Silicon Labs C8051F390-A-GMR

Overview

C8051F390-A-GMR from Silicon Labs is a mixed-signal 8051-based microcontroller with 16 kB Flash, 512 B EEPROM, and integrated 10-bit ADC (500 ksps), dual 10-bit current-output DACs, precision temperature sensor (±2 °C), and comparator - deployed in industrial sensor nodes and low-power embedded control systems operating from 1.8–3.6 V.

For engineers reviewing the C8051F390-A-GMR datasheet, C8051F390-A-GMR pinout, C8051F390-A-GMR application, or C8051F390-A-GMR equivalent, key selection considerations include its 49 MHz ±2% internal oscillator (crystal-less UART support), 24-pin QFN package, 21 GPIO, dual SMBus/I²C interfaces, and Stop mode current of 200 nA - critical for battery-powered instrumentation and edge sensing.

Technical Context

The C8051F390-A-GMR implements a pipelined CIP-51 8051 core delivering 50 MIPS at 50 MHz, with on-the-fly clock source switching between 49 MHz high-frequency and 80 kHz low-power oscillators. Its analog subsystem includes two independent 10-bit IDACs with programmable update triggers (timer overflow, CNVSTR edge) and reset-resilient output scheduling.

Digital peripherals include six 16-bit timers, a 16-bit programmable counter array (PCA) supporting PWM (8–16 bit), capture/compare, and watchdog functions; plus UART, dual SMBus (I²C-compatible), and SPI - all routed via a priority crossbar to 21 configurable I/O pins.

Key Specifications

Pinout & Package

Package: 24-pin QFN (4×4 mm, 0.5 mm pitch), wettable flank, RoHS-compliant, exposed thermal pad.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar mixed-signal microcontroller applications.

Compared with SIM3U1xx-F-GM and C8051F340-GQR, the C8051F390-A-GMR delivers optimal integration for ultra-low-power analog-intensive tasks - uniquely combining dual IDACs, ±2 °C temp sensor, and crystal-less UART in a 24-pin QFN, making it irreplaceable for compact, battery-operated sensor transmitters despite its "Not Recommended for New Designs" status.

Availability

C8051F390-A-GMR is available at Aetrix Electronics and suitable for industrial sensor nodes, smart transmitter modules, and low-power edge controllers requiring stable component supply and long-term obsolescence management.

Supply support for C8051F390-A-GMR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Silicon Labs is a fabless semiconductor company specializing in silicon timing, IoT connectivity, and mixed-signal MCU solutions for industrial, automotive, and consumer markets.

The C8051F39x family was designed for cost-sensitive, low-power embedded systems requiring high analog integration - especially where small footprint, crystal-less operation, and on-die temperature sensing reduce BOM count and calibration overhead.

FAQ

What is the maximum ADC sampling rate supported by the C8051F390-A-GMR?

The C8051F390-A-GMR supports a maximum ADC0 throughput of 500 ksps under optimal conditions - achieved with single-ended inputs, internal 2.4 V reference, and minimal track time configuration. Actual sustained rate depends on channel count, resolution mode, and reference source; the 10-bit result is right-justified in the ADC0H:ADC0L registers. This rate enables real-time acquisition of fast-changing analog signals such as vibration or acoustic waveforms in the C8051F390-A-GMR's target applications.

Does the C8051F390-A-GMR support crystal-less UART operation?

Yes, the C8051F390-A-GMR supports crystal-less UART operation using its 49 MHz ±2% internal high-frequency oscillator. This oscillator provides sufficient accuracy for standard UART baud rates (e.g., 9600, 115200) without requiring an external crystal or resonator - reducing BOM cost and PCB area. The C8051F390-A-GMR achieves this via factory-trimmed oscillator calibration and dynamic frequency adjustment logic, as documented in Section 26.2 of the datasheet.

What is the operating temperature range for the C8051F390-A-GMR?

The C8051F390-A-GMR is rated for operation from –40 °C to +105 °C - consistent with the 'F39x' variant designation in the C8051F39x/37x family. This extended industrial temperature range allows deployment in demanding environments such as motor drives, outdoor sensors, and under-hood automotive modules. The on-die temperature sensor maintains ±2 °C accuracy across this full range without user calibration, directly supporting thermal protection and compensation functions within the C8051F390-A-GMR.

How many I²C-compatible interfaces does the C8051F390-A-GMR provide?

The C8051F390-A-GMR integrates two fully independent SMBus interfaces (SMBus0 and SMBus1), both compliant with I²C protocol specifications including clock stretching, arbitration, and 7-bit addressing. Each interface supports master and slave modes, configurable SCL timeout, and hardware address recognition - enabling simultaneous communication with multiple sensors or peripherals. This dual-SMBus capability is a key differentiator of the C8051F390-A-GMR in sensor hub and multi-device control applications.

Is the C8051F390-A-GMR pin-compatible with other devices in the C8051F39x family?

Yes, the C8051F390-A-GMR shares the same 24-pin QFN package and pinout with C8051F391/394/395 variants - confirmed by Figure 4.2 (C8051F390/1/4/5 Pinout Diagram) in the datasheet. All share identical power, ground, debug, oscillator, and primary I/O pin assignments. Functional differences (e.g., Flash size, RAM, peripheral enable bits) are software-configurable; hardware layout is interchangeable across these variants, simplifying design reuse for the C8051F390-A-GMR and its siblings.