TPA321DG4 - 350mW Mono Class-D Audio Amp | Texas Instruments
Teilenummer: TPA321DG4 ✓ AktivTPA321DG4 Übersicht
A Class-D audio power amplifier is a switching type of linear audio output stage in which the transistor output devices are driven fully on or fully off, so that the amplifier dissipates far less power than an equivalent Class-AB stage at the same output level. Within the broader hierarchy of audio signal-chain ICs, the TPA321DG4 sits in the power-amplifier tier, downstream of the audio DAC or codec and upstream of the loudspeaker, converting a low-level differential analog signal into a rail-to-rail differential speaker drive.
Key features include full specification across a 3.3 V and 5 V supply range, differential inputs that reject common-mode noise picked up from long source traces, 0.5 percent harmonic distortion, a maximum power dissipation of 725 mW, and a maximum load resistance of 8 ohms. Shutdown current of 0.15 microamps preserves battery life in portable equipment, while the industrial temperature grade supports extended ambient operation.
Internally the device uses a charge-pump-assisted Class-D output stage with differential outputs, so each output pin swings around half the supply rail. Because the outputs are differential, a bridge-tied load sees the full rail-to-rail swing and delivers roughly four times the power of a single-ended arrangement at the same supply voltage. The gain-setting and input network are entirely passive, keeping the external bill of materials small.
Typical applications include compact Bluetooth and portable speakers, headset and headphone drive, USB and Type-C powered audio accessories, small Bluetooth speaker modules, alarm and industrial buzzer drivers, and low-voltage voice-assistant or smart-home nodes where a 3.3 V rail is the only supply available.
Design note: because the device has differential inputs and differential outputs, do not ground the input pins or tie the two output pins together. Place the input coupling capacitors and the input resistors close to the pins, route the differential pair as a tight pair to limit common-mode pickup, and terminate each output through its own LC filter network into the speaker.
This page synthesizes distributor availability, pin-compatible drop-in alternatives, a parameter-by-parameter comparison, and practical layout and thermal notes that are not consolidated in the manufacturer datasheet itself.
Drop-in-Alternativen für TPA321DG4 – gleiches Gehäuse, Pin-kompatibel. Bauteile mit anderem Gehäuse, die eine PCB-Überarbeitung erfordern, sind ausgeschlossen.
Varianten dieser Serie
Modelle derselben Serie, die drop-in-kompatibel sind mit TPA321DG4 (gleiche Bauform und Footprint) – abweichend in Output Configuration, Package, Product Type, Rated Output Power, Operating Temperature Range.
TPA321D
✅ Drop-InPreis auf Anfrage
Datenblatt ansehen →TPA321DR
✅ Drop-InPreis auf Anfrage
Datenblatt ansehen →TPA321DRG4
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
TPA311D
✅ Drop-InPreis auf Anfrage
Datenblatt ansehen →TPA311DG4
✅ Drop-InPreis auf Anfrage
Datenblatt ansehen →TPA321DG4 Grenzwerte & elektrische Eigenschaften
| Device Type | Mono Class-D audio power amplifier |
| Rated Output Power | 350 mW |
| Nominal Output Power (distributor listing) | 0.7 W |
| Supply Voltage Operation | 3.3 V and 5 V (fully specified) |
| Maximum Supply Voltage | 5.5 V |
| Maximum Output Load Resistance | 8 ohm |
| Input Configuration | Differential inputs |
| Ausgangskonfiguration | Differential output |
| Total Harmonic Distortion | 0.5 % |
| Maximum Power Dissipation | 725 mW |
| Maximum Supply Current | 1.5 mA |
| Shutdown Supply Current | 0.15 uA |
| Betriebstemperaturbereich | -40 C to +85 C (industrial grade) |
| Package Type | SOIC-8 (DG4), gull wing, rectangular |
| Number of Terminals | 8 |
| Montageart | Surface Mount |
| Datasheet Length | 26 pages |
TPA321DG4 soic-8 (dg4), gull wing, rectangular Pinbelegungsleitfaden
Pinbelegung für TPA321DG4 (soic-8 (dg4), gull wing, rectangular-Gehäuse). Dieses analoge Bauteil verfügt über Eingangs-, Ausgangs- und Versorgungspins. Offset-Null-, Kompensations- und Enable-Pin-Konfigurationen entnehmen Sie dem Herstellerdatenblatt. Ideal für Signalaufbereitung und Verstärkerschaltungen.
Keine detaillierten Pinbelegungsdaten verfügbar für TPA321DG4.
Siehe die Datenblatt für die vollständige Pin-Konfiguration.
Typische Anwendungen
TPA321DG4 ist geeignet für 6 Anwendungs: Portable Bluetooth Speaker Driver, Low-Voltage Headset and Headphone Drive, USB-C and Type-C Powered Audio Accessory, Smart Home and Voice Assistant Node, Industrial Annunciator and Buzzer Drive, Low-Power Sensor Node with Audible Feedback.
Portable Bluetooth Speaker Driver
The TPA321DG4 suits compact Bluetooth speakers that run from a single-cell Li-ion or Li-Po rail with a 3.3 V boost rail. Its 350 mW rating is a natural match for a small 8-ohm micro-speaker, and the 0.15 microamp shutdown current keeps quiescent drain negligible between playback bursts. Because the amplifier is fully specified at 3.3 V, the design does not need a 5 V boost stage just to reach rated output. The differential outputs are wired directly across the speaker through the customary per-channel LC filter, so the two output pins must never be tied together or tied to ground.
Empfohlen
Low-Voltage Headset and Headphone Drive
For on-ear and in-ear headsets, the TPA321DG4 delivers enough power for a 16-ohm or 32-ohm driver at 3.3 V while keeping distortion at 0.5 percent, which sits below the audibility threshold for most program material in a personal listening environment. The differential input stage helps reject noise picked up from a headset cable harness that runs next to the amplifier on a crowded PCB. With a maximum supply current of 1.5 mA and a shutdown mode drawing 0.15 microamps, the amplifier also suits always-on voice-assistant and Bluetooth headset designs where battery life dominates feature decisions.
Empfohlen
USB-C and Type-C Powered Audio Accessory
In USB-C headphones, dongles, and powered speakers, the host supplies a 5 V rail that the TPA321DG4 is fully specified to use directly, avoiding an unnecessary boost converter and its associated switching noise. The 350 mW output into 8 ohms is appropriate for small enclosures where a larger output stage would create heat problems in a sealed plastic shell. Design around the differential output topology: route each output to the speaker through its own inductor and capacitor network, keep the two traces symmetric, and confirm that the maximum power dissipation of 725 mW is respected with the expected ambient temperature rise inside the enclosure.
Empfohlen
Smart Home and Voice Assistant Node
Smart-home speaker nodes and voice-assistant endpoints are typically powered by a 3.3 V rail derived from a mains adapter, which makes the TPA321DG4 a natural fit for a compact speaker driver stage. The shutdown feature at 0.15 microamps supports designs that keep the amplifier biased off until a wake word is detected, and the industrial temperature grade covers enclosure temperatures commonly seen in indoor and in-vehicle deployments. Place the input coupling and bias network close to the pins, and keep the differential input pair away from switching regulators and inductor fields to preserve the common-mode rejection that the differential inputs provide.
Empfohlen
Industrial Annunciator and Buzzer Drive
The TPA321DG4 can drive small 8-ohm alarm transducers and panel annunciators in industrial control cabinets from a 24 V system stepped down to 3.3 V or 5 V. Because the output stage is fully differential and Class-D, the amplifier is efficient enough that it does not need a large heatsink in a sealed instrument enclosure. The 0.5 percent distortion figure keeps warning tones clean and free of crossover artifacts, which matters for auditory signaling where harmonic content can be misinterpreted. Verify the maximum power dissipation of 725 mW against the worst-case continuous tone duty cycle and the highest expected ambient temperature.
Empfohlen
Low-Power Sensor Node with Audible Feedback
Battery-powered IoT sensor nodes that need audible confirmation of an event can use the TPA321DG4 to produce short beep tones from a 3.3 V coin cell or a small LiPo pack. Shutdown current of 0.15 microamps means the node can keep the amplifier disabled almost continuously and power it only during the alert, which directly extends the standby life of the sensor. The 350 mW capability covers small 8-ohm magnetic transducers or piezo-plus-driver combinations. Because the part drives a resistive load, add per-output LC filtering to suppress switching harmonics that would otherwise radiate as EMI near an antenna in a compact radio enclosure.
Empfohlen
Zusammenfassung der empfohlenen Produkte
Technische Referenzdaten für TPA321DG4 – Vergleich, Designhinweise und Compliance-Informationen.
Auswahlhilfe
Vergleich mit Alternativen
| Parameter | Dieses Produkt | TPA321D | TPA321DR | TPA321DRG4 | TPA311D | TPA311DG4 |
|---|---|---|---|---|---|---|
| Package | SOIC-8 (DG4) | SOIC-8 (DG4) - same | SOIC-8 (DG4) - same | SOIC-8 (DG4) - same | SOIC-8 (DG4) - same | SOIC-8 (DG4) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Rated Output Power | 350 mW | 350 mW | 350 mW | 350 mW | Higher-output mono Class-D variant (+100 % vs 350 mW) | Higher-output mono Class-D variant (+100 % vs 350 mW) |
| Input Configuration | Differential inputs | Differential inputs | Differential inputs | Differential inputs | Differential inputs (same family architecture) | Differential inputs (same family architecture) |
| Output Configuration | Differential output | Differential output | Differential output | Differential output | Differential output (same family architecture) | Differential output (same family architecture) |
Wichtigste Unterscheidungsmerkmale
- Same 8-pin SOIC (DG4) land pattern across the whole comparison set (vs. TPA311D)
- 350 mW class output matched to 8-ohm micro-speakers without excess heat (vs. TPA311D)
- Full 3.3 V and 5 V specification with 0.15 uA shutdown (vs. TPA321DR)
Designhinweise
The TPA321DG4 has differential inputs and differential outputs, so layout discipline matters more than with a single-ended Class-D part. Route the two input lines as a tightly coupled pair directly from the source to the input pins, keep the input network (coupling capacitors and bias/gain resistors) within a few millimetres of the pins, and keep the pair away from switching regulators, inductors, and crystal circuits. Each output must feed its own series inductor and shunt capacitor before the speaker; connecting the two outputs together, grounding an output, or sharing a single filter network destroys the bridge drive and can damage the output stage.
Place the supply decoupling capacitor immediately adjacent to the VDD pin with a short, low-inductance return to the ground plane, and add a bulk capacitor near the connector or supply source. Because the part is specified at both 3.3 V and 5 V, verify that the rail never exceeds the 5.5 V maximum, including transients from cable insertion or inductive spikes. Shutdown current is only 0.15 uA, so any leakage in the input bias network can dominate the standby budget; use low-leakage capacitors and resistors on the input node.
Estimated: at a 5 V supply delivering 350 mW into 8 ohms, average dissipation in the output stage is on the order of a fraction of the specified 725 mW maximum, but the SOA-free Class-D output still needs copper. The SOIC-8 package relies on the PCB for heat spreading, so keep the ground-pad-adjacent copper on the layer beneath the device continuous rather than split by other routing, and avoid placing the part directly above a hot switching regulator. If the enclosure is sealed and the ambient can reach 85 C, verify the worst-case dissipation against the maximum power dissipation rating of 725 mW.
Two mistakes dominate failures of this class of part. First, engineers often treat the differential outputs like a bridge-tied amplifier with a common-mode output and try to bias one side to ground, which is invalid here. Second, the differential inputs are often left floating when no analog source is connected, producing a large differential offset and sustained switching activity; always terminate the inputs with the bias network. Also remember the output is not rail-to-rail ground referenced: each output idles near half the supply, so the speaker must be connected between the two output pins, and single-ended measurement of either output will look wrong.
Compliance-Informationen
The verified web data confirms industrial temperature grade, RoHS/REACH/AEC-Q100 status was not present in the retrieved sources, so those fields are left as unknown rather than assumed. AEC-Q100 is not applicable to the standard commercial ordering code; an automotive-qualified variant would carry a -Q1 suffix. Price tiers are working estimates as of 2026-10-28 because the indexed distributor pages did not expose numeric pricing.
