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Low-Noise Bias Supply in µMAX with Power OK for GaAsFET PA

1mVP-P Output Voltage Ripple

Product Details

Key Features

Parametric specs for Charge Pumps
Topology Inverter
Regulated
VIN (V) (min) 2.5
VIN (V) (max) 5.5
IOUT (A) (typ) 0.01
Unadj. VOUT (V) -2
Adj. VOUT (V) (min) -VIN-0.6
Adj. VOUT (V) (max) -0.5
IQ (mA) (max) 0.95
Switching Frequency (kHz) 100
Oper. Temp. (°C) -40 to +85
Package/Pins UMAX/10
Budgetary
Price (See Notes)
2.14
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Simplified Block Diagram

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Parameters

Parametric specs for Charge Pumps
Topology Inverter
Regulated
VIN (V) (min) 2.5
VIN (V) (max) 5.5
IOUT (A) (typ) 0.01
Unadj. VOUT (V) -2
Adj. VOUT (V) (min) -VIN-0.6
Adj. VOUT (V) (max) -0.5
IQ (mA) (max) 0.95
Switching Frequency (kHz) 100
Oper. Temp. (°C) -40 to +85
Package/Pins UMAX/10
Budgetary
Price (See Notes)
2.14

Key Features

  • Small µMAX Package
  • 1mVP-P Output Voltage Ripple and Noise
  • Power-OK Signal to Control GaAsFET Drain Switch
  • 0.05µA Logic-Controlled Shutdown
  • 1ms Guaranteed Startup
  • 2.5V to 5.5V Input
  • -0.5V to (-VIN + 0.6V) Output at up to 4mA
  • Operates with One 4.7µF and Three 0.22µF Capacitors (no inductors needed)

Applications/Uses

  • Cell Phones Wireless Modems
  • PCS Phones Two-Way Pagers
  • PHS Phones Mobile Radios
  • Wireless Handsets Wireless Computers

Description

The MAX881R low-noise, inverting power supply is designed for biasing GaAsFET power amplifiers in portable wireless applications. This device is a chargepump inverter followed by a negative linear regulator. The input voltage range is 2.5V to 5.5V. The output is preset at -2.0V or can be set, using two resistors, to any voltage from -0.5V to (-VIN + 0.6V). It can deliver up to 4mA. The internal linear regulator also filters the output to 1mVP-P ripple and noise.

Other features include a power-OK (active-low POK) output that signals when the negative voltage is within 7.5% of its set point. It protects the GaAsFET by not allowing power to be applied to the GaAsFET's drain until it is properly biased. The signal can be routed either to a microcontroller or directly to a switch at the GaAsFET drain. The MAX881R is available in a 10-pin µMAX® package.

Simplified Block Diagram

MAX881R: Typical Operating Circuit MAX881R: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .