LP2981-33DBVT Equivalent & Substitute Parts

Part Overview

The LP2981-33DBVT is a linear voltage regulator IC from Texas Instruments, delivering a fixed 3.3V output at 100mA in a SOT-23-5 surface mount package. This device is classified as Last Time Buy, indicating discontinued production. The regulator features integrated protection against overcurrent, overtemperature, and short circuit conditions, with an enable control feature for power management applications.

Finding equivalent and substitute parts is necessary due to the Last Time Buy status of the LP2981-33DBVT. Alternative models with identical or compatible electrical and mechanical specifications ensure design continuity and supply chain reliability.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	100mA
Input Voltage (Max)	16V
Dropout Voltage (Max)	0.37V @ 100mA
Quiescent Current	95 µA
PSRR	63dB (1kHz)
Operating Temperature Range	-40°C to 125°C
Package	SOT-23-5 (SC-74A)
Protection Features	Over Current, Over Temperature, Short Circuit
Control Features	Enable
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the LP2981-33DBVT are grouped based on strict electrical and mechanical parameter equivalence. The primary substitution criteria are:

Critical Parameters for Substitution:

Fixed output voltage of 3.3V
Output current rating of 100mA
Maximum input voltage of 16V
Dropout voltage of 0.37V @ 100mA
Quiescent current of 95 µA
PSRR of 63dB (1kHz)
Operating temperature range of -40°C to 125°C
SOT-23-5 package configuration
Protection features: Over Current, Over Temperature, Short Circuit
Enable control feature

Grouping Categories:

Group 1: Texas Instruments LP2981 Series (Parametric Equivalents) All parts maintain identical electrical specifications and differ only in packaging format (Cut Tape vs. Tape & Reel) or product status. These include LP2981-33DBVR, LP2981A-33DBVR, LP2981A-33DBVT, LP2981A-33DBVTG4, LP2981AIM5-3.3/NOPB, LP2981AIM5X-3.3/NOPB, LP2981IM5-3.3/NOPB, and LP2981IM5X-3.3/NOPB.

Group 2: STMicroelectronics LD2981 Series (Manufacturer Recommended Alternatives) The LD2981ABM33TR and LD2981CM33TR from STMicroelectronics provide functional equivalence with minor parameter variations. Quiescent current is 150 µA (versus 95 µA), and maximum supply current is 2.6 mA (versus 1.7 mA). Dropout voltage is 0.375V @ 100mA. Protection features include Over Current and Over Temperature, with Short Circuit protection not specified. These parts maintain the same output voltage, current rating, input voltage maximum, operating temperature range, and SOT-23-5 package.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage (Max)	Quiescent Current	PSRR	Operating Temp	Package	Product Status
LP2981-33DBVT	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Last Time Buy
LP2981-33DBVR	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Active
LP2981A-33DBVR	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Active
LP2981A-33DBVT	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Last Time Buy
LP2981A-33DBVTG4	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Discontinued at DiGi Electronics
LP2981AIM5-3.3/NOPB	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Active
LP2981AIM5X-3.3/NOPB	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Active
LP2981IM5-3.3/NOPB	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Active
LP2981IM5X-3.3/NOPB	Texas Instruments	3.3V	100mA	16V	0.37V @ 100mA	95 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Active
LD2981ABM33TR	STMicroelectronics	3.3V	100mA	16V	0.375V @ 100mA	150 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Active
LD2981CM33TR	STMicroelectronics	3.3V	100mA	16V	0.375V @ 100mA	150 µA	63dB (1kHz)	-40°C to 125°C	SOT-23-5	Active

Engineering Selection Recommendations

Primary Substitutes (Texas Instruments LP2981 Series):

For direct replacement with identical electrical performance, select from the Active status parts within the Texas Instruments LP2981 family: LP2981-33DBVR, LP2981A-33DBVR, LP2981AIM5-3.3/NOPB, LP2981AIM5X-3.3/NOPB, LP2981IM5-3.3/NOPB, or LP2981IM5X-3.3/NOPB. These maintain 95 µA quiescent current and 0.37V dropout voltage specifications. Selection among these variants depends on packaging requirements: Cut Tape (CT) & Digi-Reel for standard applications, or Tape & Reel (TR) for high-volume production.

Secondary Substitutes (STMicroelectronics LD2981 Series):

The LD2981ABM33TR and LD2981CM33TR from STMicroelectronics are functionally equivalent alternatives with ROHS3 compliance and Active product status. These parts accept the same input voltage range and deliver the same 3.3V output at 100mA in SOT-23-5 packaging. The trade-off is increased quiescent current (150 µA versus 95 µA) and marginally higher dropout voltage (0.375V versus 0.37V). These differences are acceptable in applications where power consumption is not critical or where the slightly higher dropout voltage does not impact system operation.

Compliance Considerations:

All substitute parts maintain ROHS3 compliance, MSL Level 1 (Unlimited), and REACH Unaffected status, ensuring regulatory alignment with the original LP2981-33DBVT.

Frequently Asked Questions (FAQ)

Q: Can I use LP2981-33DBVR as a direct replacement for LP2981-33DBVT?

A: Yes. Both parts are Texas Instruments LP2981 regulators with identical electrical specifications: 3.3V fixed output, 100mA current, 0.37V dropout voltage, and 95 µA quiescent current. The difference is packaging format and product status. LP2981-33DBVR is Active status with Digi-Reel packaging, while LP2981-33DBVT is Last Time Buy with Cut Tape packaging.

Q: What is the difference between LP2981AIM5-3.3/NOPB and LP2981AIM5X-3.3/NOPB?

A: Both parts are parametrically identical with 3.3V output, 100mA current, and identical protection and control features. The designation difference reflects internal die or manufacturing process variations, but electrical performance is equivalent. Both are Active status with Cut Tape & Digi-Reel packaging.

Q: Can I substitute an STMicroelectronics LD2981 part for the Texas Instruments LP2981?

A: Functional substitution is possible. The LD2981ABM33TR and LD2981CM33TR maintain the same 3.3V output, 100mA current, 16V maximum input, and SOT-23-5 package. However, quiescent current is higher (150 µA versus 95 µA), and dropout voltage is slightly higher (0.375V versus 0.37V). Verify these differences do not impact your application's power budget or minimum input voltage requirements.

Q: What does "Last Time Buy" status mean for the LP2981-33DBVT?

A: Last Time Buy indicates the manufacturer has discontinued production. Existing inventory may be available, but no new manufacturing runs are planned. Transitioning to an Active status equivalent such as LP2981-33DBVR or LP2981A-33DBVR ensures long-term supply availability.

Q: Are all substitute parts available in the same SOT-23-5 package?

A: Yes. All listed substitute parts use the SOT-23-5 (SC-74A) surface mount package, ensuring mechanical and electrical compatibility with existing PCB layouts and solder reflow processes.

Q: Do all substitute parts include short circuit protection?

A: Texas Instruments LP2981 variants include Over Current, Over Temperature, and Short Circuit protection. STMicroelectronics LD2981 parts include Over Current and Over Temperature protection, with Short Circuit protection not specified in the provided data. Verify short circuit protection requirements for your application before selecting LD2981 alternatives.

Q: What is the significance of the "/NOPB" designation in part numbers like LP2981AIM5-3.3/NOPB?

A: The "/NOPB" suffix indicates "No Plumbum" (lead-free) packaging, confirming ROHS3 compliance. This is standard for modern electronic components and does not affect electrical performance or substitution compatibility.

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