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参数资料
| 型号： | MAX771EPA+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST 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： | 90% |
| 电源电压： | 3 V ~ 16.5 V |
| 降压： | 无 |
| 升压： | 是 |
| 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： | 8-DIP（0.300"，7.62mm） |
| 包装： | 管件 |
5V/12V/15V or Adjustable, High-Efficiency,
Low I Q , Step-Up DC-DC Controllers
I C(PEAK)
L
MAX770
MAX771
MAX773
MAX772
I B
R BASE
EXT
N
EXTH
NPN
EXTL
CS
R SENSE
CS
R SENSE
Figure 8a. Use an N-Channel MOSFET with the
Figure 8c. Using an NPN Transistor with the MAX773
MAX770/MAX771/MAX772
preferably under 20m ? . To minimize radiated noise,
use a toroid, a pot core, or a shielded coil.
MAX773
EXTH
L
N
Table 2 lists inductor suppliers and specific recom-
mended inductors.
Power Transistor Selection
Use an N-channel MOSFET power transistor with the
L ≥ ——————————
EXTL
CS
R SENSE
Figure 8b. Using an N-Channel MOSFET with the MAX773
The standard operating circuits use a 22μH inductor.
If a different inductance value is desired, select L
such that:
V IN (max) x t ON (min)
I LIM / 2
Larger inductance values tend to increase the start-up
time slightly, while smaller inductance values allow the
coil current to ramp up to higher levels before the
switch turns off, increasing the ripple at light loads.
Inductors with a ferrite core or equivalent are recom-
mended; powder iron cores are not recommended for
use with high switching frequencies. Make sure the
inductor’s saturation current rating (the current at which
the core begins to saturate and the inductance starts to
fall) exceeds the peak current rating set by R SENSE .
However, it is generally acceptable to bias the inductor
into saturation by approximately 20% (the point where
the inductance is 20% below the nominal value). For
highest efficiency, use a coil with low DC resistance,
MAX770/MAX771/MAX772 (Figure 8a).
Use an N-FET whenever possible with the MAX773. An
NPN transistor can be used, but be extremely careful
when determining the base current (see NPN
Transistors section). An NPN transistor is not recom-
mended when using the shunt regulator.
N-Channel MOSFETs
To ensure the external N-channel MOSFET (N-FET) is
turned on hard, use logic-level or low-threshold
N-FETs when the input drive voltage is less than 8V. This
applies even in bootstrapped mode, to ensure start-up.
N-FETs provide the highest efficiency because they do
not draw any DC gate-drive current, but they are typi-
cally more expensive than NPN transistors. When using
an N-FET with the MAX773, connect EXTH and EXTL to
the N-FET’s gate (Figure 8b).
When selecting an N-FET, three important parameters
are the total gate charge (Q g ), on resistance (r DS(ON) ),
and reverse transfer capacitance (C RSS ).
Q g takes into account all capacitances associated with
charging the gate. Use the typical Q g value for best
results; the maximum value is usually grossly over-
specified since it is a guaranteed limit and not the mea-
sured value. The typical total gate charge should be
50nC or less. With larger numbers, the EXT pins may
not be able to adequately drive the gate. The EXT
rise/fall time with various capacitive loads as shown in
the Typical Operating Characteristics.
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX771EPA+ | 功能描述:DC/DC 开关控制器 5/12/15/AdjV Step Up 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 |
| MAX771ESA | 功能描述:DC/DC 开关控制器 5/12/15/AdjV Step Up 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 |
| MAX771ESA+ | 功能描述:DC/DC 开关控制器 5/12/15/AdjV Step Up 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 |
| MAX771ESA+T | 功能描述:DC/DC 开关控制器 5/12/15/AdjV Step Up 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 |
| MAX771ESA-T | 功能描述:DC/DC 开关控制器 5/12/15/AdjV Step Up 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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