TPA321DR - 700mW Mono Class-AB Amplifier | Texas Instruments
MPN: TPA321DR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.6856 | $0.69 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
TPA321DR Overview
What is a Class-AB audio amplifier? A Class-AB amplifier is an analog audio power amplifier that uses both transistor biasing approaches to reduce crossover distortion compared with a pure Class-A or Class-B stage. In a BTL configuration, the differential outputs drive the speaker in a push-pull manner, eliminating the need for a speaker coupling capacitor and improving use of the available supply voltage. The TPA321DR is therefore a power-management and signal-conditioning IC intended for compact speaker systems.
The verified features include differential inputs, short-circuit protection, thermal protection, a mono Class-AB output, and operation across both 3.3V and 5V supply systems. The manufacturer states that no special supply-bypassing, gain-setting, or stability considerations differ between 3.3V and 5V operation; the main consideration is the achievable output power. Its analog input structure allows system designers to set gain with external resistors according to the manufacturer application guidance.
The TPA321 architecture uses a bridge-tied load to support an internal speaker without a traditional output coupling capacitor. Its output stage is designed for low-voltage operation, making it suitable for portable equipment, small consumer audio products, voice terminals, and embedded audio systems. The BTL outputs should be treated as differential outputs, not as independent single-ended speaker outputs.
Typical applications include compact Bluetooth speaker accessories, portable audio products, voice-call terminals, USB-powered audio accessories, and small embedded sound modules. In each case, the designer must verify speaker impedance, supply headroom, thermal dissipation, input common-mode limits, and the stability of the external gain network against the datasheet.
A key design consideration is supply bypassing. Place the recommended bypass capacitors close to the power and ground pins, keep the BTL output routing away from sensitive analog input traces, and verify that the selected speaker does not present a load outside the manufacturer-supported operating range. The main engineering tradeoff is output power versus thermal dissipation: a higher supply voltage increases available output power but also raises internal stress.
This page consolidates the verified manufacturer and distributor information for TPA321DR, including supply range, package, output class, protection features, pricing context, and design guidance. It also distinguishes verified facts from parameters that still require a complete manufacturer datasheet review.
Drop-in alternatives for TPA321DR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with TPA321DR (same form factor and footprint) — differing in Output Configuration, Package, Product Type, Supply Voltage Range.
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Request AlternativesTPA321DR Maximum Ratings & Electrical Characteristics
| Product Type | Mono analog-input Class-AB audio amplifier |
| Maximum Output Power | 700mW |
| Output Power at 3.3V, 8Ω | 250mW continuous power at less than 1% THD+N |
| Supply Voltage Range | 2.5V to 5.5V |
| Supported Supply Operation | 3.3V and 5V |
| Output Configuration | Mono bridge-tied load (BTL) |
| Output Type | Differential output |
| Input Configuration | Differential inputs |
| Maximum Load Resistance | 8Ω |
| Operating Temperature | -40°C to +85°C |
| Package | 8-pin SOIC surface-mount package |
| Package Pin Count | 8 pins |
| Protection Features | Short-circuit protection and thermal protection |
| Power Dissipation | 725mW maximum |
| Quiescent Supply Current | Ultralow supply current in shutdown mode; exact value not provided |
| Gain | Set with external resistors |
TPA321DR 8 pins Pin Configuration Guide
Pin configuration for TPA321DR (8 pins package). This power device features gate, drain, and source terminals. For non-polarized packages, refer to the manufacturer datasheet for exact pin 1 orientation and footprint details. Common applications include power supply design, motor driving, and load switching.
No detailed pinout data available for TPA321DR.
Refer to the datasheet for full pin configuration.
Typical Applications
TPA321DR is suitable for 6 applications: Compact Bluetooth Speaker, Portable Voice Terminal, USB-Powered Audio Accessory, Small Consumer Audio Product, Industrial Audible Alarm, Portable Learning Device.
Compact Bluetooth Speaker
The TPA321DR fits a compact Bluetooth speaker that needs a mono internal-speaker driver from a low-voltage supply. Its verified 700mW amplifier capability and 250mW continuous output into an 8Ω load at 3.3V provide a practical starting point for small speaker systems, while Class-AB operation avoids the switching-node EMI concerns of a Class-D design. The BTL output should be connected to the speaker as a differential load, and the designer must confirm battery regulation, peak current, thermal rise, and output distortion before production.
Recommended
Portable Voice Terminal
The TPA321DR can provide speaker amplification for a portable voice terminal or communications accessory powered from a 2.5V to 5.5V source. Differential inputs are useful when the system must reject common-mode noise or accept a balanced microphone or line signal, while the BTL topology drives a small speaker without a conventional series output capacitor. The main constraints are analog input headroom, gain-network design, speaker impedance, and thermal performance at the maximum operating voltage.
Recommended
USB-Powered Audio Accessory
The TPA321DR is suitable for a USB-powered speaker or audio accessory when the available rail remains within the verified 2.5V to 5.5V supply range. Its 700mW device capability can support compact transducers, but the actual acoustic output depends on the USB supply current limit, protection scheme, speaker impedance, and enclosure acoustics. The manufacturer states that 3.3V and 5V operation use the same basic bypassing and gain-setting considerations, simplifying the power architecture across common USB voltage options.
Recommended
Small Consumer Audio Product
The TPA321DR can serve as the speaker driver in a small consumer audio product such as a personal audio device, educational toy, or compact monitor accessory. The 8-pin SOIC package supports conventional surface-mount assembly, and the -40°C to +85°C operating range covers many commercial and industrial environments. Designers should select external gain resistors and bypass capacitors according to the manufacturer guidance, preserve the BTL routing geometry, and validate audible distortion at the required output level.
Recommended
Industrial Audible Alarm
The TPA321DR can drive a small internal transducer in an audible alarm, status indicator, or equipment-feedback module when the system needs a clean analog mono speaker output. Its differential BTL arrangement helps reduce output coupling requirements, while short-circuit and thermal protection provide useful safeguards for a compact embedded design. The alarm designer must verify startup behavior, maximum continuous tone power, speaker excursion, fault behavior, and the supply tolerance of the industrial system.
Recommended
Portable Learning Device
The TPA321DR is appropriate for a portable learning or assistive-audio device that uses a small speaker and a low-voltage battery or USB-derived supply. The analog differential input structure allows an audio codec or preamplifier to drive the amplifier while limiting common-mode pickup in a compact enclosure. Because Class-AB power can dissipate more heat than a switching amplifier at low output levels, the board should provide adequate copper area and verify the enclosure temperature rise under sustained speech or music playback.
Recommended
Recommended Products Summary
Engineering reference data for TPA321DR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TPA301D | TPA321DG4 |
|---|---|---|---|
| Package | SOIC-8 | SOIC-8 | SOIC-8 |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments |
Key Differentiators
- Low-voltage mono Class-AB output with differential BTL drive (vs TPA301D)
- Verified 3.3V continuous-output reference (vs TPA321DG4)
- Integrated fault protection for compact audio products (vs TPA301D)
Design Notes
Calculate the available output power against the actual supply rail rather than using the 700mW device capability as a guaranteed speaker rating. At 3.3V, the verified continuous example is 250mW into 8Ω at less than 1% THD+N. Check the USB or battery current limit, regulator dropout behavior, startup current, and speaker excursion before selecting the transducer. The BTL output uses both differential output nodes, so verify that the load is connected between the correct pins.
Place the manufacturer-recommended bypass capacitors close to the supply and ground pins, and route the BTL output pair as a compact differential pair. Keep the analog input and gain-setting network away from the output traces where practical. A SOIC-8 footprint is mechanically compatible with the target package class, but the pin assignments and exposed thermal requirements must be checked in the official datasheet before layout release.
Thermal design should use the verified maximum power-dissipation value of 725mW together with the actual supply voltage, output voltage, and load current. Estimated: Pdiss equals approximately (Vsupply minus Vout) multiplied by Iout for a linear Class-AB stage, but actual efficiency, quiescent current, and protection behavior must be confirmed from operating measurements. Provide copper area and verify the enclosure temperature during sustained playback to avoid relying on the package rating alone.
Use the differential input network and external gain resistors specified by the manufacturer, and check input common-mode range at the lowest expected supply voltage. Differential outputs should be treated as a bridge-tied load and must not be connected independently to ground or to unrelated amplifier outputs. Validate gain, THD+N, and stability with the actual speaker cable and enclosure because speaker inductance and PCB capacitance can affect the final audio performance.
Compliance Information
The supplied verified web data does not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status for TPA321DR.
