znbg3110 Zetex Semiconductors plc., znbg3110 Datasheet - Page 9

• Manufacturer Part Number: znbg3110
• Description: Fet Bias Controller With Polarisation Switch And Tone Detection
• Manufacturer: Zetex Semiconductors plc.

The following schematic shows the function of the V
numberd Q1 and Q2 are powered at any one time, their selection is controlled by the input V
This input is designed to be wired to the power input of the LNB via a high value (10k) resistor.
With the input voltage of the LNB set at or below 14V, FET Q2 will be enabled. With the input
voltage at or above 15.5V, FET Q1 will be enabled. The disabled FET has its gate driven low and
its drain terminal is switched open circuit. It is permissible to connect the drain pins D1 and D2
together if required by the application circuit. FET number Q3 is always active regardless of the
voltage applied to V
Control Input Switch Function
Input Sense
14 volts
15.5 volts
Polarisation
Vertical
Horizontal
POL
.
Select
FET Q2
FET Q1
4-131
POL
input. Only one of the two external FETs
ZNBG3110
ZNBG3111
POL
.