LM2575BU Buck Switching Regulator IC Equivalent & Substitute Parts

Part Overview

The LM2575BU is a buck switching regulator IC manufactured by Microchip Technology, designed for positive adjustable output applications with 1A output current capability. This part operates in the 4V to 40V input range and delivers adjustable output from 1.23V to 37V at 52kHz switching frequency in a TO-263-6 (D2PAK) surface mount package.

The LM2575BU is classified as obsolete. Identifying equivalent and substitute parts is necessary to ensure design continuity, maintain supply chain flexibility, and support long-term product availability for applications currently using this component.

Key Parameters

Parameter	Value
Function	Step-Down (Buck)
Output Configuration	Positive
Output Type	Adjustable
Number of Outputs	1
Voltage - Input (Min)	4V
Voltage - Input (Max)	40V
Voltage - Output (Min/Fixed)	1.23V
Voltage - Output (Max)	37V
Current - Output	1A
Frequency - Switching	52kHz
Operating Temperature	-40°C to 125°C (TJ)
Package / Case	TO-263-6, D2PAK (5 Leads + Tab)
Mounting Type	Surface Mount
RoHS Status	RoHS Non-Compliant

Substitute Part Grouping Explanation

Substitution of the LM2575BU is determined by the following critical parameters:

Function: Step-Down topology
Output Configuration: Positive adjustable output
Voltage Range: Input 4V–40V, Output 1.23V–37V adjustable
Current Rating: 1A minimum output capability
Switching Frequency: 52kHz nominal
Package: TO-263-6 (D2PAK) surface mount form factor
Operating Temperature: -40°C to 125°C

Substitute parts must maintain compatibility across these parameters. Parts are grouped by manufacturer and product status to reflect design continuity and supply availability.

Parameter Comparison

Parameter	LM2575BU	LM2575WU	LM2596DSADJR4G	TL2575-ADJIKTTR	TL2575-ADJIKTTRG3
Manufacturer	Microchip Technology	Microchip Technology	onsemi	Texas Instruments	Texas Instruments
Product Status	Obsolete	Active	Active	Active	Active
Function	Step-Down	Step-Down	Buck, Boost, Buck-Boost	Step-Down	Step-Down
Output Configuration	Positive	Positive	Positive or Negative	Positive	Positive
Output Type	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable
Voltage - Input (Min)	4V	4V	4.5V	4.75V	4.75V
Voltage - Input (Max)	40V	40V	40V	40V	40V
Voltage - Output (Min/Fixed)	1.23V	1.23V	1.23V	1.23V	1.23V
Voltage - Output (Max)	37V	37V	37V	37V	37V
Current - Output	1A	1A	3A	1A	1A
Frequency - Switching	52kHz	52kHz	150kHz	52kHz	52kHz
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
Package / Case	TO-263-6, D2PAK	TO-263-6, D2PAK	TO-263-6, D2PAK	TO-263-6, D2PAK	TO-263-6, D2PAK
RoHS Status	RoHS Non-Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)	3 (168 Hours)	1 (Unlimited)	3 (168 Hours)	3 (168 Hours)

Engineering Selection Recommendations

LM2575WU (Microchip Technology) — Direct functional equivalent with identical electrical specifications and package. Active product status ensures ongoing availability. ROHS3 compliant, addressing environmental compliance requirements where the original LM2575BU does not. Recommended as the primary replacement for direct substitution in new designs and legacy system updates.

TL2575-ADJIKTTR and TL2575-ADJIKTTRG3 (Texas Instruments) — Functionally equivalent buck regulators with matching 1A output current and 52kHz switching frequency. Both are active products with ROHS3 compliance. TL2575-ADJIKTTRG3 is supplied in Tape & Reel packaging; TL2575-ADJIKTTR is supplied in Cut Tape format. Minimum input voltage is 4.75V versus 4V for the LM2575BU. Suitable for applications where input voltage remains above 4.75V.

LM2596DSADJR4G (onsemi) — Offers expanded functionality with buck, boost, and buck-boost topology options while maintaining positive or negative adjustable output. Output current capability is 3A, exceeding the 1A requirement. Switching frequency is 150kHz, higher than the original 52kHz. MSL rating is 1 (Unlimited), providing superior moisture handling. Suitable for applications requiring higher current capacity or multi-topology flexibility. Input voltage minimum is 4.5V.

All substitute parts maintain the TO-263-6 (D2PAK) package form factor, ensuring PCB layout compatibility. Selection should account for input voltage floor requirements, output current headroom, and compliance certifications specific to the application environment.

Frequently Asked Questions (FAQ)

Q: Can LM2575WU directly replace LM2575BU without circuit modifications?

A: Yes. LM2575WU is a direct functional equivalent with identical electrical specifications, output voltage range, current rating, and switching frequency. Both use the same TO-263-6 package. The primary difference is product status (LM2575WU is active) and RoHS compliance (LM2575WU is ROHS3 compliant). No circuit modifications are required.

Q: What is the minimum input voltage difference between LM2575BU and TL2575-ADJIKTTR?

A: LM2575BU operates at 4V minimum input; TL2575-ADJIKTTR requires 4.75V minimum. Applications operating below 4.75V input voltage must use LM2575BU or LM2575WU. For applications with input voltage at or above 4.75V, TL2575-ADJIKTTR is compatible.

Q: Why does LM2596DSADJR4G have higher switching frequency (150kHz vs. 52kHz)?

A: LM2596DSADJR4G is a higher-performance device with enhanced specifications. The 150kHz switching frequency allows for smaller external filter components and improved transient response. This is a superset capability; applications designed for 52kHz operation will function with 150kHz switching, though external component values may require recalculation for optimal performance.

Q: Is LM2596DSADJR4G suitable if I only need 1A output current?

A: Yes. LM2596DSADJR4G is rated for 3A output current, making it suitable for applications requiring 1A or less. The higher current rating provides design margin and does not negatively impact 1A applications. However, verify that the boost and buck-boost topology options are not required for your application, as they add complexity not present in the original LM2575BU design.

Q: What is the significance of MSL (Moisture Sensitivity Level) differences?

A: MSL indicates moisture absorption limits during storage and handling. LM2575BU, LM2575WU, TL2575-ADJIKTTR, and TL2575-ADJIKTTRG3 are rated MSL 3 (168 hours maximum floor life). LM2596DSADJR4G is rated MSL 1 (unlimited floor life). MSL 1 provides superior protection in high-humidity environments and extended storage scenarios. For standard manufacturing environments, MSL 3 is acceptable.

Q: Are all substitute parts available in the same packaging options?

A: Packaging availability varies by manufacturer and distributor. LM2575WU is supplied in Tube packaging. LM2596DSADJR4G is supplied in Cut Tape and Digi-Reel format. TL2575-ADJIKTTR is supplied in Cut Tape format. TL2575-ADJIKTTRG3 is supplied in Tape & Reel format. All maintain the TO-263-6 (D2PAK) component package. Verify packaging availability with your component supplier for production requirements.

Q: Can I use LM2596DSADJR4G in a design originally specified for LM2575BU?

A: LM2596DSADJR4G is electrically compatible for buck topology operation with identical output voltage range and superior current capacity. However, the higher switching frequency (150kHz vs. 52kHz) may require recalculation of external inductor and capacitor values to maintain the same filtering characteristics. Consult the LM2596DSADJR4G datasheet for design guidance. The boost and buck-boost topology options are not required for LM2575BU replacement but do not interfere with buck-only operation.

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