Raspberry Pi 5 - ⚡ Power & USB Current Management

The Raspberry Pi 5 introduces a more rigorous power management system than previous models. This system monitors the power supply, USB-C Power Delivery (PD) negotiation, and the current available to USB peripherals.

When the power supply does not correctly communicate the expected profile, the system may limit the power delivered to the USB ports and display warnings to the user. This document explains how to correctly configure the system, based exclusively on the official Raspberry Pi documentation.

How To Avoid “Under-voltage Detected” Errors On Raspberry Pi

Power Architecture on the Raspberry Pi 5

The Raspberry Pi 5 uses:

1. Main power input via USB-C with USB Power Delivery
2. Power management controlled by EEPROM firmware
3. Dynamic current distribution to:
4. CPU/GPU
5. USB ports
6. Connected peripherals

The official power supply provides 5 V ⎓ 5 A (25–27 W) and communicates this profile via USB Power Delivery. Power supplies that do not negotiate correctly may still work, but with limitations.

Official reference:

Raspberry Pi Hardware Documentation – Power

https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#power-supply

1. Raspberry pi 5
2. Mean Well RS-25-5 - Fonte de alimentação 5V 5A 25W

Objective

Allow the Raspberry Pi to provide the maximum possible current to the USB ports whenever the power supply allows it.

Correct file (Raspberry Pi OS Bookworm)

Command to edit

Parameter to add

Apply changes

Verification

Official reference:

config.txt – USB power control

https://www.raspberrypi.com/documentation/computers/config_txt.html

The firmware records events of:

1. Undervoltage
2. Thermal throttling
3. Power limiting

Recommended command

Values other than 0x0 indicate events that are active or have occurred in the past.

Official reference:

vcgencmd

https://www.raspberrypi.com/documentation/computers/os.html#vcgencmd

What the EEPROM is

The EEPROM contains the boot firmware and power policies. Changes:

1. Are persistent
2. Survive operating system reinstalls
3. Must be made with caution

Edit configuration

⚠️ Important note

Raspberry Pi does not officially document parameters to force maximum current while ignoring PD negotiation. Undocumented changes may:

1. Disable protection mechanisms
2. Cause instability
3. Lead to data corruption

Official recommendation:

Always use a USB-C PD–compatible power supply with adequate power.

Official reference:

EEPROM configuration

https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#raspberry-pi-boot-eeprom

The Raspberry Pi 5 supports a rechargeable RTC battery.

Enable charging (only if applicable)

⚠️ Use only with compatible rechargeable batteries.

Official reference:

https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#rtc

RTC documentation - Recommended Best Practices (Official)

1. Use a certified USB-C PD power supply
2. Use a USB-C cable rated for 5 A
3. Avoid “forcing” power configurations
4. Monitor get_throttled on critical systems

The Raspberry Pi 5 offers a modern and secure power system, provided that USB-C PD negotiation is respected. Proper configuration through config.txt allows optimisation of USB port usage, while EEPROM changes should be reserved for experienced users.

This document follows exclusively official Raspberry Pi recommendations and documentation, ensuring reliability and safety.