ZLNB2012
DUAL TONE AND POLARITY SWITCH
LNB MULTIPLEX CONTROLLER
DEVICE DESCRIPTION
The ZLNB2012 dual polarisation and tone switch
controller is one of a wide range of satellite receiver
LNB support circuits available from Zetex. It features
two completely independent channels, each providing
logic outputs to control LNB polarisation selection,
local oscillator selection and downfeed disable. It is
intended for use in Twin, Quad and multiple feed
Universal LNBs, replacing many discrete components
to save both manufacturing cost and PCB size whilst
improving reliability.
The two highly accurate polarisation control inputs of
the ZLNB2012 have a nominal threshold of 14.25V and
to meet the required demanding needs from some
broadcasters they have a switching range of 14.0V to
14.5V. The threshold is temperature compensated to
minimise drift. 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/disconnected, with attendant cable mismatch
problems. To ease design for this situation, each
polarisation input of the ZLNB2012 has a second
threshold set at 9V. An input voltage below this
threshold indicates“ receiver not present”, and
switches the relevant control channels high. This logic
output can be used to disable the associated downfeed
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 polarisation control voltage. To facilitate this
function, the ZLNB2012 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 ZLNB2012 has been specifically designed to
minimise the solution cost whilst being flexible. The
ZLNB2012 only requires two external components per
channel to give full user control and functionality. The
ZLNB2012 also includes complimentary outputs so
that it can directly drive many multiplexer IC’s without
the need of an inverter. Any unused outputs can be left
open circuit without any effect to the remaining circuits
operation Polarisation switch and tone detector
outputs can directly drive TTL and CMOS logic, pin
diodes, IF-amp supply switching and multiplexer IC’s.
The ZLNB2012 operates from a single supply which
can be anything from 5-8V. Its quiescent current is
typically only 9mA and this does not change
significantly with load or logic state. It is available in the
space saving QSOP16 surface mount package.
FEATURES
·
Dual polarisation and tone switch
·
Reduced Cost Solution, only 2 external components
per channel
·
Close tolerance (14-14.5V) and temperature
compensated polarisation switch
·
Multiplexer IC direct drive
·
Tone and pol. Outputs are TTL, CMOS, Pin diode and
IF amp capable
·
Transient resistant inputs
·
Includes Receiver-Off detector
·
User adjustable filter centre frequency and
bandwidth
·
Low frequency and DiSEqC
rejection
control signals
·
E lim in a t e s m an y c l o s e t o l e r an ce d i scr et e
components
·
Wide supply operating range
·
Low quiescent current
APPLICATIONS
·
Twin Universal LNB’s
·
Quad Universal LNB’s
·
Multi Feed Universal LNB’s
·
LNB switch boxes
PROVISIONAL ISSUE A - OCTOBER 2001
1
ZLNB2012
ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):
T
amb= 25 C,VCC
=5V
SYMBOL
PARAMETER
CONDITIONS
Min
TD 1,2 Outputs
V
VHIGH
V
VLOW
Voltage high
Voltage Low
BTD 1,2 Outputs
V
VHIGH
V
VLOW
Voltage high
Voltage Low
IBTD 1,2=-100 A, Test Circuit 1,
Tone disabled
IBTD 1,2=15mA, Test Circuit 1,
Tone enabled
V
CC
-1.0 V
CC
-0.7
0
0.3
V
CC
0.5
V
V
ITD 1,2=-100 A, Test Circuit 1,
Tone enabled
ITD 1,2=15mA, Test Circuit 1,
Tone disabled
V
CC
-1.0 V
CC
-0.7
0
0.3
V
CC
0.5
V
V
LIMITS
Typ
Max
UNITS
Note:-
1) The parameters Filter Amplifier V
OUT
, I
OUT
, Rectifier V
OUT
and Comparator Threshold Voltage are all directly (linearly)
related to Vcc.
2) Applied via 1k resistors
3) These parameters are linear related to V
CC
PROVISIONAL ISSUE A - OCTOBER 2001
3
ZLNB2012
The following diagram shows a typical block diagram
for a twin universal LNB design. The ZLNB2012 device
provides the two polarity and two tone switches
required to decode the two independent receiver
feeds. The device is also able to detect the absence of a
revceiver connection to either port of the LNB
providing all outputs to go high hence disabling of the
port. This allows the avoidance of unwanted signal
reflections from an unterminated down feed cable.
Additionally the front end bias requirements of the LNB
are provided by the ZNBG4000 or ZNBG6000 offering a
very efficient and cost effective solution
Horizontal
Gain Stage
GaAs/HEMTFET
Antenna
High Band
Control Input
<=13V-Horizontal
>=14.5V-Vertical
DC Input
13-25V
High Band
Horizontal
Low Band
Horizontal
H/V Output 1
+
Mixer
1
3
+
Low Band
Low Band
High Band
+
2
High Band
ASTRA
10.95 GHz-11.7 GHz
Standard Band
10.7 GHz-11.8 GHz
Enhanced Band
Bias Generator
ZNBG40XX
Series
ZLNB2012 Series
Dual H/V Switch
&
22kHz Switch
Control
PIN
Diode
MUX
IF down feed
950-1750 MHz
- Standard Band
950-2050 MHz
- Enhanced Band
High Band
Vertical
Low Band
Vertical
4
H/V Output 2
Mixer
Vertical
Antenna
Gain Stage
GaAs/HEMTFET
+
Low Band
PROVISIONAL ISSUE A - OCTOBER 2001
5
Power technology
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