NAU85L40YG - Quad 24-bit Audio ADC with FLL | Nuvoton
MPN: NAU85L40YG ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.21 | $22.10 |
| 100 | $1.95 | $195.00 |
| 500 | $1.72 | $860.00 |
| 1,000 | $1.49 | $1,490.00 |
NAU85L40YG Overview
An audio ADC is a special-purpose data converter that samples analog audio signals - typically from microphones - and converts them into digital data streams for DSP processing or transmission over digital audio buses. In the system hierarchy, it sits between analog front-end circuitry (microphones, preamplifiers) and digital audio processors such as voice engines, echo cancellers, and speech-recognition pipelines. Quad-channel audio ADCs like this one are purpose-built for microphone arrays used in far-field voice capture.
Key features include four low-noise, high common-mode-rejection differential microphone inputs (MIC1 to MIC4), each followed by a programmable gain amplifier offering -1 dB to +36 dB gain with a fixed 12 kOhm input impedance. The integrated fractional-N FLL (frequency-locked loop) generates accurate audio sample-rate clocks from any system clock between 8 MHz and 33 MHz, eliminating the need for a dedicated audio crystal. Audio data can be routed to two I2S output ports for flexible multi-channel system integration.
Architecturally, each channel combines the differential input stage, PGA, and a sigma-delta modulator followed by digital decimation filtering to achieve 24-bit output at 48 kHz. The preamplifier integration significantly reduces external component count, board area, and BOM cost in microphone-array designs.
Typical applications include smart speakers and far-field voice assistants, conferencing and beamforming microphone arrays, and automotive or industrial voice-command front ends. The low-power profile suits always-listening, battery-conscious products.
Design consideration: use the I2C interface to configure PGA gain per channel and verify FLL lock with the chosen system clock before bringing up the I2S links.
This page synthesizes verified distributor data, drop-in alternatives, and design guidance not found in the manufacturer datasheet.
Drop-in alternatives for NAU85L40YG — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
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NAU85L40YGB
✅ Drop-In📋 Reference alternative (not in catalog)
NAU85L40YG Maximum Ratings & Electrical Characteristics
| Function | Quad-channel audio ADC |
| Resolution | 24 bit |
| Sample Rate | 48 kSample/s |
| Number of ADC Channels | 4 (differential microphone inputs MIC1-MIC4) |
| Input Type | Differential |
| PGA Gain Range | -1 dB to 36 dB |
| Input Impedance | 12 kOhm (fixed) |
| Interfaces | I2C (control), I2S x2 (audio data) |
| Clock | Integrated fractional FLL, system clock 8 MHz to 33 MHz |
| Package | 28-QFN (4x4 mm) |
| Mounting Type | Surface Mount |
| Application Target | Microphone array, far-field voice capture |
NAU85L40YG 28-qfn (4x4 mm) Pin Configuration Guide
Pin configuration for NAU85L40YG (28-qfn (4x4 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 NAU85L40YG.
Refer to the datasheet for full pin configuration.
Typical Applications
NAU85L40YG is suitable for 6 applications: Smart Speakers and Voice Assistants, Conferencing and Beamforming Microphone Arrays, Automotive Voice Command Front Ends, Industrial Voice and Acoustic Monitoring, Security and Surveillance Audio, Set-Top Boxes and Smart Home Hubs.
Smart Speakers and Voice Assistants
The NAU85L40YG is purpose-built for smart-speaker microphone arrays: its four matched differential inputs (MIC1-MIC4) with per-channel -1 dB to 36 dB PGAs and 12 kOhm input impedance give beamforming algorithms the channel-to-channel gain and phase consistency they require. Nuvoton explicitly targets this part at microphone array applications, and the integrated fractional FLL derives the 48 ksample/s audio clock from a shared 8-33 MHz SoC clock, removing the dedicated audio crystal that generic codecs need. In a typical design the ADC sits between a MEMS microphone array and the host SoC, streaming four I2S channels of 24-bit audio for wake-word and far-field capture. The low-power profile suits always-listening duty cycles, while high CMRR suppresses common-mode noise on longer mic traces inside acoustically dense speaker enclosures.
Recommended
Conferencing and Beamforming Microphone Arrays
USB or network conferencing bars and ceiling-array microphones rely on quad ADCs like the NAU85L40YG to digitize multiple microphones synchronously. The four differential inputs with high common-mode rejection ratio reject noise picked up on microphone wiring routed across a metal housing, while the -1 dB to 36 dB PGA range accommodates mixed microphone sensitivities without external gain stages - Nuvoton notes the integrated preamplifiers significantly reduce external component requirements. The 24-bit resolution at 48 ksample/s preserves full voice-band dynamic range for acoustic echo cancellation and noise-reduction DSPs running downstream. Because the FLL accepts any 8 MHz to 33 MHz system clock, the array can be clocked from the conference SoC's existing oscillator, guaranteeing sample-synchronous capture across all four channels for accurate beam steering.
Recommended
Automotive Voice Command Front Ends
In-cabin voice-control modules benefit from the NAU85L40YG's multi-channel capture: four differential microphone inputs support corner-array microphones placed around the headliner for driver and passenger localization. The high CMRR of each input is critical in vehicles where microphone harnesses run near switching loads, and the 24-bit/48 ksample/s conversion chain retains enough dynamic range for keyword spotting under road-noise conditions. The integrated FLL allows the ADC to be clocked from the body-processor's 8-33 MHz clock domain, simplifying clocking architecture in mixed ECU environments. Differential inputs also tolerate common-mode voltage shifts between remote microphone ground and ADC ground better than single-ended alternatives, improving robustness in automotive harness topologies.
Recommended
Industrial Voice and Acoustic Monitoring
Industrial equipment increasingly uses microphone arrays for acoustic anomaly detection, operator voice commands in noisy factories, and predictive-maintenance listening nodes. The NAU85L40YG's four high-CMRR differential inputs capture multiple sensors synchronously, and its 24-bit resolution at 48 ksample/s covers the audio band needed for bearing and motor signature analysis. The fixed 12 kOhm input impedance and -1 dB to 36 dB PGA let designers match diverse microphone or hydrophone outputs without external gain stages, which Nuvoton cites as a key integration benefit. The FLL-based clocking (8-33 MHz input) synchronizes acquisition to the plant controller's clock, while low power suits battery- or energy-harvesting-powered monitoring nodes deployed across large facilities.
Recommended
Security and Surveillance Audio
IP cameras and doorbell products capture audio alongside video for analytics and two-way talk. The NAU85L40YG supplies up to four synchronized microphone channels - enough for a small beamforming array that isolates speech from ambient noise in outdoor or lobby environments. Its 24-bit, 48 ksample/s output feeds directly into the camera SoC's I2S audio input, and the FLL derives the audio clock from the camera system clock in the 8-33 MHz range, eliminating an extra crystal. The high CMRR differential front end is valuable in camera housings where microphone wiring passes near LED drivers and motorized IR-cut filters. Low quiescent operation also suits battery-powered doorbells that keep a wake-word engine always active.
Recommended
Set-Top Boxes and Smart Home Hubs
Smart-home hubs and set-top boxes add far-field voice control using integrated microphone arrays, and the NAU85L40YG fits this role directly: four differential inputs feed a compact MEMS array behind the product grille, while per-channel PGAs (-1 dB to 36 dB) balance microphone placement asymmetries digitally rather than with external components. Nuvoton's integrated preamplifiers reduce the external BOM, and the fractional FLL generates the 48 ksample/s rate from the hub's 8-33 MHz master clock, keeping audio synchronous with media playback pipelines routed over the two available I2S ports. The compact 4x4 mm QFN fits the crowded PCB area typical of consumer hub designs, and low power consumption matters for products that remain plugged in and listening continuously.
Recommended
Recommended Products Summary
Engineering reference data for NAU85L40YG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | NAU85L40YGB |
|---|---|---|
| Package | 28-QFN (4x4 mm) | 28-QFN (4x4 mm) - same |
| Brand | Nuvoton Technology | Nuvoton Technology |
| Resolution | 24 bit | 24 bit |
| Sample Rate | 48 kSample/s | 48 kSample/s |
| Input Channels | 4 differential (MIC1-MIC4) | 4 differential (MIC1-MIC4) |
| PGA Gain Range | -1 dB to 36 dB | -1 dB to 36 dB |
| Clock Source | Integrated FLL, 8-33 MHz system clock | Integrated FLL, 8-33 MHz system clock |
| Audio Interface | I2S x2, I2C control | I2S x2, I2C control |
Key Differentiators
- Quad matched differential inputs in one package (vs Generic single/dual-channel audio codec ADC)
- Crystal-less clocking via fractional FLL (vs Codec ADCs requiring dedicated audio crystal)
- Only verified drop-in alternative is the same-die NAU85L40YGB (vs NAU85L40YGB)
Design Notes
Route the four differential microphone pairs (MIC1N/MIC1P through MIC4N/MIC4Px) as tightly coupled, length-matched pairs, keeping them away from the I2S, I2C, and any switching-regulator traces. Channel-to-channel phase matching directly affects beamforming accuracy in microphone arrays. The inputs have a fixed 12 kOhm impedance per the datasheet, so series protection resistors will form dividers - account for this in gain budgeting. Keep the PGA gain below maximum when microphones are close to loudspeakers to avoid clipping the -1 dB to 36 dB range.
Use a solid, unbroken ground plane beneath the 28-QFN (4x4 mm) and solder the exposed pad to it - this provides both the low-impedance ground return and the primary thermal path. Place 100 nF ceramic decoupling capacitors within 2 mm of each supply pin, plus bulk capacitance per the Nuvoton application recommendations. Separate the analog microphone ground region from the I2S/I2C digital section, joining them at a single point under the ADC. This minimizes ground-borne noise entering the high-CMRR differential inputs.
Verify FLL lock range before committing to a system clock: the fractional FLL accepts 8 MHz to 33 MHz inputs per the datasheet, and a clock outside this range will not produce a valid 48 ksample/s audio clock. Configure each channel PGA over I2C before audio capture - default gain may under- or over-drive quiet MEMS microphones. When substituting the NAU85L40YGB for the NAU85L40YG on an existing board, confirm register-map and bond-out revisions against the latest Nuvoton errata before mass production.
Compliance Information
Compliance status not stated in the verified web data retrieved; confirm with Nuvoton product page or distributor environmental data before procurement.
