Voltage Regulation

Overview

The Rocket2 ECU uses a high-efficiency switching regulator to step down the 24V primary battery bus to a stable 3.3V logic rail. This rail powers the STM32, all onboard sensors, and communication modules.

Rocket2 Power Diagram Figure 2: Voltage Regulation System Diagram

Hardware Specifications

Parameter Value Note
Regulator (U7) RECOM RPM6.0-3.3 LGA Power Module
Input Range 24V Nominal Protected against transients
Output Current 6.0A Max Limited by L2 (3A)
Switching Freq 500 kHz RECOM RPM6.0-3.3 fixed frequency PWM

Connections & Interfaces

  • 24VIN: Primary power input sourced from the Battery/GSE bus via a dedicated barrel jack or XT60.
  • 3.3V_out: The regulated output of the U7 RECOM module.
  • Test Point (TP26): Main 3.3V probe point located immediately after the inductor/capacitor stage.

Regulator Schematic

Rocket2 Voltage Regulator Schematic *Figure 3: Voltage Regulation: Schematic

Design Details

Input Stage & Pi-Filter

  • 24V Diodes: Upgraded to 100V 8A Schottky diodes to prevent back-feeding and allow high-current supply for propulsion requirements.
  • Pi-Filter: To block inductive noise, a filter is implemented using C11, C13, C109, C110 (10µF each) and L2 (2.2µH).
    • Note: L2 is 3A rated; if 6A logic draw is required, this component must be bypassed/upgraded.

Status & Control Logic

  • Visual Status: LED D6 (Green) is tied to the PGood pin. It illuminates only when the 3.3V rail is stable (>90% of nominal).
  • Always-On Logic: The CTRL pin (C1) is NC (No Connection), ensuring the regulator initializes immediately upon 24V application.

Bringup, Failure Modes, & Debugging

  • Bringup: Ensure R85 Isolation during testing. Confirm LED ON status prior to powering stm32.
  • Troubleshooting: If LED D6 is Dim/Off --> remove R85, check resistance to GND.
  • Debugging: Test Point (TP26): Main 3.3V probe point located immediately after the inductor/capacitor stage.