@Muse - This circuit implements a complete high-power ATX conversion architecture driven by an automotive or marine Lead-Acid/AGM battery bank ($11\text{ V}$ to $15\text{ V}$). It includes an independent, always-on **5VSB** rail, active-low **PS_ON** gating via power FET switching, and **interleaved multi-phase** stages on the high-demand rails.
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### Hardware ATX PS_ON Gating Architecture
In standard ATX specifications, main rails must remain fully unpowered until the motherboard pulls pin 16 (green wire) to ground:
1. **Always-On Standby Rail (#5VSB):**
- Fed directly from the unswitched battery bus #bat via high-efficiency buck stage #Qsb, #Dsb, #Lsb, and #Csb.
- Remains active at all times ($5\text{ V}$), powering the motherboard Super I/O / BMC power-management circuitry.
2. **Active-Low Control (#PSON):**
- Pull-up resistor #Rpu holds the control line to #5VSB when the PC is off.
- Switch #SW_ON simulates the motherboard's open-drain / open-collector pull-down transistor.
3. **Solid-State Power Disconnect (#Qmain):**
- When #SW_ON is open (#PSON $\approx 5\text{ V}$ high): Transistor #Qinv is off, pulling the gate node #g_en up toward battery voltage via the PNP junction. The main distribution switch #Qmain turns completely off, cutting the switched bus #bat_sw to $0\text{ V}$. All downstream converters (#12V, #5V, #3V3) stay completely powered down.
- When #SW_ON closes (#PSON grounded to $0\text{ V}$): Base-emitter current flows through #Qinv, driving pull-down resistor #Rpd and pulling #g_en low. This turns on power MOSFET #Qmain, energizing the internal rail #bat_sw to enable all primary converters.
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### Interleaved Multi-Phase Operation & Current Sharing
To deliver the high continuous output ratings ($1000\text{ W}$ on #12V, $500\text{ W}$ on #5V) while reducing thermal stress:
- **2-Phase Interleaved 12V Stage (#Q12_1, #Q12_2):**
- Driven by pulse generators #Vg12_1 and #Vg12_2 with a **$180^\circ$ phase shift** (`delay=50%`).
- Interleaving cuts the RMS ripple current in output filter capacitor #C12 dramatically and splits the $83\text{ A}+$ load across two parallel channels, cutting individual MOSFET conduction heating ($I^2 R$) by a factor of 4 per branch.
- **2-Phase Interleaved 5V Stage (#Q5_1, #L5_1 & #Q5_2, #L5_2):**
- Driven with alternating $180^\circ$ out-of-phase switching pulses (#Vg5_1, #Vg5_2).
- The interleaved inductor currents sum into output capacitor #C5, producing an effective ripple frequency of $100\text{ kHz}$ ($2 \times f_{\text{sw}}$). This minimizes ripple voltage on the $100\text{ A}$ rail while keeping individual inductor sizes compact.
- **Dedicated 3.3V Step-Down (#Q3, #L3, #C3):**
- Sized with a generous continuous current margin to deliver clean, quiet power to PCIe, memory terminations, and peripheral logic.
