S36012 Power Supply Circuit Diagram Link

Understanding the S36012 Power Supply Circuit Diagram

The S36012 is a widely recognized model in the realm of switched-mode power supplies (SMPS), typically found in industrial equipment, LED displays, CCTV systems, and 3D printers. It is a single-output, enclosed power supply known for delivering 12V DC at high current (often up to 30A). Understanding its circuit diagram is crucial for troubleshooting, repair, or custom integration.

Below is a breakdown of the key stages typically found in the S36012 schematic.

A. Input Protection & Filtering

At the entry point of the circuit, you will find the Fuse (F1), usually rated around 3.15A or 4A. Immediately following the fuse are NTC Thermistors (to limit inrush current) and X/Y Capacitors forming the EMI filter. If the fuse is blown, it indicates a catastrophic short circuit, usually in the next stage. s36012 power supply circuit diagram

3. Convert to Constant Current Source

Add a 0.01Ω shunt on the low side. Feed its amplified signal (via LM358) into a comparator that pulls the FB pin low when current exceeds the setpoint. This overrides the voltage loop.

2. Key Sections of the Circuit Diagram

Below is a breakdown of the critical stages you will find in a schematic diagram of the S36012 board. Understanding the S36012 Power Supply Circuit Diagram The

3. Detailed Circuit Diagram Analysis (Section by Section)

Let’s break down the schematic into functional blocks.

DIY Modifications Based on the S36012 Circuit Diagram

Once you master the S36012 power supply circuit diagram, you can modify it: Increase Output Voltage to 48V: Requires changing the

  1. Increase Output Voltage to 48V: Requires changing the input capacitor voltage rating, the feedback divider, and ensuring the MOSFET Vds rating > 60V.
  2. Add a Digital Voltmeter (DVM): Tap the output terminals through a voltage divider to a cheap 3-wire DVM module.
  3. Convert to a Battery Charger: Add a second op-amp circuit to latch the output when the charge current drops below a threshold.

Section D: Secondary Rectification & LC Filter

  • Diodes: Two parallel pairs of MBR20100CT (20A, 100V Schottky). Total capacity ~40A.
  • LC Filter: The output of the diodes is a 60kHz pulsating DC. This goes through:
    • L1: A toroidal choke (yellow-white core, ~50µH) – blocks high-frequency ripple.
    • C19, C20: 2200µF/16V low-ESR electrolytics – smooth the DC.
    • Small ceramic caps (0.1µF): Shunt remaining high-frequency noise.
  • Result: Clean 12V DC with <150mV ripple.

Stage 2: The Switching Power Stage (Buck Converter)

This is the power train of the S36012.

  • High-Side MOSFET (Q1): An N-channel MOSFET that connects the input voltage to the inductor when turned on.
  • Low-Side MOSFET (Q2): The synchronous rectifier. Instead of a diode, this MOSFET turns on during the off-cycle to allow current to flow through the inductor, drastically reducing losses.
  • Inductor (L1): A large toroidal or shielded drum inductor (typically 47µH – 100µH). It stores energy during the on-time and releases it during the off-time.
  • Output Capacitors (C_OUT): Low-ESR electrolytic and ceramic capacitors to smooth the output voltage.

2. The Heart: PWM Controller (U1)

Most S36012 clones use the XL4016 – a 40V, 8A asynchronous buck converter. Wait, 8A? But the module claims 12A. This is the first design trick: The XL4016 drives an external MOSFET (Q1) to boost current capability to 12A.

Pinout of U1 (XL4016) in this circuit:

  • Pin 1 (SW): Connects to Gate of Q1 (via a 10Ω resistor)
  • Pin 2 (GND): Power ground
  • Pin 3 (VCC): Internal regulator output (bypass cap)
  • Pin 4 (FB): Feedback input – connected to voltage divider from Vout
  • Pin 5 (VSENSE): Current sense input – connected across R_sense
  • Pin 6 (VIN): Input voltage (6V to 40V)