SPX3940AM3-L-5-0 Equivalent & Substitute Parts

Part Overview

The SPX3940AM3-L-5-0 is a linear voltage regulator IC from MaxLinear, Inc., designed to deliver a fixed 5V output at 1A in a surface-mount SOT-223-3 package. This part is classified as a Power Management PMIC and provides essential voltage regulation with integrated protection features including over-current, over-temperature, reverse polarity, short-circuit, and transient voltage protection. The part is currently discontinued at DiGi Electronics, making equivalent substitutes necessary for ongoing design support and production continuity.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	5V
Output Current	1A
Input Voltage (Max)	16V
Voltage Dropout (Max)	0.55V @ 1A
Operating Temperature Range	-40°C ~ 125°C
Package Type	SOT-223-3
Mounting Type	Surface Mount
Protection Features	Over Current, Over Temperature, Reverse Polarity, Short Circuit, Transient Voltage
RoHS Status	RoHS Compliant

Substitute Part Grouping Explanation

Substitution of the SPX3940AM3-L-5-0 is determined by the following critical parameters:

Output Voltage: Must be fixed at 5V
Package Type: Must be SOT-223-3 for PCB compatibility
Mounting Type: Must be surface mount
Operating Temperature Range: Must support -40°C ~ 125°C
Output Current Capability: Minimum 1A required for direct replacement; lower current ratings may be used in current-limited applications
Input Voltage Rating: Must support up to 16V maximum input
Protection Features: Over-current and over-temperature protection are essential; additional protection features enhance reliability

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

Category 1 - Full Current Rating (1A Output): MIC39100-5.0WS and MIC39100-5.0WS-TR provide direct 1A replacement capability with identical output current specifications.

Category 2 - Reduced Current Rating (250mA-500mA Output): MCP1703-5002E/DB, MCP1703A-5002E/DB, MCP1703AT-5002E/DB, MCP1754ST-5002E/DB, MIC5209-5.0YS, and MIC5209-5.0YS-TR offer lower output current ratings suitable for applications requiring less than 1A.

Parameter Comparison

Parameter	SPX3940AM3-L-5-0	MIC39100-5.0WS-TR	MCP1703AT-5002E/DB	MCP1754ST-5002E/DB	MIC5209-5.0YS-TR
Manufacturer	MaxLinear, Inc.	Microchip Technology	Microchip Technology	Microchip Technology	Microchip Technology
Output Voltage	5V	5V	5V	5V	5V
Output Current	1A	1A	250mA	150mA	500mA
Input Voltage (Max)	16V	16V	16V	16V	16V
Voltage Dropout (Max)	0.55V @ 1A	0.63V @ 1A	0.65V @ 250mA	0.5V @ 150mA	0.6V @ 500mA
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C
Package Type	SOT-223-3	SOT-223-3	SOT-223-3	SOT-223-3	SOT-223-3
Product Status	Discontinued	Active	Active	Active	Active
RoHS Status	RoHS Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (1A Output Current)

MIC39100-5.0WS-TR is the primary substitute for the SPX3940AM3-L-5-0. Both parts deliver 1A output current with identical 5V fixed output voltage and SOT-223-3 packaging. MIC39100-5.0WS-TR is currently in active production status with 30,300 units in stock, ensuring supply continuity. The part is ROHS3 compliant and maintains the same operating temperature range. Voltage dropout is slightly higher at 0.63V compared to the original 0.55V, which is acceptable for most 5V regulation applications.

MIC39100-5.0WS (tube packaging) is functionally equivalent to the -TR variant and provides the same electrical performance with 6,542 units available.

Reduced Current Substitutes (250mA-500mA Output)

For applications where output current requirements are less than 1A, the following parts are suitable:

MCP1703AT-5002E/DB (250mA): Highest inventory availability at 1,000,100 units. Active product status with ROHS3 compliance. Voltage dropout of 0.65V @ 250mA.
MIC5209-5.0YS-TR (500mA): Provides intermediate current capability between 250mA and 1A options. 1,313 units in stock. Superior PSRR performance at 75dB (120Hz) compared to other options.
MCP1754ST-5002E/DB (150mA): Lowest current rating. Lowest voltage dropout at 0.5V @ 150mA. Suitable only for minimal current draw applications.

All substitute parts maintain ROHS3 compliance, -40°C ~ 125°C operating temperature range, and SOT-223-3 surface-mount packaging required for PCB compatibility.

Frequently Asked Questions (FAQ)

Q: Can MCP1703AT-5002E/DB replace SPX3940AM3-L-5-0 in all applications?

A: MCP1703AT-5002E/DB is electrically compatible but has a reduced output current rating of 250mA versus the original 1A. It is suitable only for applications drawing 250mA or less. For applications requiring the full 1A output current, use MIC39100-5.0WS-TR.

Q: What is the difference between MIC39100-5.0WS and MIC39100-5.0WS-TR?

A: Both parts are electrically identical with 1A output current and 5V fixed output. The difference is packaging format: MIC39100-5.0WS is supplied in tube packaging, while MIC39100-5.0WS-TR is supplied in cut tape and Digi-Reel format. Select based on your procurement and assembly requirements.

Q: Is the voltage dropout difference between SPX3940AM3-L-5-0 (0.55V) and MIC39100-5.0WS-TR (0.63V) significant?

A: The 0.08V difference is minor for most 5V regulation applications. Both parts maintain stable 5V output across the specified input voltage range of up to 16V. Verify dropout performance only if your application operates with input voltages close to the minimum required for regulation.

Q: Are all substitute parts RoHS compliant?

A: Yes. The original SPX3940AM3-L-5-0 is RoHS Compliant. All substitute parts listed are ROHS3 Compliant, meeting current environmental and regulatory requirements.

Q: Can I use MIC5209-5.0YS-TR instead of MIC39100-5.0WS-TR?

A: MIC5209-5.0YS-TR has a 500mA output current rating, which is lower than the 1A requirement of the original part. Use this substitute only if your application requires 500mA or less. For full 1A capability, use MIC39100-5.0WS-TR.

Q: What protection features do the substitute parts provide?

A: All substitute parts include over-current and over-temperature protection. MIC39100 and MIC5209 series additionally include reverse polarity protection. The original SPX3940AM3-L-5-0 includes reverse polarity, short-circuit, and transient voltage protection. Verify that the protection feature set meets your application requirements.

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