LP3966ESX-ADJ Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LP3966ESX-ADJ is a linear voltage regulator IC from Texas Instruments designed for positive adjustable output applications. This Surface Mount device delivers 3A output current in a TO-263 (DDPAK-5) package and operates across -40°C to 125°C. The part is classified as "Not For New Designs," making identification of equivalent and substitute components essential for ongoing production support, legacy system maintenance, and design flexibility.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Output Configuration	Positive
Output Type	Adjustable
Current - Output	3A
Voltage - Input (Max)	7V
Voltage - Output (Min/Fixed)	1.216V
Voltage - Output (Max)	5.1V
Voltage Dropout (Max)	1.2V @ 3A
Operating Temperature	-40°C ~ 125°C
Package / Case	TO-263-6, D2PAK (5 Leads + Tab)
Mounting Type	Surface Mount
Protection Features	Over Current, Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitution eligibility for the LP3966ESX-ADJ is determined by the following critical parameters:

Primary Compatibility Criteria:

Output Configuration: Positive
Output Type: Adjustable (voltage range 1.216V to 5.1V)
Current - Output: 3A minimum
Package / Case: TO-263-6 or D2PAK (5 Leads + Tab) compatible
Mounting Type: Surface Mount
Protection Features: Over Current and Over Temperature protection minimum

Secondary Compatibility Criteria:

Voltage - Input (Max): 7V or greater
Voltage Dropout (Max): 1.2V @ 3A or lower
Operating Temperature Range: Must encompass -40°C to 125°C or equivalent

Parts meeting these criteria are classified as direct substitutes. Parts with enhanced specifications (higher input voltage, lower quiescent current, improved PSRR) are classified as recommended alternatives.

Parameter Comparison

Parameter	LP3966ESX-ADJ	LP3966ESX-ADJ/NOPB	NCP5663DSADJR4G
Manufacturer	Texas Instruments	Texas Instruments	onsemi
Product Status	Not For New Designs	Active	Active
Output Configuration	Positive	Positive	Positive
Output Type	Adjustable	Adjustable	Adjustable
Current - Output	3A	3A	3A
Voltage - Input (Max)	7V	7V	9V
Voltage - Output (Min)	1.216V	1.216V	0.9V
Voltage - Output (Max)	5.1V	5.1V	7.7V
Voltage Dropout (Max)	1.2V @ 3A	1.2V @ 3A	1.3V @ 3A
Current - Quiescent (Iq)	9 mA	9 mA	3 mA
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 85°C
Package / Case	TO-263-6, D2PAK (5 Leads + Tab)	TO-263-6, D2PAK (5 Leads + Tab)	TO-263-6, D2PAK (5 Leads + Tab)
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Protection Features	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)	3 (168 Hours)	1 (Unlimited)

Engineering Selection Recommendations

LP3966ESX-ADJ/NOPB (Texas Instruments)

This part is the direct equivalent to LP3966ESX-ADJ with identical electrical specifications and package configuration. The primary distinction is product status: LP3966ESX-ADJ/NOPB is Active, whereas the original part is Not For New Designs. This part carries ROHS3 compliance and is available in Cut Tape (CT) & Digi-Reel® packaging. Selection of this part is appropriate for applications requiring Texas Instruments sourcing continuity and full compliance with RoHS3 regulations.

NCP5663DSADJR4G (onsemi)

This part is a manufacturer-recommended alternative offering enhanced specifications within the same package footprint. Key advantages include higher maximum input voltage (9V vs. 7V), expanded output voltage range (0.9V to 7.7V vs. 1.216V to 5.1V), and significantly lower quiescent current (3 mA vs. 9 mA). The part is Active and ROHS3 compliant with superior moisture sensitivity rating (MSL 1 vs. MSL 3). The operating temperature range is -40°C to 85°C, which does not extend to 125°C. Selection of this part is appropriate for applications where extended input voltage range, lower power consumption, or improved moisture tolerance are beneficial, provided the maximum operating temperature requirement does not exceed 85°C.

Frequently Asked Questions (FAQ)

Q: Can LP3966ESX-ADJ/NOPB be used as a direct replacement for LP3966ESX-ADJ?

A: Yes. Both parts share identical electrical specifications, output configuration (positive adjustable), current rating (3A), voltage parameters, dropout characteristics, and package type (TO-263 DDPAK-5). The primary difference is product status and compliance certification. LP3966ESX-ADJ/NOPB is the active production equivalent.

Q: What are the key differences between LP3966ESX-ADJ and NCP5663DSADJR4G?

A: Both parts deliver 3A output in adjustable positive configuration within the same package. NCP5663DSADJR4G offers higher input voltage tolerance (9V vs. 7V), wider output voltage range (0.9V to 7.7V vs. 1.216V to 5.1V), and lower quiescent current (3 mA vs. 9 mA). However, NCP5663DSADJR4G maximum operating temperature is 85°C, whereas LP3966ESX-ADJ operates to 125°C. Verify temperature requirements before substitution.

Q: Are all substitute parts compatible with the same PCB layout?

A: Yes. All listed substitute parts use TO-263-6 or D2PAK (5 Leads + Tab) package configuration with identical pin assignments for Surface Mount applications. PCB layout modifications are not required for mechanical compatibility.

Q: Which substitute part should be selected for new designs?

A: LP3966ESX-ADJ/NOPB is recommended for new designs requiring Texas Instruments sourcing. NCP5663DSADJR4G is recommended for applications benefiting from enhanced specifications (higher input voltage, lower quiescent current, improved moisture tolerance) and where the 85°C maximum operating temperature is acceptable.

Q: What is the impact of RoHS compliance on part selection?

A: LP3966ESX-ADJ is RoHS non-compliant. Both LP3966ESX-ADJ/NOPB and NCP5663DSADJR4G are ROHS3 compliant. Selection of compliant parts is necessary for applications subject to RoHS regulations or customer requirements.

Q: How does moisture sensitivity level (MSL) affect handling and storage?

A: LP3966ESX-ADJ and LP3966ESX-ADJ/NOPB carry MSL 3 rating, requiring storage at controlled humidity (≤60% RH) with a maximum floor life of 168 hours after bag opening. NCP5663DSADJR4G carries MSL 1 rating with unlimited floor life, providing greater handling flexibility and reduced risk of moisture-induced failures during assembly.

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