Item specifics
Description
The STM32F103CBU6 is a mainstream Arm Cortex-M3 performance line MCU from STMicroelectronics, belonging to the medium-density product line, UFQFPN-48 package (7×7×0.55 mm). 72 MHz Cortex-M3 core, 1.25 DMIPS/MHz, single-cycle multiplication and hardware division. 128 KB Flash, 20 KB SRAM[reference:26][reference:27]. This model is the ultra-compact QFN-packaged version of the STM32F103CBT6, offering an ideal solution for space-constrained designs that demand full performance. It integrates CAN 2.0B, USB 2.0 FS, dual 12-bit ADCs (10 channels, 1 µs), 7-channel DMA, 7 timers (3×16-bit GP/IC/OC/PWM/quadrature encoder, 1×16-bit advanced-control/PWM/deadtime/emergency stop, 2 watchdogs, 24-bit SysTick), 9 communication interfaces (2×I2C/3×USART/2×SPI/USB/CAN). 37 I/Os, all 5 V-tolerant, mappable on 16 external interrupt vectors. VDD 2.0 V–3.6 V, -40 °C to 85 °C, ECOPACK®2. Comparison with LQFP-48 Package: This model shares identical core specifications with the STM32F103CBT6 (128 KB Flash, 20 KB SRAM, 7 timers, 9 communication interfaces). The only difference is the package — upgraded from LQFP-48 (7×7×1.45 mm) to UFQFPN-48 (7×7×0.55 mm), featuring a thinner profile ideal for SMT surface mount designs with height constraints.
Core: Arm Cortex-M3 72 MHz, 1.25 DMIPS/MHz, single-cycle multiplication/hardware division, SWD & JTAG debug, 43 maskable interrupt channels Memory: 128 KB Flash, 20 KB SRAM, CRC, 96-bit unique ID CAN 2.0B: Industrial fieldbus communication USB 2.0 FS: BCD and LPM support Dual 12-bit ADCs: 10 channels, 1 µs, 0–3.6 V, temperature sensor, dual-sample and hold capability 7-ch DMA: Supporting timers, ADC, SPI, I2C, USART 7 Timers: 3×16-bit GP (IC/OC/PWM/quadrature encoder/pulse counter), 1×16-bit advanced-control (PWM/deadtime/emergency stop), 2 watchdogs, 24-bit SysTick Communication: 2×I2C (SMBus/PMBus), 3×USART (ISO 7816/LIN/IrDA/modem control), 2×SPI (18 Mbit/s), USB 2.0 FS, CAN 2.0B Low Power: Sleep/Stop/Standby, VBAT for RTC and backup registers Clock: 4–16 MHz XTAL, 32 kHz RTC XTAL (calibrated), 8 MHz RC (factory-trimmed), 40 kHz RC, PLL I/Os: 37 fast I/Os, all 5 V-tolerant, mappable on 16 ext. interrupt vectors Supply/Temp: VDD 2.0 V–3.6 V, POR/PDR/PVD, -40 °C to 85 °C Package: UFQFPN-48 (7×7×0.55 mm), Tray
Industrial: PLCs, sensor transmitters, RS-485/CAN nodes, inverters, industrial automation Motor Control: BLDC motors, servo motors, fans, pumps (advanced-control timer with 6-ch PWM/deadtime/emergency stop) Consumer: Remote controls, handhelds, PC peripherals, GPS platforms, gaming peripherals, video and imaging devices Medical: Handheld medical terminals, health monitoring devices Home Appliances: Panels, HVAC, alarms, video intercoms Security: Access control, alarms, smoke detectors IoT: Wireless sensors, environmental monitoring, smart home LED Lighting: Dimming, RGB strips, SMPS Automotive: Light control, window anti-pinch, sensor nodes (non-safety-critical) Compact Designs: Space-constrained portable devices requiring CAN/USB dual interface and advanced timers
Arm Cortex-M3 Core: 72 MHz, 1.25 DMIPS/MHz, single-cycle multiplication/hardware division, far exceeding Cortex-M0/M0+ performance UFQFPN-48 Ultra-Compact Package: 7×7×0.55 mm, 37 I/Os (all 5 V-tolerant), thickness only 1/2.6 of LQFP-48, ideal for space-constrained compact designs CAN + USB Dual Interface: Rare in this class, meeting both industrial bus and general communication needs 128 KB Flash + 20 KB SRAM: For high-complexity application demands 7 Timers (incl. Advanced-Control): 1 advanced-control timer (6-ch PWM/deadtime/emergency stop) + 3 GP timers (quadrature encoder), ideal for motor control and complex timing generation Dual 12-bit ADCs: 1 µs conversion time, 10 channels, temperature sensor, dual-sample and hold capability 7-ch DMA: Direct peripheral-to-memory transfers, offloads CPU 9 Communication Interfaces: 2×I2C + 3×USART + 2×SPI + USB + CAN, meeting multi-bus connectivity needs Calendar RTC: VBAT backup, ideal for scheduled sensing and low-power applications Mature STM32 Ecosystem: CubeIDE/CubeMX/HAL/LL libraries, abundant development boards and reference designs Cost-Effective Performance Line: 32-bit ARM + CAN + USB + dual ADCs + advanced timer + DMA, ideal upgrade from 8/16-bit MCUs
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FAQ:
What is the STM32F103CBU6 and how does it differ from the STM32F103C8T6?
The STM32F103CBU6 is a 72 MHz Arm Cortex‑M3 microcontroller with 128 KB Flash and 20 KB SRAM, housed in a compact VFQFPN‑48 package. It offers the same core and memory as the popular C8T6, but in a smaller, space‑saving QFN body with up to 37 I/Os. This makes it the ideal choice for space‑constrained designs that still need a proven 32‑bit processor, CAN, USB, and multiple serial interfaces. Unlike the C8T6 (LQFP‑48), the CBU6 comes in a leadless QFN package, which requires reflow soldering but saves significant PCB area.
Why choose the VFQFPN‑48 package over the LQFP‑48 or LQFP‑64? What are the trade‑offs?
The VFQFPN‑48 measures only 7 × 7 mm, saving significant PCB area compared to LQFP‑48 or LQFP‑64 packages. It provides up to 37 I/Os, which is enough for CAN, USB, two USARTs, SPI, I2C, and a few GPIOs. You sacrifice hand‑solderability (QFN requires reflow or hot‑air) and the FSMC, but gain a much smaller footprint. This package is perfect for miniature sensor nodes, USB dongles, and compact motor controllers where board space is at a premium.
Can the STM32F103CBU6 really run CAN and USB simultaneously with only 37 I/Os?
Yes, with careful pin planning. The CAN TX/RX pins and USB D+/D‑ signals are fixed to specific pins, and they do not conflict. You can allocate CAN, USB, two USARTs, one SPI, one I2C, and still have a few GPIOs left. STM32CubeMX is essential for verifying the exact pin‑multiplexing. This makes the CBU6 a capable, ultra‑compact communication node for CAN‑to‑USB bridges, sensor gateways, and portable data loggers.
Is 128 KB Flash and 20 KB SRAM enough for an RTOS, CAN, USB, and application code?
Yes, for well‑optimized, dedicated applications. A lightweight RTOS (e.g., FreeRTOS), a USB device stack, a CANopen protocol, and control logic can be tightly packed into 128 KB. The 20 KB SRAM requires careful buffer management—using DMA for UART/SPI transfers and placing constants in Flash helps save RAM. Many proven CAN‑to‑USB converters, compact motor drives, and portable instruments use this exact configuration.
How does the STM32F103CBU6 compare to the STM32F103TBU6? Is it a drop‑in replacement?
Both share the same Cortex‑M3 core, 128 KB Flash, and 20 KB SRAM, but the CBU6 comes in a VFQFPN‑48 package with 37 I/Os, while the TBU6 uses a smaller VFQFPN‑36 with 26 I/Os. The CBU6 is not a drop‑in replacement for the TBU6 due to different pinout, but it offers additional I/Os for designs that need more peripherals without moving to a larger 64‑pin package. Choose the CBU6 when 37 I/Os are needed; the TBU6 is even smaller for ultra‑compact designs.
Does the STM32F103CBU6 have a built‑in DAC or FSMC? What are my options for adding these features?
No, the CBU6 does not include a DAC or an FSMC. If you need an analog output, you can use an external SPI or I2C DAC chip, or generate a PWM signal with an RC low‑pass filter. For external memory, you can connect serial Flash or PSRAM via the SPI ports. If your design absolutely requires a built‑in DAC or FSMC, the larger STM32F103VCT6 (LQFP‑100) or F4 series are more suitable.
Is the STM32F103CBU6 suitable for battery‑powered devices? What are its low‑power capabilities?
The chip supports Sleep, Stop, and Standby modes. In Stop mode with all 20 KB SRAM retained, the typical current is around 14 µA. Wake‑up from Stop is fast enough to respond to CAN, USB, or external interrupts. While it is not as power‑efficient as the STM32L series, the CBU6 can still be used in battery‑powered sensors and portable instruments that spend most of their time in deep sleep and wake up periodically to process data and communicate.
Can I perform over‑the‑air (OTA) firmware updates with the 128 KB single‑bank Flash?
Yes. You can partition the 128 KB Flash into a small bootloader (8–16 KB) and a compact application. The 20 KB SRAM can temporarily buffer the new firmware image received via USB, CAN, UART, or an external wireless module. A CRC check ensures a safe update. An A/B update scheme is not practical with this Flash size; a download‑and‑overwrite approach is recommended.
What are the typical applications for the STM32F103CBU6?
It is widely used in space‑constrained CAN nodes, USB‑to‑serial converters, miniature motor controllers, portable medical devices, and compact IoT sensor hubs. Any design that needs a proven 32‑bit processor with CAN and USB in the smallest possible footprint, with a moderate number of I/Os, will benefit from the CBU6's combination of performance, memory, and tiny VFQFPN‑48 package.
What development tools and libraries support the STM32F103CBU6? Is the F1 ecosystem mature?
The CBU6 is fully supported by STM32CubeIDE, Keil MDK, and IAR EWARM. The vast STM32F1 HAL/LL library, countless online tutorials, and community‑driven code examples make development straightforward. You can prototype on a NUCLEO‑F103RB board (64‑pin, same core and memory) and then easily migrate to the CBU6 by adjusting the pin‑out and linker script in CubeMX.