One chip powers and controls low noise blocks

The LNBH21 a power supply and control IC for the low noise blocks (LNBs) used in set-top boxes and integrated digital televisions.

The LNBH21 a power supply and control IC for the low noise blocks (LNBs) used in set-top boxes and integrated digital televisions.

The LNBH21 includes a step-up voltage convertor that works from a single input voltage between 8 and 15V, simplifying system design.

The convertor is typically 94% efficient at a 750mA load.

The part also keeps the voltage drop on the internal linear regulator to a typical 2.2V, as compared with the 3.4V of previous models, reducing the power dissipation to 1.1W at 500mA load.

The part has an I2C interface and 22kHz tone signalling to provide a complete bidirectional interface between the LNB and the system that is controlling it.

This further simplifies design and makes the part suitable for energy-saving digital set-top box designs.

The fast startup of the oscillator enables DiSEqC encoding and the integrated tone detector supports bidirectional DiSEqC 2.0 signalling.

Two output pins can be used to bypass any output filters, to avoid tone distortion.

The part is compliant with both the Eutelsat and DirecTV output specification and offers digital compensation for cable length.

The part also offers LNB short-circuit and overtemperature protection, with diagnostic bits presented to the I2C interface.

It supports two output currents, of 450 and 750mA and has an ESD rating of 4kV on the power output pins.

US pricing is US $1.25 in quantities of 1000.

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