MIC39151-2.5BU TR Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The MIC39151-2.5BU TR is a linear voltage regulator IC from Microchip Technology designed to deliver a fixed 2.5V output at 1.5A in a TO-263-5 surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The regulator features enable control, over-current protection, over-temperature protection, and reverse polarity protection, with an operating temperature range of -40°C to 125°C.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	2.5V
Output Current	1.5A
Input Voltage (Max)	16V
Voltage Dropout (Max)	0.5V @ 1.5A
Output Configuration	Positive Fixed
Package Type	TO-263-5 (D2PAK, 5 Leads + Tab)
Mounting Type	Surface Mount
Operating Temperature	-40°C to 125°C
Protection Features	Over Current, Over Temperature, Reverse Polarity
Control Features	Enable

Substitute Part Grouping Explanation

Substitution for the MIC39151-2.5BU TR is determined by the following critical parameters:

Fixed output voltage of 2.5V
Output current capability of 1.5A minimum
TO-263-5 package compatibility
Surface mount configuration
Operating temperature range of -40°C to 125°C
Enable control feature
Protection against over-current, over-temperature, and reverse polarity conditions

Substitute parts are grouped into two categories based on these criteria:

Category 1: Direct Microchip Equivalents – Parts maintaining identical electrical specifications and the same manufacturer lineage.

Category 2: Cross-Manufacturer Substitutes – Parts from National Semiconductor, Texas Instruments, and Analog Devices that meet or exceed the electrical and thermal requirements while maintaining package compatibility.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout @ Rated Current	Package	Status	RoHS Compliance
MIC39151-2.5BU TR	Microchip Technology	2.5V	1.5A	16V	0.5V @ 1.5A	TO-263-5	Obsolete	Non-compliant
MIC39151-2.5WU-TR	Microchip Technology	2.5V	1.5A	16V	0.5V @ 1.5A	TO-263-5	Active	ROHS3 Compliant
LP3962ES-2.5/NOPB	National Semiconductor	2.5V	1.5A	7V	0.55V @ 1.5A	TO-263-5	Active	Not specified
LP3962ESX-2.5/NOPB	National Semiconductor	2.5V	1.5A	7V	0.55V @ 1.5A	TO-263-5	Active	Not specified
LP3965ES-2.5/NOPB	Texas Instruments	2.5V	1.5A	7V	0.55V @ 1.5A	TO-263-5	Active	ROHS3 Compliant
LP3965ESX-2.5/NOPB	Texas Instruments	2.5V	1.5A	7V	0.55V @ 1.5A	TO-263-5	Active	ROHS3 Compliant
LP3966ES-2.5/NOPB	Texas Instruments	2.5V	3A	7V	1.2V @ 3A	TO-263-5	Active	ROHS3 Compliant
LP3966ESX-2.5/NOPB	Texas Instruments	2.5V	3A	7V	1.2V @ 3A	TO-263-5	Active	ROHS3 Compliant
LT1764AEQ-2.5#PBF	Analog Devices Inc.	2.5V	3A	20V	0.66V @ 3A	DDPAK-5	Active	ROHS3 Compliant
LT1764AEQ-2.5#TRPBF	Analog Devices Inc.	2.5V	3A	20V	0.66V @ 3A	DDPAK-5	Active	ROHS3 Compliant
LT1764EQ-2.5#PBF	Analog Devices Inc.	2.5V	3A	20V	0.66V @ 3A	DDPAK-5	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: MIC39151-2.5WU-TR

The MIC39151-2.5WU-TR is the direct active equivalent from Microchip Technology. It maintains identical electrical specifications to the obsolete MIC39151-2.5BU TR while offering ROHS3 compliance and active product status. This part is the preferred choice for direct replacement in existing designs.

Secondary Recommendations: LP3965ES-2.5/NOPB and LP3965ESX-2.5/NOPB

Texas Instruments LP3965 series parts meet the 2.5V, 1.5A output requirements with ROHS3 compliance and active status. These parts are suitable for applications where input voltage does not exceed 7V. The LP3965ESX-2.5/NOPB variant in tape and reel packaging is available in higher inventory quantities.

Alternative for Higher Current Applications: LP3966ES-2.5/NOPB and LP3966ESX-2.5/NOPB

For designs requiring higher output current capability, the LP3966 series delivers 3A output at 2.5V with ROHS3 compliance and active status. These parts are pin-compatible in the TO-263-5 package and suitable for applications with input voltages up to 7V.

Extended Input Voltage Range: LT1764AEQ-2.5#TRPBF

The Analog Devices LT1764AEQ-2.5#TRPBF supports input voltages up to 20V, exceeding the original part's 16V maximum. This part delivers 3A output current, ROHS3 compliance, and active product status. The tape and reel packaging variant offers the highest inventory availability among Analog Devices options.

Frequently Asked Questions (FAQ)

Q: Can I use LP3962 or LP3965 parts as direct replacements for the MIC39151-2.5BU TR?

A: Yes, both the LP3962 and LP3965 series meet the core electrical requirements: 2.5V fixed output, 1.5A minimum current capability, and TO-263-5 package compatibility. However, these parts have a maximum input voltage of 7V compared to the original part's 16V. Verify that your application's input voltage does not exceed 7V before selection.

Q: What is the difference between LP3965ES-2.5/NOPB and LP3965ESX-2.5/NOPB?

A: Both parts are electrically identical. The primary difference is packaging: LP3965ES-2.5/NOPB is supplied in tube packaging, while LP3965ESX-2.5/NOPB is supplied in tape and reel format. Tape and reel packaging is standard for automated assembly processes.

Q: Why would I choose an LP3966 part over an LP3965 part?

A: The LP3966 series provides 3A output current compared to the LP3965's 1.5A. If your application requires higher current capability or if you need design margin for future upgrades, the LP3966 is suitable. Both maintain the same 2.5V output voltage and TO-263-5 package compatibility.

Q: Are all substitute parts ROHS3 compliant?

A: The MIC39151-2.5WU-TR, LP3965 series, LP3966 series, and LT1764 series are all ROHS3 compliant. The LP3962 series compliance status is not specified in the available data. For applications requiring ROHS3 certification, select from the compliant options listed above.

Q: What is the advantage of the LT1764 series over other substitutes?

A: The LT1764 series supports input voltages up to 20V, providing the widest input voltage range among available substitutes. It also features the lowest quiescent current (1.5 mA) and highest PSRR (63dB at 120Hz), making it suitable for noise-sensitive applications. The trade-off is higher dropout voltage at rated current (0.66V @ 3A) compared to some alternatives.

Q: Can I use these parts interchangeably in my PCB design?

A: All substitute parts use the TO-263-5 or DDPAK-5 package, which are mechanically and electrically compatible. Pin assignments are identical across all listed parts. However, verify input voltage requirements and current specifications for your specific application before final selection.

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