DIODES ZLNB254DEETA

The ZLNB254 is a dual DiSEqC tone detector IC for multi-output LNBs, satellite distribution systems, set-top boxes, and DiSEqC peripherals. Although designed to process 22kHz DiSEqC signals, the ZLNB254 can operate across a frequency range of 10kHz to 60kHz, enabling detection of standard 22kHz satellite band control signals as well as regional variants used in markets such as Japan.

This two-channel tone filter and fast envelope detector requires minimal external components. The ZLNB254 is particularly suited for DiSEqC signal detection applications involving low signal levels and high distortion.

The ZLNB254 incorporates the necessary circuitry to detect the presence of a 22kHz tone on the input of an LNB or switch box. When a valid tone or DiSEqC signal is detected at the FIN input, the TD output is pulled low.

To maximize system flexibility, gain and filter lower cutoff frequency can be controlled per channel using a single external resistor and capacitor. The filter upper cutoff frequency is set internally to above 60kHz. No other external components are required for the remaining detection circuitry.

The tone detector can be used to detect continuous tones or coded tone bursts, such as those used in DiSEqC and similar control systems. To ensure system reliability, the tone detector can reject unwanted signals such as transients from other parts of the LNB system without requiring any external components.

The TD output is designed to be compatible with LSTTL and CMOS loads, enabling direct drive of microcontrollers or other logic circuits.

For additional protection, the resistor used to set the filter gain also provides ESD protection.

The ZLNB254 offers a compact, simple solution in a TDFN2020-6 SMT package.

• DiSEqC-controlled LNBs
• Satellite distribution systems
• Monolithic LNB DiSEqC actuators
• Set-top boxes
• Satellite test equipment
• AC satellite control signal detection