LP3985IM5-3.3 Equivalent & Substitute Parts

Part Overview

The LP3985IM5-3.3 is a linear voltage regulator IC from Texas Instruments, delivering a fixed 3.3V output at 150mA in a SOT-23-5 surface mount package. This part is classified as Last Time Buy, indicating end-of-life status. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain resilience, and support ongoing production requirements for applications requiring 3.3V regulation with 150mA output capability.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	150mA
Input Voltage (Max)	6V
Voltage Dropout (Max)	0.1V @ 150mA
Quiescent Current (Iq)	150 µA
Package Type	SOT-23-5 (SC-74A)
Operating Temperature Range	-40°C to 125°C
Control Features	Enable
Protection Features	Over Current, Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitute parts are organized into three categories based on electrical and mechanical compatibility:

Direct Equivalents (Texas Instruments LP3985 Series): Parts LP3985IM5-3.3/NOPB and LP3985IM5X-3.3/NOPB maintain identical electrical specifications, output voltage, current rating, dropout voltage, and package configuration. These differ only in packaging format (Cut Tape vs. Tape & Reel) and product status (Active vs. Last Time Buy).

Parametric Equivalents (Texas Instruments LP5951 Series): Parts LP5951MF-3.3, LP5951MF-3.3/NOPB, and LP5951MFX-3.3/NOPB deliver the same 3.3V output and 150mA current rating in identical SOT-23-5 packaging. Key differences include lower quiescent current (55 µA vs. 150 µA), higher dropout voltage (0.35V @ 150mA vs. 0.1V), and reduced maximum input voltage (5.5V vs. 6V). These parts are suitable for applications where lower standby power consumption is beneficial.

Manufacturer-Recommended Alternatives: Parts from STMicroelectronics (LD3985M33R, LDS3985M33R), Analog Devices Inc. (LTC1844ES5-3.3#TRMPBF, LTC1844ES5-3.3#TRPBF), and Maxim Integrated (MAX8867EUK50+T) provide functional equivalence with variations in quiescent current, dropout voltage, protection features, and operating temperature ranges. The LDS3985M33R variant supports 300mA output, exceeding the 150mA requirement.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout @ Rated Current	Iq (µA)	Package	Status
LP3985IM5-3.3	Texas Instruments	3.3V	150mA	6V	0.1V @ 150mA	150	SOT-23-5	Last Time Buy
LP3985IM5-3.3/NOPB	Texas Instruments	3.3V	150mA	6V	0.1V @ 150mA	150	SOT-23-5	Active
LP3985IM5X-3.3/NOPB	Texas Instruments	3.3V	150mA	6V	0.1V @ 150mA	150	SOT-23-5	Active
LP5951MF-3.3	Texas Instruments	3.3V	150mA	5.5V	0.35V @ 150mA	55	SOT-23-5	Active
LP5951MF-3.3/NOPB	Texas Instruments	3.3V	150mA	5.5V	0.35V @ 150mA	55	SOT-23-5	Active
LP5951MFX-3.3/NOPB	Texas Instruments	3.3V	150mA	5.5V	0.35V @ 150mA	55	SOT-23-5	Active
LD3985M33R	STMicroelectronics	3.3V	150mA	6V	0.1V @ 150mA	150	SOT-23-5	Active
LDS3985M33R	STMicroelectronics	3.3V	300mA	6V	0.25V @ 300mA	150	SOT-23-5	Active
LTC1844ES5-3.3#TRMPBF	Analog Devices Inc.	3.3V	150mA	6.5V	0.15V @ 150mA	80	TSOT-23-5	Active
LTC1844ES5-3.3#TRPBF	Analog Devices Inc.	3.3V	150mA	6.5V	0.15V @ 150mA	80	TSOT-23-5	Active
MAX8867EUK50+T	Analog Devices Inc./Maxim Integrated	5V	150mA	6.5V	0.165V @ 150mA	180	SOT-23-5	Active

Engineering Selection Recommendations

First Priority - Direct Equivalents: LP3985IM5-3.3/NOPB and LP3985IM5X-3.3/NOPB are recommended as primary replacements. Both maintain Active product status, identical electrical specifications, and full compatibility with existing designs. These parts require no circuit modifications and provide drop-in replacement capability.

Secondary Priority - Texas Instruments LP5951 Series: LP5951MF-3.3/NOPB and LP5951MFX-3.3/NOPB are suitable for applications where reduced quiescent current (55 µA vs. 150 µA) provides system-level benefits. The higher dropout voltage (0.35V vs. 0.1V) and lower maximum input voltage (5.5V vs. 6V) must be evaluated against circuit design margins. These parts are Active and ROHS3 compliant.

Alternative Manufacturers: LD3985M33R from STMicroelectronics provides electrical equivalence with Active status and identical specifications. LTC1844ES5-3.3 variants from Analog Devices Inc. offer improved dropout voltage (0.15V) and higher maximum input voltage (6.5V) with lower quiescent current (80 µA), though package designation differs (TSOT-23-5 vs. SOT-23-5). MAX8867EUK50+T is not recommended as a direct substitute due to 5V output voltage specification, which does not match the 3.3V requirement.

Higher Current Requirement: LDS3985M33R supports 300mA output current, suitable only for applications requiring current capacity beyond the 150mA specification of the original part.

Frequently Asked Questions (FAQ)

Q: Can LP5951MF-3.3/NOPB replace LP3985IM5-3.3 in all applications?

A: LP5951MF-3.3/NOPB is electrically compatible for 3.3V regulation at 150mA. However, the higher dropout voltage (0.35V vs. 0.1V) and lower maximum input voltage (5.5V vs. 6V) require verification against circuit design specifications. Applications with tight input voltage margins or requiring minimal voltage drop may not be suitable.

Q: What is the difference between LP3985IM5-3.3/NOPB and LP3985IM5X-3.3/NOPB?

A: Both parts are electrically identical with identical specifications. The difference is in manufacturing process designation (IM5 vs. IM5X). Both are Active status and suitable for direct substitution.

Q: Are TSOT-23-5 and SOT-23-5 packages interchangeable?

A: TSOT-23-5 (Thin SOT-23-5) and SOT-23-5 (SC-74A) are mechanically compatible for PCB placement and soldering. Both are 5-pin surface mount packages with identical pin pitch and footprint. Verify with component datasheets for specific thermal and mechanical requirements.

Q: Why is MAX8867EUK50+T listed if it outputs 5V instead of 3.3V?

A: MAX8867EUK50+T is included in the substitute list but is not recommended for direct replacement due to output voltage mismatch. It is listed for reference only and would require circuit redesign to implement.

Q: Which substitute part has the lowest quiescent current?

A: LP5951MF-3.3/NOPB and LP5951MFX-3.3/NOPB have the lowest quiescent current at 55 µA, compared to 150 µA for the original LP3985IM5-3.3. LTC1844ES5-3.3 variants provide 80 µA quiescent current as an intermediate option.

Q: Are all substitute parts ROHS3 compliant?

A: All listed substitute parts are ROHS3 compliant. Verify REACH status in procurement documentation for specific regulatory requirements.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message