Designing Buck Converter for Raspberry Pi

johnn9

johnn9

now make changes to my design Input voltage: 24 V Output voltage: 5 V Maximum output current: 5 A Switching frequency: 300kHz Inductor: 10 μH Output capacitor: 220 μF Diode: 1N5817 MOSFET: IRF540N To calculate the duty cycle (D) of the MOSFET: D = Vout / Vin = 5 / 12 = 0.4167 To calculate the peak inductor current (Ipk): Ipk = (Vout x D) / (L x (1 - D)) = (5 x 0.4167) / (10 x (1 - 0.4167)) = 1.39 A To calculate the RMS inductor current (Irms): Irms = (Ipk / sqrt(2)) x (D / (1 - D)) = (1.39 / sqrt(2)) x (0.4167 / (1 - 0.4167)) = 1.22 A To calculate the output capacitor ripple voltage (Vripple): Vripple = (Iout x (1 - D)) / (C x f) = (2 x (1 - 0.4167)) / (220 x 10^-6 x 100,000) = 0.072 V To calculate the power loss of the MOSFET: Ploss = (Ipk^2 x Rds(on)) / 2 = (1.39^2 x 0.077) / 2 = 0.078 W- BARGUNAN PONNUSAMY To calculate the power loss of the diode: Ploss = (Iout^2 x Rd) = (2^2 x 0.05) = 0.2 W Overall efficiency of the converter: η = (Pout / Pin) x 100% = (5 x 2 / 12 x 1.22) x 100% = 68.3%
186 days

flux

2:01

Accessing knowledge base.

I’ll update your design to a 24 V → 5 V, 5 A buck at 300 kHz, replace unsuitable parts, add a proper regulator IC, and wire it to your terminals.
Planned changes:
  • Add a 5 A, 24 V-capable buck regulator IC (prefer synchronous). If asynchronous, add a ≥40 V, ≥5 A Schottky Diode; remove 1N5817 and IRF540N.
  • Keep 10 µH inductor but pick a part with Isat ≥ 1.2× peak and low DCR: 10uH Inductor.
  • Add input ceramics (10 µF 50 V X7R in parallel plus 100 nF) and output caps (low‑ESR ceramics + bulk, ≥1.5× Vout).
  • Set feedback for 5.0 V and program 300 kHz; wire to IN / IN - and OUT / OUT -. We’ll verify ripple (20–40% target) and ERC/DRC.
Note: your earlier math used 12 V; we’ll correct to 24 V and recompute duty, ripple, and peak currents accordingly.
Click Start on the plan bar to proceed, or tell me if you prefer an integrated synchronous IC or an async controller + external diode.
Pick synchronous IC
Choose async controller
Recalculate duty cycle
Search inductor specs
Select output capacitors
186 days

Started implementing a plan

# Goal

- Update the project to a 24 V to 5 V, 5 A buck converter operating at 300 kHz. Replace non-compliant parts (1N5817 and IRF540N), add a suitable integrated 5 A buck regulator IC, validate the 10 µH inductor ratings, add the required input/output capacitors and feedback network, and wire the schematic to the IN+/IN− and OUT+/OUT− terminals.

# Implementation plan

1. **Buck Regulator Update**

1. Select and add a 5 A buck regulator IC capable of 24 V input and 5 V output at 300 kHz (preferably with synchronous rectification to improve efficiency).

2. Configure the IC for the 5 V output and 300 kHz operating frequency. If the selected part is asynchronous, add a Schottky catch diode rated at ≥40 V and ≥5 A; otherwise, use the built-in synchronous rectification.

2. **Component Replacement and Validation**

1. Remove the existing 1N5817 Schottky diode and replace it with a proper ≥40 V, ≥5 A Schottky diode (if required by the design).

2. Remove the IRF540N MOSFET and ensure that the selected regulator either integrates a MOSFET or uses an external MOSFET that meets a 60 V, logic-level criterion if needed.

3. Validate and select a 10 µH inductor with Isat ≥1.2× the peak load current and low DCR, ensuring it meets the design’s requirements on ripple current (20–40% of full load).

3. **Supporting Components Addition**

1. Add input capacitors: parallel combination of a 10 µF (50 V, X7R) capacitor and a 100 nF ceramic capacitor for decoupling.

2. Add output capacitors: a combination of low-ESR ceramics and a bulk capacitor rated at ≥1.5× Vout.

3. Calculate and add the appropriate feedback resistors to set the 5 V output using the buck regulator’s feedback network.

4. **Schematic Connections and Checks**

1. Wire the new components and supporting parts as follows:

1. Connect all input components to the IN+ and IN− terminals.

2. Connect the output path (buck regulator, inductor, capacitors) to the OUT+ and OUT− terminals.

2. Run electrical rule checks (ERC) and design rule checks (DRC) to validate the schematic configuration.

# Success criteria

- A buck regulator assembly that meets the requirements: 24 V input, 5 V output, 5 A max, operating at 300 kHz.

- All replaced components (diode, MOSFET) and validated inductor ratings meet the design specifications.

- Proper input/output capacitors and a correctly set feedback network are added for stable operation.

- The schematic is fully wired with IN+/IN− and OUT+/OUT− connections and passes all ERC/DRC.

186 days
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