AP1501-33K5L-13 Equivalent & Substitute Parts

Part Overview

The AP1501-33K5L-13 is a buck switching regulator IC manufactured by Diodes Incorporated, rated for 3.3V fixed output at 3A maximum current. This device operates across a 4.5V to 40V input range with a 150kHz switching frequency and is housed in a TO-263-6 (D2PAK) surface mount package. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Manufacturer	Diodes Incorporated
Part Number	AP1501-33K5L-13
Product Status	Obsolete
Function	Step-Down (Buck)
Output Voltage	3.3V Fixed
Output Current	3A
Input Voltage Range	4.5V to 40V
Switching Frequency	150kHz
Package	TO-263-6 (D2PAK, 5 Leads + Tab)
Operating Temperature	-20°C to 85°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the AP1501-33K5L-13 is determined by the following critical parameters:

Output Voltage: Must be fixed at 3.3V
Output Current Capability: Minimum 3A to match or exceed the original specification
Input Voltage Range: Must accommodate 4.5V to 40V operation
Package Type: TO-263-6 (D2PAK, 5 Leads + Tab) for mechanical and thermal compatibility
Topology: Buck (step-down) configuration
Product Status: Active status preferred for long-term availability

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

Category A - Full Current Match (3A Output): Parts with 3A or greater output current capability, providing direct functional replacement with identical current handling.

Category B - Reduced Current (1A to 1.7A Output): Parts with lower output current ratings. These are suitable only for applications where the actual load current does not exceed the substitute part's rating, despite the original design specification of 3A.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Min-Max)	Switching Frequency	Package	Operating Temperature	Product Status
AP1501-33K5L-13	Diodes Incorporated	3.3V	3A	4.5V - 40V	150kHz	TO-263-6	-20°C to 85°C	Obsolete
LM2576-3.3WU	Microchip Technology	3.3V	3A	4V - 40V	52kHz	TO-263-6	-40°C to 125°C	Active
LM2576-3.3WU-TR	Microchip Technology	3.3V	3A	4V - 40V	52kHz	TO-263-6	-40°C to 125°C	Active
MIC4576-3.3WU	Microchip Technology	3.3V	3A	4V - 36V	200kHz	TO-263-6	-40°C to 85°C	Active
LM2575S-3.3/NOPB	Texas Instruments	3.3V	1A	4V - 40V	52kHz	TO-263-6	-40°C to 125°C	Active
LM2575SX-3.3/NOPB	Texas Instruments	3.3V	1A	4V - 40V	52kHz	TO-263-6	-40°C to 125°C	Active
LM2591HVS-3.3/NOPB	Texas Instruments	3.3V	1A	4.5V - 60V	150kHz	TO-263-6	-40°C to 125°C	Active
LM2591HVSX-3.3/NOPB	Texas Instruments	3.3V	1A	4.5V - 60V	150kHz	TO-263-6	-40°C to 125°C	Active
MIC4575-3.3WU	Microchip Technology	3.3V	1.7A (Switch)	4V - 24V	200kHz	TO-263-6	-40°C to 85°C	Active
MIC4575-3.3WU-TR	Microchip Technology	3.3V	1.7A (Switch)	4V - 24V	200kHz	TO-263-6	-40°C to 85°C	Active
LM2598S-3.3/NOPB	National Semiconductor	3.3V	1A	4.5V - 40V	150kHz	TO-263-8	-40°C to 125°C	Active

Engineering Selection Recommendations

Primary Substitutes (Full Current Capability - 3A)

The LM2576-3.3WU and LM2576-3.3WU-TR from Microchip Technology are the preferred direct replacements. Both maintain the 3A output current specification, operate across the required 4V to 40V input range, and are in active production status. The LM2576-3.3WU-TR variant is supplied in Tape & Reel packaging, matching the original part's packaging format. Both devices are ROHS3 compliant and operate across an extended temperature range of -40°C to 125°C, exceeding the original -20°C to 85°C specification.

The MIC4576-3.3WU from Microchip Technology also provides 3A output current in the TO-263-6 package with active product status. This device operates at 200kHz switching frequency and supports input voltages from 4V to 36V. The reduced maximum input voltage (36V versus 40V) must be verified against application requirements.

Secondary Substitutes (Reduced Current Capability - 1A to 1.7A)

The LM2575S-3.3/NOPB and LM2575SX-3.3/NOPB from Texas Instruments provide 1A output current in the TO-263-6 package with active status and ROHS3 compliance. These are suitable only for applications where the actual load current does not exceed 1A. The LM2575SX-3.3/NOPB is supplied in Cut Tape & Digi-Reel packaging.

The LM2591HVS-3.3/NOPB and LM2591HVSX-3.3/NOPB from Texas Instruments offer 1A output current with extended input voltage range (4.5V to 60V) and 150kHz switching frequency, matching the original part's frequency. These devices are suitable for applications requiring higher input voltage tolerance but with reduced output current requirements.

The MIC4575-3.3WU and MIC4575-3.3WU-TR from Microchip Technology provide 1.7A switch current in the TO-263-6 package. These devices support both buck and buck-boost topologies but are limited to 4V to 24V input range, making them unsuitable for applications requiring the full 40V input capability of the original part.

Package Consideration

The LM2598S-3.3/NOPB uses a TO-263-8 (D2PAK, 7 Leads + Tab) package, which differs from the original TO-263-6 (5 Leads + Tab). This package change requires PCB layout modification and is not recommended as a direct mechanical substitute.

Frequently Asked Questions (FAQ)

Q: Can I use a 1A substitute part in place of the 3A AP1501-33K5L-13?

A: Only if your application's actual load current does not exceed 1A. The original part is rated for 3A maximum output current. Using a lower-rated substitute in a 3A application will cause the regulator to exceed its current limit, resulting in thermal shutdown or device damage. Verify your actual load current before selecting a reduced-current substitute.

Q: What is the difference between LM2576-3.3WU and LM2576-3.3WU-TR?

A: Both parts are electrically identical with 3A output current and identical electrical specifications. The difference is packaging format: LM2576-3.3WU is supplied in Tube packaging, while LM2576-3.3WU-TR is supplied in Tape & Reel (TR) format. For automated assembly, the Tape & Reel variant is preferred.

Q: Why does the MIC4575-3.3WU have a lower maximum input voltage (24V) than the original part (40V)?

A: The MIC4575 is designed for buck-boost topology with a narrower input voltage range. If your application requires operation at input voltages above 24V, this part is not suitable. Verify your input voltage requirements before selection.

Q: Are all substitute parts ROHS3 compliant?

A: All listed substitute parts are ROHS3 compliant, matching the original part's environmental compliance status.

Q: Can I use the LM2598S-3.3/NOPB as a direct replacement?

A: The LM2598S-3.3/NOPB uses a different package (TO-263-8 with 7 leads versus TO-263-6 with 5 leads). This requires PCB redesign and is not a direct mechanical substitute. Use only if your PCB layout can accommodate the different pinout and package footprint.

Q: What is the switching frequency difference, and does it matter?

A: The original AP1501 operates at 150kHz. Most substitutes operate at 52kHz (LM2575/LM2576 series) or 200kHz (MIC4575/MIC4576 series). Lower switching frequency may result in larger output filter components; higher frequency allows smaller components. Verify that your PCB layout and filtering design accommodate the substitute part's switching frequency.

Q: Which substitute offers the widest input voltage range?

A: The LM2591HVS-3.3/NOPB and LM2591HVSX-3.3/NOPB support 4.5V to 60V input range, exceeding the original 4.5V to 40V specification. However, these parts are limited to 1A output current.

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