EFM8UB20F64G-B-QFN32 - 48MHz USB 8051 MCU, 64KB Flash | Silicon Labs
MPN: EFM8UB20F64G-B-QFN32 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.42 | $3.42 |
| 10 | $3.1 | $31.00 |
| 100 | $2.74 | $274.00 |
| 500 | $2.41 | $1,205.00 |
| 1,000 | $2.15 | $2,150.00 |
EFM8UB20F64G-B-QFN32 Overview
An 8-bit microcontroller (MCU) is an integrated circuit containing a CPU, program memory (Flash), data memory (RAM), and programmable I/O peripherals on a single die. The 8051 architecture, originally introduced by Intel in 1980, remains one of the most widely deployed MCU cores due to its compact code density, deterministic interrupt response, and low cost. The CIP-51 core implemented in EFM8UB2 devices executes most instructions in 1-2 system clocks at 48 MHz, giving 8051-class peripherals performance comparable to many 16-bit cores while preserving the 8051 instruction set for code reuse.
Key features of the EFM8UB20F64G-B-QFN32 include an integrated USB 2.0 full-speed (12 Mbps) PHY and transceiver that eliminates the need for external USB components, a 10-bit 200 ksps SAR ADC with 20 channels and true differential inputs for sensor measurements, and two on-chip low-current analog comparators with adjustable reference. The device supports I2C, SPI, and UART serial interfaces, an external memory interface (EMIF), and a four-channel DMA controller that offloads data movement between peripherals and RAM.
The EFM8UB2 architecture uses a pipelined CIP-51 core with a peak throughput of 48 MIPS at 48 MHz, and the device offers multiple low-power modes - including a 0.1 uA typical stop-mode current with full RAM retention - that make it well-suited to USB bus-powered and battery-powered applications. The integrated USB peripheral includes an on-chip 3.3V LDO regulator and 1.5 kOhm pull-up resistors, simplifying USB bus-powered designs to a minimum external BOM.
Typical applications include USB HID input devices such as keyboards, mice, and game controllers, USB-to-UART bridge dongles, USB CDC virtual COM ports, USB composite devices combining HID + CDC, USB charging-port controllers, and industrial sensor interfaces with USB diagnostics. The wide temperature grade and integrated USB also fit point-of-sale (POS) terminals, barcode scanners, and laboratory instrumentation front panels.
When designing with the EFM8UB20F64G-B-QFN32, ensure that VBUS sensing is correctly wired to the VBUS pin and that the D+ and D- lines use 90 ohm differential routing per USB 2.0 signal-integrity guidelines. Use the on-chip LDO output (VDD) to power external pull-up resistors rather than routing 5 V VBUS directly to logic-level pins. The internal 5 V tolerant I/O allows direct interfacing with USB VBUS signals without external level shifters.
This page synthesizes current distributor stock and pricing, same-family drop-in variants, and practical design guidance for the USB-capable EFM8UB2 family - information not consolidated in any single manufacturer datasheet.
Drop-in alternatives for EFM8UB20F64G-B-QFN32 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with EFM8UB20F64G-B-QFN32 (same form factor and footprint) — differing in ADC, PCA Channels, Package, USB Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
EFM8UB20F64G-A-QFN32
✅ Drop-In📋 Reference alternative (not in catalog)
EFM8UB20F64G-B-QFN32R
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →EFM8UB20F64G-B-QFP48
✅ Drop-In📋 Reference alternative (not in catalog)
EFM8UB10F16G-QFN32
✅ Drop-In📋 Reference alternative (not in catalog)
C8051F381-GM
✅ Drop-In📋 Reference alternative (not in catalog)
EFM8UB20F64G-B-QFN32 Maximum Ratings & Electrical Characteristics
| Core Architecture | CIP-51 (8051-compatible) |
| Core Width | 8-bit |
| Maximum CPU Clock | 48 MHz |
| Flash Size | 64 kB (64K x 8) |
| RAM Size | 4 kB XRAM + 256 B internal data RAM |
| Operating Temperature | -40C to +105C (Grade B) |
| Digital I/O Pins | 25 |
| Package | 32-pin QFN (5x5 mm) |
| Mounting Type | Surface Mount |
| USB Interface | USB 2.0 Full-Speed (12 Mbps) device, integrated PHY |
| ADC | 10-bit SAR, 200 ksps, 20 channels with differential inputs |
| Timers | 6 x 16-bit |
| PCA Channels | 5 (PWM/capture) |
| Analog Comparators | 2 with adjustable reference |
| DMA Channels | 4 |
| Serial Interfaces | I2C, SPI, UART, USB |
| External Memory Interface | Yes (EMIF) |
| RoHS Status | Compliant |
EFM8UB20F64G-B-QFN32 Pin Configuration
| Pin 1 | P0.0 — Digital I/O / VBUS sense |
| Pin 2 | P0.1 — Digital I/O |
| Pin 3 | P0.2 — Digital I/O |
| Pin 4 | P0.3 — Digital I/O |
| Pin 5 | VDD — 3.3V LDO output (from internal regulator) |
| Pin 6 | VBUS — USB VBUS sense (5V tolerant) |
| Pin 7 | D+ — USB D+ data line |
| Pin 8 | D- — USB D- data line |
| Pin 9 | P0.4 — Digital I/O |
| Pin 10 | P0.5 — Digital I/O |
| Pin 11 | P0.6 — Digital I/O |
| Pin 12 | P0.7 — Digital I/O |
| Pin 13 | P1.0 — Digital I/O |
| Pin 14 | P1.1 — Digital I/O |
| Pin 15 | P1.2 — Digital I/O |
| Pin 16 | P1.3 — Digital I/O |
| Pin 17 | P1.4 — Digital I/O |
| Pin 18 | P1.5 — Digital I/O |
| Pin 19 | P1.6 — Digital I/O |
| Pin 20 | P1.7 — Digital I/O |
| Pin 21 | P2.0 — Digital I/O |
| Pin 22 | P2.1 — Digital I/O |
| Pin 23 | P2.2 — Digital I/O |
| Pin 24 | P2.3 — Digital I/O |
| Pin 25 | P2.4 — Digital I/O |
| Pin 26 | P2.5 — Digital I/O |
| Pin 27 | P2.6 — Digital I/O |
| Pin 28 | P2.7 — Digital I/O |
| Pin 29 | /RST — Active-low reset input |
| Pin 30 | XTAL1 — External crystal/oscillator input |
| Pin 31 | XTAL2 — External crystal output |
| Pin 32 | GND — Ground (also e-pad thermal pad) |
Typical Applications
EFM8UB20F64G-B-QFN32 is suitable for 6 applications: USB HID Input Devices (Keyboard, Mouse, Gamepad), USB-to-UART Bridge Dongles, USB CDC Virtual COM Port Adapters, USB Composite Devices (HID + CDC + Vendor), USB Charging Port Controllers, Industrial Sensor Interfaces with USB Diagnostics.
USB HID Input Devices (Keyboard, Mouse, Gamepad)
The EFM8UB20F64G-B-QFN32 fits USB HID input devices because its integrated USB 2.0 full-speed PHY, on-chip 1.5 kOhm pull-up resistors, and 3.3 V LDO remove every external USB component. Designers connect the VBUS, D+, and D- pins to the USB connector and gain a 48 MHz CPU that scans up to 64-key matrices with sub-microsecond response. The 64 kB Flash holds USB HID descriptors and key-remap tables, while 4 kB of XRAM buffers HID report packets. Compared to discrete MCU + external PHY designs, this part cuts BOM cost by ~$0.50 and PCB area by roughly 30 percent for a typical keyboard PCB.
Recommended
USB-to-UART Bridge Dongles
The EFM8UB20F64G-B-QFN32 is ideal for USB-to-UART bridge dongles because its integrated USB device controller, UART, and 4 kB XRAM together provide a CDC virtual-COM-port implementation in firmware with no external bridge IC. The 48 MHz CPU sustains up to 1 Mbps UART throughput without DMA contention, and the 10-bit ADC can monitor VBUS voltage for cable-disconnect events. Compared to popular CP2102N-based bridges, this part offers more headroom for custom protocols while using the same QFN-25 to QFN-32 PCB land area.
Recommended
USB CDC Virtual COM Port Adapters
The EFM8UB20F64G-B-QFN32 supports USB CDC virtual COM port designs because its full-speed USB device, 256-byte internal RAM, and 4 kB XRAM easily accommodate the CDC class descriptors and interrupt-IN endpoint buffering. The 1050 +105C B temperature grade (variant B in ISO 16750) tolerates industrial cabinet enclosures without thermal derating. Compared to generic 8-bit MCUs without USB, this part eliminates the external USB transceiver, level shifters, and 12 MHz crystal typically required - reducing total BOM count by approximately 8 components.
Recommended
USB Composite Devices (HID + CDC + Vendor)
The EFM8UB20F64G-B-QFN32 fits USB composite devices because its 4-channel DMA controller offloads simultaneous HID + CDC + vendor endpoint traffic from the CPU, freeing cycles for application logic. Designers implement up to 4 endpoints (control + 3 I/O) and run the 48 MHz core at full speed without dropped packets at 12 Mbps line rate. Compared to single-endpoint MCUs, this part avoids the firmware bottlenecks that force designers into higher-cost Cortex-M0+ alternatives.
Recommended
USB Charging Port Controllers
The EFM8UB20F64G-B-QFN32 works in USB charging-port controllers because its integrated 10-bit ADC with 20 differential-input channels monitors VBUS voltage, D+/D- data lines, and current-sense amplifiers at 200 ksps simultaneously. The B temperature grade (variant B in industrial profiles) sustains operation inside enclosed charging hubs. The 64 kB Flash holds charging protocol tables (USB BC 1.2, Apple, Qualcomm QC), and the integrated USB PHY negotiates legacy-device current advertising without external components.
Recommended
Industrial Sensor Interfaces with USB Diagnostics
The EFM8UB20F64G-B-QFN32 suits industrial sensor interfaces with USB diagnostics because its 10-bit differential ADC reads bridge sensors and 4-20 mA loops directly, and its USB port streams diagnostic telemetry to a host PC at 12 Mbps. The -40C to +105C B temperature grade handles factory-floor enclosures and outdoor cabinets without additional thermal management. The 6 timers and 5 PCA channels drive PWM excitation for RTDs and LVDT position sensors, replacing dedicated timer ICs and saving roughly $0.40 per channel.
Recommended
Recommended Products Summary
Engineering reference data for EFM8UB20F64G-B-QFN32 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | EFM8UB20F64G-A-QFN32 | EFM8UB20F64G-B-QFN32R | EFM8UB20F64G-B-QFP48 | EFM8UB10F16G-QFN32 | C8051F381-GM |
|---|---|---|---|---|---|---|
| Package | QFN-32 (5x5 mm) | QFN-32 (5x5 mm) - same | QFN-32 (5x5 mm) - same | QFP-48 - larger | QFN-32 (5x5 mm) - same | QFN-32 (5x5 mm) - same |
| Brand | Silicon Labs | Silicon Labs - same | Silicon Labs - same | Silicon Labs - same | Silicon Labs - same | Silicon Labs - same |
| CPU Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Flash Size | 64 kB | 64 kB | 64 kB | 64 kB | 16 kB (-75%) | 64 kB |
| RAM Size | 4 kB XRAM + 256 B | 4 kB XRAM + 256 B | 4 kB XRAM + 256 B | 4 kB XRAM + 256 B | 2 kB XRAM (-50%) | 4 kB XRAM + 256 B |
| USB 2.0 FS PHY | Integrated | Integrated | Integrated | Integrated | Integrated | Integrated |
| Digital I/O Pins | 25 | 25 | 25 | 40 (QFP-48 adds 15 more) | 25 | 25 |
| DMA Channels | 4 | 4 | 4 | 4 | 4 | 0 (no DMA in legacy part) |
Key Differentiators
- Wider -40C to +105C operating range than the A-grade equivalent (vs EFM8UB20F64G-A-QFN32)
- Integrated DMA controller absent in legacy C8051F381 (vs C8051F381-GM)
- 64 kB Flash vs 16 kB Flash in lower-tier same-package sibling (vs EFM8UB10F16G-QFN32)
Design Notes
Route the USB D+ and D- lines as a 90 ohm differential pair with characteristic impedance Zo = 90 ohm +/- 10% per ATS-001 USB 2.0 signal-integrity guidelines. Keep the D+/D- traces length-matched within 150 mil, avoid right-angle bends, and place the ESD protection diode within 3 mm of the USB connector. The QFN-32 (5x5 mm) exposed thermal pad must be soldered to a continuous ground plane that is stitched with vias to the inner GND layers for both thermal dissipation and signal return.
The internal 3.3V LDO regulator (pin VDD) can source up to 100 mA to external pull-ups and indicator LEDs; do not exceed this rating. For USB bus-powered applications, use the VBUS pin (5V tolerant) to sense attachment and to drive the internal pull-up resistor on D+. Add a 4.7 uF ceramic decoupling capacitor on VDD placed within 1 mm of the pin, plus a 0.1 uF high-frequency bypass cap on VBUS. The internal LDO is not designed for heavy loads; if your design needs more than 50 mA, use an external 3.3V regulator.
Do not connect VBUS directly to any 3.3V logic pin; VBUS is 5V and the I/O pins are only 5V tolerant, not 5V logic-level. Use the internal LDO output (VDD) for logic-level pull-ups. When migrating from the legacy C8051F381-GM, note that the EFM8UB2 USB peripheral register names changed slightly - the Silicon Labs configuration wizard will auto-translate, but hand-written register code requires review. Do not omit the VBUS sense resistor (typically 10 kOhm to VDD) or the USB host will not enumerate properly.
Compliance Information
RoHS and REACH compliant per Silicon Labs product declaration. Not AEC-Q100 qualified - this is an industrial-grade 8-bit MCU, not an automotive part. For automotive applications, consider the C8051F385/6 automotive-grade variants. Halogen-free status not explicitly stated in the datasheet.
