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低噪声、稳压型、-2V GaAsFET偏置电源

可使用小电容工作,低至0.22µF

产品详情

主要特征

应用/用途

Parametric specs for Charge Pumps
Topology Inverter
Regulated
VIN (V) (min) 2.5
VIN (V) (max) 10
IOUT (A) (typ) 0.01
Unadj. VOUT (V) -2
Adj. VOUT (V) (min) -VIN-0.6
Adj. VOUT (V) (max) -0.5
ICC (mA) (max) 1.3
Switching Frequency (kHz) 100
Oper. Temp. (°C) -40 to +85
-20 to +85
Package/Pins SOIC (N)/8
Budgetary
Price (See Notes)
1.84
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参量

Parametric specs for Charge Pumps
Topology Inverter
Regulated
VIN (V) (min) 2.5
VIN (V) (max) 10
IOUT (A) (typ) 0.01
Unadj. VOUT (V) -2
Adj. VOUT (V) (min) -VIN-0.6
Adj. VOUT (V) (max) -0.5
ICC (mA) (max) 1.3
Switching Frequency (kHz) 100
Oper. Temp. (°C) -40 to +85
-20 to +85
Package/Pins SOIC (N)/8
Budgetary
Price (See Notes)
1.84

主要特征

  • Fixed -2V or Adjustable -0.5V to -9.4V Output at 4mA (MAX840)
  • 2.5V to 10V Input Voltage Range
  • Operate with Small Capacitors (as low as 0.22µF)
  • 1mVp-p Output Voltage Ripple
  • Charge-Pump Switching Frequency:
    • 100kHz in Normal Operation
    • 20kHz in Shutdown Mode (MAX844)
  • 1µA Max Logic-Level Shutdown Over Temp. (MAX840/MAX843)
  • Small 8-Pin SO Package

应用/用途

  • 蜂窝电话
  • 连续可调的GaAsFET偏置
  • GaAsFET功率放大器模块
  • LCD偏置对比度控制
  • 个人通信装置、PDA
  • 稳定的负电源
  • 无线数据记录仪

描述

The MAX840/MAX843/MAX844 low-noise, inverting charge-pump power supplies are ideal for biasing GaAsFETs in cellular telephone transmitter amplifiers. They operate with inputs down to 2.5V.

The MAX840 offers both a -2V preset output and a -0.5V to -9.4V adjustable output. The MAX843/MAX844 use an external positive control voltage to set the negative output voltage. Input voltage range for all the devices is 2.5V to 10V, and output current is 4mA with VIN > 2.7V. These circuits can operate with small capacitors, as low as 0.22µF.

An internal linear regulator reduces the MAX840's output voltage ripple to 1mVp-p. With a well-filtered control voltage (VCTRL), the MAX843/MAX844 also achieve less than 1mVp-p typical output ripple. Supply current is 750µA, and reduces to less than 1µA in shutdown (MAX840/MAX843). The MAX844's unregulated output is active in shutdown, with the charge pump switching at 20kHz. It provides a low-power LCD supply.

简化框图

MAX840、MAX843、MAX844:典型工作电路 MAX840、MAX843、MAX844:典型工作电路 Zoom icon

技术文档

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