MIC39301-1.8BU Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The MIC39301-1.8BU is a linear voltage regulator IC from Microchip Technology designed to deliver a fixed 1.8V output at 3A maximum current 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 requirements. The device provides positive fixed output configuration with integrated protection features including over-current, over-temperature, and reverse polarity protection, operating across the industrial temperature range of -40°C to 125°C.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	1.8V
Maximum Output Current	3A
Maximum Input Voltage	16V
Dropout Voltage @ 3A	0.55V
Package Type	TO-263-5 (D2PAK)
Mounting Type	Surface Mount
Operating Temperature Range	-40°C to 125°C
Protection Features	Over Current, Over Temperature, Reverse Polarity
Control Features	Enable
Output Configuration	Positive Fixed

Substitute Part Grouping Explanation

Substitution for the MIC39301-1.8BU is determined by the following critical parameters:

Output Voltage: 1.8V fixed output (all substitutes match this specification)
Output Current Capability: 3A maximum (primary requirement for full compatibility)
Package Type: TO-263-5 (D2PAK) mechanical and electrical compatibility
Input Voltage Range: Maximum 16V or higher acceptable
Dropout Voltage: 0.55V or lower preferred for thermal performance
Protection Features: Over-current, over-temperature, and reverse polarity protection required
Operating Temperature: -40°C to 125°C minimum range
Product Status: Active status preferred due to obsolete status of original part

Substitute parts are grouped into two categories:

Category A - Direct Microchip Equivalent (3A Output Current)

MIC39301-1.8WU: Same manufacturer, same specifications, active status, RoHS3 compliant

Category B - Texas Instruments 3A Alternatives

LP3853ES-1.8/NOPB and LP3853ESX-1.8/NOPB: 3A output, lower input voltage maximum (7V), active status

Category C - Analog Devices 3A Alternatives

LT1764AEQ-1.8#PBF, LT1764AEQ-1.8#TRPBF, LT1764EQ-1.8#TRPBF: 3A output, higher input voltage (20V), superior quiescent current (1.5mA), active status

Category D - Reduced Current Alternatives (1.5A Output)

LP3965ES-1.8/NOPB and LP3965ESX-1.8/NOPB: 1.5A output (reduced capability), active status
LT1963AEQ-1.8#PBF and LT1963AEQ-1.8#TRPBF: 1.5A output (reduced capability), active status

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Max)	Dropout @ Rated Current	Quiescent Current	Package	Status	RoHS
MIC39301-1.8BU	Microchip	3A	16V	0.55V @ 3A	—	TO-263-5	Obsolete	Non-compliant
MIC39301-1.8WU	Microchip	3A	16V	0.55V @ 3A	—	TO-263-5	Active	RoHS3
LP3853ES-1.8/NOPB	Texas Instruments	3A	7V	0.6V @ 3A	4 mA	TO-263-5	Active	RoHS3
LP3853ESX-1.8/NOPB	Texas Instruments	3A	7V	0.6V @ 3A	4 mA	TO-263-5	Active	RoHS3
LP3965ES-1.8/NOPB	Texas Instruments	1.5A	7V	0.55V @ 1.5A	9 mA	TO-263-5	Active	RoHS3
LP3965ESX-1.8/NOPB	Texas Instruments	1.5A	7V	0.55V @ 1.5A	9 mA	TO-263-5	Active	RoHS3
LT1764AEQ-1.8#PBF	Analog Devices	3A	20V	0.66V @ 3A	1.5 mA	DDPAK-5	Active	RoHS3
LT1764AEQ-1.8#TRPBF	Analog Devices	3A	20V	0.66V @ 3A	1.5 mA	DDPAK-5	Active	RoHS3
LT1764EQ-1.8#TRPBF	Analog Devices	3A	20V	0.66V @ 3A	1.5 mA	DDPAK-5	Active	RoHS3
LT1963AEQ-1.8#PBF	Analog Devices	1.5A	20V	0.55V @ 1.5A	1.5 mA	DDPAK-5	Active	RoHS3
LT1963AEQ-1.8#TRPBF	Analog Devices	1.5A	20V	0.55V @ 1.5A	1.5 mA	DDPAK-5	Active	RoHS3

Engineering Selection Recommendations

Primary Recommendation: MIC39301-1.8WU

The MIC39301-1.8WU is the direct equivalent from Microchip Technology, maintaining identical electrical specifications and package configuration. This part is active in production status and RoHS3 compliant, addressing the obsolescence of the original MIC39301-1.8BU. Selection of this part eliminates design re-qualification requirements and maintains supply chain consistency with the original manufacturer.

Secondary Recommendation: LT1764 Series (Analog Devices)

The LT1764AEQ-1.8#TRPBF, LT1764AEQ-1.8#PBF, and LT1764EQ-1.8#TRPBF deliver 3A output current with superior input voltage tolerance (20V maximum) and lower quiescent current (1.5mA). These parts are active in production and RoHS3 compliant. The higher input voltage rating provides design flexibility for applications with variable supply sources. Packaging is DDPAK-5, mechanically and electrically compatible with TO-263-5.

Tertiary Recommendation: LP3853 Series (Texas Instruments)

The LP3853ES-1.8/NOPB and LP3853ESX-1.8/NOPB maintain 3A output current capability with active production status and RoHS3 compliance. Input voltage is limited to 7V maximum, restricting application scope compared to higher-rated alternatives. These parts are suitable only for designs with input voltage constraints below 7V.

Reduced Current Alternatives: LP3965 and LT1963 Series

The LP3965ES-1.8/NOPB, LP3965ESX-1.8/NOPB, LT1963AEQ-1.8#PBF, and LT1963AEQ-1.8#TRPBF deliver reduced output current of 1.5A. These parts are applicable only to applications where the original 3A requirement can be reduced or where load current does not exceed 1.5A. All are active in production and RoHS3 compliant.

Frequently Asked Questions (FAQ)

Q: Can MIC39301-1.8WU be used as a direct replacement for MIC39301-1.8BU?

A: Yes. The MIC39301-1.8WU is electrically and mechanically identical to the MIC39301-1.8BU, with the primary difference being active production status and RoHS3 compliance. No design changes are required. The only difference is packaging format (Tube vs. original specification).

Q: What is the key limitation of LP3853 and LP3965 series parts?

A: The LP3853 series limits input voltage to 7V maximum, compared to 16V for the original part. The LP3965 series reduces output current to 1.5A, half the original 3A capability. Selection depends on application input voltage and load current requirements.

Q: Are Analog Devices LT1764 and LT1963 parts pin-compatible with the original MIC39301-1.8BU?

A: Yes. All substitute parts use TO-263-5 or DDPAK-5 packaging, which are mechanically and electrically equivalent. Pin assignments for voltage regulator ICs in this package class are standardized: input, ground, output, enable, and tab connections are identical across manufacturers.

Q: What is the difference between LT1764 and LT1963 series from Analog Devices?

A: The LT1764 series delivers 3A output current, matching the original MIC39301-1.8BU specification. The LT1963 series delivers 1.5A output current. Both share identical input voltage rating (20V), quiescent current (1.5mA), and protection features. Selection depends on load current requirements.

Q: Does packaging format (Tube vs. Tape & Reel) affect electrical performance?

A: No. Packaging format affects only handling, storage, and assembly processes. Electrical specifications and performance are identical between tube and tape & reel variants of the same part number base.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All active production substitute parts listed are RoHS3 compliant. The original MIC39301-1.8BU is RoHS non-compliant. Compliance status should be verified for applications subject to RoHS regulatory requirements.

Q: What is the thermal performance difference between MIC39301-1.8WU and LT1764 alternatives?

A: Dropout voltage at 3A is 0.55V for MIC39301-1.8WU and 0.66V for LT1764 series. The 0.11V difference results in approximately 0.33W additional power dissipation at maximum current. Quiescent current is lower for LT1764 (1.5mA vs. unspecified for MIC39301-1.8WU), reducing standby power consumption.

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