LM21305-Based Power Distribution Board

Overview

This project describes a compact power distribution board (PDB) for multicopter applications. The design is based on the LM21305 synchronous buck regulator and provides regulated 5 V outputs alongside direct battery connections.

The board follows a 30 × 30 mm mounting pattern, compatible with standard flight controller stacks.

Features

• LM21305-based DC-DC regulation
• 30 × 30 mm mounting pattern
• Maximum output current: 5 A
• 3 × regulated 5 V outputs (JST-PH 2.0)
• 2 × battery outputs (JST-PH 2.0)

Specifications

LM21305 Regulator Summary

The LM21305 is a synchronous step-down (buck) DC-DC converter with integrated power MOSFETs and peak current-mode control. :contentReference[oaicite:0]{index=0}

Key characteristics:

• Input voltage range: 3 V to 18 V
• Output current capability: up to 5 A
• Adjustable switching frequency: 300 kHz to 1.5 MHz
• Integrated high-side and low-side MOSFETs

Functional features:

• Peak current-mode control for fast transient response
• Internal soft-start and enable control
• Cycle-by-cycle overcurrent protection and thermal shutdown
• Overvoltage and undervoltage protection

These characteristics enable high efficiency and compact external component selection.

Electrical Interfaces

5 V Outputs (3×)

• 5 V
• Ground

Battery Outputs (2×)

• VBAT
• Ground

Mechanical Details

• Mounting hole spacing: 30 mm × 30 mm (M3 compatible)

Contributions

Contributions and issue reports are welcome.