Diodes ZNBG3116 - Manual (Page 11)

ZNBG3115
ZNBG3116
ISSUE 2 - JUNE 2006
11
ZNBG3115/16
Regulator
Single Universal LNB Block Diagram
The following block diagram shows the main section of an LNB designed for use with the Astra series of satellites.
The ZNBG3115/16 is the core bias and control element of this circuit. The ZNBG provides the negative rail, FET
bias control, polarisation switch control, tone detection and band switching with the minimum of external
components. Compared to other discrete component solutions the ZNBG circuit reduces component count and
overall size required.
APPLICATIONS INFORMATION(cont)
Tone detection and band switching is provided on the ZNBG3115/16 devices. The following diagrams describes
how this feature operates in an LNB and the external components required. The presence or absence of a 22kHz
tone applied to pin F
IN
enables one of two outputs, L
B
and H
B
. A tone present enables H
B
and tone absent enables
L
B
. The L
B
and H
B
outputs are designed to be compatible with both MMIC and discrete (bipolar or FET) local
oscillator applications, selected by pin L
OV
. Referring to Figure 1 wiring pin L
OV
to ground will force L
B
and H
B
to
switch between -2.6V (disabled) and 0V (enabled). Referring to Figures 2 and 3 wiring pin L
OV
to a positive voltage
source (e.g. a potential divider across V
CC
and ground set to the required oscillator supply voltage, V
OSC
) will
force the L
B
and H
B
outputs to provide the required oscillator supply, V
OSC
, when enabled and 0V when disabled.
Tone Detection Function
L
OV
F
IN
L
B
H
B
L
B
H
B
G
ND
22kHz Disabled Enabled -3 volts G
ND
— Enabled Disabled G
ND
-3 volts
V
OSC
22kHz Disabled Enabled Note 1 V
OSC
— Enabled Disabled V
OSC
Note 1
Note 1: 0 volts in typical LNB applications but ependent on extenal circuits.