参数资料
| 型号： | MAX8940EXK28+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 6/9页 |
| 文件大小： | 0K |
| 描述： | IC REG LDO 2.8V .12A SC70-5 |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| 稳压器拓扑结构： | 正，固定式 |
| 输出电压： | 2.8V |
| 输入电压： | 最高 6V |
| 电压 - 压降（标准）： | 0.135V @ 120mA |
| 稳压器数量： | 1 |
| 电流 - 输出： | 120mA（最小） |
| 电流 - 限制（最小）： | 130mA |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 6-TSSOP（5 引线），SC-88A，SOT-353 |
| 供应商设备封装： | SC-70-5 |
| 包装： | 标准包装 |
| 产品目录页面： | 1411 (CN2011-ZH PDF) |
| 其它名称： | MAX8940EXK28+TDKR |
Low-Noise, High PSRR,
Low-Dropout, 120mA Linear Regulator
Pin Description
PIN
1
2
3
4
5
NAME
IN
GND
SHDN
BP
OUT
FUNCTION
Unregulated Input Supply
Ground
Shutdown. Pull low to disable the regulator.
Noise Bypass for Low-Noise Operation. Connect a 10nF capacitor from BP to OUT. It is short to OUT
in shutdown mode.
Regulated Output Voltage. Bypass with a capacitor to GND. See the Capacitor Selection and Regulator
Stability section for more details.
Detailed Description
The MAX8940 is a low-noise, low-dropout, low-quies-
cent current linear regulator designed for space-
restricted applications. The part is available with preset
output voltages 2.8V or 3.0V. This device can supply
loads up to 120mA. As shown in the Functional
Diagram , the MAX8940 consist of an innovative
bandgap core and noise bypass circuit, error amplifier,
p-channel pass transistor, and internal feedback volt-
age-divider.
The 1.225V bandgap reference is connected to the
error amplifier’s inverting input. The error amplifier com-
pares this reference with the feedback voltage and
amplifies the difference. If the feedback voltage is
lower than the reference voltage, the pass-transistor
gate is pulled low. This allows more current to pass to
the output and increases the output voltage. If the feed-
back voltage is too high, the pass transistor gate is
pulled high, allowing less current to pass to the output.
The output voltage is fed back through an internal resis-
tor voltage-divider connected to the OUT pin.
An external bypass capacitor connected to BP reduces
noise at the output. Additional blocks include a current
limiter, thermal sensor, and shutdown logic.
Internal P-Channel Pass Transistor
The MAX8940 features a 1 ? (typ) p-channel MOSFET
pass transistor. This provides seve-ral advantages over
similar designs using a PNP pass transistor, including
longer battery life. The p-channel MOSFET requires no
base drive, which considerably reduces quiescent cur-
rent. PNP-based regulators waste considerable current
in dropout when the pass transistor saturates. They
also use high base-drive current under heavy loads.
The MAX8940 does not suffer from these problems and
consume only 40μA of quiescent current in light load
and 220μA in dropout (see the Typical Operating
Characteristics).
Shutdown
The MAX8940 features a low-power shutdown mode that
reduces quiescent current less than 1μA. Driving SHDN
low disables the voltage reference, error amplifier, gate-
drive circuitry, and pass transistor (see the Functional
Diagram), and the device output enters a high-imped-
ance state. Connect SHDN to IN for normal operation.
Current Limit
The MAX8940 includes a current limiter, which monitors
and controls the pass transistor’s gate voltage, limiting
the output current to 200mA. For design purposes, con-
sider the current limit to be 130mA (min) to 300mA (max).
The output can be shorted to ground for an indefinite
amount of time without damaging the part.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation
in the MAX8940. When the junction temperature exceeds
T J = +160°C, the thermal sensor signals the shutdown
logic, turning off the pass transistor and allowing the IC
to cool down. The thermal sensor turns the pass transis-
tor on again after the IC’s junction temperature drops by
10°C, resulting in a pulsed output during continuous
thermal-overload conditions.
Thermal-overload protection is designed to protect the
MAX8940 in the event of a fault condition. For continual
operation, do not exceed the absolute maximum junc-
tion temperature rating of T J = +150°C.
Operating Region and Power Dissipation
The MAX8940 maximum power dissipation depends on
the thermal resistance of the case and circuit board,
6
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| MAX8940EXK30+T | 功能描述:线性稳压器 - 标准 PSRR 120mA Linear Regulator RoHS:否 制造商:STMicroelectronics 输出类型: 极性: 输出电压:1.8 V 输出电流:150 mA 负载调节: 最大输入电压:5.5 V 线路调整率: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOT-323-5L |
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