LP3985IM5-3.0 Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LP3985IM5-3.0 is a linear voltage regulator IC from Texas Instruments designed for positive fixed 3V output at 150mA in SOT-23-5 surface mount packaging. This part is classified as "Not For New Designs," indicating it has been superseded in the manufacturer's product portfolio. Finding equivalent and substitute parts is necessary for legacy system support, design continuity, and ensuring supply chain availability for ongoing production or maintenance applications.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Part Number	LP3985IM5-3.0
Output Voltage	3V Fixed
Output Current	150mA
Input Voltage (Max)	6V
Dropout Voltage	0.1V @ 150mA
Quiescent Current	150 µA
Package	SOT-23-5 (SC-74A)
Operating Temperature	-40°C to 125°C
Protection Features	Over Current, Over Temperature, Short Circuit
Control Features	Enable
Product Status	Not For New Designs
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitute parts for the LP3985IM5-3.0 are grouped based on the following critical parameters that determine functional equivalence:

Primary Substitution Criteria:

Output voltage: 3V fixed
Output current capability: 150mA minimum
Package type: SOT-23-5 surface mount
Input voltage range: 6V maximum or higher
Dropout voltage: 0.1V to 0.35V @ 150mA
Operating temperature range: -40°C to 125°C
Protection features: Over current, over temperature, short circuit

Grouping Logic:

Group 1 - Direct Parametric Equivalents (Texas Instruments LP3985 Series): Parts LP3985IM5-3.0/NOPB and LP3985IM5X-3.0/NOPB maintain identical electrical specifications to the main part. These are active product variants with improved RoHS3 compliance status.

Group 2 - Enhanced Parametric Equivalents (Texas Instruments LP5951 Series): Parts LP5951MF-3.0/NOPB and LP5951MFX-3.0/NOPB provide 3V output at 150mA with lower quiescent current (55 µA vs. 150 µA) and improved PSRR performance. Input voltage maximum is 5.5V, which is acceptable for most 6V input applications. Dropout voltage is 0.35V @ 150mA.

Group 3 - Manufacturer-Recommended Alternatives (STMicroelectronics): Parts LD3985M30R and LDS3985M30R from STMicroelectronics provide equivalent or enhanced specifications. LD3985M30R matches the LP3985 specifications exactly. LDS3985M30R offers doubled output current capability (300mA) while maintaining 3V output and SOT-23-5 packaging.

Group 4 - Cross-Manufacturer Alternatives (Analog Devices/Maxim): MAX8877EUK30+T provides 3V output at 150mA with superior dropout voltage (0.165V typical) and additional reverse polarity protection. MAX8868EUK30+T is an obsolete alternative. MAX8867EUK50+T and MAX8868EUK50+T are 5V output variants and are not direct substitutes for 3V applications.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage	Quiescent Current	Package	Product Status	RoHS Status
LP3985IM5-3.0	Texas Instruments	3V	150mA	6V	0.1V @ 150mA	150 µA	SOT-23-5	Not For New Designs	RoHS non-compliant
LP3985IM5-3.0/NOPB	Texas Instruments	3V	150mA	6V	0.1V @ 150mA	150 µA	SOT-23-5	Active	ROHS3 Compliant
LP3985IM5X-3.0/NOPB	Texas Instruments	3V	150mA	6V	0.1V @ 150mA	150 µA	SOT-23-5	Active	ROHS3 Compliant
LP5951MF-3.0/NOPB	Texas Instruments	3V	150mA	5.5V	0.35V @ 150mA	55 µA	SOT-23-5	Active	ROHS3 Compliant
LP5951MFX-3.0/NOPB	Texas Instruments	3V	150mA	5.5V	0.35V @ 150mA	55 µA	SOT-23-5	Active	ROHS3 Compliant
LD3985M30R	STMicroelectronics	3V	150mA	6V	0.1V @ 150mA	150 µA	SOT-23-5	Active	ROHS3 Compliant
LDS3985M30R	STMicroelectronics	3V	300mA	6V	0.25V @ 300mA	150 µA	SOT-23-5	Active	ROHS3 Compliant
MAX8877EUK30+T	Analog Devices Inc./Maxim Integrated	3V	150mA	6.5V	0.165V @ 150mA (Typ)	180 µA	SOT-23-5	Active	ROHS3 Compliant
MAX8868EUK30+T	Analog Devices Inc./Maxim Integrated	3V	150mA	6.5V	0.165V @ 150mA (Typ)	180 µA	SOT-23-5	Obsolete	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement with Active Product Status: LP3985IM5-3.0/NOPB and LP3985IM5X-3.0/NOPB are the primary recommendations. Both maintain identical electrical specifications to the original part while offering active product status and ROHS3 compliance. These variants are suitable for new production runs and legacy system support.

For Improved Compliance and Performance: LD3985M30R from STMicroelectronics provides exact electrical equivalence with active product status and ROHS3 compliance. This part is recommended when cross-manufacturer sourcing is acceptable and supply chain diversification is desired.

For Enhanced Current Capability: LDS3985M30R offers doubled output current (300mA) while maintaining 3V output and SOT-23-5 packaging. This part is suitable for applications requiring higher current delivery without package redesign.

For Superior Dropout Performance: MAX8877EUK30+T provides lower typical dropout voltage (0.165V vs. 0.1V) and extended input voltage range (6.5V). This part is recommended for applications with marginal input voltage headroom or requiring enhanced reverse polarity protection.

Parts to Avoid: MAX8868EUK30+T is classified as obsolete and should not be selected for new designs or ongoing production. MAX8867EUK50+T and MAX8868EUK50+T output 5V and are not suitable for 3V applications.

Frequently Asked Questions (FAQ)

Q: Can LP5951MF-3.0/NOPB replace LP3985IM5-3.0 directly? A: Yes, with design considerations. The LP5951 maintains 3V output at 150mA in SOT-23-5 packaging. However, input voltage maximum is 5.5V versus 6V, and dropout voltage is 0.35V versus 0.1V. Verify your input voltage does not exceed 5.5V and that the higher dropout voltage is acceptable for your application.

Q: What is the difference between LP3985IM5-3.0 and LP3985IM5-3.0/NOPB? A: Both parts are electrically identical. The /NOPB suffix indicates "No Plumbum" (lead-free) and ROHS3 compliance. The original LP3985IM5-3.0 is RoHS non-compliant. For new designs and production, use the /NOPB variant.

Q: Can LDS3985M30R be used as a drop-in replacement? A: LDS3985M30R is pin-compatible in SOT-23-5 packaging and provides 3V output. However, it delivers 300mA output current versus 150mA. This higher current capability does not prevent use in 150mA applications, but verify that your PCB layout and thermal management are adequate for the part's power dissipation characteristics.

Q: Why is MAX8877EUK30+T recommended over MAX8868EUK30+T? A: MAX8877EUK30+T is active product status, while MAX8868EUK30+T is obsolete. Both provide 3V output at 150mA, but MAX8877 ensures long-term availability and supply chain stability.

Q: Are there output voltage variants I should avoid? A: Yes. MAX8867EUK50+T and MAX8868EUK50+T output 5V, not 3V. These are not suitable for applications requiring 3V output and will cause circuit malfunction if substituted.

Q: What packaging considerations apply to these substitutes? A: All recommended substitutes use SOT-23-5 (SC-74A) surface mount packaging, identical to the original part. No PCB layout modifications are required for package compatibility.

Q: Which substitute offers the best compliance profile? A: LP3985IM5-3.0/NOPB, LP3985IM5X-3.0/NOPB, LD3985M30R, LDS3985M30R, MAX8877EUK30+T, and MAX8868EUK50+T all carry ROHS3 compliance. The original LP3985IM5-3.0 is RoHS non-compliant and should be replaced in new designs.

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