LP2951CS-L-3-3/TR Equivalent & Substitute Parts

Part Overview

The LP2951CS-L-3-3/TR is a linear voltage regulator IC manufactured by MaxLinear, Inc., designed for positive fixed 3.3V output applications with 100mA current capacity in an 8-SOIC surface mount package. This part is currently in active product status with 7163 units in stock.

Substitute parts are necessary when the original LP2951CS-L-3-3/TR becomes unavailable due to supply constraints, end-of-life transitions, or when alternative packaging formats are required for manufacturing flexibility. The LP2951 family offers multiple output voltage configurations and packaging options that maintain electrical and mechanical compatibility within defined parameter ranges.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	100mA
Input Voltage (Max)	30V
Voltage Dropout (Max)	0.45V @ 100mA
Quiescent Current	170 µA
Operating Temperature Range	-40°C ~ 125°C
Package Type	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Protection Features	Over Current, Over Temperature
RoHS Status	RoHS Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the LP2951CS-L-3-3/TR is determined by the following critical parameters:

Electrical Compatibility Requirements:

Output voltage configuration: Fixed 3.3V output
Output current rating: 100mA minimum
Input voltage maximum: 30V
Package/case type: 8-SOIC (0.154", 3.90mm Width)
Mounting type: Surface Mount
Operating temperature range: -40°C ~ 125°C minimum

Acceptable Variations:

Voltage dropout may vary within acceptable limits for the application
Quiescent current variations are acceptable provided they do not exceed specified maximums
Packaging format (Tube, Cut Tape, Tape & Reel) does not affect electrical substitution but affects procurement and assembly processes
Manufacturer differences are acceptable provided all electrical and mechanical parameters align

The substitute parts are grouped into two categories:

Category 1: Fixed 3.3V Output Parts – Direct electrical equivalents with identical output voltage configuration (LP2951ACD-3.3R2G, LP2951ACM-3.3/NOPB, LP2951ACMX-3.3/NOPB)

Category 2: Adjustable Output Parts with 3.3V Configuration – Parts configured for 3.3V fixed output through adjustable topology (LP2951-33D, LP2951-33DR, LP2951ACM-3.3/NOPB, LP2951ACMX-3.3/NOPB)

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout (Max)	Iq (Max)	Package	Packaging Format	Product Status
LP2951CS-L-3-3/TR	MaxLinear, Inc.	3.3V (Fixed)	100mA	30V	0.45V @ 100mA	170 µA	8-SOIC	Tape & Reel	Active
LP2951-30D	Texas Instruments	1.235V (3V)	100mA	30V	0.6V @ 100mA	120 µA	8-SOIC	Tube	Last Time Buy
LP2951-30DR	Texas Instruments	1.235V (3V)	100mA	30V	0.6V @ 100mA	120 µA	8-SOIC	Cut Tape	Last Time Buy
LP2951-33D	Texas Instruments	1.235V (3.3V)	100mA	30V	0.6V @ 100mA	120 µA	8-SOIC	Tube	Last Time Buy
LP2951-33DR	Texas Instruments	1.235V (3.3V)	100mA	30V	0.6V @ 100mA	120 µA	8-SOIC	Cut Tape & Digi-Reel	Active
LP2951-50D	Texas Instruments	1.235V (5V)	100mA	30V	0.6V @ 100mA	120 µA	8-SOIC	Tube	Last Time Buy
LP2951-50DR	Texas Instruments	1.235V (5V)	100mA	30V	0.6V @ 100mA	120 µA	8-SOIC	Cut Tape & Digi-Reel	Active
LP2951ACD-3.3R2G	onsemi	3.3V (Fixed)	100mA	30V	0.45V @ 100mA	120 µA	8-SOIC	Cut Tape & Digi-Reel	Active
LP2951ACDR2G	onsemi	1.235V (5V)	100mA	30V	0.45V @ 100mA	120 µA	8-SOIC	Cut Tape & Digi-Reel	Active
LP2951ACM-3.3/NOPB	Texas Instruments	1.235V (3.3V)	100mA	30V	0.6V @ 100mA	120 µA	8-SOIC	Tube	Active
LP2951ACMX-3.3/NOPB	Texas Instruments	1.235V (3.3V)	100mA	30V	0.6V @ 100mA	120 µA	8-SOIC	Cut Tape & Digi-Reel	Active

Engineering Selection Recommendations

Primary Recommendation for Direct Substitution:

LP2951ACD-3.3R2G (onsemi) is the preferred direct substitute. This part maintains identical fixed 3.3V output voltage, matching dropout voltage specification (0.45V @ 100mA), and is in active product status with 2616 units in stock. The Cut Tape & Digi-Reel packaging provides manufacturing flexibility equivalent to the original Tape & Reel format.

Secondary Recommendation:

LP2951ACMX-3.3/NOPB (Texas Instruments) offers the highest inventory availability (163,395 units) with active product status. While dropout voltage is slightly higher at 0.6V @ 100mA compared to the original 0.45V, this remains within acceptable operating margins for most 3.3V applications. Cut Tape & Digi-Reel packaging supports standard assembly processes.

Alternative for Long-Term Availability:

LP2951-33DR (Texas Instruments) provides active product status with 65,400 units in stock. This adjustable-topology part is configured for 3.3V fixed output and offers Cut Tape & Digi-Reel packaging. The slightly elevated dropout voltage (0.6V @ 100mA) and inclusion of Short Circuit protection provide additional design margin.

Parts to Avoid for New Designs:

LP2951-30D, LP2951-30DR, LP2951-33D, and LP2951-50D are designated as Last Time Buy and should not be selected for new production designs due to end-of-life status.

Frequently Asked Questions (FAQ)

Q: Can LP2951-33DR be used as a direct replacement for LP2951CS-L-3-3/TR?

A: Yes. Both parts deliver 3.3V fixed output at 100mA with identical 8-SOIC packaging and -40°C to 125°C operating range. The LP2951-33DR uses adjustable topology configured for 3.3V output rather than fixed topology, but the electrical output is equivalent. Dropout voltage is 0.6V @ 100mA versus 0.45V @ 100mA on the original, which is acceptable for standard 3.3V rail applications.

Q: What is the difference between fixed and adjustable output topology in the LP2951 family?

A: Fixed output parts (LP2951CS-L-3-3/TR, LP2951ACD-3.3R2G) have the output voltage set internally by the manufacturer. Adjustable output parts (LP2951-33DR, LP2951ACM-3.3/NOPB) use external resistor networks to set output voltage, but when configured for 3.3V, deliver identical electrical performance. Both topologies are electrically equivalent when output voltage matches.

Q: Does packaging format (Tube vs. Cut Tape vs. Tape & Reel) affect electrical performance?

A: No. Packaging format affects only procurement, storage, and assembly processes. Tube, Cut Tape, and Tape & Reel formats contain electrically identical components. Selection should be based on manufacturing equipment compatibility and supply chain requirements.

Q: Why do some substitute parts show higher quiescent current (120 µA vs. 170 µA)?

A: The original LP2951CS-L-3-3/TR specifies 170 µA quiescent current. Substitute parts with 120 µA quiescent current represent improved power efficiency and are fully compatible. Lower quiescent current does not create compatibility issues and may reduce standby power consumption in battery-powered applications.

Q: Can LP2951-50DR be used if 3.3V output is required?

A: No. LP2951-50DR is configured for 5V fixed output (1.235V adjustable topology set to 5V). Using this part would deliver 5V instead of 3.3V, causing overvoltage conditions on 3.3V logic circuits. Only parts explicitly configured for 3.3V output are acceptable substitutes.

Q: What is the significance of "Last Time Buy" product status?

A: Last Time Buy indicates the manufacturer will no longer produce the part after existing inventory is depleted. Parts with this status should not be selected for new designs. Use only Active status parts (LP2951-33DR, LP2951ACD-3.3R2G, LP2951ACMX-3.3/NOPB) for production designs requiring long-term availability.

Q: Are all substitute parts RoHS compliant?

A: Yes. The original LP2951CS-L-3-3/TR is RoHS Compliant. All listed substitute parts carry either RoHS Compliant or ROHS3 Compliant certification, meeting regulatory requirements for lead-free manufacturing.

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