LP38691SDX-3.3 Linear Voltage Regulator — Equivalent & Substitute Parts

Part Overview

The LP38691SDX-3.3 is a linear voltage regulator IC from Texas Instruments, delivering a fixed 3.3V output at 500mA in a 6-WSON (3x3) surface mount package. This part is classified as obsolete, making identification of active equivalent and substitute parts essential for ongoing design support and procurement.

The device is qualified to AEC-Q100 automotive standards and includes over-temperature protection. Due to its obsolete status, direct substitutes with active product status are available from the same manufacturer, maintaining electrical and mechanical compatibility while ensuring continued supply chain access.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	500mA
Input Voltage (Max)	10V
Voltage Dropout (Max)	0.55V @ 500mA
Quiescent Current (Iq)	55 µA
PSRR	55dB (120Hz)
Operating Temperature Range	-40°C ~ 125°C
Package	6-WSON (3x3)
Mounting Type	Surface Mount
Grade	Automotive
Qualification	AEC-Q100
Protection Features	Over Temperature

Substitute Part Grouping Explanation

Substitution of the LP38691SDX-3.3 is determined by strict equivalence across the following electrical and mechanical parameters:

Fixed output voltage of 3.3V
Output current rating of 500mA
Maximum input voltage of 10V
Voltage dropout specification of 0.55V @ 500mA
Quiescent current of 55 µA
PSRR of 55dB (120Hz)
Operating temperature range of -40°C ~ 125°C
6-WSON (3x3) package with exposed pad
Surface mount configuration
Automotive grade with AEC-Q100 qualification
Over-temperature protection

All substitute parts listed maintain identical electrical performance and mechanical compatibility. Differences exist only in product status (active vs. obsolete), packaging format (Tape & Reel vs. Cut Tape), and RoHS compliance status.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage	Iq	PSRR	Temp Range	Package	Product Status	Packaging Format	RoHS Status
LP38691SDX-3.3	Texas Instruments	3.3V	500mA	10V	0.55V @ 500mA	55 µA	55dB (120Hz)	-40°C ~ 125°C	6-WSON (3x3)	Obsolete	—	RoHS non-compliant
LP38691SDX-3.3/NOPB	Texas Instruments	3.3V	500mA	10V	0.55V @ 500mA	55 µA	55dB (120Hz)	-40°C ~ 125°C	6-WSON (3x3)	Active	Tape & Reel (TR)	ROHS3 Compliant
LP38691QSD-3.3/NOPB	Texas Instruments	3.3V	500mA	10V	0.55V @ 500mA	55 µA	55dB (120Hz)	-40°C ~ 125°C	6-WSON (3x3)	Active	Tape & Reel (TR)	ROHS3 Compliant
LP38691QSDX-3.3/NOPB	Texas Instruments	3.3V	500mA	10V	0.55V @ 500mA	55 µA	55dB (120Hz)	-40°C ~ 125°C	6-WSON (3x3)	Active	Tape & Reel (TR)	ROHS3 Compliant
LP38691SD-3.3/NOPB	Texas Instruments	3.3V	500mA	10V	0.55V @ 500mA	55 µA	55dB (120Hz)	-40°C ~ 125°C	6-WSON (3x3)	Active	Cut Tape (CT) & Digi-Reel®	ROHS3 Compliant
LP38693SDX-3.3/NOPB	Texas Instruments	3.3V	500mA	10V	0.55V @ 500mA	55 µA	55dB (120Hz)	-40°C ~ 125°C	6-WSON (3x3)	Active	Tape & Reel (TR)	ROHS3 Compliant

Engineering Selection Recommendations

All listed substitute parts maintain full electrical and mechanical equivalence to the LP38691SDX-3.3. Selection among active alternatives should be based on the following criteria:

Product Status: All substitute parts carry active product status, ensuring long-term availability and manufacturing support compared to the obsolete main part.

RoHS Compliance: All substitute parts are ROHS3 compliant, meeting current environmental and regulatory requirements. The original LP38691SDX-3.3 is RoHS non-compliant and should be replaced in new designs.

Packaging Format: LP38691SDX-3.3/NOPB, LP38691QSD-3.3/NOPB, LP38691QSDX-3.3/NOPB, and LP38693SDX-3.3/NOPB are supplied in Tape & Reel format, suitable for automated assembly. LP38691SD-3.3/NOPB is available in Cut Tape & Digi-Reel format for lower-volume or manual assembly applications.

Inventory Availability: LP38691SDX-3.3/NOPB offers the highest stock level (21,800 units), followed by LP38691SD-3.3/NOPB (10,100 units), LP38691QSD-3.3/NOPB (4,782 units), LP38691QSDX-3.3/NOPB (2,368 units), and LP38693SDX-3.3/NOPB (1,010 units).

Automotive Qualification: All parts maintain AEC-Q100 qualification and automotive-grade classification, preserving compliance for automotive applications.

Frequently Asked Questions (FAQ)

Q: Can LP38691SDX-3.3 be directly replaced with LP38691SDX-3.3/NOPB?

A: Yes. Both parts are electrically and mechanically identical. The primary difference is product status (obsolete vs. active) and RoHS compliance. LP38691SDX-3.3/NOPB is the active equivalent and recommended for new designs and procurement.

Q: What is the difference between the various substitute part numbers?

A: All substitute parts deliver identical electrical performance and operate in the same 6-WSON (3x3) package. Differences are limited to internal die or qualification variants (indicated by QSD vs. SD designations) and packaging format (Tape & Reel vs. Cut Tape). These variants do not affect functional compatibility.

Q: Are all substitute parts suitable for automotive applications?

A: Yes. All listed substitutes maintain automotive grade classification and AEC-Q100 qualification, meeting automotive industry standards.

Q: Does packaging format affect electrical performance?

A: No. Packaging format (Tape & Reel, Cut Tape, or Digi-Reel) affects only supply chain logistics and assembly handling. Electrical and thermal performance remain identical across all packaging options.

Q: Is the 6-WSON (3x3) package compatible with existing PCB layouts designed for LP38691SDX-3.3?

A: Yes. All substitute parts use the identical 6-WSON (3x3) package with exposed pad, ensuring direct footprint compatibility with existing designs.

Q: What is the significance of the /NOPB suffix?

A: The /NOPB suffix indicates lead-free (Pb-free) and RoHS-compliant packaging. This is standard for current production parts and required for most regulatory and environmental compliance frameworks.

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