High-side IGBTs require a gate voltage referenced to their emitter (the phase output), which floats up and down. The schematic top shows this clever trick:
Without these components, the high-side switches will not turn on. The schematic top often uses dashed lines to indicate that these capacitors must be supplied externally.
AC Input -- Fuse -- NTC -- CM Choke -- X-Cap -- Bridge Rectifier (+) --- HV Startup Resistor --- Bulk Cap (+) ------> Transformer T1 primary start | | +-----> PS42419HA Pin 1 (D/ST) | | Transformer T1 auxiliary winding --> Diode --> VCC Cap (+) --- PS42419HA Pin 2 (VCC) | +-----> Zener OVPPS42419HA Pin 6 (FB) <---- Optocoupler Transistor Collector | | GND Optocoupler LED cathode ---- TL431 Cathode TL431 Ref ---- Resistor Divider from Output (+) TL431 Anode ---- GND (secondary) PS42419HA Pin 5 (CS) --- RC Filter --- Current Sense Resistor --- MOSFET Source PS42419HA Pin 4 (OUT) --- Gate Resistor --- MOSFET Gate MOSFET Drain --- Transformer T1 primary end
Transformer T1 secondary --- Schottky Diode --- Output Capacitor --- Vout (+) | GND (secondary)
Connect the rectified mains output (e.g., from a diode bridge + 450V electrolytic capacitor) across P and N. Ensure the capacitor is rated for at least 400V and has low ESR.
When you open the datasheet for the PS42419HA, the “Top Schematic” usually reveals six distinct functional blocks. Let’s break them down.