LM4128AMF-2.5 Equivalent & Substitute Parts

Part Overview

The LM4128AMF-2.5 is a Series Voltage Reference IC from Texas Instruments, delivering a fixed 2.5V output with ±0.1% tolerance in a SOT-23-5 surface mount package. This precision voltage reference is designed for applications requiring stable reference voltages with low noise and minimal supply current. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	2.5V
Output Current	20 mA
Tolerance	±0.1%
Temperature Coefficient	75 ppm/°C
Noise (0.1Hz to 10Hz)	275 µVp-p
Input Voltage Range	2.9V ~ 5.5V
Supply Current	100 µA
Operating Temperature	-40°C ~ 125°C
Package	SOT-23-5 (SC-74A)
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution for the LM4128AMF-2.5 is determined by the following critical parameters: fixed 2.5V output voltage, ±0.1% tolerance, 20 mA output current capability, 75 ppm/°C temperature coefficient, SOT-23-5 package, and -40°C to 125°C operating temperature range.

Substitute parts are grouped into two categories:

Parametric Equivalents maintain all electrical specifications and package requirements, differing only in product status (active vs. obsolete) or packaging format (bulk vs. tape & reel). These parts are direct functional replacements.

Manufacturer Recommended Substitute (MAX6037AAUK25+T) offers compatible output voltage and package but with relaxed tolerance (±0.2% vs. ±0.1%), lower output current (5 mA vs. 20 mA), improved temperature coefficient (25 ppm/°C vs. 75 ppm/°C), and lower noise characteristics. This part is suitable for applications where the tighter tolerance and higher output current of the original are not required.

Parameter Comparison

Parameter	LM4128AMF-2.5	LM4128AMF-2.5/NOPB	LM4128AMFX-2.5/NOPB	LM4128AQ1MF2.5/NOPB	LM4128AQ1MFX2.5/NOPB	MAX6037AAUK25+T
Manufacturer	Texas Instruments	National Semiconductor	Texas Instruments	National Semiconductor	Texas Instruments	Analog Devices Inc./Maxim Integrated
Output Voltage	2.5V	2.5V	2.5V	2.5V	2.5V	2.5V
Tolerance	±0.1%	±0.1%	±0.1%	±0.1%	±0.1%	±0.2%
Output Current	20 mA	20 mA	20 mA	20 mA	20 mA	5 mA
Temperature Coefficient	75 ppm/°C	75 ppm/°C	75 ppm/°C	75 ppm/°C	75 ppm/°C	25 ppm/°C
Noise (0.1Hz to 10Hz)	275 µVp-p	275 µVp-p	275 µVp-p	275 µVp-p	275 µVp-p	14 µVp-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	100 µA	100 µA	100 µA	100 µA	100 µA	275 µA
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	Not specified	ROHS3 Compliant	ROHS3 Compliant
Automotive Grade	No	No	No	Yes (AEC-Q100)	Yes (AEC-Q100)	No

Engineering Selection Recommendations

For direct replacement of the LM4128AMF-2.5 in active production, select from the parametric equivalent parts: LM4128AMF-2.5/NOPB, LM4128AMFX-2.5/NOPB, LM4128AQ1MF2.5/NOPB, or LM4128AQ1MFX2.5/NOPB. All maintain identical electrical specifications and package requirements.

For new designs or applications where component availability is critical, LM4128AMFX-2.5/NOPB and LM4128AQ1MFX2.5/NOPB are preferred due to active product status and ROHS3 compliance.

For automotive applications requiring AEC-Q100 qualification, select LM4128AQ1MF2.5/NOPB or LM4128AQ1MFX2.5/NOPB.

The MAX6037AAUK25+T is suitable only for applications where the relaxed tolerance (±0.2%), lower output current (5 mA), and higher supply current (275 µA) are acceptable. This part offers superior temperature stability (25 ppm/°C) and lower noise performance but does not meet the 20 mA output current requirement of the original specification.

Frequently Asked Questions (FAQ)

Q: Can I use MAX6037AAUK25+T as a direct replacement for LM4128AMF-2.5?

A: No. While both parts share the same 2.5V output voltage and SOT-23-5 package, the MAX6037AAUK25+T has a maximum output current of 5 mA compared to the LM4128AMF-2.5's 20 mA capability. Use this part only if your application requires less than 5 mA output current.

Q: What is the difference between LM4128AMF-2.5/NOPB and LM4128AMFX-2.5/NOPB?

A: Both parts are electrically identical with the same specifications. The primary differences are manufacturer (National Semiconductor vs. Texas Instruments), product status (both active), and RoHS compliance (ROHS3 for the AMFX variant). The AMFX variant is preferred for new designs due to explicit ROHS3 compliance.

Q: Are the automotive-grade variants (AQ1) suitable for non-automotive applications?

A: Yes. The LM4128AQ1MF2.5/NOPB and LM4128AQ1MFX2.5/NOPB maintain all electrical specifications of the standard variants and include AEC-Q100 qualification. These parts can be used in any application requiring the LM4128 specifications.

Q: What packaging options are available?

A: All substitute parts use the SOT-23-5 (SC-74A) surface mount package. Packaging formats differ: bulk packaging for LM4128AQ1MF2.5/NOPB, tape & reel for LM4128AQ1MFX2.5/NOPB and MAX6037AAUK25+T, and standard format for LM4128AMF-2.5/NOPB and LM4128AMFX-2.5/NOPB.

Q: Is the LM4128AMF-2.5 still available for purchase?

A: The LM4128AMF-2.5 is listed as obsolete. For ongoing production, use active equivalents: LM4128AMF-2.5/NOPB, LM4128AMFX-2.5/NOPB, LM4128AQ1MF2.5/NOPB, or LM4128AQ1MFX2.5/NOPB.

Q: What are the key electrical parameters that determine substitution compatibility?

A: The critical parameters are fixed 2.5V output voltage, ±0.1% tolerance, 20 mA output current, 75 ppm/°C temperature coefficient, and -40°C to 125°C operating temperature range. Any substitute must maintain these specifications for direct replacement.

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