LP38691SDX-ADJ Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LP38691SDX-ADJ is a linear voltage regulator IC from Texas Instruments designed for positive adjustable output applications. This Surface Mount device delivers 500mA output current in a compact 6-WSON (3x3) package and is qualified to AEC-Q100 automotive standards. The main part number is currently listed as Obsolete, making equivalent substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Output Configuration	Positive
Output Type	Adjustable
Number of Regulators	1
Voltage - Input (Max)	10V
Voltage - Output (Min/Fixed)	1.25V
Voltage - Output (Max)	9V
Current - Output	500mA
Current - Quiescent (Iq)	55 µA
Current - Supply (Max)	100 µA
PSRR	55dB (120Hz)
Protection Features	Over Temperature
Operating Temperature	-40°C ~ 125°C
Grade	Automotive
Qualification	AEC-Q100
Mounting Type	Surface Mount
Package / Case	6-WDFN Exposed Pad
Supplier Device Package	6-WSON (3x3)
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the LP38691SDX-ADJ are qualified based on identical electrical and mechanical parameters across the LP38691 product family. All substitute parts maintain the same:

Output configuration (Positive, Adjustable)
Voltage specifications (1.25V to 9V output range, 10V max input)
Current delivery (500mA output, 55 µA quiescent)
Performance characteristics (55dB PSRR at 120Hz)
Thermal protection and operating temperature range (-40°C to 125°C)
Automotive qualification (AEC-Q100)
Package form factor (6-WSON 3x3 with exposed pad)
Moisture sensitivity (MSL 1)

Substitution differences are limited to product status (Active vs. Obsolete), packaging format (Tape & Reel vs. standard), and RoHS compliance status. The LP38691QSD-ADJ/NOPB variant includes specified dropout voltage (0.45V @ 500mA), while other variants do not specify this parameter.

Parameter Comparison

Part Number	Manufacturer	Product Status	Packaging	Output (mA)	Iq (µA)	Dropout (Max)	RoHS Status	Inventory (Pcs)
LP38691SDX-ADJ	Texas Instruments	Obsolete	Standard	500	55	Not Specified	RoHS Non-Compliant	1,220
LP38691SDX-ADJ/NOPB	Texas Instruments	Active	Standard	500	55	Not Specified	ROHS3 Compliant	123,279
LP38691QSD-ADJ/NOPB	Texas Instruments	Active	Tape & Reel (TR)	500	55	0.45V @ 500mA	ROHS3 Compliant	1,436
LP38691QSDX-ADJ/NOPB	Texas Instruments	Active	Tape & Reel (TR)	500	55	Not Specified	ROHS3 Compliant	1,402
LP38691SD-ADJ/NOPB	Texas Instruments	Active	Tape & Reel (TR)	500	55	Not Specified	ROHS3 Compliant	19,200

Engineering Selection Recommendations

All listed substitute parts are functionally equivalent to the LP38691SDX-ADJ and share identical electrical performance within the specified parameters. Selection should be based on the following criteria:

Product Status: The main part LP38691SDX-ADJ is Obsolete. All substitute parts (LP38691SDX-ADJ/NOPB, LP38691QSD-ADJ/NOPB, LP38691QSDX-ADJ/NOPB, LP38691SD-ADJ/NOPB) are Active and suitable for new designs and ongoing production.

RoHS Compliance: The original LP38691SDX-ADJ is RoHS non-compliant. All substitute parts carry ROHS3 Compliant status, meeting current environmental and regulatory requirements for automotive and industrial applications.

Packaging Format: LP38691SDX-ADJ/NOPB maintains standard packaging. LP38691QSD-ADJ/NOPB, LP38691QSDX-ADJ/NOPB, and LP38691SD-ADJ/NOPB are supplied in Tape & Reel format, suitable for automated assembly processes.

Inventory Availability: LP38691SD-ADJ/NOPB offers the highest stock level (19,200 pcs), followed by LP38691SDX-ADJ/NOPB (123,279 pcs). Both provide reliable procurement for volume production.

Dropout Voltage Specification: LP38691QSD-ADJ/NOPB explicitly specifies 0.45V dropout at 500mA. Other variants do not specify this parameter. If dropout voltage is a critical design parameter, LP38691QSD-ADJ/NOPB provides documented performance.

Frequently Asked Questions (FAQ)

Q: Can I directly replace LP38691SDX-ADJ with LP38691SDX-ADJ/NOPB?

A: Yes. Both parts are electrically and mechanically identical. The primary difference is RoHS compliance status (ROHS3 Compliant vs. non-compliant) and product status (Active vs. Obsolete). The /NOPB designation indicates lead-free solder ball material, meeting current manufacturing standards.

Q: What is the difference between the "Q" and non-"Q" variants?

A: The "Q" designation (LP38691QSD-ADJ/NOPB, LP38691QSDX-ADJ/NOPB) indicates qualification to higher automotive standards. All variants listed are AEC-Q100 qualified. The primary distinction is packaging format and inventory availability.

Q: Are all substitute parts in the same package?

A: Yes. All parts use the 6-WSON (3x3) package with exposed pad (6-WDFN). Packaging format differs only in delivery method: standard vs. Tape & Reel (TR). The physical component remains identical.

Q: Which part should I select for a new automotive design?

A: Any Active substitute part is suitable. LP38691SD-ADJ/NOPB is recommended for volume production due to highest inventory availability (19,200 pcs) and Tape & Reel packaging for automated assembly. All parts meet AEC-Q100 automotive qualification and ROHS3 compliance.

Q: Does dropout voltage affect part selection?

A: Only if your circuit requires documented dropout voltage specification. LP38691QSD-ADJ/NOPB specifies 0.45V @ 500mA. Other variants do not specify this parameter in the provided data. If dropout voltage is not a design constraint, all parts are interchangeable.

Q: Can I use these parts interchangeably in existing designs?

A: Yes, within the same package footprint (6-WSON 3x3). All electrical parameters, thermal characteristics, and protection features are identical. Verify that your PCB layout and assembly process accommodate the selected packaging format (standard vs. Tape & Reel).

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