LNBP20 / LNBP1X series

Description (continued)

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Description (continued)

For slave operation in single dish, dual receiver systems, the bypass function is

implemented by an electronic switch between the Master Input pin (MI) and the LNBA pin,

thus leaving all LNB powering and control functions to the Master Receiver. This electronic

switch is closed when the device is powered and EN pin is LOW.

The regulator outputs can be logic controlled to be 13 or 18 V (typ.) by mean of the VSEL

pin for remote controlling of LNBs. Additionally, it is possible to increment by 1V (typ.) the

selected voltage value to compensate the excess voltage drop along the coaxial cable (LLC

pin HIGH).

In order to reduce the power dissipation of the device when the lowest output voltage is

respectively at 16V (min) and 23V (min), and an internal switch automatically will select the

suitable supply pin according to the selected output voltage. If adequate heatsink is

provided and higher power losses are acceptable, both supply pins can be powered by the

same 23V source without affecting any other circuit performance.

The ENT (Tone Enable) pin activates the internal oscillator so that the DC output is

modulated by a ±0.3 V, 22KHz (typ.) square wave. This internal oscillator is factory trimmed

within a tolerance of ±2KHz, thus no further adjustments neither external components are

required.

A burst coding of the 22KHz tone can be accomplished thanks to the fast response of the

ENT input and the prompt oscillator start-up. This helps designers who want to implement

In order to improve design flexibility and to allow implementation of newcoming LNB remote

control standards, an analogic modulation input pin is available (EXTM). An appropriate DC

blocking capacitor must be used to couple the modulating signal source to the EXTM pin.

When external modulation is not used, the relevant pin can be left open.

Two pins are dedicated to the overcurrent protection/monitoring: CEXT and OLF. The

overcurrent protection circuit works dynamically: as soon as an overload is detected in

connected between CEXT and GND. Simultaneously the OLF pin, that is an open collector

diagnostic output flag, from HIGH IMPEDANCE state goes LOW.

in HIGH IMPEDANCE. If the overload is still present, the protection circuit will cycle again

4.7µF external capacitor is used.

This dynamic operation can greatly reduce the power dissipation in short circuit condition,

still ensuring excellent power-on start up even with highly capacitive loads on LNB outputs.

The device is packaged in PowerSO-20 for surface mounting. When a limited functionality in

a smaller package matches design needs, a range of cost-effective PowerSO-10 solutions

is also offered. All versions have built-in thermal protection against overheating damage.