LP3985IM5X-3.3 Equivalent & Substitute Parts

Part Overview

The LP3985IM5X-3.3 is a linear voltage regulator IC from Texas Instruments designed to deliver a fixed 3.3V output at 150mA in a SOT-23-5 surface mount package. This part is classified as Obsolete, which necessitates identification of equivalent and substitute components for new designs or production continuity. The device provides positive fixed output regulation with integrated protection features including over-current, over-temperature, and short-circuit protection, making it suitable for low-power applications requiring stable 3.3V rails.

Key Parameters

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

Substitute Part Grouping Explanation

Substitution for the LP3985IM5X-3.3 is determined by the following critical parameters:

Output voltage fixed at 3.3V
Output current capability of 150mA minimum
SOT-23-5 package compatibility
Input voltage rating of 5.5V or higher
Operating temperature range of -40°C to 125°C
Integrated protection features (over-current, over-temperature, short-circuit)

Parts are grouped into three categories: direct manufacturer equivalents from Texas Instruments with identical specifications, parametric equivalents from Texas Instruments with modified electrical characteristics, and cross-manufacturer alternatives meeting the core functional requirements.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage @ 150mA	Quiescent Current	Product Status	RoHS Status
LP3985IM5X-3.3	Texas Instruments	3.3V	150mA	6V	0.1V	150 µA	Obsolete	Non-compliant
LP3985IM5X-3.3/NOPB	Texas Instruments	3.3V	150mA	6V	0.1V	150 µA	Active	ROHS3 Compliant
LP3985IM5-3.3	Texas Instruments	3.3V	150mA	6V	0.1V	150 µA	Last Time Buy	ROHS3 Compliant
LP3985IM5-3.3/NOPB	Texas Instruments	3.3V	150mA	6V	0.1V	150 µA	Active	ROHS3 Compliant
LP5951MF-3.3	Texas Instruments	3.3V	150mA	5.5V	0.35V	55 µA	Active	Not specified
LP5951MF-3.3/NOPB	Texas Instruments	3.3V	150mA	5.5V	0.35V	55 µA	Active	ROHS3 Compliant
LP5951MFX-3.3/NOPB	Texas Instruments	3.3V	150mA	5.5V	0.35V	55 µA	Active	ROHS3 Compliant
NCP700BSN33T1G	onsemi	3.3V	200mA	5.5V	0.185V @ 200mA	110 µA	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Equivalents (Recommended for Immediate Replacement)

LP3985IM5X-3.3/NOPB and LP3985IM5-3.3/NOPB are the primary substitutes, offering identical electrical specifications to the obsolete LP3985IM5X-3.3. Both are Active status parts with ROHS3 compliance, ensuring long-term availability and regulatory alignment. LP3985IM5X-3.3/NOPB carries the highest inventory (91,100 units) and is available in standard Cut Tape and Digi-Reel packaging formats.

Parametric Equivalents (Alternative with Modified Characteristics)

The LP5951 series (LP5951MF-3.3/NOPB, LP5951MFX-3.3/NOPB) maintains 3.3V output and 150mA current capability but operates with reduced quiescent current (55 µA versus 150 µA) and higher dropout voltage (0.35V versus 0.1V). These parts are suitable for applications where lower standby power consumption is beneficial and input voltage headroom permits the increased dropout specification. All LP5951 variants are Active status with ROHS3 compliance.

Cross-Manufacturer Alternative

NCP700BSN33T1G from onsemi provides 3.3V output with enhanced current capability (200mA) and improved dropout voltage (0.185V @ 200mA). This part is Active status, ROHS3 compliant, and offers superior performance margins. Selection requires confirmation that the 5-TSOP package variant is mechanically compatible with the original SOT-23-5 footprint in the application.

Frequently Asked Questions (FAQ)

Q: Can LP3985IM5-3.3/NOPB directly replace LP3985IM5X-3.3?

A: Yes. Both parts deliver identical electrical performance: 3.3V fixed output, 150mA current, 0.1V dropout at 150mA, and -40°C to 125°C operating range. The primary difference is product status (Active versus Obsolete) and RoHS compliance (ROHS3 Compliant versus Non-compliant). The /NOPB suffix indicates lead-free solder ball construction.

Q: What is the difference between LP3985 and LP5951 series?

A: The LP5951 series reduces quiescent current from 150 µA to 55 µA, lowering standby power consumption. However, dropout voltage increases from 0.1V to 0.35V at 150mA output. Both maintain 3.3V output and 150mA current capability. Selection depends on whether the application prioritizes low quiescent current or minimal dropout voltage.

Q: Is NCP700BSN33T1G a direct substitute?

A: NCP700BSN33T1G is functionally compatible but not a direct substitute. It provides higher output current (200mA versus 150mA) and lower dropout voltage (0.185V @ 200mA), making it suitable for applications requiring performance margins. The package is 5-TSOP, which must be verified for mechanical compatibility with the original SOT-23-5 footprint.

Q: Why is the original LP3985IM5X-3.3 marked Obsolete?

A: Obsolete status indicates Texas Instruments has discontinued production. The Active equivalents LP3985IM5X-3.3/NOPB and LP3985IM5-3.3/NOPB provide identical specifications with continued manufacturing support and regulatory compliance.

Q: Are all substitute parts RoHS compliant?

A: All recommended substitutes carry ROHS3 Compliant status except LP5951MF-3.3, which has unspecified RoHS status. For applications requiring RoHS certification, select LP3985IM5X-3.3/NOPB, LP3985IM5-3.3/NOPB, LP5951MF-3.3/NOPB, LP5951MFX-3.3/NOPB, or NCP700BSN33T1G.

Q: What packaging formats are available?

A: LP3985IM5X-3.3/NOPB is available in Cut Tape (CT) and Digi-Reel formats. LP5951MF-3.3/NOPB is supplied in Tape & Reel (TR). LP5951MFX-3.3/NOPB is available in Cut Tape and Digi-Reel. NCP700BSN33T1G is supplied in Tape & Reel. Confirm packaging compatibility with assembly requirements before procurement.

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