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参数资料
| 型号： | MAX881REUB+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 6/8页 |
| 文件大小： | 0K |
| 描述： | IC SUPPLY BIAS LN 10-UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 充电泵，无线设备 |
| 输入电压： | 2.5 V ~ 5.5 V |
| 输出数： | 1 |
| 输出电压： | -2V，-2.5 V ~ 6.1 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 供应商设备封装： | 10-µMAX |
| 包装： | 带卷 (TR) |
Low-Noise Bias Supply in μMAX
with Power-OK for GaAsFET PA
V CC FOR
V IN
OUT
TO PA
GATE BIAS
POWER AMPLIFIER
C3
0.22 μ F
MAX881R
C4
100k
C1
0.22 μ F
C1+
IN
OUT
C4
V OUT = -2V
POK
P
ON
C1-
MAX881R
4.7 μ F
TO
OFF
SHDN
POWER
AMPLIFIER
C2
NEGOUT
GND
FB
POK
Figure 2. Using the POK Function
Detailed Description
The MAX881R, a low-noise, inverting, regulated charge-
pump power supply, is designed for biasing GaAsFET
devices such as power-amplifier modules in cellular
handsets.
The applied input voltage (V IN ) is inverted to a negative
voltage at NEGOUT by a capacitive charge pump. This
0.22 μ F
Figure 3a. Standard Application Circuit for Minimum Capacitor
Values
V IN
C3
1 μ F
voltage is regulated by an internal linear regulator at
C1+
IN
OUT (Figure 1). With FB connected to GND, V OUT is
regulated at -2V. Alternatively, use a voltage-divider at
FB to adjust the output voltage between -0.5V and -(V IN
ON
C1
1 μ F
C1-
MAX881R
OUT
V OUT = -2V
C4
10 μ F
- 0.6V) (see the section Setting the Output Voltage ).
OFF
SHDN
The internal linear regulator reduces the ripple noise
induced by the charge-pump inverter to 1mVp-p at
OUT (circuit of Figure 3b). In addition, the excellent AC
C2
1 μ F
NEGOUT
GND
FB
POK
rejection of the linear regulator attenuates noise from
the incoming supply.
Power-OK Signal
The MAX881R has an active-low, open-drain, power-OK
( POK ) output. This output goes low when OUT reaches
92.5% of the regulated output voltage. POK can be
used to drive the gate of a P-MOSFET that switches
power to the GaAsFET power amplifier (Figure 2), there-
by ensuring that the power amplifier is not powered
before the required negative bias voltage is present.
Use a 50k ? or larger pull-up resistor to signal a logic
high when POK goes high impedance.
Shutdown Mode
The MAX881R features a shutdown mode that reduces
supply current to less than 1μA over temperature. SHDN
is an active-low, logic-level input. Start-up time coming
out of shutdown mode is typically 0.5ms. OUT and
NEGOUT are switched to GND in shutdown mode.
Figure 3b. Standard Application Circuit for Minimum Output
Noise
Applications Information
Setting the Output Voltage
Select either a fixed or adjustable output for the
MAX881R. Connect FB to GND for a fixed -2V output
(Figure 3). Select an alternative output voltage by con-
necting FB to the midpoint of a resistor-divider from
OUT to GND (Figure 4). When operating under full load
(4mA), the voltage at IN should be at least 0.6V higher
than the absolute voltage required at OUT. Note that
the minimum input voltage required for operation is
2.5V, regardless of the desired output voltage.
Choose R1 to be between 100k ? and 400k ? and cal-
culate R2. For greater accuracy, use resistors with 1%
or better tolerance.
R2 = R1 (2 x | V OUT | - 1)
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX881REUB-TG069 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX881REUB-TG074 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX881REUB-TG075 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8821ETI+ | 功能描述:LED照明驱动器 White LED Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX8821ETI+T | 功能描述:LED照明驱动器 White LED Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
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