LP2957ISX Linear Voltage Regulator - Equivalent & Substitute Parts

Part Overview

The LP2957ISX is a linear voltage regulator IC from Texas Instruments designed for positive fixed 5V output applications with 250mA current capacity in a TO-263 (DDPAK-5) surface mount package. This device is classified as obsolete, making identification of active equivalent parts essential for ongoing production and design continuity. The LP2957 series provides regulated 5V output with integrated protection features including over-current, over-temperature, and reverse polarity protection, suitable for applications requiring stable low-voltage power distribution.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	5V
Output Current	250mA
Input Voltage (Max)	30V
Dropout Voltage (Max)	0.8V @ 250mA
Quiescent Current	200 µA
Operating Temperature Range	-40°C ~ 125°C
Package Type	TO-263-6 (D2PAK, 5 Leads + Tab)
Protection Features	Over Current, Over Temperature, Reverse Polarity
Control Features	Enable

Substitute Part Grouping Explanation

Substitute parts for the LP2957ISX are determined by strict equivalence across the following critical parameters:

Fixed output voltage of 5V
Output current rating of 250mA
Maximum input voltage of 30V
Dropout voltage specification of 0.8V @ 250mA
Identical package configuration: TO-263-6 (D2PAK-5)
Matching protection features: Over Current, Over Temperature, Reverse Polarity
Enable control feature
Operating temperature range of -40°C ~ 125°C

The LP2957ISX/NOPB and LP2957AISX/NOPB are parametric equivalents meeting all electrical and mechanical specifications. The primary distinction is product status and compliance certification, not functional performance.

Parameter Comparison

Parameter	LP2957ISX	LP2957ISX/NOPB	LP2957AISX/NOPB
Manufacturer	Texas Instruments	Texas Instruments	Texas Instruments
Product Status	Obsolete	Active	Active
Output Voltage	5V	5V	5V
Output Current	250mA	250mA	250mA
Input Voltage (Max)	30V	30V	30V
Dropout Voltage (Max)	0.8V @ 250mA	0.8V @ 250mA	0.8V @ 250mA
Quiescent Current	200 µA	200 µA	200 µA
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C
Package / Case	TO-263-6, D2PAK (5 Leads + Tab)	TO-263-6, D2PAK (5 Leads + Tab)	TO-263-6, D2PAK (5 Leads + Tab)
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant
Packaging Format	Bulk	Tape & Reel (TR)	Tape & Reel (TR)

Engineering Selection Recommendations

For new designs and ongoing production requiring a 5V/250mA linear regulator in TO-263 packaging, select either LP2957ISX/NOPB or LP2957AISX/NOPB. Both parts are active products with ROHS3 compliance and identical electrical specifications to the obsolete LP2957ISX.

LP2957ISX/NOPB is the direct active equivalent with 2200 pcs inventory availability and Tape & Reel packaging suitable for automated assembly.

LP2957AISX/NOPB provides an alternative with 1383 pcs inventory availability, also in Tape & Reel format, with identical performance characteristics and compliance certifications.

The original LP2957ISX (4189 pcs available) is obsolete and should not be selected for new designs despite current inventory levels.

Frequently Asked Questions (FAQ)

Q: Can LP2957ISX/NOPB and LP2957AISX/NOPB be used interchangeably with the original LP2957ISX?

A: Yes. All three parts share identical electrical specifications: 5V fixed output, 250mA current capacity, 0.8V dropout voltage, and TO-263-6 package configuration. Pin-to-pin compatibility is complete. The primary differences are product status (active vs. obsolete) and RoHS compliance certification.

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

A: The "/NOPB" designation indicates the part is supplied without plumbum (lead-free), reflecting RoHS3 compliance. This is a packaging and compliance designation, not a functional difference.

Q: Are there differences in performance between LP2957ISX/NOPB and LP2957AISX/NOPB?

A: No. Both parts have identical electrical performance: 5V output, 250mA capacity, 0.8V dropout voltage, 200 µA quiescent current, and -40°C ~ 125°C operating range. Selection between them should be based on inventory availability and packaging format preference.

Q: Is the TO-263-6 package compatible with existing PCB designs for the LP2957ISX?

A: Yes. All three parts use the identical TO-263-6 (D2PAK, 5 Leads + Tab) package. PCB footprints, thermal characteristics, and mechanical mounting are fully compatible.

Q: What protection features are included in these regulators?

A: All three parts include over-current protection, over-temperature protection, and reverse polarity protection. These features are consistent across LP2957ISX, LP2957ISX/NOPB, and LP2957AISX/NOPB.

Q: Should the obsolete LP2957ISX be used if inventory is available?

A: For new designs, select LP2957ISX/NOPB or LP2957AISX/NOPB. Both are active products with current manufacturer support and RoHS3 compliance. The obsolete LP2957ISX should be reserved for legacy system maintenance only.

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