LM4128CMF-2.5 Equivalent & Substitute Parts

Part Overview

The LM4128CMF-2.5 is a series voltage reference IC from Texas Instruments, delivering a fixed 2.5V output with ±0.5% tolerance in a SOT-23-5 surface mount package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The part operates across a -40°C to 125°C temperature range with 100µA supply current and 20mA output capability, suitable for precision analog applications requiring stable voltage references.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	2.5V
Output Tolerance	±0.5%
Output Current	20 mA
Temperature Coefficient	100ppm/°C
Noise (0.1Hz to 10Hz)	275µVp-p
Input Voltage Range	2.9V ~ 5.5V
Supply Current	100µA
Operating Temperature	-40°C ~ 125°C
Package	SOT-23-5 (SC-74A)
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution for the LM4128CMF-2.5 is determined by the following critical parameters: fixed 2.5V output voltage, ±0.5% tolerance, 20mA output current capability, SOT-23-5 package compatibility, and -40°C to 125°C operating temperature range. Parts are grouped into two categories:

Direct Equivalents (Parametric Match): Parts maintaining identical electrical specifications across output voltage, tolerance, current rating, temperature coefficient, and noise characteristics. These include LM4128CMF-2.5/NOPB, LM4128CMFX-2.5/NOPB, LM4128CQ1MF2.5/NOPB, and LM4128CQ1MFX2.5/NOPB. All share the same base product number (LM4128) and package footprint.

Enhanced Equivalent (Manufacturer Recommended): The MAX6037AAUK25+T offers superior performance specifications (±0.2% tolerance, 25ppm/°C temperature coefficient, lower noise) while maintaining the same 2.5V output, SOT-23-5 package, and operating temperature range. This part is suitable for applications where improved accuracy is beneficial.

Parameter Comparison

Parameter	LM4128CMF-2.5	LM4128CMF-2.5/NOPB	LM4128CMFX-2.5/NOPB	LM4128CQ1MF2.5/NOPB	LM4128CQ1MFX2.5/NOPB	MAX6037AAUK25+T
Output Voltage	2.5V	2.5V	2.5V	2.5V	2.5V	2.5V
Tolerance	±0.5%	±0.5%	±0.5%	±0.5%	±0.5%	±0.2%
Output Current	20 mA	20 mA	20 mA	20 mA	20 mA	5 mA
Temperature Coefficient	100ppm/°C	100ppm/°C	100ppm/°C	100ppm/°C	100ppm/°C	25ppm/°C
Noise (0.1Hz to 10Hz)	275µVp-p	275µVp-p	275µVp-p	275µVp-p	275µVp-p	14µVp-p
Input Voltage Range	2.9V ~ 5.5V	2.9V ~ 5.5V	2.9V ~ 5.5V	2.9V ~ 5.5V	2.9V ~ 5.5V	2.7V ~ 5.5V
Supply Current	100µA	100µA	100µA	100µA	100µA	275µA
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C
Package	SOT-23-5	SOT-23-5	SOT-23-5	SOT-23-5	SOT-23-5	SOT-23-5
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	Non-compliant	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement: Select LM4128CMF-2.5/NOPB, LM4128CMFX-2.5/NOPB, LM4128CQ1MF2.5/NOPB, or LM4128CQ1MFX2.5/NOPB when electrical specifications must match the original design exactly. All four parts are active products with identical parametric performance. The LM4128CQ1MF2.5/NOPB and LM4128CQ1MFX2.5/NOPB variants include AEC-Q100 automotive qualification and are suitable for automotive-grade applications. The CMFX and CQ1MFX variants include extended temperature screening. All direct equivalents are ROHS3 compliant.

For Enhanced Performance: Select MAX6037AAUK25+T when improved accuracy and lower noise are acceptable. This part offers ±0.2% tolerance (versus ±0.5%), 25ppm/°C temperature coefficient (versus 100ppm/°C), and significantly reduced noise (14µVp-p versus 275µVp-p). The trade-off is reduced output current capability (5mA versus 20mA) and increased supply current (275µA versus 100µA). This substitution is suitable for precision analog applications where output current demand does not exceed 5mA.

Compliance Considerations: The original LM4128CMF-2.5 is RoHS non-compliant. All active substitutes are ROHS3 compliant, supporting modern manufacturing and environmental requirements.

Frequently Asked Questions (FAQ)

Q: Can LM4128CMF-2.5/NOPB directly replace LM4128CMF-2.5?

A: Yes. Both parts share identical electrical specifications, output voltage, tolerance, current ratings, and SOT-23-5 package. The primary difference is product status: the original is obsolete while the /NOPB variant is active. No circuit modifications are required.

Q: What is the difference between LM4128CMFX-2.5/NOPB and LM4128CMF-2.5/NOPB?

A: Both parts are parametrically identical. The "X" suffix indicates extended temperature screening and tape & reel packaging. Select the CMFX variant for applications requiring documented temperature performance verification.

Q: Are the automotive-qualified variants (LM4128CQ1MF2.5/NOPB and LM4128CQ1MFX2.5/NOPB) suitable for non-automotive applications?

A: Yes. Automotive-qualified parts meet AEC-Q100 standards and are fully compatible with non-automotive designs. They provide additional qualification documentation and reliability assurance.

Q: Can MAX6037AAUK25+T replace LM4128CMF-2.5 in all applications?

A: Not universally. The MAX6037AAUK25+T is suitable only when output current requirements do not exceed 5mA. Applications requiring the full 20mA output capability must use LM4128 variants. The MAX6037 is recommended for precision measurement and low-current reference applications.

Q: Are all substitute parts available in the same package?

A: Yes. All listed substitutes use the SOT-23-5 (SC-74A) package with identical pin configuration and footprint compatibility. No PCB layout modifications are necessary.

Q: What is the impact of increased supply current in MAX6037AAUK25+T?

A: The MAX6037 draws 275µA versus 100µA for LM4128 variants. In battery-powered or ultra-low-power applications, this 2.75× increase may impact system power budget. Evaluate power consumption requirements before selection.

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