LP2950ACN-L-3-3/TR Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LP2950ACN-L-3-3/TR is a linear voltage regulator IC manufactured by MaxLinear, Inc., designed to deliver a fixed 3.3V output at 100mA in a TO-92-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The part functions as a positive fixed output regulator with integrated over-current and over-temperature protection, suitable for applications requiring low-current 3.3V regulation from input sources up to 30V.

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	TO-92-3 (TO-226AA)
Mounting Type	Through Hole
Protection Features	Over Current, Over Temperature

Substitute Part Grouping Explanation

Substitution eligibility for the LP2950ACN-L-3-3/TR is determined by the following critical parameters:

Fixed output voltage of 3.3V
Output current capability of 100mA or greater
Input voltage rating of 30V or higher
TO-92-3 package configuration
Through-hole mounting compatibility
Operating temperature range encompassing -40°C to 125°C or a subset thereof

Substitute parts are grouped into two categories based on output current capability:

Category A: 100mA Output Current (Direct Equivalents) Parts with exactly 100mA output current rating, maintaining identical electrical load specifications.

Category B: 150mA Output Current (Higher Capacity Alternatives) Parts with 150mA output current rating, providing increased headroom for applications with variable or marginal current demands.

All substitute parts maintain the same fixed 3.3V output voltage, TO-92-3 package, and through-hole mounting configuration as the original part.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage	Quiescent Current	Operating Temp Range	Product Status	Package
LP2950ACN-L-3-3/TR	MaxLinear, Inc.	3.3V	100mA	30V	0.45V @ 100mA	170 µA	-40°C ~ 125°C	Obsolete	TO-92-3
L78L33ABZ-AP	STMicroelectronics	3.3V	100mA	30V	—	5.5 mA	-40°C ~ 125°C	Active	TO-92-3
L78L33ACZ-AP	STMicroelectronics	3.3V	100mA	30V	—	5.5 mA	0°C ~ 125°C	Active	TO-92-3
L78L33ACZTR	STMicroelectronics	3.3V	100mA	30V	—	5.5 mA	0°C ~ 125°C	Active	TO-92-3
LP2950-33LPRE3	Texas Instruments	3.3V	100mA	30V	0.6V @ 100mA	120 µA	-40°C ~ 125°C	Active	TO-92-3
LP2950ACZ-3.3/NOPB	Texas Instruments	3.3V	100mA	30V	0.6V @ 100mA	120 µA	-40°C ~ 125°C	Active	TO-92-3
LP2950ACZ-3.3RAG	onsemi	3.3V	100mA	30V	0.45V @ 100mA	120 µA	-40°C ~ 125°C	Active	TO-92-3
LP2950CZ-3.3/LFT3	Texas Instruments	3.3V	100mA	30V	0.6V @ 100mA	120 µA	-40°C ~ 125°C	Active	TO-92-3
LP2950CZ-3.3RAG	onsemi	3.3V	100mA	30V	0.45V @ 100mA	120 µA	-40°C ~ 125°C	Active	TO-92-3
LT1121CZ-3.3#TRPBF	Analog Devices Inc.	3.3V	150mA	30V	0.7V @ 150mA	50 µA	0°C ~ 125°C	Active	TO-92-3
LT1121IZ-3.3#TRPBF	Linear Technology	3.3V	150mA	30V	0.7V @ 150mA	50 µA	-40°C ~ 125°C	Active	TO-92-3

Engineering Selection Recommendations

For Direct Replacement (100mA Output Current):

The LP2950-33LPRE3, LP2950ACZ-3.3/NOPB, and LP2950CZ-3.3/LFT3 from Texas Instruments are active products with full temperature range support (-40°C ~ 125°C) matching the original part. These maintain the LP2950 base product lineage and are ROHS3 compliant.

The LP2950ACZ-3.3RAG and LP2950CZ-3.3RAG from onsemi are active alternatives with identical dropout voltage (0.45V @ 100mA) to the original part and full temperature range coverage. Both are ROHS3 compliant.

The L78L33ABZ-AP from STMicroelectronics supports the full temperature range (-40°C ~ 125°C) and is ROHS3 compliant. The L78L33ACZ-AP and L78L33ACZTR variants have a reduced operating temperature range (0°C ~ 125°C) and are suitable only for applications not requiring sub-zero operation.

For Higher Current Applications (150mA Output Current):

The LT1121IZ-3.3#TRPBF from Linear Technology provides 150mA output current with full temperature range (-40°C ~ 125°C) and is ROHS3 compliant, suitable for designs requiring additional current margin.

The LT1121CZ-3.3#TRPBF from Analog Devices Inc. offers 150mA output current with a reduced operating range (0°C ~ 125°C) and is ROHS3 compliant.

All substitute parts are active products with established supply chains and are suitable for new designs and production continuity.

Frequently Asked Questions (FAQ)

Q: Can I use a 150mA regulator as a substitute for the 100mA LP2950ACN-L-3-3/TR?

A: Yes. The LT1121 series regulators rated at 150mA are electrically compatible substitutes. The higher current rating provides additional design margin without affecting circuit operation at 100mA load levels. All other electrical parameters (output voltage, input voltage rating, package, and temperature range) remain compatible.

Q: What is the difference between the L78L33 and LP2950 series regulators?

A: Both are 3.3V, 100mA linear regulators in TO-92-3 packages. The L78L33 series (STMicroelectronics) and LP2950 series (Texas Instruments, onsemi) differ in quiescent current specifications and dropout voltage characteristics. The L78L33 variants have lower quiescent current (5.5 mA) compared to LP2950 variants (120 µA). Dropout voltage specifications vary by manufacturer variant. Both are functionally equivalent for standard 3.3V regulation applications.

Q: Are all substitute parts ROHS3 compliant?

A: All listed substitute parts are ROHS3 compliant. The original LP2950ACN-L-3-3/TR is obsolete and does not carry current compliance certifications.

Q: Does the operating temperature range affect substitution?

A: Yes, for applications requiring operation below 0°C. The L78L33ACZ-AP, L78L33ACZTR, and LT1121CZ-3.3#TRPBF are rated only to 0°C minimum and are not suitable for designs requiring -40°C operation. All other substitute parts support the full -40°C ~ 125°C range.

Q: Can I interchange different packaging variants of the same part number?

A: No. Packaging designations (Cut Tape, Bulk, Tape & Reel) indicate different supply formats but do not affect electrical performance. However, the physical package type (TO-92-3) must remain consistent for PCB compatibility. All listed substitutes use the same TO-92-3 through-hole package.

Q: What is the significance of dropout voltage differences between substitutes?

A: Dropout voltage determines the minimum input-to-output voltage differential required for proper regulation. The original part specifies 0.45V @ 100mA. Substitutes with higher dropout voltage (0.6V or 0.7V) require proportionally higher input voltage to maintain stable 3.3V output. For applications with marginal input voltage headroom, select substitutes with lower dropout voltage specifications.

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