C8051F125 Equivalent & Substitute Parts

Part Overview

The C8051F125 is an 8-bit microcontroller from Silicon Labs' C8051F12x series, featuring a 50MHz 8051 core with 128KB FLASH program memory and integrated analog/digital conversion capabilities. This device is classified as Obsolete, making equivalent and substitute parts necessary for ongoing production, maintenance, and new design considerations. The part operates within a 2.7V to 3.6V supply range and includes comprehensive peripheral support including PWM, temperature sensing, and watchdog timer functionality.

Key Parameters

Parameter	Value
Core Processor	8051
Core Size	8-Bit
Speed	50MHz
Program Memory Size	128KB (128K x 8)
Program Memory Type	FLASH
RAM Size	8.25K x 8
Voltage Supply (Vcc/Vdd)	2.7V ~ 3.6V
Number of I/O	32
Data Converters	A/D 8x8b, 8x12b; 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 / Case	64-TQFP (10x10)
Mounting Type	Surface Mount
Moisture Sensitivity Level (MSL)	3 (168 Hours)

Substitute Part Grouping Explanation

Substitution for the C8051F125 is determined by strict equivalence across the following critical parameters:

Core Architecture: 8051 processor family
Memory Configuration: 128KB FLASH program memory, 8.25K x 8 RAM
Operating Specifications: 50MHz clock speed, 2.7V–3.6V supply voltage range
I/O Count: 32 I/O pins
Peripheral Set: Identical analog/digital conversion capabilities, connectivity interfaces, and support functions
Package Compatibility: 64-TQFP (10x10) surface mount form factor
Thermal Range: -40°C to 85°C operating temperature

The C8051F125-GQ variant maintains full electrical and functional equivalence to the base C8051F125, with differences limited to packaging format (Tray vs. standard) and regulatory compliance status.

Parameter Comparison

Parameter	C8051F125	C8051F125-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)	128KB (128K x 8)
Program Memory Type	FLASH	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	32	32
Data Converters	A/D 8x8b, 8x12b; D/A 2x12b	A/D 8x8b, 8x12b; 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	64-TQFP (10x10)	64-TQFP (10x10)
Mounting Type	Surface Mount	Surface Mount
Moisture Sensitivity Level (MSL)	3 (168 Hours)	3 (168 Hours)
Product Status	Obsolete	Not For New Designs
RoHS Status	RoHS non-compliant	RoHS Compliant

Engineering Selection Recommendations

The C8051F125-GQ is a direct functional equivalent to the C8051F125 across all electrical and mechanical specifications. Selection between these variants should be based on regulatory and compliance requirements:

C8051F125: Suitable for legacy system maintenance and replacement in existing designs where RoHS compliance is not mandated. Product status is Obsolete.
C8051F125-GQ: Appropriate for applications requiring RoHS compliance. Product status is Not For New Designs, indicating limited availability for future production.

Both variants share identical core functionality, memory configuration, I/O capability, and thermal operating range. Packaging format differs (standard vs. Tray), which may affect procurement and handling procedures but does not impact electrical performance or board-level integration.

Frequently Asked Questions (FAQ)

Q: Can C8051F125-GQ replace C8051F125 in existing designs?

A: Yes. The C8051F125-GQ is electrically and functionally equivalent. All core specifications—processor architecture, memory size, clock speed, supply voltage, I/O count, and peripheral functionality—are identical. Packaging format (Tray) is the only difference and does not affect circuit operation.

Q: What is the difference between C8051F125 and C8051F125-GQ?

A: The primary differences are packaging format (standard vs. Tray) and regulatory compliance. C8051F125-GQ is RoHS Compliant, while C8051F125 is RoHS non-compliant. Both maintain identical electrical specifications and pin compatibility in the 64-TQFP (10x10) package.

Q: Why is the C8051F125 marked as Obsolete?

A: Obsolete status indicates the part is no longer in active production by the manufacturer. For ongoing applications, the C8051F125-GQ variant is available, though it is also marked as Not For New Designs. Alternative microcontroller families should be evaluated for new product development.

Q: Are there any compatibility concerns when substituting these parts?

A: No compatibility concerns exist between C8051F125 and C8051F125-GQ. Both use the same 64-TQFP (10x10) package footprint, require identical supply voltage (2.7V–3.6V), and support the same peripheral interfaces and I/O configuration. Firmware and board-level design require no modification.

Q: What does "Not For New Designs" mean for the C8051F125-GQ?

A: This status indicates the manufacturer does not recommend using this part in new product designs. It may be used for maintenance, repair, or replacement in existing systems, but long-term availability is not guaranteed. New designs should consider alternative microcontroller solutions.

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