EFM8BB21F16I-C-QFN20R is an 8-bit MCU from Silicon Labs' EFM8 Busy Bee family.

EFM8BB21F16I-C-QFN20R

EFM8BB21F16I-C-QFN20R is an 8-bit MCU from Silicon Labs’ EFM8 Busy Bee series. It adopts a pipelined C8051 core in a compact QFN20 (3×3 mm) package. The suffix R denotes tape-and-reel packaging; Grade I indicates industrial temperature grade. It is a general-purpose control chip featuring highly integrated analog peripherals, small form factor and low cost.

Key Specifications

- Core: Pipelined 8-bit C8051, up to 50 MHz

- Memory: 16 KB Flash, 2.25 KB RAM, no DAC

- Supply Voltage: 2.2 V ~ 3.6 V, integrated LDO

- Temperature Range: -40 ℃ ~ +125 ℃ (Industrial Grade)

- I/O: 16 GPIO pins, 5 V-tolerant I/Os

- Analog: 12-bit ADC with 15 external channels; 2 analog comparators; on-chip temperature sensor

- Timer / PWM: 5 general-purpose 16-bit timers; 3 PCA channels (PWM capable with hardware shutdown)

- Communication: 2 × UART, 1 × SPI, SMBus/I2C (master/slave) + dedicated high-speed I2C slave

- Package: QFN20, 3×3 mm, tape-and-reel (R)

- Debug: C2 single-wire debug interface

Functions

1. Basic I/O control: Key scan, indicator LED, digital input sensing, small load driving

2. Analog signal acquisition: Sampling voltage, current, temperature and sensor signals; threshold detection with comparators

3. PWM output: LED dimming, small motor speed regulation, fan control. PCA supports hardware fault shutdown for improved safety

4. Multi-interface communication: UART/SPI/I2C communication with host MCUs, sensors and modules; commonly used as a co-MCU to expand I/O and analog ports

5. Low-power standby: Multiple sleep modes supported, suitable for battery-powered devices

6. Flexible crossbar: Peripheral pins can be software-assigned for easier PCB layout

Applications

- Consumer Electronics: LED dimming, small home appliance control boards, handheld devices, battery sub-boards, key panels

- Sensor Modules: Temperature/pressure & current transmitters, signal conditioning boards

- Industrial Control: Small valve controllers, I/O acquisition modules, miniature drivers, industrial sensors

- Motor Control: Small DC motors, cooling fan speed control

- Portable Medical: Portable detection modules (non-high-grade medical)

- Auxiliary MCU: USB main boards, peripheral expansion for host chips, power monitoring boards