LM2576-3.3BU Equivalent & Substitute Parts

Part Overview

The LM2576-3.3BU is a buck switching regulator IC from Microchip Technology designed for positive fixed 3.3V output applications with 3A output current capability. The device is housed in a TO-263-6 (D2PAK) package with 5 leads plus tab and operates across an input voltage range of 4V to 40V. This part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Manufacturer	Microchip Technology
Part Number	LM2576-3.3BU
Function	Step-Down (Buck)
Output Voltage	3.3V Fixed
Output Current	3A
Input Voltage Range	4V to 40V
Switching Frequency	52kHz
Package	TO-263-6 (D2PAK, 5 Leads + Tab)
Operating Temperature	-40°C to 125°C (TJ)
Product Status	Obsolete
RoHS Status	RoHS Non-Compliant

Substitute Part Grouping Explanation

Substitution for the LM2576-3.3BU is determined by the following critical parameters:

Output Voltage: 3.3V fixed output
Package Type: TO-263-6 (D2PAK) mechanical and electrical compatibility
Operating Temperature Range: -40°C to 125°C
Mounting Type: Surface mount
Output Configuration: Positive, single output

Substitute parts are grouped into two categories based on output current capability:

Category 1 - Direct Current Match (3A Output) The LM2576-3.3WU from Microchip Technology maintains identical output current specification (3A) and switching frequency (52kHz), providing the closest functional equivalence to the obsolete LM2576-3.3BU.

Category 2 - Reduced Current Substitutes (1A Output) Texas Instruments LM2575 and LM2591 series devices provide functional buck regulation at 3.3V output with reduced output current (1A). These parts share the same package footprint and operating temperature range but deliver lower maximum output current. Selection from this category requires circuit design verification to confirm 1A output current is sufficient for the application.

Parameter Comparison

Parameter	LM2576-3.3BU	LM2576-3.3WU	LM2575S-3.3/NOPB	LM2575SX-3.3/NOPB	LM2591HVS-3.3/NOPB	LM2591HVSX-3.3/NOPB	TL2575-33IKTTR	TL2575HV-33IKTTR
Manufacturer	Microchip	Microchip	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments
Output Voltage	3.3V	3.3V	3.3V	3.3V	3.3V	3.3V	3.3V	3.3V
Output Current	3A	3A	1A	1A	1A	1A	1A	1A
Input Voltage (Min)	4V	4V	4V	4V	4.5V	4.5V	4.75V	4.75V
Input Voltage (Max)	40V	40V	40V	40V	60V	60V	40V	60V
Switching Frequency	52kHz	52kHz	52kHz	52kHz	150kHz	150kHz	52kHz	52kHz
Package	TO-263-6	TO-263-6	TO-263-6	TO-263-6	TO-263-6	TO-263-6	TO-263-6	TO-263-6
Operating Temperature	-40°C to 125°C	-40°C to 125°C	-40°C to 125°C	-40°C to 125°C	-40°C to 125°C	-40°C to 125°C	-40°C to 125°C	-40°C to 125°C
RoHS Status	Non-Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

Primary Substitute: LM2576-3.3WU

The LM2576-3.3WU from Microchip Technology is the recommended direct substitute for the LM2576-3.3BU. This part maintains identical electrical specifications including 3A output current and 52kHz switching frequency. The LM2576-3.3WU is currently in active production status and is ROHS3 compliant, addressing the regulatory limitations of the obsolete original part. Packaging is identical (TO-263-6), ensuring mechanical compatibility with existing PCB layouts.

Secondary Substitutes: Texas Instruments LM2575 Series

The LM2575S-3.3/NOPB and LM2575SX-3.3/NOPB are functionally equivalent buck regulators with identical input voltage range (4V to 40V) and switching frequency (52kHz). These parts are suitable for applications where 1A output current is sufficient. Both are ROHS3 compliant and in active production. The LM2575SX-3.3/NOPB offers higher inventory availability (17,530 units).

Alternative Substitutes: Texas Instruments LM2591 Series

The LM2591HVS-3.3/NOPB and LM2591HVSX-3.3/NOPB extend the maximum input voltage to 60V and increase switching frequency to 150kHz. These parts are suitable for applications requiring higher input voltage tolerance or reduced output filter component size. Output current is limited to 1A. Both are ROHS3 compliant and in active production.

Alternative Substitutes: Texas Instruments TL2575 Series

The TL2575-33IKTTR and TL2575HV-33IKTTR provide 1A output current with 52kHz switching frequency. The TL2575HV-33IKTTR variant extends maximum input voltage to 60V. Both are ROHS3 compliant and in active production.

Frequently Asked Questions (FAQ)

Q: Can I use a 1A substitute part in place of the 3A LM2576-3.3BU?

A: Only if your circuit design requires maximum output current of 1A or less. The LM2575 and LM2591 series devices are rated for 1A maximum output current. Exceeding this rating will cause thermal shutdown and circuit malfunction. Review your load current requirements before selecting a 1A substitute.

Q: What is the difference between LM2575 and LM2591 series devices?

A: The LM2591 series operates at 150kHz switching frequency compared to 52kHz for LM2575, and supports input voltages up to 60V compared to 40V for standard LM2575. The higher switching frequency allows use of smaller output filter components. Input voltage range and switching frequency are the primary differentiators.

Q: Are all substitute parts pin-compatible with the LM2576-3.3BU?

A: Yes. All listed substitute parts use the TO-263-6 (D2PAK) package with identical pin configuration and mechanical footprint. PCB layout changes are not required for package compatibility.

Q: Why is the LM2576-3.3BU listed as obsolete?

A: The original part is no longer in active production. The LM2576-3.3WU from Microchip Technology is the direct replacement, offering identical specifications with current production status and improved regulatory compliance (ROHS3).

Q: What is the impact of switching frequency differences between substitutes?

A: Higher switching frequency (150kHz for LM2591 vs. 52kHz for LM2575) allows use of smaller inductors and capacitors in the output filter circuit, reducing board space and component cost. Lower switching frequency generates less EMI but requires larger filter components. Circuit design must account for these differences.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All active production substitute parts listed are ROHS3 compliant. The original LM2576-3.3BU is RoHS non-compliant, making substitution necessary for applications with RoHS compliance requirements.

Q: What packaging options are available for substitute parts?

A: Substitute parts are available in multiple packaging formats including Tube, Cut Tape with Digi-Reel, and Tape & Reel. Select packaging based on procurement volume and assembly process requirements. All packaging options maintain identical electrical and mechanical specifications.

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