NAU8331VG - 8W Class-D Mono Boost Amplifier | Nuvoton
MPN: NAU8331VG ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.95 | $1.95 |
| 10 | $1.76 | $17.60 |
| 100 | $1.45 | $145.00 |
| 500 | $1.24 | $620.00 |
| 1,000 | $1.05 | $1,050.00 |
NAU8331VG Overview
A Class-D audio amplifier is a switching amplifier that uses output transistors driven as switches with pulse-width or pulse-density modulation to achieve efficiencies far above Class-AB linear amplifiers. Within the power-management and audio signal-chain hierarchy, an audio amplifier IC takes a low-level analog input and delivers speaker-level output power; a boosted amplifier such as the NAU8331 additionally raises the supply voltage internally, allowing higher output power from a single low-voltage battery rail without an external boost stage.
Key features of the NAU8331 include the integrated multi-level Class-G boost converter, which improves efficiency compared with a fixed-rail Class-D amplifier by dynamically adapting the supply rail to the audio signal envelope. The speaker I/V sense function monitors output voltage and current, enabling real-time speaker protection algorithms and aiding acoustic tuning. Mono single-channel output delivers up to 8W, and the tiny WLCSP-35 footprint suits space-constrained portable designs.
Technically, the device combines a boost power stage with the Class-D modulator on one die, reducing external component count versus discrete boost-plus-amplifier solutions. Multi-level boosting reduces switching losses and electromagnetic interference relative to two-level topologies, an important consideration in smartphone and tablet layouts where sensitive radios sit nearby.
Typical applications include smartphone and tablet loudspeaker drivers, portable Bluetooth speakers, notebook and tablet audio, and smart-home voice-interface devices, where high output power must be extracted from a single-cell lithium-ion battery. The I/V sense capability supports smart-amp speaker protection in these designs.
Design consideration: boosted Class-D amplifiers place significant pulsed current demand on the battery rail, so input decoupling capacitance and PCB power-plane layout directly affect output ripple, EMI, and low-frequency stability. Follow the Nuvoton datasheet layout guidance closely.
This page synthesizes distributor pricing and availability, package data, and practical design guidance consolidated from multiple sources not found in the manufacturer datasheet alone.
Drop-in alternatives for NAU8331VG — 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 NAU8331VG (same form factor and footprint) — differing in Amplifier Type, Channels.
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Request AlternativesNAU8331VG Maximum Ratings & Electrical Characteristics
| Amplifier Type | Class D, 1-Channel (Mono) |
| Output Power | 8 W (mono) |
| Boost Converter | Class-G multi-level boost |
| Speaker Sensing | I/V sense (current and voltage) |
| Package | 35-WLCSP (3.83 x 2.55 mm) |
| Mounting Type | Surface Mount |
| Channels | 1 (Mono) |
| Protection Features | Speaker protection via I/V sense |
| Packaging | Tape & Reel (DigiKey ordering code 816-NAU8331VGTR-ND) |
| Applications Domain | Portable / battery-powered audio |
NAU8331VG 35-wlcsp (3.83 x 2.55 mm) Pin Configuration Guide
Pin configuration for NAU8331VG (35-wlcsp (3.83 x 2.55 mm) package). This analog component features input, output, and power supply pins. Refer to the manufacturer datasheet for offset null, compensation, and enable pin configurations. Ideal for signal conditioning and amplifier circuits.
No detailed pinout data available for NAU8331VG.
Refer to the datasheet for full pin configuration.
Typical Applications
NAU8331VG is suitable for 6 applications: Smartphone Loudspeaker Driver, Portable Bluetooth Speakers, Tablet and Notebook Audio, Smart Home Voice Interface Devices, Wearable and IoT Audio Devices, Automotive Infotainment Alert Audio.
Smartphone Loudspeaker Driver
The NAU8331VG fits smartphone loudspeaker driving because it delivers up to 8W mono output from a single-cell lithium-ion battery rail, a level unattainable by fixed-rail Class-D amplifiers at battery voltage. Its 35-ball WLCSP measuring 3.83 x 2.55 mm consumes minimal board area, which is critical inside a smartphone where every square millimeter is contested. In the circuit, the integrated multi-level Class-G boost raises the modulator rail dynamically with the audio envelope, improving efficiency over a fixed boosted rail and reducing thermal load on the handset chassis. The speaker I/V sense feedback supports excursion and temperature protection algorithms, allowing designers to safely push small speakers to higher loudness without mechanical or thermal damage. Performance trade-off: pulsed boost currents demand careful input decoupling near the battery connector to avoid rail droop and audible artifacts at high output.
Recommended
Portable Bluetooth Speakers
Portable Bluetooth speakers benefit directly from the NAU8331VG's integration of a multi-level Class-G boost converter with an 8W Class-D output stage. Battery-powered speakers typically run from a single 3.7V lithium cell, and the NAU8331VG's internal boost eliminates the discrete boost converter that would otherwise be required, cutting component count, board area, and quiescent losses. The speaker I/V sense inputs enable smart-amp protection, which is valuable in portable speakers where small drivers are frequently driven to maximum volume and thermal margins are slim. Real-time current and voltage monitoring keeps excursion and coil temperature in bounds, extending battery life and speaker reliability. Consideration: multi-level boosting reduces switching-related EMI compared with two-level topologies, easing coexistence with the Bluetooth radio, but shielding and layout following the Nuvoton datasheet remain necessary for radio compliance.
Recommended
Tablet and Notebook Audio
Tablets and thin notebook PCs require loud, clear speaker output from constrained battery rails and even more constrained board space, which is precisely the NAU8331VG's design envelope. Its 8W boosted mono output provides substantially higher acoustic output than fixed-supply amplifiers, and the 3.83 x 2.55 mm WLCSP-35 package mounts under shielding cans alongside other mobile components. The multi-level Class-G boost adapts the supply rail to signal level, improving playback efficiency and therefore battery runtime compared with a continuously boosted fixed rail. The I/V sense feature supports OEM smart-amp tuning for consistent sound across production units. In these designs the amplifier is typically fed I2S audio from the platform codec or SoC; verify the interface configuration in the Nuvoton datasheet. Layout care around the boost inductor and output filter is essential to keep the platform's audio noise floor low.
Recommended
Smart Home Voice Interface Devices
Smart speakers and voice-assistant devices need amplified audio output plus reliable speaker protection for always-on duty, making the NAU8331VG a strong fit. Its 8W boosted output delivers sufficient loudness for room-filling voice prompts and media playback from a single supply rail, while the integrated boost converter removes an external power stage from the bill of materials. The speaker I/V sense inputs are especially relevant in voice devices: protection algorithms prevent long-term speaker degradation from continuous voice prompt playback, and the sensed signals can support acoustic diagnostics such as detecting blocked or damaged speakers. The compact WLCSP-35 footprint suits the densely packed boards typical of smart displays and plugs. Trade-off: always-on designs should budget for the amplifier's idle consumption, so consult the Nuvoton datasheet quiescent and shutdown current figures when calculating standby power for energy-regulated products.
Recommended
Wearable and IoT Audio Devices
Compact IoT endpoints with audio feedback - doorbells, intercoms, security sensors, and connected appliances - can use the NAU8331VG where small size and loud output from low-voltage supplies are simultaneous requirements. The 3.83 x 2.55 mm WLCSP-35 package fits onto miniature controller boards, and the integrated multi-level Class-G boost derives the audio rail from the same battery or low-voltage DC rail powering the rest of the system, avoiding a dedicated audio supply. Output of up to 8W gives designers acoustic headroom for chimes, voice prompts, and alarms. The I/V sense function lets firmware verify speaker connectivity and health, which matters for unattended IoT deployments where a silent failure would otherwise go unnoticed. Design caution: place boost and output components per the Nuvoton datasheet reference layout to control EMI near wireless modules co-located on the same small PCB.
Recommended
Automotive Infotainment Alert Audio
In-vehicle alert sounders, e-call speakers, and compact infotainment channels require loud output despite a nominally 12V-tolerant but drooping supply environment, and the NAU8331VG can serve low-voltage-rail zones of such systems. Its integrated boost maintains audio rail integrity across supply dips such as engine cranking, keeping alert tones audible when supply voltage sags - a genuine functional advantage over fixed-rail amplifiers. The speaker I/V sense provides loudspeaker health monitoring suitable for safety-relevant alert paths, where a failed speaker must be detectable. The miniature WLCSP-35 package also suits the compact amplifier modules placed near the speaker rather than at the head unit. Important note: the standard NAU8331VG should not be assumed AEC-Q100 qualified; confirm qualification status with Nuvoton before deploying in any automotive safety-related path, and apply appropriate transient suppression on vehicle power inputs.
Recommended
Recommended Products Summary
Engineering reference data for NAU8331VG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product |
|---|---|
| Package | 35-WLCSP (3.83 x 2.55 mm) |
| Brand | Nuvoton Technology |
| Amplifier Type | Class D Mono, 1-Channel |
| Output Power | 8 W |
| Boost Converter | Integrated multi-level Class-G boost |
| Speaker I/V Sense | Yes |
| Mounting Type | Surface Mount (WLCSP) |
| Packaging | Tape & Reel |
Key Differentiators
- Integrated multi-level Class-G boost converter (vs Fixed-rail Class-D amplifiers (generic))
- Speaker I/V sense for smart-amp protection (vs Basic Class-D amplifiers without sensing (generic))
- Ultra-compact 35-ball WLCSP footprint (vs Larger QFN/SOIC-packaged audio amplifiers (generic))
Design Notes
The NAU8331VG's multi-level Class-G boost converter draws high pulsed currents from the battery rail. Place the input decoupling network - typically a bulk capacitor plus a small ceramic - directly at the supply pins, with a solid, low-inductance ground return. Route the boost switching node as a short, compact loop, and follow the reference layout in the Nuvoton datasheet. WLCSP ball-pitch routing requires via-in-pad or fanout microvias; confirm stack-up capability with your fabricator before locking the footprint.
Boosted Class-D amplifiers combine switching from both the boost stage and the Class-D modulator, so EMI control matters, especially in devices with co-located radios. The multi-level topology of the NAU8331VG inherently reduces switching-edge energy versus two-level designs, but shielding cans, careful filter component placement, and output filter selection per the Nuvoton datasheet remain necessary. Pre-scan radiated emissions with a near-field probe during bring-up rather than discovering issues at regulatory test.
Do not omit the speaker I/V sense network: it is required for the protection algorithms that justify this part over simpler amplifiers, and mis-sensed current or voltage can cause false protection trips or, worse, undetected speaker overstress. Also verify the exact ball map from the official Nuvoton datasheet revision before layout; WLCSP parts are frequently revised and ball assignments can change between datasheet revisions. Confirm operating temperature range and supply limits in the latest datasheet before finalizing derating analysis.
Compliance Information
Compliance statuses were not present in the retrieved source data and must be confirmed on the official Nuvoton product page or distributor environmental data before ordering for regulated markets.
