Switch Controller 16-Pin QSOP T/R

The ZLNB200X 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 Universal LNBs, replacing many discrete components to save both manufacturing cost and PCB size whilst improving reliability.The two polarization control inputs of the ZLNB200X have a nominal threshold of 14.75V. The threshold is temperature compensated to minimize 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.Twin Universal LNBs can be called to operate with one of their controlling receivers powered down/disconnected, with attendant cable mismatch problems. To ease design for this situation, each polarization input of the ZLNB200X has a second threshold set at 9.5V. An input voltage below this threshold indicates "receiver not present", switching the channels Enable pin low. 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 ZLNB200X includes a separate tone detector for each channel. Full control of detector bandwidth and sensitivity is provided using two external resistors and capacitors. In the ZLNB2003/4, additional control of tone switch delays is provided to assist with the rejection of low frequency control signals intended for other systems.Polarization switch and tone detector outputs can source and sink 10mA making them suitable to drive TTL and CMOS logic, pin diodes and for IF-amp supply switching.The ZLNB200X operates from a single supply which can be anything from 5-10V. Its quiescent current is typically only 6mA and this does not change significantly with load or logic state. It is available in the space saving QSOP16 surface mount package.

• Dual polarization switch
• Temperature compensated polarization switch threshold
• Transient resistant inputs
• Includes Receiver-Off detector
• Dual tone switch
• User adjustable filter center frequency and bandwidth
• User adjustable tone switching delays (ZLNB2003/4only)
• Tone and pol.outputs TTL, CMOS, Pin diode and IF amp capable
• Receiver-Off detector TTL and CMOS compatible
• Wide supply operating range
• Low quiescent current
• Few external components
• Eliminates many discrete components