RP2350 vs RP2354: Four Microcontroller Variants Compared

Quick answer

RP2350A offers a small package with flexible external flash capacity, while RP2354A eliminates the separate flash IC when 2 MB of integrated storage is enough. For applications requiring 48 GPIO pins, RP2350B provides external flash flexibility, while RP2354B includes the flash within the package. Raspberry Pi Pico 2 and Pico 2 W use RP2350A with separate 4 MB flash, not RP2354.

Microcontrollers are used in many embedded systems, including motor controllers, sensor interfaces, digital synthesizers, and portable instruments. Such applications often need precise control over inputs and outputs, along with enough processing power and memory to run the required firmware. Engineers must also consider practical constraints such as the number of available pins, PCB area, and component cost.

Raspberry Pi's RP2350 and RP2354 microcontrollers address many of these requirements. Both belong to the same family of dual-core microcontrollers, with Arm Cortex-M33 and Hazard3 RISC-V processor options, programmable I/O (PIO), and USB support. The main difference is the arrangement of their program memory. RP2350 uses external flash memory, while RP2354 includes 2 MB of flash within the microcontroller package.

The four variants differ in two ways: RP2350 versus RP2354 determines whether flash memory is included, while RP2350A/RP2354A versus RP2350B/RP2354B determines the package size and number of available GPIO pins.

RP2350A and RP2354A use smaller, 60-pin packages with 30 general-purpose input/output (GPIO) pins. RP2350B and RP2354B use larger, 80-pin packages with 48 GPIO pins.

The designation A4 sometimes appears alongside the RP2350 part number. A4 identifies a silicon stepping, meaning a revision of the chip's implementation. It does not identify the RP2350A or RP2354A package.

RP2350A vs RP2350B vs RP2354A vs RP2354B

The following table compares the four microcontrollers and explains how their differences affect component selection and PCB design.

Flash in package means the nonvolatile flash memory is physically included in the microcontroller package rather than mounted as a separate component on the PCB. RP2354A and RP2354B contain two stacked silicon dies: the RP2350 controller die and a 2 MB QSPI NOR flash die. The integrated flash stores firmware and supports execute-in-place (XIP) operation, which allows the processor to execute code from flash without first copying the entire program into SRAM.

Raspberry Pi's official microcontroller specifications confirm the four configurations. RP2350A and RP2350B require separate flash for conventional flash-based firmware storage, with 30 and 48 GPIO pins respectively. RP2354A and RP2354B offer the same corresponding GPIO counts but include 2 MB of flash in the package.

Choose RP2350 if

RP2350A and RP2350B are better suited to designs where external flash capacity and component selection matter more than minimizing the number of components.

RP2350 is worth considering when:

• The application needs more than 2 MB of primary program flash and requires an external QSPI device with a selected capacity.
• Flash vendor choice, package availability, component qualification, or second-source options matter to the production design.
• The target board is similar to Raspberry Pi Pico 2, which uses RP2350A with 4 MB of external flash.
• Firmware assets, filesystems, language runtimes, or field-update images are expected to exceed 2 MB.

For a design with up to 30 GPIO pins, RP2350A provides a 7 × 7 mm QFN-60 package. Choose RP2350B when the application needs up to 48 GPIO pins and the larger 10 × 10 mm QFN-80 package is acceptable.

RP2350A is a familiar starting point for hobby projects because Raspberry Pi uses the same microcontroller in Pico 2. Pico 2 is a development board that includes the RP2350A chip, external flash, and supporting circuitry. Engineers can use the Pico 2 schematic as a reference when designing a custom RP2350A board. For an example of RP2350A in a practical design, Flux's macropad tutorial covers a Pico 2 project with mechanical keys, rotary encoders, and USB connectivity.

For production, the selection should account for GPIO requirements, expected firmware growth, memory sourcing, manufacturing tests, and PCB area rather than copying a development board without reviewing the requirements.

Choose RP2354 if

RP2354A and RP2354B are useful when the integrated 2 MB flash provides enough program storage and the design would benefit from fewer components.

Consider RP2354 for designs with the following requirements:

• The bootloader, application, settings, firmware-update strategy, and storage margin can fit within the integrated 2 MB flash throughout the expected product lifetime.
• Reducing the number of components in the microcontroller and flash circuit is a priority.
• The PCB design would benefit from eliminating a separate flash package and the traces connecting the flash to the microcontroller.
• Board area is limited, and reducing the component footprint matters more than selecting a larger flash capacity.

Choose RP2354A when 30 GPIO pins are enough and PCB area is a priority. Its 7 × 7 mm package includes the primary flash memory, so a separate flash IC is unnecessary.

Choose RP2354B when the design needs 48 GPIO pins along with integrated flash. The larger 10 × 10 mm package takes more space, but it provides the additional I/O connections.

RP2354A will often provide the smallest complete microcontroller and primary flash implementation. However, removing the external flash IC does not automatically reduce the total cost. Device pricing, supply agreements, availability, and assembly costs can change. A cost comparison should account for the MCU, any external memory, PCB area, and assembly costs rather than MCU pricing alone.

Shared architecture: Arm, RISC-V, security, and RP2040 context

After selecting the appropriate flash configuration and package, the processor architecture is another consideration. All four variants have the same processor options, memory architecture, and baseline security features. Engineers can therefore make the flash and package decision without selecting a different processor family.

RP2350 includes two processor sockets. Each socket can independently select an Arm Cortex-M33 or Hazard3 RISC-V processor. Mixed configurations are also supported, with Arm on core 0 and RISC-V on core 1, or the reverse. The architecture selection is controlled through separate ARCHSEL register bits.

Cortex-M33 is a practical choice for existing Arm firmware or applications requiring TrustZone. Hazard3 supports RISC-V development while providing access to the same peripheral set. However, secure boot requires Arm mode because the RP2350 boot ROM does not implement secure boot for RISC-V.

The RP2350 family also includes 8 kB of one-time programmable (OTP) memory, optional signed boot enforced by mask ROM, and a hardware SHA-256 accelerator. A cryptographic key fingerprint can be stored in OTP to verify signed firmware during boot.

With Cortex-M33, Arm TrustZone can divide memory into Secure and Non-secure regions. Software running in a Non-secure region cannot directly access memory configured as Secure.

The supported security features also depend on the silicon revision. Manufacturers publish errata to identify known hardware or firmware defects, the affected silicon revisions, and any available fixes or workarounds.

For example, the A4 silicon stepping updates the RP2350 boot ROM. According to the RP2350 datasheet, A4 fixes or mitigates security-relevant issues including RP2350-E18, E24, and E25. The boot ROM avoids the E18 boot failure, although the underlying OTP error-correction hardware issue is not eliminated. Flux's RP2350 A4 stepping article provides additional background on the revision and its practical implications.

The errata details in the article are based on the RP2350 datasheet dated July 29, 2025, build d126e9e-clean. Production designs should use the latest available documentation. For secure boot applications, specify acceptable silicon stepping, use a current Pico SDK, review the errata, and test provisioning and recovery on the production hardware.

Compared with RP2040, RP2350 adds Cortex-M33 and Hazard3 processor options, more SRAM, a higher maximum clock frequency, additional security features, and more programmable I/O capability. RP2040 can still be suitable for simpler designs that have already completed qualification. A closer comparison of the two generations is available in Flux's Raspberry Pi Pico 2 vs Pico article.

Design considerations that change the schematic or PCB

Choosing a variant also affects the supporting circuitry. Flash integration and package selection can change the required memory connections, power configuration, and PCB routing. The following design considerations should be reviewed before finalizing the schematic.

Power supply and decoupling

The RP2350 family uses several power supply connections for its processor core, GPIO pins, USB interface, and internal regulator.

IOVDD supplies the digital GPIO pins and supports a nominal voltage of 1.8 to 3.3 V. DVDD supplies the processor core at a nominal 1.1 V, while USB_OTP_VDD powers the USB physical interface and OTP memory at a nominal 3.3 V.

The internal voltage regulator accepts 2.7 to 5.5 V through VREG_VIN and can generate the required core voltage. When the internal buck regulator is used, the circuit requires:

• At least 4.7 µF of input capacitance at VREG_VIN.
• A fully shielded, polarity-marked 3.3 µH ±20% inductor connected to VREG_LX.
• A 4.7 µF ±20% output capacitor on the filtered 1.1 V supply.

Connect VREG_FB and DVDD to the filtered output, and connect VREG_PGND to ground. Follow the manufacturer's recommended component specifications and layout, including the inductor orientation.

For decoupling, place a 100 nF capacitor close to each of the two DVDD pins nearest the regulator. Place a 4.7 µF capacitor near the furthest DVDD pin. USB_OTP_VDD and ADC_AVDD, the analog-to-digital converter supply, each need a 100 nF capacitor close to the corresponding pin.

VREG_AVDD is the analog supply for the internal voltage regulator. It operates at a nominal 3.3 V and should be filtered according to the manufacturer's reference design.

RP2354A and RP2354B have an additional power constraint. Their integrated flash operates at 3.3 V, so QSPI_IOVDD must be supplied at 3.3 V. If a secondary flash or PSRAM device uses a GPIO for chip select, IOVDD must also operate at 3.3 V.

Clock and crystal

The Raspberry Pi reference design uses a 12 MHz crystal connected across XIN and XOUT. The recommended ABM8-272-T3 crystal specifies 10 pF load capacitance.

Keep the crystal traces short and away from noisy signals. The required load capacitors depend on the selected crystal and PCB parasitics, so their values should be determined from the crystal specifications and layout.

The RP2350 datasheet directs designers to the Pico 2 schematic for an example of the crystal circuit rather than specifying universal capacitor values.

Programming and debug

RP2350 and RP2354 support programming and debugging through Serial Wire Debug (SWD) and USB bootloader interfaces.

Expose SWDIO, SWCLK, and ground for debugging. RUN is the active-low asynchronous reset input, while BOOTSEL can place the device into its ROM bootloader.

For a BOOTSEL button, pull QSPI_SS low through an appropriate resistance. The datasheet identifies 4.7 kΩ to ground as a suitable intermediate value because it can overcome the internal pull-up without interfering with normal chip-select output levels.

For USB operation, connect USB D+ and D− through 27 Ω series resistors to USB_DP and USB_DM. The USB physical interface includes the required pull-up and pull-down resistors.

RP2350A and RP2350B normally boot firmware from a populated external primary flash device. RP2354A and RP2354B use the flash integrated into the package.

Security provisioning also affects manufacturing. Once OTP keys or irreversible security policy bits have been programmed, some recovery and debugging options may no longer be available.

Consequently, the production test procedure should define key programming, firmware signing, debug access policy, serial-number assignment, and failure recovery before manufacturing begins.

Flash routing and board area

RP2350A and RP2350B need external flash for conventional flash-based program storage. Place the QSPI flash close to the MCU and keep the clock and data traces short. Avoid unnecessary vias and stubs, and follow the recommended memory-device specifications and reference layout.

The external flash IC also needs a bypass capacitor, PCB traces, and placement area. Depending on the layout, the additional components can offset some of the space saved by the smaller RP2350A package.

For RP2354A and RP2354B, the primary flash connection is contained within the package, so the PCB does not need an external primary flash circuit.

A second QSPI flash or pseudo-static RAM (PSRAM) device can still be connected through the shared QSPI bus. Such a device uses a separate chip-select signal, commonly called CS1, driven by a GPIO.

However, the additional device should be treated as supplementary memory rather than a direct replacement for the primary boot flash. The datasheet describes the internal flash as the primary device but does not establish that the boot ROM automatically searches CS1 for an initial firmware image.

When a secondary QSPI device is installed on RP2354A or RP2354B, both QSPI_IOVDD and IOVDD must operate at 3.3 V.

RF and layout

RP2350A, RP2350B, RP2354A, and RP2354B do not include Wi-Fi, Bluetooth, or another RF transceiver.

A custom wireless design therefore needs a separate radio IC or module. Depending on the chosen component, the PCB may also need power filtering, controlled RF routing, antenna matching, or a defined antenna keepout area. Certification requirements should be reviewed during hardware planning.

For comparison, Raspberry Pi Pico 2 W combines an RP2350 microcontroller with a separate Infineon CYW43439 wireless device. Wireless connectivity comes from the external radio rather than a special radio-enabled version of RP2354.

Toolchain and ecosystem

All four variants use the Raspberry Pi Pico SDK, but software compatibility also depends on the chosen processor architecture.

Before development, confirm compiler, debugger, real-time operating system (RTOS), and library support. Arm Cortex-M33 has a more established embedded development ecosystem, while RISC-V projects may need different library configurations or debugging tools.

Package selection can also determine whether an existing PCB layout can be reused. RP2350A and RP2354A use QFN-60 packages, while RP2350B and RP2354B use QFN-80 packages. The two package sizes require different PCB footprints and pin maps.

RP2350A and RP2354A are designed as pin-compatible counterparts, as are RP2350B and RP2354B. Still, verify the latest datasheet, power requirements, and electronic design automation (EDA) library symbols before creating a PCB that supports either flash configuration.

Minimal buildable reference circuits

The following component checklists describe the basic circuitry needed for RP2350 and RP2354 designs. Use the manufacturer's reference schematics and layout files to complete the electrical design and verify the connections. Flux also has a guide to designing PCBs from templates, including existing Pico reference designs that can be adapted for new projects.

RP2350A and RP2350B

The RP2350A circuit provides up to 30 GPIO pins through the smaller QFN-60 package. RP2350B provides up to 48 GPIO pins through QFN-80, but the additional connections can require more routing area or PCB layers.

RP2354A and RP2354B

RP2354A and RP2354B use the same basic power, clock, reset, USB, and debugging circuits. The main schematic difference is the integrated flash.

A secondary memory device can provide additional storage or RAM capacity, but it should not be treated as a drop-in replacement for the integrated boot flash.

Pico 2 chip variants

Raspberry Pi Pico 2 and Pico 2 W are development boards built around the RP2350 family. Both use external flash memory, which makes their schematics useful examples for engineers designing custom RP2350A boards.

Raspberry Pi Pico 2 uses RP2350A with 4 MB of external flash, identified in the Pico 2 datasheet as Winbond W25Q32RV. The board provides the external clock, power regulation, USB connection, and other components needed to operate the microcontroller.

Pico 2 W follows the same RP2350 external-flash architecture and also includes 4 MB of flash. Its wireless capabilities come from a separate Infineon CYW43439 device, which provides Wi-Fi and Bluetooth connectivity.

The Pico 2 boards expose 26 GPIO connections, fewer than the 30 GPIO pins available on the RP2350A chip. Engineers designing a custom board can therefore use the Pico 2 schematic as a starting point while selecting the connections required for the application.

Availability and lifecycle

As of October 2026, Raspberry Pi lists all four microcontroller variants on its official RP2350 product page and provides a purchasing interface. The page also identifies JLCPCB as an assembly option, although it does not display live stock counts.

Raspberry Pi publishes a production commitment through at least January 2045 for the RP2350 family.

Distributor inventory, lead times, and pricing can change, so procurement decisions should use current supplier information. For a production design, the published availability commitment can help with long-term component planning.

FAQs

What is the difference between RP2350 and RP2354?

What is the difference between RP2350A and RP2350B?

Which RP2350 variant makes the smallest board?

Can RP2354 use more than 2 MB of flash?

Does Raspberry Pi Pico 2 use RP2350 or RP2354?

Sources and revision basis

• RP2350 Datasheet: Technical reference reviewed, build 2025-07-29, d126e9e-clean. Includes silicon-stepping details and errata.
• RP2350 product page: Official overview of all four variants, package specifications, and purchasing information.
• RP2350 product brief: Variant summary and architecture specifications.
• Raspberry Pi Pico 2 datasheet: Release 5, build date July 3, 2026, build d4e0f1799616. Includes the RP2350A implementation and external 4 MB flash.
• Raspberry Pi Pico 2 W datasheet: Release 2, build date July 3, 2026. Covers external flash and the separate CYW43439 radio.
• Hardware design with RP2350: Manufacturer guidance for minimal board circuits, component selection, and PCB layout.
• PCN 32: Pico 2 products moving to RP2350 A4 silicon stepping: Manufacturer notice covering the move to the A4 silicon revision.