UCC2750,UCC3750,pdf(Source Rin

The UCC3750 Source Ringer Controller provides a complete control and drive solution for a four quadrant flyback-based ring generator circuit. The IC controls a primary side switch, which is modulated when power transfer is taking place from input to output. It also controls two secondary switches which act as synchronous rectifier switches during positive power flow. These switches are pulse-width-modulated when the power is being delivered back to the source.

The UCC3750 has an onboard sine wave reference with programmable frequencies of 20Hz, 25Hz and 50Hz. The reference is derived from a high-frequency (32kHz) crystal connected externally. Two frequency-select pins control an internal divider to give a sinusoidal output at 20Hz, 25Hz or 50Hz.