LP3990MF-3.3 Equivalent & Substitute Parts

Part Overview

The LP3990MF-3.3 is a linear voltage regulator IC from Texas Instruments designed to deliver a fixed 3.3V output at 150mA in a SOT-23-5 surface mount package. This part is classified as obsolete, which necessitates identification of active equivalent and substitute components for new designs and ongoing production support. The device provides positive fixed output regulation with integrated enable control and thermal/short-circuit protection suitable for low-power applications requiring stable 3.3V rails.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	150mA
Input Voltage (Max)	6V
Dropout Voltage	0.2V @ 150mA
Quiescent Current	80 µA
Package	SOT-23-5
Operating Temperature Range	-40°C to 85°C
Control Features	Enable
Protection Features	Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Output voltage matching at 3.3V fixed
Output current capability equal to or greater than 150mA
Input voltage maximum of 6V or higher
Surface mount packaging (SOT-23-5, SOT-25, or 5-SSOP variants)
Operating temperature range covering -40°C to 85°C minimum
Enable control feature presence
Protection against over-temperature and short-circuit conditions

Substitute parts are grouped into three categories based on output current capacity and product status: direct equivalents (150mA, active status), higher-current alternatives (300mA–600mA, active status), and specialized variants with enhanced specifications or automotive qualification.

Parameter Comparison

Part Number	Manufacturer	Output Current	Dropout Voltage	Quiescent Current	Package	Product Status	RoHS Status
LP3990MF-3.3	Texas Instruments	150mA	0.2V @ 150mA	80 µA	SOT-23-5	Obsolete	Non-compliant
LP3990MF-3.3/NOPB	Texas Instruments	150mA	0.2V @ 150mA	80 µA	SOT-23-5	Active	ROHS3 Compliant
LP3990MFX-3.3/NOPB	Texas Instruments	150mA	0.2V @ 150mA	80 µA	SOT-23-5	Active	ROHS3 Compliant
MIC5256-3.3YM5-TR	Microchip Technology	150mA	0.25V @ 150mA	150 µA	SOT-23-5	Active	ROHS3 Compliant
MIC5317-3.3YD5-T5	Microchip Technology	150mA	0.31V @ 150mA	39 µA	TSOT-23-5	Active	ROHS3 Compliant
AP7331-33WG-7	Diodes Incorporated	300mA	0.55V @ 300mA	75 µA	SOT-25	Active	ROHS3 Compliant
AP7335-33WG-7	Diodes Incorporated	300mA	0.2V @ 300mA	80 µA	SOT-25	Active	ROHS3 Compliant
AP7365-33WG-7	Diodes Incorporated	600mA	0.4V @ 600mA	80 µA	SOT-25	Active	ROHS3 Compliant
BU33SD2MG-MTR	Rohm Semiconductor	200mA	0.15V @ 100mA	80 µA	5-SSOP	Active	ROHS3 Compliant
BU33SD5WG-TR	Rohm Semiconductor	500mA	0.15V @ 100mA	80 µA	5-SSOP	Active	ROHS3 Compliant
BU33UC3WG-TR	Rohm Semiconductor	300mA	0.22V @ 300mA	90 µA	5-SSOP	Not For New Designs	ROHS3 Compliant

Engineering Selection Recommendations

For direct replacement of the obsolete LP3990MF-3.3 in existing designs, LP3990MF-3.3/NOPB or LP3990MFX-3.3/NOPB from Texas Instruments are the primary choices. Both maintain identical electrical specifications and package format while offering active product status and ROHS3 compliance.

For new designs requiring 150mA output at 3.3V, MIC5256-3.3YM5-TR and MIC5317-3.3YD5-T5 from Microchip Technology provide active alternatives in SOT-23-5 packaging with ROHS3 compliance. MIC5317-3.3YD5-T5 offers superior quiescent current performance (39 µA versus 80 µA) and higher PSRR (80dB–65dB across 1kHz–10kHz).

For applications requiring higher output current capacity, Diodes Incorporated AP7335-33WG-7 (300mA) and AP7365-33WG-7 (600mA) provide active alternatives with improved dropout voltage characteristics. Rohm Semiconductor BU33SD2MG-MTR (200mA) and BU33SD5WG-TR (500mA) offer enhanced dropout voltage performance and automotive qualification (AEC-Q100) where applicable.

BU33UC3WG-TR carries a "Not For New Designs" status and should be avoided for new development despite active inventory availability.

Frequently Asked Questions (FAQ)

Q: Can LP3990MF-3.3/NOPB directly replace the obsolete LP3990MF-3.3?

A: Yes. Both parts share identical electrical specifications, output current rating (150mA), dropout voltage (0.2V @ 150mA), and SOT-23-5 packaging. The primary difference is product status (active versus obsolete) and RoHS compliance (ROHS3 compliant versus non-compliant).

Q: What is the difference between LP3990MF-3.3/NOPB and LP3990MFX-3.3/NOPB?

A: Both are parametrically equivalent with identical electrical performance. The primary distinction is packaging format: LP3990MF-3.3/NOPB is supplied in Cut Tape and Digi-Reel format, while LP3990MFX-3.3/NOPB is supplied in Tape & Reel format. Selection depends on procurement and assembly requirements.

Q: Can I use a higher-current part like AP7335-33WG-7 (300mA) as a substitute?

A: Yes, provided the application circuit accommodates the SOT-25 package instead of SOT-23-5. Higher output current capability does not create compatibility issues in designs requiring 150mA or less. However, PCB layout and thermal management may differ due to package geometry changes.

Q: What is the significance of the dropout voltage difference between LP3990MF-3.3 (0.2V) and MIC5256-3.3YM5-TR (0.25V)?

A: The 0.05V difference is negligible for most applications. Both maintain adequate headroom with a 6V maximum input. Selection should consider the specific input voltage range and minimum output voltage requirement of the application circuit.

Q: Why is BU33UC3WG-TR marked "Not For New Designs"?

A: This designation indicates the manufacturer recommends against using this part in new product development. While inventory is available and the part is RoHS3 compliant, active alternatives with better long-term support should be prioritized for new designs.

Q: Are all substitute parts RoHS3 compliant?

A: All listed substitute parts carry ROHS3 Compliant status. The original LP3990MF-3.3 is RoHS non-compliant, making the active substitutes necessary for applications requiring regulatory compliance.

Q: What is the operating temperature range difference between LP3990MF-3.3 (-40°C to 85°C) and MIC5317-3.3YD5-T5 (-40°C to 125°C)?

A: MIC5317-3.3YD5-T5 extends the upper operating temperature limit to 125°C, providing additional thermal margin. This is beneficial for applications in elevated ambient conditions or high-power dissipation environments, though not required for standard -40°C to 85°C specifications.

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