LP3990SD-2.5/NOPB Equivalent & Substitute Parts

Part Overview

The LP3990SD-2.5/NOPB is a linear voltage regulator IC from Texas Instruments, classified as a Power Management (PMIC) component. This device delivers a fixed 2.5V output at 150mA with a 6-WSON (3x3) surface mount package. The part is currently marked as Obsolete, necessitating identification of functionally equivalent alternatives for ongoing design support and procurement.

Key Parameters

Parameter	LP3990SD-2.5/NOPB
Manufacturer	Texas Instruments
Output Voltage (Fixed)	2.5V
Output Current	150mA
Input Voltage (Max)	6V
Voltage Dropout (Max)	0.2V @ 150mA
Quiescent Current	80 µA
Package Type	6-WDFN Exposed Pad (3x3)
Operating Temperature	-40°C ~ 85°C
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the LP3990SD-2.5/NOPB are identified based on the following critical parameters:

Fixed output voltage of 2.5V
Output current capability of 150mA
Surface mount 6-WDFN package with exposed pad
Positive fixed output configuration
Enable control feature and over-temperature/short-circuit protection
Operating temperature range of -40°C ~ 85°C
RoHS3 compliance

The LP5900 series variants meet these core electrical and mechanical requirements. All substitute parts maintain the same output voltage, current rating, and protection features. Variations in input voltage maximum (5.5V vs. 6V), dropout voltage, quiescent current, and PSRR performance are secondary parameters that do not prevent functional substitution in applications designed for the LP3990SD-2.5/NOPB.

Parameter Comparison

Parameter	LP3990SD-2.5/NOPB	LP5900SD-2.5	LP5900SD-2.5/NOPB	LP5900SDX-2.5/NOPB
Manufacturer	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments
Output Voltage (Fixed)	2.5V	2.5V	2.5V	2.5V
Output Current	150mA	150mA	150mA	150mA
Input Voltage (Max)	6V	5.5V	5.5V	5.5V
Voltage Dropout (Max)	0.2V @ 150mA	0.15V @ 150mA	0.15V @ 150mA	0.15V @ 150mA
Quiescent Current	80 µA	50 µA	50 µA	50 µA
Package Type	6-WDFN Exposed Pad (3x3)	6-WDFN Exposed Pad (2.2x2.5)	6-WDFN Exposed Pad (2.2x2.5)	6-WDFN Exposed Pad (2.2x2.5)
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Product Status	Obsolete	Last Time Buy	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For new designs and ongoing procurement, LP5900SD-2.5/NOPB is the primary recommended substitute. This part carries Active product status, ensuring long-term availability and supply chain stability. It maintains full electrical compatibility with the obsolete LP3990SD-2.5/NOPB while offering improved performance characteristics including lower dropout voltage (0.15V vs. 0.2V) and reduced quiescent current (50 µA vs. 80 µA).

LP5900SDX-2.5/NOPB is an alternative Active part with identical electrical specifications to LP5900SD-2.5/NOPB. Both parts are suitable for direct substitution.

LP5900SD-2.5 carries Last Time Buy status and should be considered only for legacy support or when specific procurement constraints apply.

All substitute parts are ROHS3 compliant and maintain the same operating temperature range. The primary design consideration is the package footprint change from 3x3mm to 2.2x2.5mm, which requires PCB layout verification for mechanical fit.

Frequently Asked Questions (FAQ)

Q: Can LP5900SD-2.5/NOPB directly replace LP3990SD-2.5/NOPB in existing designs?

A: Electrical substitution is valid. The LP5900SD-2.5/NOPB maintains identical output voltage (2.5V), output current (150mA), and protection features. However, the package footprint differs: LP3990 uses 6-WSON (3x3mm) while LP5900 uses 6-WSON (2.2x2.5mm). PCB layout modification is required.

Q: What are the key differences between LP5900SD-2.5 and LP5900SD-2.5/NOPB?

A: Both parts have identical electrical specifications. The primary difference is product status: LP5900SD-2.5 is Last Time Buy, while LP5900SD-2.5/NOPB is Active. For new designs, LP5900SD-2.5/NOPB is preferred for supply continuity.

Q: Does the lower input voltage maximum (5.5V vs. 6V) on LP5900 variants affect compatibility?

A: Applications operating at or below 5.5V input voltage experience no functional impact. Designs requiring input voltages between 5.5V and 6V must verify system requirements before substitution.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. LP5900SD-2.5, LP5900SD-2.5/NOPB, and LP5900SDX-2.5/NOPB are all ROHS3 compliant, matching the compliance status of the original LP3990SD-2.5/NOPB.

Q: What is the significance of the package size reduction from 3x3mm to 2.2x2.5mm?

A: The smaller footprint of LP5900 variants enables more compact PCB layouts. Existing designs must verify that thermal management and trace routing accommodate the reduced package dimensions.

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