Ht48f06e Hopping Decoder

  
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The Supertex HV440 is used for implementing a pulse width modulated high voltage ring generator for telecommunication applications. The HV440 CAN operate in both closed-loop or open-loop. A closed-loop design is more complex but provides better load regulation and lower THD compared to an open-loop design. In this application note, a closed-loop d
Ht48f06e Hopping Decoder - schematic

esign is discussed. The output ring voltage is 62VRMS at 20Hz with load capabilities of 5 RENs and 20 RENs. The telephone must see a minimum of 40VRMS, otherwise ringing is not guaranteed. Ring generators are typically sinusoidal. Common ring frequencies are 20Hz and 25Hz. Telephone loads are rated in RENs (ring equivalent number). One North American REN is equivalent to 6930 in series with 8. 0 µF. For a given telephone line, the ring generator must be able to drive 5 RENs. The output MOSFETs integrated in the HV440 CAN drive up to 5 North American RENs. For applications requiring loads greater than 5 RENs, the HV440 CAN also drive external Supertex MOSFETs TP2522N8 and TN2524N8 for loads of up to 20 RENs. Complete schematics for a 5 REN and a 20 REN ring generator with their bill of materials CAN be found at the end of this application note. Sine Wave Reference A low Voltage Reference sine wave signal is required to generate the output ringer signal. A wien-bridge Oscillator was chosen to generate the reference sine wave as shown in Figure 2. The Wien-Bridge Oscillator was selected for its simplicity. Other ways of generating the reference sine wave are by using sine wave generator integrated circuits such as an Exar XR-2206 a Micro Linear ML2035, or a Philips PCD3311C.



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