LM317MBSTT3 Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LM317MBSTT3 is a positive adjustable linear voltage regulator IC manufactured by onsemi, rated for 500mA output current in a SOT-223 (TO-261) surface mount package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

The LM317MBSTT3 provides adjustable output voltage regulation from 1.2V to 37V with integrated protection features including over-current, over-temperature, and short-circuit protection. The regulator operates across an industrial temperature range of -40°C to 125°C and accepts input voltages up to 40V.

Key Parameters

Parameter	Value
Output Configuration	Positive
Output Type	Adjustable
Number of Regulators	1
Voltage - Input (Max)	40V
Voltage - Output (Min/Fixed)	1.2V
Voltage - Output (Max)	37V
Current - Output	500mA
Current - Quiescent (Iq)	10 mA
PSRR	80dB ~ 65dB (120Hz)
Protection Features	Over Current, Over Temperature, Short Circuit
Operating Temperature	-40°C ~ 125°C (TJ)
Mounting Type	Surface Mount
Package / Case	TO-261-4, TO-261AA
Supplier Device Package	SOT-223 (TO-261)
Base Product Number	LM317
RoHS Status	RoHS non-compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the LM317MBSTT3 is determined by the following critical parameters:

Direct Equivalents maintain identical electrical specifications: 500mA output current, 1.2V minimum output voltage, 40V maximum input voltage, SOT-223 package, and equivalent protection features. These parts are pin-compatible and functionally interchangeable without circuit modification.

Similar Substitutes share the same base product architecture (LM317 family) and package form factor but differ in output current rating (1.5A vs. 500mA). These parts are electrically compatible for applications requiring equal or lower current than the substitute's rating, though they represent a design upgrade rather than a direct replacement.

Substitution compatibility is strictly limited to parts meeting these criteria:

Positive adjustable output configuration
SOT-223 or TO-261 package family
Maximum input voltage of 40V or greater
Output voltage range encompassing 1.2V to 37V
Integrated over-current, over-temperature, and short-circuit protection

Parameter Comparison

Part Number	Manufacturer	Output Current	Voltage - Output (Min)	Voltage - Output (Max)	Voltage - Input (Max)	Operating Temperature	Product Status	RoHS Status	Package
LM317MBSTT3	onsemi	500mA	1.2V	37V	40V	-40°C ~ 125°C	Obsolete	RoHS non-compliant	SOT-223
LM317MBSTT3G	onsemi	500mA	1.2V	37V	40V	-40°C ~ 125°C	Active	ROHS3 Compliant	SOT-223
LM317MDCYR	Texas Instruments	500mA	1.25V	37V	40V	-40°C ~ 125°C	Active	ROHS3 Compliant	SOT-223-4
LM317AEMP/NOPB	Texas Instruments	1.5A	1.25V	37V	40V	-40°C ~ 125°C	Active	ROHS3 Compliant	SOT-223-4
LM317AEMPX/NOPB	Texas Instruments	1.5A	1.25V	37V	40V	-40°C ~ 125°C	Active	ROHS3 Compliant	SOT-223-4
LM317DCY	Texas Instruments	1.5A	1.25V	37V	40V	0°C ~ 125°C	Active	ROHS3 Compliant	SOT-223-4
LM317DCYG3	Texas Instruments	1.5A	1.25V	37V	40V	0°C ~ 125°C	Active	ROHS3 Compliant	SOT-223-4
LM317DCYR	UMW	1.5A	1.2V	37V	40V	0°C ~ 125°C	Active	ROHS3 Compliant	SOT-223
LM317DCYRG3	Texas Instruments	1.5A	1.25V	37V	40V	0°C ~ 125°C	Active	ROHS3 Compliant	SOT-223-4
LM317EMP/NOPB	Texas Instruments	1.5A	1.25V	37V	37V	0°C ~ 125°C	Active	ROHS3 Compliant	SOT-223-4
LM317EMPX/NOPB	Texas Instruments	1.5A	1.25V	37V	37V	0°C ~ 125°C	Active	ROHS3 Compliant	SOT-223-4

Engineering Selection Recommendations

Direct Replacement (Preferred for Obsolete Part Mitigation):

LM317MBSTT3G is the primary direct equivalent. This onsemi part maintains 500mA output current and identical voltage specifications while offering active product status and ROHS3 compliance. The transition from the obsolete LM317MBSTT3 to LM317MBSTT3G requires no circuit modification and provides improved regulatory compliance for new designs.

LM317MDCYR (Texas Instruments) provides an alternative direct equivalent with 500mA output current and active status. The minimum output voltage specification of 1.25V versus 1.2V represents a negligible difference for most applications. ROHS3 compliance and active product status support long-term supply chain stability.

Upgraded Substitutes (Higher Current Capability):

LM317AEMP/NOPB, LM317AEMPX/NOPB, LM317DCY, LM317DCYG3, LM317DCYR (UMW), LM317DCYRG3, LM317EMP/NOPB, and LM317EMPX/NOPB all provide 1.5A output current while maintaining compatibility with the original 500mA design envelope. These parts are suitable for applications where increased current headroom is beneficial or where supply availability of 500mA variants is constrained.

Compliance Considerations:

All substitute parts listed carry ROHS3 compliance, addressing regulatory requirements for new product designs. The original LM317MBSTT3 is RoHS non-compliant; migration to any substitute improves environmental and regulatory compliance posture.

Temperature Range Considerations:

LM317DCY, LM317DCYG3, LM317DCY, LM317EMP/NOPB, and LM317EMPX/NOPB operate across 0°C to 125°C, narrowing the lower temperature limit compared to the original -40°C to 125°C specification. Applications requiring full -40°C operation must select LM317MBSTT3G, LM317MDCYR, LM317AEMP/NOPB, or LM317AEMPX/NOPB.

Input Voltage Considerations:

LM317EMP/NOPB and LM317EMPX/NOPB specify maximum input voltage of 37V, matching the maximum output voltage. Applications requiring the full 40V input specification should select alternatives with 40V maximum input rating.

Frequently Asked Questions (FAQ)

Q: Can LM317MBSTT3G directly replace the obsolete LM317MBSTT3 without circuit modification?

A: Yes. LM317MBSTT3G maintains identical electrical specifications, output current rating, voltage ranges, and SOT-223 package configuration. No circuit changes are required for direct substitution.

Q: What is the difference between 500mA and 1.5A variants?

A: Output current rating is the primary difference. The 1.5A variants (LM317AEMP/NOPB, LM317AEMPX/NOPB, LM317DCY, LM317DCYG3, LM317DCYR, LM317DCYRG3, LM317EMP/NOPB, LM317EMPX/NOPB) provide three times the current capability. These are suitable substitutes for 500mA applications but represent a design upgrade rather than a direct equivalent.

Q: Are all substitute parts RoHS compliant?

A: Yes. All listed substitute parts carry ROHS3 compliance. The original LM317MBSTT3 is RoHS non-compliant. Migration to any substitute improves regulatory compliance.

Q: Which substitute supports the full -40°C to 125°C operating temperature range?

A: LM317MBSTT3G, LM317MDCYR, LM317AEMP/NOPB, and LM317AEMPX/NOPB maintain the full -40°C to 125°C specification. Other variants operate from 0°C to 125°C.

Q: What is the significance of the minimum output voltage difference (1.2V vs. 1.25V)?

A: The 0.05V difference is negligible for most applications. Designs requiring output voltages below 1.25V must select parts specifying 1.2V minimum (LM317MBSTT3, LM317MBSTT3G, or LM317DCYR from UMW).

Q: Can I use LM317EMP/NOPB or LM317EMPX/NOPB if my application requires 40V input?

A: No. These parts specify 37V maximum input voltage. Applications requiring 40V input must select alternatives with 40V maximum input rating.

Q: What packaging options are available?

A: All substitute parts use SOT-223 or SOT-223-4 surface mount packages compatible with TO-261-4 and TO-261AA footprints. Packaging differences are limited to tape and reel configurations (Cut Tape, Digi-Reel, or Tube).

Q: Which manufacturer offers the best long-term availability?

A: Texas Instruments and onsemi both maintain active product status across multiple LM317 variants. Texas Instruments offers the widest selection of current ratings and packaging options. onsemi's LM317MBSTT3G provides the most direct equivalent to the obsolete original part.

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