znbg3115 Zetex Semiconductors plc., znbg3115 Datasheet - Page 8

• Manufacturer Part Number: znbg3115
• Description: Znbg3115 - Fet Bias Controller With Polarization Switch And Tone Detection
• Manufacturer: Zetex Semiconductors plc.

The following schematic shows the function of the V
Q2 are powered at any one time, their selection is controlled by the input V
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; this is done internally in the QSOP16 version. FET number Q3 is
always active regardless of the voltage applied to V
QSOP 20 Version
Control Input Switch Function
Input Sense
ZNBG3115
ZNBG3116
15.5 volts
14 volts
Polarisation
Vertical
Horizontal
Select
FET Q2
FET Q1
POL
POL
input. Only one of the two external FETs numberd Q1 and
8
.
POL
. This input is designed to be wired
ISSUE 2 - JUNE 2006