A8294: Single LNB Supply and Control Voltage Regulator


Intended for analog and digital satellite receivers, this single low noise block converter regulator (LNBR) is a monolithic linear and switching voltage regulator, specifically designed to provide the power and the interface signals to an LNB down converter via coaxial cable. The A8294 requires few external components, with the boost switch and compensation circuitry integrated inside of the device. A high switching frequency is chosen to minimize the size of the passive filtering components, further assisting in cost reduction. The high levels of component integration ensure extremely low noise and ripple figures.

The A8294 has been designed for high efficiency, utilizing the Allegro® advanced BCD process. The integrated boost switch has been optimized to minimize both switching and static losses. To further enhance efficiency, the voltage drop across the tracking regulator has been minimized.

For DiSEqC™ communications, several schemes are available for generating tone signals, all the way down to no-load, and using either the internal clock or an external time source.

A comprehensive set of fault registers are provided, which comply with all the common standards, including: overcurrent, thermal shutdown, undervoltage, and power not good.

The device uses a 2-wire bidirectional serial interface, compatible with the I2C™ standard, that operates up to 400 kHz.

The A8294 is supplied in a lead (Pb) free MLP/QFN package, ES, 20-contact, 4 mm × 4 mm, 0.75 nominal overall height.

This device is no longer in production. The device should not be purchased for new design applications. Samples are no longer available.
Date of status change: June 5, 2017

Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to the generation 4 and 5 devices.

Top Features

  • 2-wire serial I2C™ -compatible interface: control (write) and status (read)
  • LNB voltages (6 programmable levels) compatible with all common standards
  • Tracking switch-mode power converter for lowest dissipation
  • Integrated converter switches and current sensing
  • Provides up to 700 mA continuous load current
  • Output current limit of 800 mA minimum, with 48 ms timer
  • Static current limit circuit allows full current at startup and 13→18 V output transition; reliably starts wide load range
  • Push-pull output stage minimizes 13→18 V and 18→13 V output transition times for highly capacitive loads
  • Adjustable rise/fall time via external timing capacitor
  • Built-in tone oscillator, factory-trimmed to 22 kHz facilitates
  • DiSEqC™ tone encoding, even at no-load
  • Two methods of 22 kHz tone generation, including outgoing tone verification (TDET)
  • Auxiliary modulation input
  • LNB overcurrent with timer
  • Diagnostics for output voltage level, input supply UVLO, and DiSEqCTM tone output

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
A8294SESTR-T 20-lead QFN -20°C to 85°C Yes View Data Discontinued Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.