TPA321DR Equivalent & Substitute Parts

Part Overview

The TPA321DR is a Class AB mono audio amplifier IC manufactured by Texas Instruments, housed in an 8-SOIC surface mount package. This device delivers 700mW output power at 8Ohm load with a supply voltage range of 2.5V to 5.5V. The TPA321DR features differential inputs, short-circuit protection, thermal protection, and shutdown functionality, making it suitable for portable audio applications requiring compact form factors and integrated protection mechanisms.

The TPA321DR maintains Active product status with full RoHS3 compliance and unlimited moisture sensitivity rating (MSL 1). Substitute parts are identified when equivalent electrical performance, package compatibility, and operational specifications align with application requirements.

Substiute Parts

TPA321DR

Texas InstrumentsIn Stock: 3363TPA321DR Datasheet

Current PartRFQ

LM4818MX/NOPB

Texas InstrumentsIn Stock: 1267LM4818MX/NOPB Datasheet

MFR RecommendedRFQ

LM4819MX/NOPB

Texas InstrumentsIn Stock: 9913LM4819MX/NOPB Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the TPA321DR are qualified based on the following criteria:

Package Compatibility: All substitute parts must use the 8-SOIC surface mount package to ensure direct PCB layout compatibility without redesign.

Electrical Classification: Substitutes must be Class AB mono amplifier ICs from Texas Instruments to maintain functional equivalence in audio amplification topology.

Supply Voltage Range: The substitute must operate within or encompass the 2.5V to 5.5V supply range of the primary part.

Output Power Capability: While the TPA321DR delivers 700mW at 8Ohm, substitutes with lower output power ratings (350mW at 16Ohm) are qualified when load impedance requirements differ or when lower power operation is acceptable for the application.

Protection Features: Substitutes must include shutdown functionality as a minimum protection requirement. Additional features such as short-circuit protection, thermal protection, or depop functionality enhance but do not restrict substitution eligibility.

Compliance Status: All substitutes must maintain Active product status and RoHS3 compliance to ensure long-term availability and regulatory alignment.

The identified substitutes—LM4818MX/NOPB and LM4819MX/NOPB—meet these criteria as Texas Instruments Class AB mono amplifiers in 8-SOIC packaging with compatible supply voltage ranges and active product status.

Parameter Comparison

Engineering Selection Recommendations

Primary Selection (TPA321DR): Retain the TPA321DR when applications require 700mW output power at 8Ohm load impedance, differential input signal processing, and integrated short-circuit plus thermal protection. This part is optimal for designs where maximum power delivery and comprehensive protection are essential specifications.

Substitute Selection (LM4819MX/NOPB): The LM4819MX/NOPB is the preferred substitute when output power requirements are 350mW or lower at 16Ohm load impedance. This part maintains differential input capability matching the TPA321DR and includes depop functionality for audio quality enhancement. Both parts share identical operating temperature range, supply voltage compatibility (2V minimum vs. 2.5V minimum for TPA321DR), and 8-SOIC package geometry. Active product status and RoHS3 compliance ensure equivalent long-term availability and regulatory standing.

Alternative Substitute (LM4818MX/NOPB): The LM4818MX/NOPB is suitable for applications where single-ended input operation is acceptable and output power is limited to 350mW at 16Ohm. This part lacks differential input capability but includes depop functionality. Selection of this part requires confirmation that single-ended input architecture aligns with circuit design requirements.

Compliance Alignment: All three parts maintain Active product status, RoHS3 compliance, MSL 1 rating, and REACH unaffected status, ensuring regulatory and supply chain consistency across substitution scenarios.

Frequently Asked Questions (FAQ)

Q: Can LM4818MX/NOPB or LM4819MX/NOPB be used as direct drop-in replacements for TPA321DR?

A: Both parts share the 8-SOIC package footprint and surface mount configuration, enabling PCB-level compatibility without layout redesign. However, electrical performance differs: the LM481x series delivers 350mW at 16Ohm versus 700mW at 8Ohm for the TPA321DR. Substitution is valid only when application load impedance and power requirements align with the lower output specification. The LM4819MX/NOPB maintains differential input compatibility; the LM4818MX/NOPB requires single-ended input operation.

Q: What is the minimum supply voltage difference between TPA321DR and the LM481x substitutes?

A: The TPA321DR operates from 2.5V minimum, while LM4818MX/NOPB and LM4819MX/NOPB operate from 2V minimum. Both ranges encompass standard 3.3V and 5V supply rails. The 0.5V lower minimum for the LM481x series provides additional flexibility in low-voltage applications but does not restrict substitution in designs using 2.5V or higher supplies.

Q: Are short-circuit and thermal protection features critical for substitution decisions?

A: The TPA321DR includes integrated short-circuit and thermal protection; the LM481x series does not. If the application circuit design relies on these protection mechanisms for system-level safety, external protection components may be required when substituting with LM481x parts. If the application implements protection at the system level or does not require these specific protections, substitution proceeds without additional circuit modifications.

Q: What is the significance of the depop feature in LM481x parts?

A: Depop (de-pop) functionality reduces audible transients during power-up and shutdown sequences in audio applications. The TPA321DR does not include this feature; both LM481x substitutes do. In audio-critical applications, depop enhances perceived audio quality during state transitions. This feature does not affect substitution eligibility but represents a functional enhancement in the substitute parts.

Q: How do load impedance specifications affect substitution validity?

A: The TPA321DR is rated at 700mW into 8Ohm; the LM481x series is rated at 350mW into 16Ohm. These specifications reflect different output stage designs and impedance matching. Substitution is valid when the application load impedance and required power output align with the substitute part's rating. A design requiring 700mW into 8Ohm cannot be satisfied by LM481x substitutes; conversely, a design requiring 350mW into 16Ohm can use either substitute.

Q: Do all three parts share identical RoHS and compliance certifications?

A: Yes. TPA321DR, LM4818MX/NOPB, and LM4819MX/NOPB all maintain RoHS3 compliance, MSL 1 (unlimited moisture sensitivity), REACH unaffected status, and EAR99 ECCN classification. Regulatory and supply chain requirements do not differentiate these parts.

Q: What is the inventory status for each part?

A: TPA321DR: 3344 pieces in stock. LM4818MX/NOPB: 1165 pieces in stock. LM4819MX/NOPB: 9841 pieces in stock. Inventory levels reflect current availability; substitution decisions may consider supply continuity when long-term production volumes are required.