minimum load of V REF - V FB / R1 >15μA is
required.
PC Board Layout Guidelines
Careful PC board layout is critical to achieve low
switching losses and clean, stable operation. This is
especially true when multiple converters are on the
same PC board where one circuit can affect the other.
The switching power stages require particular attention
?
?
?
ing GND and CS inside (underneath) the μMAX
package.
When trade-offs in trace lengths must be made, it’s
preferable to allow the inductor charging path to be
made longer than the discharge path. For example,
it’s better to allow some extra distance between the
input capacitors and the high-side MOSFET than to
allow distance between the inductor and the low-
side MOSFET or between the inductor and the out-
put filter capacitor.
Ensure that the OUT connection to C OUT is short
and direct. However, in some cases it may be desir-
able to deliberately introduce some trace length
between the OUT connector node and the output
filter capacitor (see Stability Considerations ).
Route high-speed switching nodes (CS, DH, and
DL) away from sensitive analog areas (FB). Use
GND as an EMI shield to keep radiated switching
noise away from the IC’s feedback divider and ana-
log bypass capacitors.
18
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1791EUB+ | 功能描述:DC/DC 开关控制器 Step-Down for Notebook 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 |
| MAX1791EUB+ | 制造商:Maxim Integrated Products 功能描述:CONTROLLER ((NW)) |
| MAX1791EUB+T | 功能描述:DC/DC 开关控制器 Step-Down for Notebook 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 |
| MAX1791EUB-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 |
| MAX1791EVKIT | 功能描述:DC/DC 开关控制器 Evaluation Kit for the MAX1791 MAX1762 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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