LP2981A-33DBVRE4 Equivalent & Substitute Parts

Part Overview

The LP2981A-33DBVRE4 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 part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The device provides positive fixed output configuration with integrated enable control and comprehensive protection features including over-current, over-temperature, and short-circuit protection.

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)
Package	SOT-23-5 (SC-74A)
Operating Temperature	-40°C to 125°C
Control Features	Enable
Protection Features	Over Current, Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitution for the LP2981A-33DBVRE4 is determined by strict equivalence across the following critical parameters:

Fixed output voltage of 3.3V
Output current rating of 100mA
Maximum input voltage of 16V
Dropout voltage specification of 0.37V @ 100mA
Quiescent current of 95 µA
PSRR of 63dB (1kHz)
SOT-23-5 package configuration
Operating temperature range of -40°C to 125°C
Enable control feature
Over-current, over-temperature, and short-circuit protection

Substitute parts are grouped into two categories: MFR Recommended (manufacturer-endorsed direct replacements) and Parametric Equivalents (parts meeting all electrical and mechanical specifications). The LD2981ABM33TR from STMicroelectronics is included as a cross-manufacturer alternative with minor parameter variations noted in the comparison table.

Parameter Comparison

Part Number	Manufacturer	Product Status	Output Voltage	Output Current	Dropout Voltage	Quiescent Current	Package	Inventory
LP2981A-33DBVRE4	Texas Instruments	Obsolete	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	1,062 Pcs
LP2981AIM5X-3.3/NOPB	Texas Instruments	Active	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	7,272 Pcs
LP2981IM5-3.3/NOPB	Texas Instruments	Active	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	18,400 Pcs
LP2981IM5X-3.3/NOPB	Texas Instruments	Active	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	12,302 Pcs
LP2981-33DBVR	Texas Instruments	Active	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	69,150 Pcs
LP2981-33DBVT	Texas Instruments	Last Time Buy	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	4,490 Pcs
LP2981A-33DBVR	Texas Instruments	Active	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	56,100 Pcs
LP2981A-33DBVT	Texas Instruments	Last Time Buy	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	1,900 Pcs
LP2981A-33DBVTG4	Texas Instruments	Discontinued at DiGi Electronics	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	23,637 Pcs
LP2981AIM5-3.3/NOPB	Texas Instruments	Active	3.3V	100mA	0.37V @ 100mA	95 µA	SOT-23-5	4,948 Pcs
LD2981ABM33TR	STMicroelectronics	Active	3.3V	100mA	0.375V @ 100mA	150 µA	SOT-23-5	24,300 Pcs

Engineering Selection Recommendations

For direct replacement of the obsolete LP2981A-33DBVRE4, select from active-status Texas Instruments parts with identical electrical specifications. The LP2981IM5-3.3/NOPB offers the highest inventory availability (18,400 units) with active product status and full parameter equivalence. The LP2981-33DBVR provides the largest stock position (69,150 units) and is recommended for high-volume applications requiring supply security.

For applications where Texas Instruments parts are unavailable, the LD2981ABM33TR from STMicroelectronics provides functional equivalence with minor parameter variations: dropout voltage of 0.375V (versus 0.37V) and quiescent current of 150 µA (versus 95 µA). Both devices maintain the same output voltage, current rating, package configuration, and operating temperature range.

Parts designated as Last Time Buy (LP2981-33DBVT, LP2981A-33DBVT) have limited remaining inventory and should be avoided for new designs. The LP2981A-33DBVTG4 is discontinued at DiGi Electronics and should not be selected for ongoing production.

All substitute parts maintain ROHS3 compliance, MSL Level 1 (unlimited moisture sensitivity), and identical mechanical packaging in SOT-23-5 configuration, ensuring direct PCB compatibility.

Frequently Asked Questions (FAQ)

Q: Can LP2981IM5-3.3/NOPB be used as a direct replacement for LP2981A-33DBVRE4?

A: Yes. Both parts deliver identical electrical performance: 3.3V fixed output, 100mA current rating, 0.37V dropout voltage, 95 µA quiescent current, and SOT-23-5 package. The LP2981IM5-3.3/NOPB is active status with higher inventory availability.

Q: What is the difference between LP2981-33DBVR and LP2981A-33DBVR?

A: Both parts are parametrically equivalent with identical electrical specifications and SOT-23-5 packaging. The LP2981-33DBVR has significantly higher inventory (69,150 units) compared to LP2981A-33DBVR (56,100 units). Both are active status.

Q: Is the LD2981ABM33TR from STMicroelectronics a suitable alternative?

A: The LD2981ABM33TR meets the core functional requirements with 3.3V output, 100mA current, and SOT-23-5 package. However, it has higher quiescent current (150 µA versus 95 µA) and slightly higher dropout voltage (0.375V versus 0.37V). Use this part only when Texas Instruments equivalents are unavailable.

Q: Why should I avoid Last Time Buy parts?

A: Last Time Buy parts (LP2981-33DBVT, LP2981A-33DBVT) have limited remaining inventory and will not be replenished. These should be used only for existing production runs with confirmed end-of-life dates.

Q: Are all substitute parts RoHS compliant?

A: Yes. All listed substitute parts are ROHS3 compliant with MSL Level 1 (unlimited moisture sensitivity), meeting current environmental and regulatory requirements.

Q: Can I mix different substitute part numbers in the same production batch?

A: Yes. All Texas Instruments LP2981 variants listed are parametrically equivalent and can be used interchangeably without circuit modification. Cross-manufacturer substitution with LD2981ABM33TR requires verification of quiescent current and dropout voltage tolerance in your specific application.

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