CS3972 Datasheet | Cherry Semiconductor Corporation

Description The CS3972 is a 1.25A, 60V, current mode, high efficiency, switching regulator circuit. It can be configured in buck, boost, forward, isolated and non-isolated topologies, using a single-ended switch. The IC contains a 1.25A high efficiency output switch, precision bandgap reference, voltage regulator, error amplifier, oscillator, control, and protection circuitry. Output transistor efficiency is achieved by keeping the switch in quasi-saturation when it is on. This minimizes the switch turn-off delay time and power dissipation, an important consideration for applications with wide ranging loads. The precision reference is internally trimmed to 1.24V, while the oscillator frequency is internally trimmed to 40k Hz. The on board 2.3V regulator powers the internal circuitry. By keeping the voltage regulator at 2.3V, the IC is able to operate down to 3V and maintain a constant input supply current of 6m A(typ). Synchronization mode is achieved by applying a pulsating VC voltage of less than 0.2V with a duration of about 0.5µs to VC pin. The switching frequency can be adjusted from 50k Hz to 70k Hz. The IC's synchronization mode is set externally. Protection circuitry includes a variable current limit with external voltage clamp, under-voltage and over-temperature protection. Features s 75VMAX, 2APEAK Internal Switch s 3V to 60V Input Voltage Range s 6m A Input Supply Current s 1.24V Precision Reference s 40k Hz Switching Frequency s Variable Current Limit with External Voltage Clamp s Under-Voltage Protection s Over-Temperature Protection s External Synchronization Package Options Block Diagram NC VC VFB VSW VIN 2.3V Reg Output Protection 16L SO Wide Gnd NC E2 VSW NC E1 NC VIN NC NC NC 40k Hz OSC Logic Driver 1.25A, 75V Switch NC NC + VC P Gnd 1 8L PDIP E2 VSW E1 VIN 5L TO-220 Tab (Gnd) Error Amp + 1.24V Ref + Current Amp 0.22Ω 0.22Ω E2 - E1 - Gnd VFB NC 1 VC 2 VFB 3 Gnd 4 VSW 5 VIN 1 - Always connect E1 to Ground Pin on DIP package....