ZLNB2013
DUAL TONE AND POLARITY SWITCH LNB MULTIPLEX CONTROLLER
DESCRIPTION
The ZLNB2013 dual polarization 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 polarization selection,
local oscillator selection and down feed 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 polarization control inputs of the ZLNB2013
have a threshold voltage of 14.75V to meet the
switching requirement of 14.0V to 15.5V. To minimize
drift both thresholds are temperature compensated.
Each features a low and stable input current that
enables threshold trimming and 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
polarization input of the ZLNB2013 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 down feed
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 polarization control voltage. To facilitate this
function, the ZLNB2013 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 to give excellent rejection
of low frequency control signals and DiSEqC™ tone
bursts.
The ZLNB2013 has been specifically designed to
minimize the solution cost whilst being flexible. The
ZLNB2013 only requires two external components per
channel to give full user control and functionality. The
ZLNB2013 also includes complimentary outputs so
that it can directly drive many multiplexer ICs without
the need of an inverter. Any unused outputs can be left
open circuit without any effect to the remaining
circuits. Polarization switch and tone detector outputs
can directly drive TTL and CMOS logic, pin diodes,
IF-amp supply switching and multiplexer ICs.
The ZLNB2013 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 polarization and tone switch
•
Temperature compensated polarization switches
•
Reduced cost solution, only 2 external components
per channel
•
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™ control signals
rejection
•
Eliminates many close tolerance discrete
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
ISSUE 1 - AUGUST 2005
1
ZETEX [ ZETEX SEMICONDUCTORS ]
