LP38856SX-1.2 Equivalent & Substitute Parts

Part Overview

The LP38856SX-1.2 is a linear voltage regulator IC from Texas Instruments, designed to deliver a fixed 1.2V output at 3A in a TO-263 (DDPAK-5) surface mount package. This component is classified as obsolete, which necessitates identification of active equivalent parts for new designs and ongoing production requirements. The part provides essential power management functionality with integrated protection features including over-current, over-temperature, short-circuit, and under-voltage lockout protection.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	1.2V
Output Current	3A
Input Voltage (Max)	5.5V
Voltage Dropout	0.45V @ 3A
Quiescent Current	300 µA
Operating Temperature Range	-40°C to 125°C
Package Type	TO-263 (DDPAK-5)
Protection Features	Over Current, Over Temperature, Short Circuit, UVLO

Substitute Part Grouping Explanation

Substitute parts for the LP38856SX-1.2 are identified based on strict electrical and mechanical parameter matching. The critical substitution criteria are:

Fixed output voltage of 1.2V
Output current capability of 3A minimum
Maximum input voltage of 5.5V or greater
TO-263 (DDPAK-5) package compatibility
Identical protection feature set (Over Current, Over Temperature, Short Circuit, UVLO)
Operating temperature range of -40°C to 125°C or wider

Two substitute parts meet these requirements: LP38856SX-1.2/NOPB (Texas Instruments, Active status) and LP3893ESX-1.2/NOPB (National Semiconductor, Active status). Both maintain full electrical and mechanical compatibility with the obsolete LP38856SX-1.2.

Parameter Comparison

Parameter	LP38856SX-1.2	LP38856SX-1.2/NOPB	LP3893ESX-1.2/NOPB
Manufacturer	Texas Instruments	Texas Instruments	National Semiconductor
Product Status	Obsolete	Active	Active
Output Voltage	1.2V	1.2V	1.2V
Output Current	3A	3A	3A
Input Voltage (Max)	5.5V	5.5V	5.5V
Voltage Dropout (Max)	0.45V @ 3A	0.45V @ 3A	1V @ 1A
Quiescent Current	300 µA	300 µA	30 µA
Current Supply (Max)	15 mA	15 mA	8 mA
PSRR	80dB ~ 65dB (120Hz ~ 1kHz)	80dB ~ 65dB (120Hz ~ 1kHz)	80dB ~ 65dB (120Hz ~ 1kHz)
Operating Temperature	-40°C to 125°C	-40°C to 125°C	-40°C to 125°C
Package	TO-263 (DDPAK-5)	TO-263 (DDPAK-5)	TO-263 (DDPAK-5)
Protection Features	Over Current, Over Temperature, Short Circuit, UVLO	Over Current, Over Temperature, Short Circuit, UVLO	Over Current, Over Temperature, Short Circuit, UVLO
RoHS Status	Non-compliant	ROHS3 Compliant	Not specified

Engineering Selection Recommendations

LP38856SX-1.2/NOPB is the primary recommended substitute. This part is manufactured by Texas Instruments (original manufacturer), maintains Active product status, and achieves ROHS3 compliance. It provides identical electrical performance to the obsolete LP38856SX-1.2 with matching voltage dropout characteristics (0.45V @ 3A) and quiescent current (300 µA). The /NOPB suffix indicates lead-free construction and halogen-free packaging, meeting modern environmental standards.

LP3893ESX-1.2/NOPB from National Semiconductor serves as a secondary alternative. While electrically compatible in core specifications, this part exhibits lower quiescent current (30 µA versus 300 µA) and higher voltage dropout at reduced load (1V @ 1A versus 0.45V @ 3A). These differences may provide advantages in low-power standby applications but require circuit validation for full-load performance scenarios.

Both substitutes are available in Active status with established supply chains, ensuring long-term component availability for production and design continuation.

Frequently Asked Questions (FAQ)

Q: Can LP38856SX-1.2/NOPB be used as a direct replacement for LP38856SX-1.2?

A: Yes. The LP38856SX-1.2/NOPB is a direct substitute with identical electrical specifications, package type (TO-263 DDPAK-5), and protection features. The primary difference is product status (Active versus Obsolete) and RoHS compliance certification.

Q: What are the key differences between LP38856SX-1.2/NOPB and LP3893ESX-1.2/NOPB?

A: Both parts deliver 1.2V at 3A in TO-263 packaging. LP38856SX-1.2/NOPB maintains identical dropout voltage (0.45V @ 3A) and quiescent current (300 µA) to the original. LP3893ESX-1.2/NOPB offers lower quiescent current (30 µA) and lower supply current (8 mA), but exhibits higher dropout voltage at reduced loads (1V @ 1A). Selection depends on circuit requirements for dropout performance and standby power consumption.

Q: Are both substitutes compatible with existing PCB layouts designed for LP38856SX-1.2?

A: Yes. Both substitute parts use the identical TO-263 (DDPAK-5) package with matching pin configuration and thermal tab. No PCB redesign is required for mechanical or electrical integration.

Q: What is the significance of the /NOPB suffix?

A: The /NOPB designation indicates lead-free (Pb-free) construction and halogen-free packaging, meeting RoHS and environmental compliance requirements for modern manufacturing and end-of-life disposal standards.

Q: Which substitute should be selected for new designs?

A: LP38856SX-1.2/NOPB is recommended for new designs due to Texas Instruments manufacturer continuity, identical performance characteristics to the original part, and established Active product status with long-term availability assurance.

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