Raspberry Pi's RP2350 A4 Version Encountered E9 Current Leakage Issue
In a significant move, Raspberry Pi has addressed a long-standing concern for users of their RP2350 MCU – the GPIO pin current leakage issue (erratum 9, E9). This issue, which was causing significant current leakage in the A2 stepping, has been internally fixed starting from the A3 stepping, and more comprehensively addressed in the latest A4 stepping, which is now available in the market.
The E9 bug, initially unclear, has been officially defined as an input mode current leakage issue due to an internal pull-up that was too weak. In the A2 stepping, this weakness resulted in a need for external pull-down resistors to counter the leakage caused by an internal weak pull-up when a pin is configured as input with the input buffer enabled.
However, with the introduction of the A3 and A4 steppings, this workaround is no longer necessary. The A3 stepping, an internal development stepping, introduced a hardware fix for the issue. The A4 stepping, the latest version of the RP2350 MCU, combines this hardware fix with a boot ROM software fix, ensuring the issue is resolved natively.
The Raspberry Pi's new RP2350 MCU, with its hardware and software changes, is expected to offer improved functionality and reliability over the original defective A2 stepping. The A4 stepping, which is now widely available in the market, is expected to be the preferred choice for users seeking a more reliable and bug-free version of the MCU.
This development is confirmed in Raspberry Pi's July 29, 2025 Product Change Note and updated RP2350 datasheet. The company's handling of the E9 bug, from initial reporting to the eventual fix in the A3 and A4 steppings, has demonstrated their commitment to addressing issues and ensuring the reliability of their products.
For those still using the A2 stepping, it is important to note that it is still considered to be defective. The July 29 Product Change Note applies to both steppings A3 and A4 of the RP2350 MCU. The workarounds required for the E9 bug, such as external pull-downs, may no longer be necessary with the new A3 and A4 steppings of the RP2350 MCU.
In conclusion, the Raspberry Pi's RP2350 MCU issue with GPIO pin current leakage (erratum 9, E9) has been addressed as of July 29, 2024. Users seeking a reliable and bug-free version of the MCU are advised to opt for the A4 stepping, which offers both hardware and software fixes to address the E9 issue.
[1] Raspberry Pi (2025). RP2350 MCU Product Change Note. Retrieved from https://www.raspberrypi.org/documentation/hardware/computes/rp2350/pcn.md [3] Raspberry Pi (2025). RP2350 MCU Datasheet. Retrieved from https://www.raspberrypi.org/documentation/hardware/computes/rp2350/README.md
The Raspberry Pi's A4 stepping, a result of the company's technology advancements, addresses the hardware issue of GPIO pin current leakage (erratum 9, E9) that was present in the A2 stepping. This development, marked by a combination of hardware and software changes, opens the door for more reliable and secure hacking projects with the Raspberry Pi.
The Raspberry Pi's handling of the E9 bug, from initial scientific investigation to the eventual resolution in the A3 and A4 steppings, showcases their dedication to upholding the quality and reliability of their science and technology offerings.
