LP2950CN-L-3-3 Equivalent & Substitute Parts

Part Overview

The LP2950CN-L-3-3 is a linear voltage regulator IC manufactured by MaxLinear, Inc., providing a fixed 3.3V positive output at 100mA in a TO-92-3 package. This part is discontinued at DiGi Electronics, making equivalent substitutes necessary for ongoing production and maintenance applications. The device is designed for applications requiring low-dropout regulation with integrated over-current and over-temperature protection in a compact through-hole package.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	100mA
Input Voltage (Max)	30V
Voltage Dropout (Max)	0.45V @ 100mA
Quiescent Current (Iq)	170 µA
Package Type	TO-92-3 (TO-226AA)
Mounting Type	Through Hole
Operating Temperature	-40°C ~ 125°C
Protection Features	Over Current, Over Temperature
RoHS Status	RoHS Compliant

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Output voltage: 3.3V fixed
Output current capability: minimum 100mA
Package type: TO-92-3 (TO-226AA) through-hole
Input voltage rating: 30V maximum
Operating temperature range: -40°C to 125°C (preferred for industrial applications)
Protection features: Over-current and over-temperature protection required

Substitute parts are grouped into two categories:

Direct Equivalents (100mA Output): Parts with identical 100mA output current rating, matching dropout voltage specifications, and full -40°C to 125°C operating range.

Parametric Equivalents (150mA Output): Parts with higher 150mA output current capability, suitable for applications where additional current margin is beneficial. These parts maintain 3.3V output and TO-92-3 packaging but may have different dropout characteristics and quiescent current specifications.

Parameter Comparison

Part Number	Manufacturer	Output Current	Voltage Dropout (Max)	Quiescent Current (Iq)	Operating Temp Range	Product Status	Protection Features
LP2950CN-L-3-3	MaxLinear, Inc.	100mA	0.45V @ 100mA	170 µA	-40°C ~ 125°C	Discontinued	Over Current, Over Temperature
L78L33ACZ	STMicroelectronics	100mA	—	5.5 mA	0°C ~ 125°C	Active	Over Current, Over Temperature, Short Circuit
LP2950-33LPRE3	Texas Instruments	100mA	0.6V @ 100mA	120 µA	-40°C ~ 125°C	Active	Over Current, Over Temperature, Short Circuit
LP2950ACZ-3.3G	onsemi	100mA	0.45V @ 100mA	120 µA	-40°C ~ 125°C	Active	Over Current, Over Temperature
LP2950CZ-3.3/NOPB	Texas Instruments	100mA	0.6V @ 100mA	120 µA	-40°C ~ 125°C	Active	Over Current, Over Temperature
LP2950CZ-3.3G	onsemi	100mA	0.45V @ 100mA	120 µA	-40°C ~ 125°C	Active	Over Current, Over Temperature
LT1121CZ-3.3#PBF	Analog Devices Inc.	150mA	0.7V @ 150mA	50 µA	0°C ~ 125°C	Active	Over Temperature, Reverse Polarity
LT1121IZ-3.3#PBF	Analog Devices Inc.	150mA	0.7V @ 150mA	50 µA	-40°C ~ 125°C	Active	Over Temperature, Reverse Polarity
LP2950-33LPE3	Texas Instruments	100mA	0.6V @ 100mA	120 µA	-40°C ~ 125°C	Last Time Buy	Over Current, Over Temperature
LP2950ACZ-3.3/NOPB	Texas Instruments	100mA	0.6V @ 100mA	120 µA	-40°C ~ 125°C	Active	Over Current, Over Temperature

Engineering Selection Recommendations

Preferred Direct Equivalents (100mA):

LP2950ACZ-3.3G (onsemi) and LP2950CZ-3.3G (onsemi) are the primary recommendations. Both are active products with matching 0.45V dropout voltage, identical quiescent current (120 µA), full -40°C to 125°C operating range, and ROHS3 compliance. These parts provide the closest electrical match to the original LP2950CN-L-3-3.

LP2950-33LPRE3 (Texas Instruments) and LP2950CZ-3.3/NOPB (Texas Instruments) are secondary options. Both are active with full temperature range support and ROHS3 compliance. The 0.6V dropout voltage is slightly higher than the original specification but remains within acceptable limits for most applications.

Alternative Direct Equivalent:

L78L33ACZ (STMicroelectronics) is active with short-circuit protection and ROHS3 compliance. However, the operating temperature range is limited to 0°C to 125°C, making it unsuitable for applications requiring -40°C operation. This part is recommended only for commercial temperature range applications.

Higher Current Option (150mA):

LT1121IZ-3.3#PBF (Analog Devices Inc.) provides 150mA output current with full -40°C to 125°C operating range and ROHS3 compliance. This part is suitable for applications where additional current margin is required. The 0.7V dropout voltage and 50 µA quiescent current differ from the original but are acceptable for designs tolerating these specifications.

LT1121CZ-3.3#PBF (Analog Devices Inc.) is identical to LT1121IZ-3.3#PBF except for the restricted 0°C to 125°C operating temperature range, limiting its use to commercial applications.

LP2950-33LPE3 (Texas Instruments) is in Last Time Buy status and should be avoided for new designs despite meeting electrical specifications.

Frequently Asked Questions (FAQ)

Q: Can I use a 150mA regulator as a substitute for the 100mA LP2950CN-L-3-3?

A: Yes. The LT1121 series (150mA) is electrically compatible and maintains the same 3.3V output voltage and TO-92-3 package. Higher current capability does not degrade performance in 100mA applications. However, verify that the different dropout voltage (0.7V vs. 0.45V) and quiescent current (50 µA vs. 170 µA) are acceptable for your circuit design.

Q: What is the difference between LP2950ACZ-3.3G and LP2950CZ-3.3G?

A: Both are onsemi products with identical electrical specifications (0.45V dropout, 120 µA quiescent current, -40°C to 125°C range). The primary difference is packaging: LP2950ACZ-3.3G is supplied in bulk, while LP2950CZ-3.3G is supplied in bulk as well. Both are suitable for direct substitution.

Q: Why is L78L33ACZ not recommended as a primary substitute?

A: The L78L33ACZ has a restricted operating temperature range of 0°C to 125°C, compared to the original -40°C to 125°C. It is suitable only for commercial applications that do not require low-temperature operation. For industrial or military applications requiring full temperature range, use LP2950ACZ-3.3G or LP2950CZ-3.3G instead.

Q: Are all substitute parts RoHS compliant?

A: Yes. All recommended substitute parts carry ROHS3 compliance certification, matching the RoHS compliance status of the original LP2950CN-L-3-3.

Q: Can I substitute LP2950-33LPE3 for the discontinued LP2950CN-L-3-3?

A: LP2950-33LPE3 meets the electrical requirements but is in Last Time Buy status, indicating limited future availability. For new designs, select from active products such as LP2950ACZ-3.3G, LP2950CZ-3.3G, or LP2950-33LPRE3 instead.

Q: What is the impact of different dropout voltages on my circuit?

A: Dropout voltage determines the minimum input voltage required to maintain regulation. The original part specifies 0.45V dropout at 100mA. Substitutes with 0.6V or 0.7V dropout require proportionally higher input voltage to maintain 3.3V output. Verify that your power supply voltage is sufficient to accommodate the substitute part's dropout specification.

Q: Are the TO-92-3 packages from different manufacturers physically identical?

A: Yes. All substitute parts use the TO-92-3 (TO-226AA) package, which is a standardized through-hole package with identical pin configuration and physical dimensions. Direct PCB substitution is possible without layout modifications.

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