STEVAL-ISA126V1

STEVAL-ISA126V1 5 V-2 A, 115 kHz flyback with temporary extra-power management based on the VIPER28HN Data brief Description This document describes a 5 V-2 A application with 3.3 A peak current capability for 1.9 sec, using VIPer28H, a new off-line high voltage converter from STMicroelectronics. In some applications an SMPS, normally supposed to deliver a certain amount of power, from time to time undergoes load peaks that can be even two or more times as much, but only for a time interval which is short if compared to the Features thermal time constants of the power components. Typical examples of such loads are printers and Input Voltage range: 90 V to 265 V RMS RMS audio systems. Output Voltage: 5 V In these cases, it is more cost-effective to Max Output Current: I 2 A OUTmax thermally design the system for the maximum Peak Output Current: I 3 A OUTpk continuous power and not for the peak power Precision of output regulation: V 5% OUT LF demand, which will be sustained only for a limited High Frequency output Voltage ripple: time window. V 50 mV OUT HF Max ambient operating temperature: TA 60 Such a design is possible thanks to the EPT C function of VIPER28H, which allows the designer 800 V avalanche rugged power section to fix the maximum time window during which the PWM operation , at 115 kHz with frequency converter is able to manage the peak power still jittering for lower EMI maintaining output voltage regulation. If the Limiting current with adjustable set point overload lasts more than this time window, the converter is automatically shut down in auto- On-board soft-start restart mode, in order to avoid the damaging of Safe auto-restart after a fault condition, low the power components. stand-by power (< 50 mW at 265 Vac) Adjustable and accurate over voltage protection, thermal shutdown with hysteresis, delayed overload protection RoHS compliant December 2013 DocID025423 Rev 1 1/4 www.st.com For further information contact your local STMicroelectronics sales office Schematic circuit STEVAL-ISA126V1 1 Schematic circuit 1.1 Schematic circuit Figure 1: Schematic circuit 2/4 DocID025423 Rev 1 t -+