LP2951CDG Equivalent & Substitute Parts

Part Overview

The LP2951CDG is a linear voltage regulator IC from onsemi designed for positive adjustable (fixed) output applications with 100mA current capability in an 8-SOIC surface mount package. This device is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The LP2951CDG provides regulated output voltage from 1.235V to 30V with integrated over-current and over-temperature protection, suitable for low-power supply applications requiring compact form factors.

Key Parameters

Parameter	Value
Manufacturer	onsemi
Category	Power Management (PMIC)
Package / Case	8-SOIC (0.154", 3.90mm Width)
Output Configuration	Positive
Output Type	Adjustable (Fixed)
Number of Regulators	1
Voltage - Input (Max)	30V
Voltage - Output (Min/Fixed)	1.235V (5V)
Voltage - Output (Max)	30V
Current - Output	100mA
Operating Temperature	-40°C ~ 125°C
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the LP2951CDG are qualified based on the following critical parameters that determine functional equivalence:

Core Electrical Parameters:

Output configuration: Positive
Number of regulators: 1
Maximum input voltage: 30V
Output current capability: 100mA
Operating temperature range: -40°C ~ 125°C

Physical Parameters:

Package type: 8-SOIC surface mount
Package dimensions: 0.154" width (3.90mm)

Protection Features:

Over-current protection
Over-temperature protection

The LP2951 base product family maintains consistent electrical and mechanical specifications across manufacturers, allowing cross-substitution when these core parameters align. Variations in quiescent current, dropout voltage, and additional control features (such as enable pins or short-circuit protection) represent secondary differences that do not prevent functional substitution in most applications.

Parameter Comparison

Parameter	LP2951CDG (onsemi)	LP2951-50QDRQ1 (Texas Instruments)	LP2951CS-L-3-3/TR (MaxLinear)
Product Status	Obsolete	Active	Active
Output Configuration	Positive	Positive	Positive
Output Type	Adjustable (Fixed)	Adjustable (Fixed)	Fixed
Number of Regulators	1	1	1
Voltage - Input (Max)	30V	30V	30V
Voltage - Output (Min/Fixed)	1.235V (5V)	1.235V (5V)	3.3V
Voltage - Output (Max)	30V	30V	—
Voltage Dropout (Max)	0.45V @ 100mA	0.6V @ 100mA	0.45V @ 100mA
Current - Output	100mA	100mA	100mA
Current - Quiescent (Iq)	120 µA	120 µA	170 µA
Current - Supply (Max)	12 mA	14 mA	12 mA
Protection Features	Over Current, Over Temperature	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C (TJ)	-40°C ~ 125°C
Package / Case	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount	Surface Mount	Surface Mount
RoHS Status	—	ROHS3 Compliant	RoHS Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	3 (168 Hours)	1 (Unlimited)

Engineering Selection Recommendations

LP2951-50QDRQ1 (Texas Instruments): This substitute is actively manufactured and carries AEC-Q100 automotive qualification with ROHS3 compliance. The device maintains identical output current (100mA) and quiescent current (120 µA) specifications. The dropout voltage is 0.6V at 100mA, representing a 0.15V increase compared to the LP2951CDG. Additional short-circuit protection is provided. The higher moisture sensitivity level (MSL 3, 168 hours) requires controlled storage conditions. This part is suitable for applications where automotive-grade qualification and active production status are required.

LP2951CS-L-3-3/TR (MaxLinear, Inc.): This substitute is actively manufactured with RoHS compliance and unlimited moisture sensitivity (MSL 1). The fixed 3.3V output configuration limits this part to applications requiring 3.3V regulation specifically. The dropout voltage matches the LP2951CDG at 0.45V @ 100mA. Quiescent current is higher at 170 µA. This part is appropriate for 3.3V supply applications where the fixed output voltage requirement aligns with system design.

Frequently Asked Questions (FAQ)

Q: Can LP2951-50QDRQ1 directly replace LP2951CDG in all applications?

A: Functional replacement is possible for most applications due to matching output current (100mA), quiescent current (120 µA), and operating temperature range. The increased dropout voltage (0.6V vs 0.45V) must be evaluated in designs with tight input-to-output voltage margins. The MSL 3 moisture sensitivity requires appropriate handling and storage protocols.

Q: What is the key difference between LP2951-50QDRQ1 and LP2951CS-L-3-3/TR?

A: LP2951-50QDRQ1 provides adjustable/fixed output voltage selection (1.235V to 30V range), while LP2951CS-L-3-3/TR is fixed at 3.3V output. LP2951-50QDRQ1 includes short-circuit protection and automotive qualification. Selection depends on whether your application requires voltage adjustability or is specifically designed for 3.3V regulation.

Q: Are all substitute parts in the same 8-SOIC package?

A: Yes. All listed substitutes use the 8-SOIC surface mount package with 0.154" (3.90mm) width, ensuring PCB layout compatibility with the LP2951CDG.

Q: What compliance certifications should I consider?

A: LP2951-50QDRQ1 carries AEC-Q100 automotive qualification and ROHS3 compliance. LP2951CS-L-3-3/TR is RoHS compliant. Both are REACH unaffected. Select based on your application's compliance requirements.

Q: How do quiescent current differences affect circuit design?

A: LP2951CDG and LP2951-50QDRQ1 both draw 120 µA quiescent current. LP2951CS-L-3-3/TR draws 170 µA, a 50 µA increase. In battery-powered or low-power standby applications, this difference may be significant over extended operation periods.

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