ZLNB2003Q16 View Datasheet(PDF) - Zetex => Diodes

Part Name

Description

Manufacturer

ZLNB2003Q16

DUAL TONE and POLARITY SWITCH LNB MULTIPLEX CONTROLLER

Zetex => Diodes 

ZLNB2001 ZLNB2002

ZLNB2003 ZLNB2004

FURTHER INFORMATION

1) Inputs VPOL1 and VPOL2 are designed to be

wired to the power inputs of an LNB via

high value (10k) resistors. Input VPOL1

controls outputs HVout1 and Enable1.

Input VPOL2 controls outputs HVout2 and

Enable2. With either input voltage set at

or below 14V, the corresponding HVout

pin will be in active. With either input

voltage at or above 15.5V, the

corresponding HVout pin will be active.

Should the voltage applied to either VPOL

input fall below 8V, the corresponding

Enable pin will be low, otherwise these

outputs will be high.Any input or output

not required may be left open-circuit.

2) The ZLNB2001/2 includes the circuitry

necessary to detect the presence of 22kHz

tones modulated on either of two supply

inputs to the lnb. The main elements of

the detectors in each channel are an

op-amp enabling the construction of a

Sallen Key filter, a rectifier/smoother and

a comparator. Full user control is given

over the centre frequency and bandwidth

of the filter using two external resistors

and capacitors (one of these resistors

shares the function of overvoltage

protection of the corresponding VPOL pin,

i.e. the 10k referenced in note 1). The

comparator circuit utilises no external

components. The presence of a 22kHz

tone applied to pin Fin1 or Fin2 switches

the corresponding output Tout1 or Tout2

high.

3) The ZLNB2003 / 4 includes the circuitry

necessary to detect the presence of 22kHz

tones modulated on either of two supply

inputs to the LNB. The main elements of

the detectors in each channel are an

op-amp enabling the construction of a

Sallen Key filter, a rectifier/smoother and

a comparator. Full user control is given

over the centre frequency and bandwidth

of the filter using two external resistors

and capacitors (one of these resistors

shares the function of overvoltage

protection of the corresponding Vpol pin,

i.e. the 10k referenced in note 1). The

comparator circuit utilises no external

components. The presence of a 22kHz

tone applied to pin Fin1 or Fin2 switches

the corresponding output Tout1 or Tout2

high. Pins Crec1 and Crec2 make

accessible the outputs of the tone switch

rectifiers and provides a means of

controlling tone switch delays.

Significant switching delays may be

necessary to avoid incorrect operation in

the presence of unwanted interference

(e.g. switching tones intended for other

signalling systems). For correct

operation of the IC, a capacitor and a

parallel connected resistor should be

connected between each Crec pin and

ground. The Tout low to high delays are

set solely by the added capacitors at

approximately 22ms/uF. The high to low

delays are set by the time constant of

each resistor capacitor combination at

approximately 0.2CR seconds. A

capacitor of 100nF and resistor of 1MW

will give a low to high delay of around

2.2ms and a high to low delay of 20ms,

providing immunity to the 60Hz square

wave signal occasionally used for

switching between multiple LNB units.

87

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