ZLNB2016

ZLNB2016

Document number: DS32073 Rev. 1 - 2

2 of 7

www.diodes.com

February 2010

© Diodes Incorporated

A Product Line of

Diodes Incorporated

Device Description

The ZLNB2016 dual polarization and tone switch controller is

one of a wide range of satellite receiver LNB support circuits

available

from

Diodes

Incorporated.

It

features

two

completely independent channels, each providing logic

outputs to control LNB polarization selection, local oscillator

selection and down feed disable. It’s intended to be used in

voltage and tone controlled LNBs and satellite distribution

systems, replacing many discrete components to save both

manufacturing cost and PCB size whilst improving reliability.

The ZLNB2016 has been designed to be compatible in low

power consumption LNBs so to improve efficiency it

operates from a single supply of 3V to 8V and has a

quiescent current typically of only 2mA. The quiescent

current does not change significantly with load or logic state.

The two polarization control inputs of the ZLNB2016 have a

nominal threshold of 14.75V and the threshold is guaranteed

over the range of 14.0V to 15.5V. The threshold is

temperature compensated to minimize drift and it also has a

high rejection against the tone signal making the detector

very accurate without the need of further external filtering.

Each features a low and stable input current that enables

transient protection to be achieved with the addition of only a

single resistor per channel. Multi Feed LNBs can be called to

operate with one or more of their controlling receivers

powered down or disconnected, with attendant cable

mismatch problems.

To ease design for this situation, each polarization input of the

ZLNB2016 has a second threshold set at a nominal of 8V. An

input voltage below this threshold indicates “receiver not

present”, and switches the relevant Ena output low. This logic

output can be used to disable the associated down feed

driver, eliminating any problems due to cable mismatch.

Universal LNB local oscillator selection is achieved by

detection of a low level AC voltage superimposed on the

polarization control voltage. To facilitate this function, the

ZLNB2016 includes a separate tone detector for each

channel. Control of detector bandwidth and sensitivity is

provided using an external resistor and capacitor for each

channel. The tone detector has been designed give excellent

rejection of low frequency control signals and DiSEqC™ tone

bursts. The ZLNB2016 has been specifically designed to

minimize

the

solution

cost

whilst

being

flexible.

The

ZLNB2016 only requires two external components per

channel to give full user control and functionality. The

ZLNB2016 also includes complimentary outputs so that it can

directly drive many multiplexer ICs without the need of

inverters. Any unused outputs can be left open circuit without

any effect to the remaining circuits operation polarization

switch and tone detector outputs can directly drive TTL and

CMOS logic, pin diodes, IF-amp supply switching and

multiplexer ICs.