NAU8331DG - Class-D Boosted Audio Amplifier | Nuvoton
MPN: NAU8331DG ✓ Active| Qty | Unit Price | Extended |
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| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
NAU8331DG Overview
A boosted Class-D amplifier combines two power functions in one device: a switching boost converter that raises the battery voltage, and a Class-D output stage that drives the speaker from the boosted rail. This architecture is central to portable power management and audio subsystems, where battery voltage alone is insufficient to reach target acoustic output.
Key features of the NAU8331 include the integrated Class-G boost converter for high efficiency, I/V sense feedback for speaker excursion and temperature protection when paired with DSP algorithms, and a digital/audio input interface for direct connection to application processors. According to the Nuvoton product brief, the V/I-Sense architecture is specifically designed to work with external speaker excursion control algorithms.
Technically, the Class-G boost converter modulates the Class-D supply rail adaptively, reducing losses compared with fixed-rail boost designs. The I/V sense channels feed back speaker current and voltage so a DSP can model speaker cone excursion, coil temperature, and impedance in real time, enabling louder and safer audio from the same speaker.
Typical applications are smartphone and tablet speakers, portable Bluetooth speakers, smart-home voice devices, and notebook PC audio, all of which demand maximum loudness from small batteries and small speakers.
When designing with the NAU8331DG, plan the boost converter inductor and output filter per the manufacturer datasheet layout guidance, and confirm that the DSP excursion-control algorithm matches the I/V sense scaling of this device.
This page synthesizes distributor pricing context, drop-in family alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for NAU8331DG — 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 NAU8331DG (same form factor and footprint) — differing in Amplifier Type, Channels.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
NAU8331VG
✅ Drop-In✓ In Stock
$1.05 / Unit
View Datasheet →NAU8331DG Maximum Ratings & Electrical Characteristics
| Amplifier Type | Class-D monophonic boost amplifier with I/V sense |
| Boost Converter Type | Class-G boost converter (integrated) |
| Speaker Excursion Control | Supported via I/V sense with external DSP or main processor |
| Channels | 1 (monophonic) |
| Mounting Type | Surface Mount |
| Datasheet Revision | Rev 3.2 (June 24, 2020) |
NAU8331DG standard Pin Configuration Guide
Pin configuration for NAU8331DG (standard 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 NAU8331DG.
Refer to the datasheet for full pin configuration.
Typical Applications
NAU8331DG is suitable for 6 applications: Smartphone Speaker Driver, Portable Bluetooth Speakers, Smart Home Voice Assistants, Notebook and Tablet PC Audio, Wearable and IoT Audio Devices, Automotive Infotainment Alert Sounders.
Smartphone Speaker Driver
The NAU8331DG fits smartphone mono-speaker subsystems where a single-cell lithium battery (typically 3.0-4.4V) cannot deliver enough acoustic output with a plain Class-D amplifier. The integrated Class-G boost converter raises the supply rail adaptively, so loud peaks receive full swing while average power stays efficient, extending battery talk and media playback time. The I/V sense channels feed the application processor, which runs Nuvoton-compatible excursion control algorithms to prevent over-excursion and coil overheating in the tiny speaker. The mono digital input path connects directly to the SoC audio interface, minimizing board area. Performance trade-off: the boost inductor and switching activity require careful layout near sensitive RF circuits.
Recommended
Portable Bluetooth Speakers
Battery-powered Bluetooth speakers benefit from the NAU8331DG's combination of boost converter and Class-D output stage, which extracts maximum loudness from limited battery capacity. The Class-G modulation means the boost rail tracks the audio envelope, so efficiency stays high at low volumes where conventional fixed-boost designs waste power. The I/V sense output enables DSP-based speaker protection for compact drivers that would otherwise limit output power. In a typical design, the Bluetooth SoC provides both the audio stream and the protection algorithm, keeping the bill of materials to a single amplifier IC, one power inductor, and a handful of passives. Designers should budget for boost converter EMI when locating the Bluetooth antenna.
Recommended
Smart Home Voice Assistants
Voice-assistant smart speakers require clear, loud playback for prompts and music from compact enclosures, often powered by USB or small adapters. The NAU8331DG's boosted Class-D architecture drives small speakers to useful sound pressure levels while the I/V sense path lets the host processor protect the speaker during sustained loud output. Its mono configuration suits the single full-range driver typical of entry-level smart speakers. Because excursion control runs externally on the main processor, no additional protection DSP is needed, reducing cost. The integrated boost converter also accepts lower-voltage DC inputs, simplifying power tree design. Switching noise from the boost stage should be filtered to keep the far-field microphone path clean for always-on voice detection.
Recommended
Notebook and Tablet PC Audio
Thin notebooks and tablets use small down-firing speakers whose excursion limits restrict loudness; the NAU8331DG addresses this with its boost converter and I/V-sense-based software protection, letting the platform deliver louder audio safely. The device integrates into the platform power tree, boosting from the system battery rail, and its mono channel suits the common left/right paired-speaker design using two ICs or a shared mono channel. The host SoC implements the excursion and thermal protection algorithms, consistent with mainstream PC audio stacks. Efficiency of the Class-G modulation helps extend battery runtime during media playback. Layout care is required so the boost switching harmonics do not couple into the analog microphone or keyboard matrix circuits.
Recommended
Wearable and IoT Audio Devices
Compact IoT devices such as doorbell chimes, alarm panels, and voice-notification modules need audible alerts from very small speakers and batteries. The NAU8331DG's integrated boost converter lifts a low battery or single-cell supply to a level sufficient for the target SPL, while the I/V sense allows the host microcontroller to run simplified excursion protection for the tiny driver. Its mono Class-D output and small solution size fit space-constrained PCBs typical of IoT hardware. Because alerts are intermittent, the Class-G boost architecture keeps standby and average power low, extending battery life. Designers should verify the control-interface voltage levels and shutdown current against their host microcontroller before finalizing the power budget.
Recommended
Automotive Infotainment Alert Sounders
Cluster and infotainment alert sounders in vehicles benefit from high loudness in small packages; the NAU8331DG can be driven from a low-voltage regulated rail with the boost converter providing the acoustic headroom. The I/V sense and host-side excursion control keep the sounder within mechanical limits over the automotive temperature environment, improving reliability of critical alert tones. Its mono digital input integrates naturally with SoC-based infotainment audio paths. Note that the standard NAU8331DG is not stated as AEC-Q100 qualified in the retrieved data, so automotive use requires a formal qualification review with Nuvoton. EMI performance of the boost converter must be validated against CISPR-style conducted emissions limits applicable to the vehicle platform.
Recommended
Engineering reference data for NAU8331DG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | NAU8331VG |
|---|---|---|
| Brand | Nuvoton Technology | Nuvoton Technology |
| Amplifier Class | Class-D with Class-G boost | Class-D with Class-G boost |
| I/V Sense | Yes | Yes |
| Channels | 1 (mono) | 1 (mono) |
| Speaker Excursion Control | External DSP/host algorithm | External DSP/host algorithm |
| Datasheet Revision | Rev 3.2 (June 24, 2020) | Rev 3.2 (June 24, 2020) |
Key Differentiators
- Integrated Class-G boost converter in the amplifier IC (vs NAU8331VG)
- I/V sense enabling DSP excursion control (vs NAU8331VG)
- External-algorithm architecture saves BOM cost (vs NAU8331VG)
Design Notes
The NAU8331DG integrates a switching boost converter and a Class-D output stage, so layout quality directly determines performance. Place the boost inductor close to the IC's boost switch pins with a short, wide return path; keep the loop area of the boost switching node minimal to reduce EMI radiation into nearby antennas and microphones. Follow the component placement and land-pattern guidance in the Nuvoton NAU8331 datasheet Rev 3.2 exactly, since the I/V sense lines are sensitive and should be routed as a matched pair away from the boost node.
Estimate the battery current draw before finalizing the power budget: output power at the speaker divided by expected Class-D plus boost efficiency gives the battery-side current; the Class-G boost topology improves light-load efficiency because the rail tracks the audio envelope. Verify the boost inductor saturation current exceeds the datasheet peak current limit with margin, and provide adequate input capacitance close to the supply pin to handle pulsed boost currents from a battery whose impedance rises with age.
A frequent mistake is assuming the NAU8331DG implements speaker protection internally. It does not - the I/V sense signals must be consumed by an excursion-control algorithm on a DSP or main processor, per the Nuvoton product brief. If the host firmware lacks this algorithm, drive the amplifier conservatively or select a smart amplifier with integrated protection. Also confirm the DG versus VG suffix pinout against the respective Nuvoton datasheet drawings before swapping footprints; the suffixes denote different packages.
Compliance Information
No explicit compliance statements were present in the retrieved web data as of 2026-10-11. Request material declarations from Nuvoton.
