Roughy Calculation for innoswitch Device Ploss
2024年04月02日
Reference Parameters from RDR-1002
   • IPRMS = 1.142 A
   • RDS(ON) = 0.29 ohms
   • VDC.min = 255 V
   • VOR = 168 V
   • IPmax = 3.472 A
   • VDS.Vin_min = 666 V – (385 V – 255 V) = 536 V
   • FSW = 117.262 kHz ; FSWMAX = 180 kHz
   • Vshunt = 5.36 V
   • Assume Tf   20 ns




Inno5 Pro Power loss Calculation

   • Calculate the conduction loss of primary MOSFET
       Pcon ≈ IPRMS2 x RDS(ON) = 1.142 2 x 0.29 = 0.378 W

   • The INN5377C operation is DCM, the turn on voltage of Coss( Vcoss) is:
       VCoss ≈ VDC.min – VOR / 2 = 255 – 168 / 2 = 171 V

   • According to the Figure 41 from datasheet, the Coss loss of INN5377C
       Pcoss ≈ 2.6 * 60mW = 256 mW

   • The Switching loss compared with QR & SR-ZVS
       PswQR ≈ 1/6 x VDS.Vin_min x IPmax x Tf x FSW + Pcoss
             ≈ 1/6 x 536 x 3.472 x 20 ns x 117.262 kHz + 0.256 = 0.983 W

       PswSRZVS ≈ 1/6 x VDS.Vin_min x IPmax x Tf x FSW
             ≈ 1/6 x 536 x 3.472 x 20 ns x 117.262 kHz = 0.727 W
       SR-ZVS can save around 256mW Power Consumption

   • Controller Power Dissipation
       PIC ≈ PIC.Pri + PIC.Sec = Vshunt x [Is2 x (FSW / FSWMAX)] + VO * IVO
             ≈ 5.36 V x 5.16 mA x (117.262 kHz / 180 kHz) + 28 V x 8.2 mA x (117.262 kHz / 180 kHz)
                   = 0.018 W + 0.15 W = 0.167 W

   • Total inno5pro Device Roughy Power Dissipation
       Pinno5.SRZVS ≈ Pcon + PswSRZVS + PIC
                   = 0.378 W + 0.727 W + 0.167 W = 1.272 W