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参数资料
| 型号： | MAX774EPA+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 12/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR INV PWM 8-DIP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 控制器 |
| 输出数： | 1 |
| 频率 - 最大： | 300kHz |
| 占空比： | 85% |
| 电源电压： | 3 V ~ 16.5 V |
| 降压： | 无 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 是 |
| 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： | 8-DIP（0.300"，7.62mm） |
| 包装： | 管件 |
-5V/-12V/-15V or Adjustable, High-Efficiency,
Low I Q Inverting DC-to-DC Controllers
2500
2000
R SENSE = 0.05 ?
R SENSE = 0.06 ?
1000
800
R SENSE = 0.05 ?
V OUT = -12V
R SENSE = 0.06 ?
1500
600
R SENSE = 0.07 ?
1000
R SENSE = 0.07 ?
400
500
0
V OUT = -5V
R SENSE = 0.08 ?
R SENSE = 0.09 ?
200
0
R SENSE = 0.08 ?
R SENSE = 0.09 ?
3 4
5 6
7 8 9 10 11 12 13 14 15
3
4
5 6 7
8
9
L(max) ≤ _______________________________
? _______ ? < —
= ___________
INPUT VOLTAGE (V)
Figure 6. MAX774 Maximum Output Current vs. Input Voltage
(V OUT = -5V)
inductor should not be so large that the peak current
never reaches the current limit. That is:
[ V+(min) - V SW (max) ] x 12μs
I LIM (max)
This is only important if
V IN 1 t OFF (min)
V OUT 6 t ON (max)
More important is that the inductor not be so small that
the current rises much faster than the current-limit
comparator can respond. This would be wasteful and
reduce efficiency. Calculate the minimum inductor value
as follows:
INPUT VOLTAGE (V)
Figure 7. MAX775 Maximum Output Current vs. Input Voltage
(V OUT = -12V)
are recommended. Make sure that the inductor’s satura-
tion current rating is greater than I LIM (max).
Diode Selection
The ICs’ high switching frequencies demand a high-
speed rectifier. Schottky diodes such as the 1N5817 to
1N5822 families are recommended. Choose a diode
with an average current rating approximately equal to
or greater than I LIM (max) and a voltage rating higher
than V IN (max) + V OUT . For high-temperature applica-
tions, Schottky diodes may be inadequate due to their
high leakage currents; instead, high-speed silicon
diodes may be used. At heavy loads and high tempera-
ture, the benefits of a Schottky diode’s low forward volt-
age may outweigh the disadvantages of its high leak-
L(min) ≥ _______________________________
[ V+(max) - V SW (min) ] x 0.3μs
δ (I) x I LIM (min)
age current.
Current-Sense Resistor
Where L is in μH, 0.3μs is an ample time for the com-
parator response, I LIM is the current limit (see the
Current-Sense Resistor section), and δ (I) is the allow-
able percentage of overshoot. As an example, Figure
2's circuit uses a 3A peak current. If we allow a 15%
overshoot and 15V is the maximum input voltage, then
L(min) is 16μH. The actual value of L above this limit
has minimal effect on this circuit's operation.
For highest efficiency, use a coil with low DC resistance.
Coils with 30m ? or lower resistance are available. To min-
imize radiated noise, use a torroid, pot-core, or shielded-
bobbin inductor. Inductors with a ferrite core or equivalent
The current-sense resistor limits the peak switch cur-
rent to 210mV/R SENSE , where R SENSE is the value of
the current-sense resistor, and 210mV is the current-
sense comparator threshold (see Current-Limit Trip
Level in the Electrical Characteristics ).
To maximize efficiency and reduce the size and cost of
external components, minimize the peak current.
However, since the output current is a function of the
peak current, do not set the limit too low. See Figures
6–9 to determine the sense resistor, as well as the peak
current, for the required load current.
12
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX774EPA+ | 功能描述:DC/DC 开关控制器 5/12/15/AdjV- Inv DC/DC Controller 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 |
| MAX774ESA | 功能描述:DC/DC 开关控制器 5/12/15/AdjV- Inv DC/DC Controller 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 |
| MAX774ESA+ | 功能描述:DC/DC 开关控制器 5/12/15/AdjV- Inv DC/DC Controller 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 |
| MAX774ESA+T | 功能描述:DC/DC 开关控制器 5/12/15/AdjV- Inv DC/DC Controller 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 |
| MAX774ESA-T | 功能描述:DC/DC 开关控制器 5/12/15/AdjV- Inv DC/DC Controller 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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