C8051F126R Equivalent & Substitute Parts

Part Overview

The C8051F126R is an 8-bit microcontroller from Silicon Labs' C8051F12x series, featuring 128KB FLASH memory, 50MHz operation, and comprehensive peripheral integration including analog-to-digital converters, PWM, and communication interfaces. The device is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design considerations.

Key Parameters

Parameter	Value
Core Processor	8051
Core Size	8-Bit
Speed	50MHz
Program Memory Size	128KB (128K x 8) FLASH
RAM Size	8.25K x 8
Voltage Supply (Vcc/Vdd)	2.7V ~ 3.6V
Number of I/O	64
Data Converters	A/D 8x8b, 8x10b; D/A 2x12b
Connectivity	EBI/EMI, SMBus (2-Wire/I2C), SPI, UART/USART
Peripherals	Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
Operating Temperature	-40°C ~ 85°C (TA)
Package	100-TQFP (14x14)
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution of the C8051F126R is determined by strict equivalence across the following critical parameters:

Core Architecture: 8051-based processor maintaining instruction set compatibility
Memory Configuration: 128KB FLASH program memory and 8.25K x 8 RAM
Operating Frequency: 50MHz clock speed
Voltage Range: 2.7V to 3.6V supply compatibility
I/O Count: 64 I/O pins
Peripheral Set: Identical analog and digital peripheral integration
Package Form Factor: 100-TQFP (14x14) surface mount package

The C8051F126-GQ qualifies as a direct substitute based on complete alignment with all specified electrical and mechanical parameters. Differences exist only in packaging format (tray versus tube), product lifecycle status, and compliance certifications.

Parameter Comparison

Parameter	C8051F126R	C8051F126-GQ
Manufacturer	Silicon Labs	Silicon Labs
Series	C8051F12x	C8051F12x
Core Processor	8051	8051
Core Size	8-Bit	8-Bit
Speed	50MHz	50MHz
Program Memory Size	128KB (128K x 8) FLASH	128KB (128K x 8) FLASH
RAM Size	8.25K x 8	8.25K x 8
Voltage Supply (Vcc/Vdd)	2.7V ~ 3.6V	2.7V ~ 3.6V
Number of I/O	64	64
Data Converters	A/D 8x8b, 8x10b; D/A 2x12b	A/D 8x8b, 8x10b; D/A 2x12b
Connectivity	EBI/EMI, SMBus (2-Wire/I2C), SPI, UART/USART	EBI/EMI, SMBus (2-Wire/I2C), SPI, UART/USART
Peripherals	Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT	Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
Operating Temperature	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)
Package / Case	100-TQFP (14x14)	100-TQFP (14x14)
Mounting Type	Surface Mount	Surface Mount
Product Status	Obsolete	Not For New Designs
RoHS Status	RoHS non-compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)	3 (168 Hours)
ECCN	3A991A2	3A991A2
HTSUS	8542.31.0001	8542.31.0001

Engineering Selection Recommendations

The C8051F126-GQ serves as the functional equivalent for C8051F126R applications. Selection between these parts is determined by compliance and lifecycle requirements:

C8051F126-GQ is appropriate for:

Systems requiring ROHS3 compliance
Applications where RoHS certification is a contractual or regulatory requirement
Designs transitioning from obsolete inventory to compliant alternatives

C8051F126R remains suitable for:

Legacy system maintenance and repair where original part specifications are mandated
Applications with no RoHS compliance requirement
Existing designs where component substitution is not feasible

Both parts maintain identical electrical performance, memory configuration, peripheral functionality, and thermal operating range. Package form factor (tray versus tube) does not affect electrical or mechanical compatibility in circuit applications.

Frequently Asked Questions (FAQ)

Q: Are C8051F126R and C8051F126-GQ electrically interchangeable?

A: Yes. Both devices share identical core processor architecture, memory capacity, clock speed, voltage specifications, I/O count, and peripheral integration. They are pin-compatible and functionally equivalent.

Q: What is the difference between these two part numbers?

A: The primary differences are packaging format (tube versus tray), product lifecycle status (obsolete versus not for new designs), and RoHS compliance certification (non-compliant versus ROHS3 compliant). Electrical and mechanical specifications are identical.

Q: Can I use C8051F126-GQ as a direct replacement in existing C8051F126R designs?

A: Yes. The C8051F126-GQ is a direct substitute. No circuit modifications, firmware changes, or PCB layout alterations are required. The 100-TQFP package dimensions and pin assignments are identical.

Q: Does the RoHS compliance difference affect circuit performance?

A: No. RoHS compliance relates to material composition and manufacturing process, not electrical performance or functionality. Both parts operate identically within specified parameters.

Q: Are there any thermal or reliability differences between these parts?

A: No. Both parts share identical operating temperature range (-40°C to 85°C), moisture sensitivity level (MSL 3), and thermal characteristics.

Q: Which part should I specify for new designs?

A: For new designs, the C8051F126-GQ is the appropriate choice due to its ROHS3 compliance and "Not For New Designs" status indicating continued availability. The C8051F126R is classified as obsolete and should not be specified for new development.

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