MIC4576-3.3BU TR Equivalent & Substitute Parts

Part Overview

The MIC4576-3.3BU TR is a buck switching regulator IC from Microchip Technology, delivering a fixed 3.3V output at 3A in a TO-263-6 D2PAK package. This part is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements. The device operates across a 4V to 36V input range with a 200kHz switching frequency, suitable for cost-sensitive step-down conversion applications.

Key Parameters

Parameter	Value
Manufacturer	Microchip Technology
Function	Step-Down (Buck)
Output Voltage	3.3V Fixed
Output Current	3A
Input Voltage Range	4V to 36V
Switching Frequency	200kHz
Package	TO-263-6 D2PAK (5 Leads + Tab)
Operating Temperature	-40°C to 85°C
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Output voltage: 3.3V fixed
Package compatibility: TO-263-6 D2PAK (5 Leads + Tab)
Output current capability: minimum 3A for direct replacement
Input voltage range: minimum 4V to 36V overlap
Mounting type: Surface Mount
Topology: Buck switching regulator

Substitute parts are grouped into two categories:

Category 1: Direct Microchip Equivalent – MIC4576-3.3WU-TR maintains identical electrical specifications and base product number, differing only in packaging format (Cut Tape & Digi-Reel vs. Tape & Reel) and product status (Active vs. Obsolete).

Category 2: Texas Instruments SIMPLE SWITCHER® Series – LM2575, LM2591, LM2595, and LM2596 families meet the core substitution criteria of 3.3V output, TO-263-6 package, and surface mount configuration. These parts vary in output current capability, input voltage range, and switching frequency but maintain electrical and mechanical compatibility.

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Min-Max)	Switching Frequency	Operating Temperature	Product Status	RoHS Status
MIC4576-3.3BU TR	Microchip	3A	4V - 36V	200kHz	-40°C to 85°C	Obsolete	Non-compliant
MIC4576-3.3WU-TR	Microchip	3A	4V - 36V	200kHz	-40°C to 85°C	Active	ROHS3 Compliant
LM2575S-3.3/NOPB	Texas Instruments	1A	4V - 40V	52kHz	-40°C to 125°C	Active	ROHS3 Compliant
LM2575SX-3.3/NOPB	Texas Instruments	1A	4V - 40V	52kHz	-40°C to 125°C	Active	ROHS3 Compliant
LM2591HVS-3.3/NOPB	Texas Instruments	1A	4.5V - 60V	150kHz	-40°C to 125°C	Active	ROHS3 Compliant
LM2591HVSX-3.3/NOPB	Texas Instruments	1A	4.5V - 60V	150kHz	-40°C to 125°C	Active	ROHS3 Compliant
LM2595S-3.3/NOPB	Texas Instruments	1A	4.5V - 40V	150kHz	-40°C to 125°C	Active	ROHS3 Compliant
LM2596S-3.3/NOPB	Texas Instruments	3A	4.5V - 40V	150kHz	-40°C to 125°C	Active	ROHS3 Compliant
LM2596SX-3.3/NOPB	Texas Instruments	3A	4.5V - 40V	150kHz	-40°C to 125°C	Active	ROHS3 Compliant
TL2575-33IKTTR	Texas Instruments	1A	4.75V - 40V	52kHz	-40°C to 125°C	Active	ROHS3 Compliant
TL2575HV-33IKTTR	Texas Instruments	1A	4.75V - 60V	52kHz	-40°C to 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: MIC4576-3.3WU-TR

This part is the direct equivalent to the obsolete MIC4576-3.3BU TR. It maintains identical electrical and mechanical specifications while offering active product status and ROHS3 compliance. The only difference is packaging format (Cut Tape & Digi-Reel vs. Tape & Reel), which does not affect circuit performance. This is the preferred choice for designs requiring no circuit modifications.

Secondary Recommendation: LM2596S-3.3/NOPB or LM2596SX-3.3/NOPB

These Texas Instruments parts match the 3A output current requirement of the original MIC4576-3.3BU TR. Both maintain TO-263-6 package compatibility and deliver 3.3V fixed output. The LM2596SX-3.3/NOPB variant offers higher inventory availability (25,400 units) in Cut Tape & Digi-Reel packaging. These parts operate at 150kHz switching frequency versus the original 200kHz, and support input voltages from 4.5V to 40V (versus 4V to 36V). Operating temperature extends to 125°C. All substitute parts carry ROHS3 compliance.

Alternative for Lower Current Applications: LM2575SX-3.3/NOPB or TL2575-33IKTTR

If circuit load does not require the full 3A output, these 1A-rated parts provide cost-effective alternatives. Both maintain 3.3V output and TO-263-6 package compatibility. The LM2575SX-3.3/NOPB offers 17,530 units in stock with 52kHz switching frequency and 4V to 40V input range. The TL2575-33IKTTR provides 3,697 units with identical electrical specifications.

High Input Voltage Applications: LM2591HVSX-3.3/NOPB or TL2575HV-33IKTTR

For designs requiring input voltages up to 60V, these variants extend the maximum input specification. Both maintain 1A output current and 3.3V fixed output in TO-263-6 packages. The LM2591HVSX-3.3/NOPB operates at 150kHz with 2,314 units available. The TL2575HV-33IKTTR operates at 52kHz with 1,715 units available.

Frequently Asked Questions (FAQ)

Q: Can I use LM2596S-3.3/NOPB as a direct replacement for MIC4576-3.3BU TR?

A: Yes. Both parts deliver 3.3V fixed output at 3A in TO-263-6 D2PAK packages. The LM2596S-3.3/NOPB is electrically and mechanically compatible. The switching frequency differs (150kHz vs. 200kHz), and the input voltage range is slightly narrower (4.5V to 40V vs. 4V to 36V), but these differences do not prevent direct substitution in most applications.

Q: What is the difference between MIC4576-3.3BU TR and MIC4576-3.3WU-TR?

A: Both parts are identical in electrical performance and package type. The primary differences are product status (Obsolete vs. Active), RoHS compliance (Non-compliant vs. ROHS3 Compliant), and packaging format (Tape & Reel vs. Cut Tape & Digi-Reel). The MIC4576-3.3WU-TR is the active production equivalent.

Q: Why do some substitute parts have lower output current ratings?

A: The LM2575, LM2591, and LM2595 families are rated for 1A output, while the original MIC4576-3.3BU TR and LM2596 series deliver 3A. If your circuit requires the full 3A capability, select only LM2596S-3.3/NOPB, LM2596SX-3.3/NOPB, or MIC4576-3.3WU-TR. For applications drawing less than 1A, the lower-rated parts are suitable alternatives.

Q: Are all substitute parts RoHS compliant?

A: The original MIC4576-3.3BU TR is RoHS non-compliant. All listed substitute parts carry ROHS3 compliance, making them suitable for applications with RoHS requirements. The MIC4576-3.3WU-TR is the only Microchip equivalent with ROHS3 compliance.

Q: What is the impact of different switching frequencies?

A: The original MIC4576-3.3BU TR operates at 200kHz. Substitute parts operate at 52kHz (LM2575, TL2575 series) or 150kHz (LM2591, LM2595, LM2596 series). Lower switching frequencies may result in larger output filter components but do not prevent functional substitution. Circuit design review is recommended if switching frequency is critical to EMI performance.

Q: Can I use parts with higher maximum input voltage ratings?

A: Yes. Parts rated for 60V maximum input (LM2591HVSX-3.3/NOPB, TL2575HV-33IKTTR) are fully compatible with circuits designed for 36V or lower input. The higher rating provides additional design margin and flexibility for future applications.

Q: What packaging options are available for substitute parts?

A: Substitute parts are available in Tube, Cut Tape & Digi-Reel, and Tape & Reel packaging formats. All maintain the same TO-263-6 D2PAK footprint and pin configuration. Packaging selection depends on production volume and assembly requirements, not electrical performance.

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