LP3966ES-3.3 Linear Voltage Regulator — Equivalent & Substitute Parts

Part Overview

The LP3966ES-3.3 is a linear voltage regulator IC from Texas Instruments, delivering a fixed 3.3V output at 3A in a TO-263 (DDPAK-5) surface mount package. This device is classified as Last Time Buy, indicating limited future availability. The primary function is positive fixed voltage regulation with integrated protection features including over-current, over-temperature, and short-circuit protection. Finding equivalent and substitute parts is necessary due to product lifecycle status and potential supply constraints.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	3A
Input Voltage (Max)	7V
Voltage Dropout (Max)	1.2V @ 3A
Quiescent Current (Iq)	9 mA
Package / Case	TO-263-6, D2PAK (5 Leads + Tab)
Operating Temperature Range	-40°C to 125°C
Protection Features	Over Current, Over Temperature, Short Circuit
Control Features	Enable
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the LP3966ES-3.3 are classified based on strict electrical and mechanical parameter matching:

Direct Substitutes (Identical Electrical Specifications): Parts that maintain all critical electrical parameters: 3.3V fixed output, 3A output current, 7V maximum input voltage, 1.2V maximum dropout voltage at 3A, 9 mA quiescent current, and identical package configuration (TO-263 DDPAK-5). These parts are pin-compatible and functionally interchangeable without circuit modification.

Parametric Equivalents (Improved Performance Characteristics): Parts that deliver the same output voltage, current rating, and package but with enhanced electrical performance in specific areas such as reduced dropout voltage (0.6V vs 1.2V) or lower quiescent current (4-5 mA vs 9 mA). These parts are functionally superior and remain pin-compatible.

Substitution Criteria:

Output voltage: 3.3V (fixed)
Output current: 3A minimum
Input voltage rating: 7V or higher
Package: TO-263 (DDPAK-5) surface mount
Operating temperature: -40°C to 125°C minimum
Protection features: Over-current, over-temperature, short-circuit protection required

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Dropout Voltage @ 3A	Quiescent Current	Supply Current (Max)	PSRR	Product Status	Inventory
LP3966ES-3.3	Texas Instruments	3.3V	3A	1.2V	9 mA	15 mA	—	Last Time Buy	1879 Pcs
LP3966ES-3.3/NOPB	Texas Instruments	3.3V	3A	1.2V	9 mA	15 mA	—	Active	2100 Pcs
LP3853ES-3.3/NOPB	Texas Instruments	3.3V	3A	0.6V	4 mA	10 mA	73dB ~ 57dB (120Hz)	Active	1356 Pcs
LP3856ES-3.3/NOPB	Texas Instruments	3.3V	3A	0.6V	4 mA	10 mA	73dB ~ 57dB (120Hz)	Active	1120 Pcs
LP3873ES-3.3/NOPB	Texas Instruments	3.3V	3A	1.2V	9 mA	15 mA	73dB ~ 57dB (120Hz)	Active	3200 Pcs
LP3876ES-3.3/NOPB	Texas Instruments	3.3V	3A	1.2V	5 mA	15 mA	—	Active	6460 Pcs
LP3963ES-3.3/NOPB	Texas Instruments	3.3V	3A	1.2V	9 mA	15 mA	—	Active	1203 Pcs
LP3963ES-3.3	Texas Instruments	3.3V	3A	1.2V	9 mA	15 mA	—	Last Time Buy	1434 Pcs

Engineering Selection Recommendations

Primary Recommendation: LP3966ES-3.3/NOPB This part is the direct equivalent with Active product status, ensuring long-term availability. It maintains identical electrical specifications to the original LP3966ES-3.3 while offering superior supply security. The /NOPB designation indicates lead-free compliance and RoHS3 certification.

Secondary Recommendation: LP3873ES-3.3/NOPB Offers the same electrical performance as the original part with Active status and the highest inventory level (3200 Pcs). Includes PSRR specification (73dB ~ 57dB at 120Hz), providing additional performance documentation. Suitable for applications requiring noise rejection characteristics.

Performance-Enhanced Alternative: LP3853ES-3.3/NOPB or LP3856ES-3.3/NOPB These parts deliver superior performance with reduced dropout voltage (0.6V vs 1.2V) and lower quiescent current (4 mA vs 9 mA). Select these when thermal management or battery-powered operation requires improved efficiency. Both include PSRR specification and Active product status.

Efficiency-Optimized Alternative: LP3876ES-3.3/NOPB Combines the original dropout voltage specification (1.2V) with reduced quiescent current (5 mA), offering a balance between compatibility and efficiency. Highest inventory availability (6460 Pcs) ensures supply continuity.

All recommended substitutes maintain TO-263 (DDPAK-5) package compatibility, identical pin configuration, RoHS3 compliance, and MSL 3 moisture sensitivity rating. Selection should prioritize Active product status parts to avoid future lifecycle constraints.

Frequently Asked Questions (FAQ)

Q: Can LP3853ES-3.3/NOPB or LP3856ES-3.3/NOPB replace LP3966ES-3.3 without circuit modification? A: Yes. Both parts are pin-compatible with identical package configuration (TO-263 DDPAK-5), output voltage (3.3V), and output current (3A). The reduced dropout voltage (0.6V vs 1.2V) and lower quiescent current (4 mA vs 9 mA) represent performance improvements that do not require circuit changes.

Q: What is the difference between LP3966ES-3.3 and LP3966ES-3.3/NOPB? A: Both parts are electrically identical. The /NOPB designation explicitly indicates lead-free (no lead/no plumbum) manufacturing and RoHS3 compliance. LP3966ES-3.3/NOPB is the preferred specification for new designs and offers Active product status.

Q: Why do some substitute parts have different quiescent current values? A: Quiescent current varies by device architecture and internal design. LP3853ES-3.3/NOPB and LP3856ES-3.3/NOPB feature optimized designs with 4 mA quiescent current, while LP3966ES-3.3, LP3873ES-3.3/NOPB, LP3876ES-3.3/NOPB, and LP3963ES-3.3 operate at 9 mA or 5 mA. Selection depends on application power budget requirements.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All listed substitute parts maintain RoHS3 compliance and MSL 3 moisture sensitivity rating, meeting current environmental and reliability standards.

Q: What is the significance of Last Time Buy status? A: Last Time Buy indicates the manufacturer will discontinue production after current inventory is depleted. LP3966ES-3.3 and LP3963ES-3.3 carry this status. Transition to Active status parts (LP3966ES-3.3/NOPB, LP3873ES-3.3/NOPB, LP3853ES-3.3/NOPB, LP3856ES-3.3/NOPB, LP3876ES-3.3/NOPB, or LP3963ES-3.3/NOPB) is recommended for long-term supply security.

Q: Can I use LP3876ES-3.3/NOPB as a direct replacement if I need lower quiescent current? A: Yes. LP3876ES-3.3/NOPB maintains the same dropout voltage (1.2V) and output specifications as the original part while reducing quiescent current to 5 mA. It is pin-compatible and requires no circuit modification.

Q: What package considerations apply to these substitute parts? A: All substitute parts use the TO-263 (DDPAK-5) surface mount package with identical pinout and thermal characteristics. PCB layout and thermal management design remain unchanged during substitution.

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