UCC2750 Datasheet | Unitrode

FEATURES - Provides Control for Flyback Based Four Quadrant Amplifier Topology - Onboard Sine Wave Reference with Low THD - Selectable Ringing Frequency for Different Phone Systems (20Hz, 25Hz and 50Hz) - Programmable Output Amplitude and DC Offset - DC Current Limiting for Short Circuit Protection - Secondary Side Voltage Mode Control - Operates from a Single 5V Supply TYPICAL APPLICATION DESCRIPTION The UCC3750 Source Ringer Controller provides a plete 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 (32k Hz) crystal connected externally. Two frequency-select pins control an internal divider to give a sinusoidal output at 20Hz, 25Hz or 50Hz. The ring generator can also be used at other frequencies by supplying externally generated sine-waves to the chip or by clocking the crystal input at a fixed multiple of the desired frequency. Other features included in the UCC3750 are programmable DC current limit (with buffer amplifier), a charge-pump circuit for gate drive voltage, internal 3V and 7.5V references, a triangular clock oscillator and a buffer amplifier for adding programmable DC offset to the output voltage. The UCC3750 also provides an unmitted amplifier (AMP) for other signal processing requirements. VOUT 0V - 48V VIN 48V 28 26 27 25 GD2 GD3 ENBL REF 2 GD1 24 RT UCC3750 VCP VS 2 4 6 23 CT VS 1 5 1 RGOOD VDD 7 11 OUTDC 12 NEGDC OUT2 15 13 AMP OUT 14 AMP IN 22 XTAL1 NEG2 18 OUT1 16 21 XTAL2 20 FS0 19 FS1 S INREF 9 NEG1 17 S INFLT 10 S WRLY GND...