LM4128CMFX-3.3 Equivalent & Substitute Parts

Part Overview

The LM4128CMFX-3.3 is a Series Voltage Reference IC manufactured by Texas Instruments, designed to provide a fixed 3.3V output with ±0.5% tolerance in a SOT-23-5 surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The device operates across an input voltage range of 3.7V to 5.5V with a maximum output current of 20 mA, suitable for precision voltage reference applications in power management circuits.

Substiute Parts

LM4128CMFX-3.3

Texas InstrumentsIn Stock: 757LM4128CMFX-3.3 Datasheet

Current PartRFQ

LM4128CMF-3.3/NOPB

Texas InstrumentsIn Stock: 1307LM4128CMF-3.3/NOPB Datasheet

Parametric EquivalentRFQ

LM4128CMFX-3.3/NOPB

Texas InstrumentsIn Stock: 881LM4128CMFX-3.3/NOPB Datasheet

Parametric EquivalentRFQ

LM4128CQ1MF3.3/NOPB

Texas InstrumentsIn Stock: 3354LM4128CQ1MF3.3/NOPB Datasheet

Parametric EquivalentRFQ

LM4128CQ1MFX3.3/NOPB

Texas InstrumentsIn Stock: 1103LM4128CQ1MFX3.3/NOPB Datasheet

Parametric EquivalentRFQ

MAX6037AAUK33+T

Analog Devices Inc./Maxim IntegratedIn Stock: 3575MAX6037AAUK33+T Datasheet

MFR RecommendedRFQ

MAX6037BAUK33+T

Analog Devices Inc./Maxim IntegratedIn Stock: 1044MAX6037BAUK33+T Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the LM4128CMFX-3.3 are grouped based on strict electrical and mechanical compatibility criteria:

Parametric Equivalents (Texas Instruments LM4128 Series):

• LM4128CMF-3.3/NOPB
• LM4128CMFX-3.3/NOPB
• LM4128CQ1MF3.3/NOPB
• LM4128CQ1MFX3.3/NOPB

These parts maintain identical electrical specifications: 3.3V fixed output, ±0.5% tolerance, 20 mA output current, 100 ppm/°C temperature coefficient, and SOT-23-5 packaging. Differences exist only in packaging format (Tape & Reel vs. Cut Tape) and product status (Active vs. Obsolete). The automotive-qualified variants (CQ1 suffix) include AEC-Q100 certification and are suitable for automotive applications.

Manufacturer Recommended Alternatives (Analog Devices/Maxim Integrated MAX6037 Series):

• MAX6037AAUK33+T (±0.2% tolerance)
• MAX6037BAUK33+T (±0.3% tolerance)

These parts provide superior electrical performance with tighter tolerance specifications and lower temperature coefficients, while maintaining the same 3.3V output, SOT-23-5 package, and surface mount configuration. However, they feature reduced output current capability (5 mA vs. 20 mA) and higher supply current (275 µA vs. 100 µA).

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Identical Electrical Performance):

Select LM4128CMF-3.3/NOPB or LM4128CMFX-3.3/NOPB for applications requiring exact electrical equivalence to the obsolete LM4128CMFX-3.3. Both parts are Active status and ROHS3 compliant, providing modern supply chain availability. The primary difference is packaging format: CMF-3.3/NOPB is supplied in Tape & Reel, while CMFX-3.3/NOPB is also available in Tape & Reel configuration.

For Automotive Applications:

Select LM4128CQ1MF3.3/NOPB or LM4128CQ1MFX3.3/NOPB when automotive-grade qualification is required. Both variants carry AEC-Q100 certification and maintain identical electrical specifications to the standard LM4128 parts while meeting automotive reliability standards.

For Enhanced Performance Requirements:

Select MAX6037AAUK33+T (±0.2% tolerance, 25 ppm/°C) or MAX6037BAUK33+T (±0.3% tolerance, 50 ppm/°C) when superior voltage accuracy and temperature stability are required. These alternatives provide tighter tolerance and lower temperature coefficient specifications. However, verify that the reduced output current capability (5 mA vs. 20 mA) and increased supply current (275 µA vs. 100 µA) are compatible with the application circuit requirements.

All substitute parts maintain SOT-23-5 packaging compatibility and operate across the -40°C to 125°C temperature range, ensuring direct PCB layout compatibility.

Frequently Asked Questions (FAQ)

Q: Can LM4128CMF-3.3/NOPB be used as a direct replacement for LM4128CMFX-3.3?

A: Yes. Both parts provide identical electrical specifications: 3.3V fixed output, ±0.5% tolerance, 20 mA output current, 100 ppm/°C temperature coefficient, and SOT-23-5 packaging. The primary difference is packaging format (Tape & Reel). Both are Active status and ROHS3 compliant, making them suitable for production use.

Q: What is the difference between LM4128CQ1MF3.3/NOPB and LM4128CMF-3.3/NOPB?

A: The CQ1 variant includes AEC-Q100 automotive qualification and is supplied in Cut Tape & Digi-Reel format, while the standard CMF variant is supplied in Tape & Reel. Electrical specifications are identical. Select the CQ1 variant for automotive applications requiring formal qualification documentation.

Q: Why do MAX6037 parts have lower output current (5 mA vs. 20 mA)?

A: The MAX6037 series is designed for precision reference applications with tighter tolerance specifications (±0.2% to ±0.3%) and lower temperature coefficients (25-50 ppm/°C). The reduced output current reflects the intended application profile. Verify that your circuit load does not exceed 5 mA before selecting this alternative.

Q: Are all substitute parts RoHS compliant?

A: All Active status substitute parts (LM4128CMF-3.3/NOPB, LM4128CMFX-3.3/NOPB, LM4128CQ1MF3.3/NOPB, LM4128CQ1MFX3.3/NOPB, MAX6037AAUK33+T, MAX6037BAUK33+T) are ROHS3 compliant. The original LM4128CMFX-3.3 is RoHS non-compliant due to its obsolete status.

Q: Can MAX6037AAUK33+T and MAX6037BAUK33+T be used interchangeably?

A: Both parts are pin-compatible and share identical package, input voltage range, and operating temperature specifications. The difference is tolerance specification: MAX6037AAUK33+T provides ±0.2% tolerance with 25 ppm/°C temperature coefficient, while MAX6037BAUK33+T provides ±0.3% tolerance with 50 ppm/°C temperature coefficient. Select based on the accuracy requirements of your application.

Q: What is the input voltage compatibility range for all substitute parts?

A: LM4128 variants operate across 3.7V to 5.5V input range. MAX6037 variants operate across 4.6V to 5.5V input range. Verify that your power supply voltage falls within the applicable range for the selected substitute part.