Low noise block regulators for STBs and LCD TVs

30th December 2013

Nat Bowers

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Expanding the company's extensive portfolio of low noise block (LNB) regulators designed for satellite receivers in Set Top Boxes and LCD TVs, Allegro Microsystems has introduced the A8300 and A8300-1. Fully integrated linear and switching voltage regulators, they are specifically designed to provide the power and interface signals to an LNB down-converter via coaxial cable.

Both operating over a temperature range from -20 to 85°C, the A8300 is optimised for low-profile ceramic boost capacitors, while the A8300-1 is designed for use with lower cost electrolytic capacitors. With the 563 kHz switching frequency chosen to minimise the size of the passive filtering components, the devices require few external components, featuring the boost switch and compensation circuitry integrated inside of the devices.

The ICs are suitable for DiSEqC communication, providing an internal 22kHz tone that is gated with a control pin, or accepting an external 22kHz through this same pin. The regulators feature integrated tone detection capability for full two-way DiSEqC communications, and an integrated gate drive for the filter bypass FET. The I²C compatible interface provides control capabilities for complex system requirements, as well as diagnostic capabilities for system fault reporting.

It is possible to maximise power savings and quickly shut down the device if required, without using I²C control, thanks to a "sleep" pin. The A8300 and A8300-1 regulators also offer an early power failure function in order to help verify the status of the 12V rail as well as initiate shutdown routines.Supplied in a 4×4 mm, 24-contact, lead-free QFN package, with 100% matte tin plated leadframe, Allegro's A8300 and A8300-1 are available now.