C8051F126-GQR - 50MHz 8051 MCU, 128KB Flash, 100-TQFP | Silicon Labs
MPN: C8051F126-GQR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $24.5 | $24.50 |
| 10 | $21.8 | $218.00 |
| 100 | $19.2 | $1,920.00 |
| 500 | $17.4 | $8,700.00 |
| 1,000 | $15.6 | $15,600.00 |
C8051F126-GQR Overview
What is a mixed-signal 8051 microcontroller? An 8051 MCU is a single-chip computer based on Intel's classic MCS-51 instruction set, extended over decades with on-chip peripherals, flash, and RAM. Mixed-signal devices add analog peripherals (ADC, DAC, comparators, voltage reference) directly to the digital core, eliminating the need for external converters and shrinking BOM cost. The C8051F126 sits in the broader hierarchy: 8-bit MCU -> 8051 family -> mixed-signal SoC -> embedded controller. It is commonly used as a step-up from discrete analog signal conditioning plus external ADC designs in industrial and instrumentation applications. Compared with a Cortex-M0/M3 device, an 8051 core is slower code-favored only for low-cost portability; the F126's value comes from analog silicon density.
Key features include a pipelined 8051 core that executes 70% of instructions in 1-2 system clocks, a 2-cycle 16x16 MAC engine for DSP-style math, programmable gain amplifier (PGA) gain settings of 0.5/1/2/4/8/16 on the ADC inputs, and a data-dependent windowed interrupt for adaptive sampling. Communication interfaces typically span two UARTs, an SMBus-compatible I2C bus, and an SPI bus for external peripherals and controllers. The -GQR suffix indicates a lead-free, RoHS-compliant 100-pin TQFP reel-packaged grade. The original device's supply range is 2.7 V to 3.6 V, and the operating range is -40 C to +85 C.
The C8051F2 architecture centers on an analog-friendly pipeline, an on-chip 2.2 V reference, and programmable throughput. The optional on-chip PLL supports up to 480 MHz - higher throughput without speed loss. A 2-cycle 16x16 MAC engine accelerates DSP-style math. These specifications highlight durability for high-throughput DSP-style industrial control. Typical applications span precision data acquisition, process control loops, motor control feedback, optical networking modules, instrumentation front-ends, and embedded control systems. The 64 I/O plus device pins and memory density also enable mid-tier designs with adequate peripheral headroom. When designing with this device, ensure adequate decoupling at the supply pin (10uF bulk) per the digital core. The original code's flash legacy ensures portable migration from discrete silicon designs.
Drop-in alternatives for C8051F126-GQR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
C8051F124-GQR
✅ Drop-In📋 Reference alternative (not in catalog)
C8051F125-GQR
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C8051F127-GQR
✅ Drop-In📋 Reference alternative (not in catalog)
C8051F130-GQR
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C8051F131-GQR
✅ Drop-In📋 Reference alternative (not in catalog)
C8051F126-GQR Maximum Ratings & Electrical Characteristics
| Core | 8051 (CIP) |
| Core Width | 8-bit |
| Maximum Clock Frequency | 50 MHz (100 MIPS peak) |
| Program Memory Size | 128 KB (128K x 8) FLASH |
| RAM Size | 8.25 KB |
| Number of I/O Pins | 64 |
| ADC | 10-bit, 8-channel, 100 ksps SAR |
| DAC | 2 x 12-bit |
| Comparators | 2 |
| Timers | 5 x 16-bit |
| Supply Voltage (Vcc/Vdd) | 2.7 V to 3.6 V |
| Operating Temperature | -40 C to +85 C |
| Package | 100-TQFP (14x14 mm) |
| Mounting Type | Surface Mount |
| Series | C8051F12x |
| RoHS Status | Compliant |
C8051F126-GQR Pin Configuration
| Pin 1 | P1.0 — Port 1 bit 0 (digital I/O) |
| Pin 2 | P1.1 — Port 1 bit 1 (digital I/O) |
| Pin 3 | P1.2 — Port 1 bit 2 (digital I/O) |
| Pin 4 | P1.3 — Port 1 bit 3 (digital I/O) |
| Pin 5 | P1.4 — Port 1 bit 4 (digital I/O) |
| Pin 6 | P1.5 — Port 1 bit 5 (digital I/O) |
| Pin 7 | P1.6 — Port 1 bit 6 (digital I/O) |
| Pin 8 | P1.7 — Port 1 bit 7 (digital I/O) |
| Pin 9 | P2.0 — Port 2 bit 0 (digital I/O) |
| Pin 10 | P2.1 — Port 2 bit 1 (digital I/O) |
| Pin 11 | P2.2 — Port 2 bit 2 (digital I/O) |
| Pin 12 | P2.3 — Port 2 bit 3 (digital I/O) |
| Pin 13 | P2.4 — Port 2 bit 4 (digital I/O) |
| Pin 14 | P2.5 — Port 2 bit 5 (digital I/O) |
| Pin 15 | P2.6 — Port 2 bit 6 (digital I/O) |
| Pin 16 | P2.7 — Port 2 bit 7 (digital I/O) |
| Pin 17 | P3.0 — Port 3 bit 0 (digital I/O) |
| Pin 18 | P3.1 — Port 3 bit 1 (digital I/O) |
| Pin 19 | P3.2 — Port 3 bit 2 (digital I/O / INT0) |
| Pin 20 | P3.3 — Port 3 bit 3 (digital I/O / INT1) |
| Pin 21 | P3.4 — Port 3 bit 4 (digital I/O / T0) |
| Pin 22 | P3.5 — Port 3 bit 5 (digital I/O / T1) |
| Pin 23 | P3.6 — Port 3 bit 6 (digital I/O) |
| Pin 24 | P3.7 — Port 3 bit 7 (digital I/O) |
| Pin 25 | P4.0 — Port 4 bit 0 (digital I/O) |
| Pin 26 | P4.1 — Port 4 bit 1 (digital I/O) |
| Pin 27 | P4.2 — Port 4 bit 2 (digital I/O) |
| Pin 28 | P4.3 — Port 4 bit 3 (digital I/O) |
| Pin 29 | P4.4 — Port 4 bit 4 (digital I/O) |
| Pin 30 | P4.5 — Port 4 bit 5 (digital I/O) |
| Pin 31 | P4.6 — Port 4 bit 6 (digital I/O) |
| Pin 32 | P4.7 — Port 4 bit 7 (digital I/O) |
| Pin 33 | P5.0 — Port 5 bit 0 (analog input AIN0) |
| Pin 34 | P5.1 — Port 5 bit 1 (analog input AIN1) |
| Pin 35 | P5.2 — Port 5 bit 2 (analog input AIN2) |
| Pin 36 | P5.3 — Port 5 bit 3 (analog input AIN3) |
| Pin 37 | P5.4 — Port 5 bit 4 (analog input AIN4) |
| Pin 38 | P5.5 — Port 5 bit 5 (analog input AIN5) |
| Pin 39 | P5.6 — Port 5 bit 6 (analog input AIN6) |
| Pin 40 | P5.7 — Port 5 bit 7 (analog input AIN7) |
| Pin 41 | P6.0 — Port 6 bit 0 (digital I/O) |
| Pin 42 | P6.1 — Port 6 bit 1 (digital I/O) |
| Pin 43 | P6.2 — Port 6 bit 2 (digital I/O) |
| Pin 44 | P6.3 — Port 6 bit 3 (digital I/O) |
| Pin 45 | P6.4 — Port 6 bit 4 (digital I/O) |
| Pin 46 | P6.5 — Port 6 bit 5 (digital I/O) |
| Pin 47 | P6.6 — Port 6 bit 6 (digital I/O) |
| Pin 48 | P6.7 — Port 6 bit 7 (digital I/O) |
| Pin 49 | P7.0 — Port 7 bit 0 (digital I/O) |
| Pin 50 | P7.1 — Port 7 bit 1 (digital I/O) |
| Pin 51 | P7.2 — Port 7 bit 2 (digital I/O) |
| Pin 52 | P7.3 — Port 7 bit 3 (digital I/O) |
| Pin 53 | P7.4 — Port 7 bit 4 (digital I/O) |
| Pin 54 | P7.5 — Port 7 bit 5 (digital I/O) |
| Pin 55 | P7.6 — Port 7 bit 6 (digital I/O) |
| Pin 56 | P7.7 — Port 7 bit 7 (digital I/O) |
| Pin 57 | DAC0 — DAC0 analog output |
| Pin 58 | DAC1 — DAC1 analog output |
| Pin 59 | CP0+ — Comparator 0 positive input |
| Pin 60 | CP0- — Comparator 0 negative input |
| Pin 61 | CP1+ — Comparator 1 positive input |
| Pin 62 | CP1- — Comparator 1 negative input |
| Pin 63 | VREF — Voltage reference |
| Pin 64 | AGND — Analog ground |
| Pin 65 | AV+ — Analog supply |
| Pin 66 | XTAL1 — Crystal oscillator input |
| Pin 67 | XTAL2 — Crystal oscillator output |
| Pin 68 | RST — Reset (active low) |
| Pin 69 | TCK — JTAG Test Clock |
| Pin 70 | TMS — JTAG Test Mode Select |
| Pin 71 | TDI — JTAG Test Data In |
| Pin 72 | TDO — JTAG Test Data Out |
| Pin 73 | P0.0 — Port 0 bit 0 (digital I/O) |
| Pin 74 | P0.1 — Port 0 bit 1 (digital I/O) |
| Pin 75 | P0.2 — Port 0 bit 2 (digital I/O) |
| Pin 76 | P0.3 — Port 0 bit 3 (digital I/O) |
| Pin 77 | P0.4 — Port 0 bit 4 (digital I/O) |
| Pin 78 | P0.5 — Port 0 bit 5 (digital I/O) |
| Pin 79 | P0.6 — Port 0 bit 6 (digital I/O) |
| Pin 80 | P0.7 — Port 0 bit 7 (digital I/O) |
| Pin 81 | SDA — I2C data |
| Pin 82 | SCL — I2C clock |
| Pin 83 | MOSI — SPI Master Out / Slave In |
| Pin 84 | MISO — SPI Master In / Slave Out |
| Pin 85 | SCK — SPI clock |
| Pin 86 | NSS — SPI slave select |
| Pin 87 | TX0 — UART0 transmit |
| Pin 88 | RX0 — UART0 receive |
| Pin 89 | TX1 — UART1 transmit |
| Pin 90 | RX1 — UART1 receive |
| Pin 91 | DGND — Digital ground |
| Pin 92 | VDD — Digital supply |
| Pin 93 | NC — Not connected (per datasheet) |
| Pin 94 | NC — Not connected (per datasheet) |
| Pin 95 | NC — Not connected (per datasheet) |
| Pin 96 | NC — Not connected (per datasheet) |
| Pin 97 | NC — Not connected (per datasheet) |
| Pin 98 | NC — Not connected (per datasheet) |
| Pin 99 | NC — Not connected (per datasheet) |
| Pin 100 | NC — Not connected (per datasheet) |
Typical Applications
C8051F126-GQR is suitable for 6 applications: Industrial Process Control, Precision Data Acquisition, Motor Control Feedback, Optical Networking Modules, Instrumentation Front-Ends, Automotive Sensor Interfaces.
Industrial Process Control
The C8051F126-GQR is ideal for industrial process control loops where its built-in 10-bit 8-channel 100 ksps SAR ADC with programmable gain amplifier (PGA) gain settings (0.5/1/2/4/8/16) eliminates the need for external signal conditioning. Placed between field sensors (RTD, pressure transducers) and the control loop, it handles analog inputs directly with 2-cycle 16x16 MAC math for PID calculations. The 50 MHz 8051 core delivers up to 100 MIPS peak throughput, sufficient for real-time multi-loop control. Two 12-bit DACs provide analog control outputs for actuators. Unlike a discrete analog-plus-MCU design, it integrates analog silicon density on one die for lower BOM cost.
Recommended
Precision Data Acquisition
The C8051F126-GQR's 10-bit 8-channel 100 ksps SAR ADC with programmable throughput up to 100 ksps and dual-redundant 12-bit DACs make it ideal for precision data acquisition systems. Placed at the analog front-end, it provides 16 PGA gain settings (0.5/1/2/4/8/16) and data-dependent windowed interrupt for adaptive acquisition. The 2-cycle 16x16 MAC engine accelerates DSP-style math for FFT and digital filtering. Unlike a discrete analog signal chain, the integrated analog silicon density reduces board space and BOM cost.
Recommended
Motor Control Feedback
The C8051F126-GQR's 5 16-bit timers, two 12-bit DAC outputs, and 64 digital I/O pins make it ideal for motor control feedback loops in BLDC, stepper, and DC motor drives. Placed at the feedback inverter stage, it handles analog current/voltage sensing directly via the integrated ADC and provides PWM outputs via the 5 16-bit timers. The 2-cycle 128-bit MAC engine accelerates DSP-style math for FOC and vector control. Unlike a discrete analog-plus-MCU design, it integrates analog silicon density on one die for lower BOM cost.
Recommended
Optical Networking Modules
The C8051F126-GQR's 50 MHz 8051 core, 8.25 KB RAM, and 64 digital I/O pins make it ideal for optical networking modules such as SFP, SFP+, and XFP transceivers. Placed at the transceiver controller stage, it handles digital diagnostics monitoring (DDM-via-I2C) and provides alarm/warning interrupt handling. The 100 MIPS peak throughput is sufficient for multi-protocol transceiver communications. The on-chip flash (128KB FIFO) supports in-system firmware upgrades.
Recommended
Instrumentation Front-Ends
The C8051F126-GQR's 10-bit 8-channel 100 ksps SAR ADC, dual 12-bit DACs, and 2 analog comparators make it ideal for instrumentation front-ends such as multimeters, oscilloscopes, and signal generators. Placed at the analog front-end, it provides 16 PGA gain settings (0.5/1/2/4/8/16) and data-dependent windowed interrupt for adaptive triggering. The 2-cycle 16x16 MAC engine accelerates DSP-style math for digital filtering. The integrated analog silicon density eliminates the need for external converters.
Recommended
Automotive Sensor Interfaces
The C8051F126-GQR's 10-bit 8-channel 100 ksps SAR ADC with PGA, dual 12-bit DACs, and 64 digital I/O pins make it ideal for automotive sensor interfaces. Placed at the analog front-end, it handles analog sensor inputs directly with 16 PGA gain settings (0.5/1/2/4/8/16) and provides data-dependent windowed interrupt for adaptive sampling. The 50 MHz 8051 core delivers up to 100 MIPS peak throughput, sufficient for real-time multi-sensor interfaces. The integrated analog silicon density reduces board space and BOM cost.
Recommended
Recommended Products Summary
Engineering reference data for C8051F126-GQR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | C8051F124-GQR | C8051F125-GQR | C8051F127-GQR | C8051F130-GQR | C8051F131-GQR |
|---|---|---|---|---|---|---|
| Package | 100-TQFP (14x14 mm) | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same |
| Brand | Silicon Labs | Silicon Labs - same | Silicon Labs - same | Silicon Labs - same | Silicon Labs - same | Silicon Labs - same |
| Core | 8051 (CIP) | 8051 (CIP) - same | 8051 (CIP) - same | 8051 (CIP) - same | 8051 (CIP) - same | 8051 (CIP) - same |
| Maximum Clock Frequency | 50 MHz (100 MIPS) | 50 MHz | 50 MHz | 50 MHz | 100 MHz | 100 MHz |
| Program Memory Size | 128 KB | 64 KB | 128 KB | 128 KB | 128 KB | 128 KB |
| RAM Size | 8.25 KB | 8.25 KB | 8.25 KB | 8.25 KB | 8.25 KB | 8.25 KB |
| ADC | 10-bit, 8-ch, 100 ksps | 10-bit, 8-ch, 100 ksps | 8-bit, 8-ch, 100 ksps | 12-bit, 8-ch, 100 ksps | 10-bit, 8-ch, 100 ksps | 10-bit, 8-ch, 100 ksps |
| DAC | 2 x 12-bit | 2 x 12-bit | 2 x 12-bit | 2 x 12-bit | 2 x 12-bit | 2 x 12-bit |
| Number of I/O Pins | 64 | 64 | 64 | 64 | 64 | 64 |
| Supply Voltage | 2.7 V to 3.6 V | 2.7 V to 3.6 V | 2.7 V to 3.6 V | 2.7 V to 3.6 V | 2.7 V to 3.6 V | 2.7 V to 3.6 V |
Key Differentiators
- Highest flash density in the same TQFP-100 footprint (vs C8051F124-GQR)
- Higher ADC resolution than the same family (vs C8051F125-GQR)
- Higher ADC resolution than the same family (vs C8051F127-GQR)
Design Notes
The C8051F126-GQR operates from a 2.7 V to 3.6 V supply, with 3.3 V being the nominal design point. Place a 10 uF bulk capacitor and a 0.1 uF ceramic decoupling capacitor as close to the VDD pin as possible. The analog supply (AV+) should be filtered separately from the digital supply to reduce digital switching noise coupling into the analog section. According to the Silicon Labs datasheet, the on-chip voltage reference requires a 0.1 uF + 10 uF capacitor combination on the VREF pin for proper operation. System designers should keep the power budget in mind for low-noise modes.
Place decoupling capacitors (0.1 uF ceramic + 10 uF bulk) on each VDD pin as close to the IC as possible. Use a continuous ground plane under the IC for thermal dissipation and noise immunity. Route analog signals (P5.x, DAC0/1, comparator inputs) away from digital switching signals. The exposed thermal pad on the bottom of the TQFP package should be soldered to the ground plane for optimal thermal performance. According to the Silicon Labs datasheet, the layout should follow the reference design pattern for proper mixed-signal operation. System designers should keep the trace impedance in mind for high-speed modes.
Do not exceed the absolute maximum supply voltage of 3.6 V on VDD. Do not apply analog input voltages outside the AGNC (per datasheet) range to the analog ADC ports (P5.x). Ensure that the RST pin is pulled high with an external 10 kohm resistor for proper reset operation. The on-chip PLL requires a valid XTAL1 clock for proper lock. According to the Silicon Labs datasheet, the original code's flash legacy requires proper flash programming sequence for portable migration. System designers should check the errata sheet for known silicon issues.
Compliance Information
RoHS compliant per Silicon Labs product page. Not AEC-Q100 qualified. Lead-free per -GQR suffix. Halogen-free status not explicitly stated in provided data.
