Soundec Developer

# SNC8508 Datasheet

Audio processor for AIoT human-machine interaction, integrating high-quality Codec, high-performance DSP, and high-speed USB

# Overview

SNC8508 is an audio processor optimized for AIoT human-interaction solution, providing capability for low power, highly integrated sub-system based on microphone array and sensors. It supports up to 10 digital microphones and 2 analog microphones, Tensilica HiFi3 DSP, which can integrate rich AI audio algorithms; Integrates UAC1.0/2.0 audio service, built-in PMU and rich peripheral interfaces, only need to add a few passive components to provide a complete professional audio solution; realize highly integrated, high performance, low BOM cost product.

# Features

# Core and Memory

  • Cadence® Tensilica® HiFi3 audio DSP @ max. 200MHz

  • Single-cycle MAC, vector FPU, SIMD

  • JTAG debug and trace

  • Proprietary hardware accelerators

  • 256KB IRAM, 256KB DRAM, 48KB cache RAM

  • On-chip 1MB NOR Flash

  • One-Time Programmable electrical fuse

# Audio

  • Two 24-bit audio ADC, SNR>=106dB, with sampling rates: 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48, 88.2, 96, 176.4, 192kHz

    • Two audio ADC line-in supports single-end or differential input

    • Up to 10 Digital microphone interfaces with programmable DMIC clock frequency and support of low power mode

    • Automatic Gain/Level Control (AGC) with SNR optimizer

    • Voice activity detection for low power mode

    • Programmable Wind Noise Filter (WNF)

  • Two 24-bit audio DAC, SNR>=110dB, with sampling rates: 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48, 88.2, 96, 176.4, 192kHz

    • Embedded headphone amplifier

    • Dynamic Range Control for audio output

  • Two duplex I2S, sampling rates: 8K~192KHz, max. 32bits

  • On-chip USB 2.0 PHY, supports USB Audio Control 1.0/2.0

# DSP

  • Patented noise cancellation for both near-field and far-field

  • Active echo cancellation

  • Dereverberation

  • EQ for audio input/output

  • Beam forming, DOA

# Power, Clock

  • Power supply from 3.3V to 5.5V

  • On-chip ultra-low power management unit

  • DC-DC regulators and LDOs for all on-chip supply voltages

  • POR-BOR, overvoltage protection

  • Always-on domain for ultra-low-power sleep mode

  • Crystal oscillator @24MHz and 26MHz

  • On-chip PLL provides all necessary clocks to meet SoC proper operation

# Peripherals

  • Max. 8 GPIOs

  • Two duplex I2S, sampling rate 8K~192KHz, max. 32bits

  • Two I2C master/slave controller

  • One duplex UART

  • One USB 2.0 PHY, supports USB Audio Control 1.0/2.0

  • Tow 12-bit SAR ADC, can be used for headset button detection, battery monitor, or other analog sensor input measurement.

# Applications

  • Far-end audio recording

  • AIoT audio application

  • Audio monitor equipment

  • Sensor application

# Functional Block Diagram

SNC8508 combines the benefits of a USB audio codec with the power of HiFi3 DSP core. With on-chip 24-bits/192KSps digital and analog microphone interface, pre-amplifiers, and a capless headphone amplifier, SNC8508 is a truly single-chip solution for high quality audio with low power consumption.

SNC8508 integrates a Cadence HiFi3 core up to 200MHz for system control and digital signal processing, and a high-quality 24-bits/192Ksps Codec with stereo input and stereo output, 2 analog microphones, and up to 10 digital microphones. It provides up to 512KB zero-wait RAM and a size configurable Flash memory (1MB by default). The on-chip power management unit provides all power supply to meet the on-chip requirements with one power supply. There is one always-on domain to achieve low power consumption. It provides rich peripheral interfaces: one USB 2.0 PHY, tow I2S, two I2C, one UART, up to 8 GPIOs. It supports two auxiliary ADC which can be used for button recognition, analog sensor applications.

SNC8508 provides a powerful digital signal processor to facilitate features and performance for high quality audio applications and products, like automatic echo cancellation, noise cancellation, audio equalization, automatic gain control (AGC), and customized audio effects

# Device Package

Part Number Package Body Size (NOM)
SNC8508 BGA 80 4.50mm*6.20mm

# Pin Configuration and Functions

Pin name list with description and ball position:

Function Pin name 80 Ball BGA Type Description
Xtal Oscillator XI D1 Analog 24MHz crystal port
XO C1 Analog 24MHz crystal port
PMU VDD_IP33 J1 Analog 3.3V for analog block
VDD_IO33 K1 Analog 3.3V for IO
CODEC_VDD K9 Analog 3.3V for Codec
AVDPWR_RAR K5 Analog External power supply
AVDPWR_ESR K6 Analog External power supply
OPM_VOUT K10 Analog Protection LDO output
VDD_CORE11 K2 Analog 1.1V for digital core
ESR_LX K7 Analog DCDC2 switch pin
VSENSE_ESR K8 Analog DCDC2 sense pin
RAR_LX K4 Analog DCDC1 switch pin
VSENSE-RAR K3 Analog DCDC1 sense pin
EFUSE_VDDQ J7 Analog Supply for eFuse
Digital Interface I2C_CLK A3 I/O I2C interface clock
I2C_DAT B3 I/O I2C interface data
GPIO0 B4 I/O I2S1_clk
GPIO1 B5 I/O I2s1_ws
GPIO2 B6 I/O I2s1_sdi
GPIO3 B7 I/O I2s1_sdo
GPIO4 A4 I/O I2s2_clk
GPIO5 A5 I/O I2s2_ws
GPIO6 A6 I/O I2s2_sdi
GPIO7 A7 I/O I2s2_sdo
DMIC_IN1 A10 I DMIC1/2 input (GPIO9)
DMIC_IN2 A9 I DMIC3/4 input
DMIC_IN3 A8 I DMIC5/6 input
DMIC_CLK11 B10 O DMIC1/2 clock (GPIO8)
DMIC_CLK21 B9 O DMIC3/4 clock
DMIC_CLK31 B8 O DMIC5/6 clock
RST_N J9 I Chip reset
GPIOAO J8 I Always-on wake up
UART_TXD A1 O UART TX data
UART_RXD A2 I UART RX data
DFU_N J10 I Firmware update enable
Backup_Boot B11 I For backup boot vector
GPIO10 J4 I/O
GPIO11 J3 I/O
GPIO12 G2 I/O
GPIO13 F2 I/O
GPIO14 E2 I/O
GPIO15 D2 I/O
TEST-EN C11 I/O
Audio Interface VREG F12 Analog Audio supply
VCAP G12 Analog Audio biasing De-cap
AIP1 A12 Analog MIC1 input P port
AIN1 B12 Analog MIC1 input N port
AIP2 D12 Analog MIC2 input N port
AIN2 C12 Analog MIC2 input P port
MICBIAS1 A11 Analog Micbias 1
MICBIAS2 E12 Analog Micbias 2
AOHPLP H12 Analog Left DAC P port
AOHPLN J12 Analog Left DAC N port
AOHPRN K12 Analog Right DAC N port
AOHPRP K11 Analog Right DAC P port
Auxiliary ADC VINP0_ADC B1 Analog GPADC0 input
VINP1_ADC B2 Analog GPADC1 input
USB NC(TXRTUNE) H1 Analog NC or (USB tuning)
DM G1 Analog USB DP
DP F1 Analog USB DM
NC(VBUS) E1 Analog NC or (VBUS detection)
GND VSSA_ADC C2 Analog Analog GND
VSSA_USB H2 Analog Analog GND
VSSD F5678,E5678 Analog Digital GND
VSSA_AVS H11,G11,F11 Analog Codec analog GND
AVS_ESR J6 Analog DCDC2 GND
AVS_RAR J5 Analog DCDC1 GND
GNDSENSE J2 Analog All regulator GNDsenses
VSSA_A0 J11 Analog DAC driver GND
VREFN E11,D11 Analog Codec reference GND

# Specifications

# Absolute Maximum Ratings

Parameter Symbol Min. Max. Unit
Power AVDPWR -0.3 5.5 V
AVDD -0.3 3.63 V
VDD_IP33 -0.3 3.63 V
VDD_IO33 -0.3 3.63 V
VDD_OPM -0.3 3.63 V
VDD_eFuse -0.3 2.75 V

# Handling Ratings

Parameter SymbolMin Max Unit
Ambient Temperature Ta -20 80 °C
ESD HBM -2000 2000 V
CMD -500 500 V
Parameter Test condition Min. Typ. Max. Unit
AVDPWR Power Supply Voltage range Referenced to VSS 3.3 5 5.5 V
AVDD Referenced to AVSS 3.2 3.3 3.4
VDD_IP33 Referenced to AVSS 3.2 3.3 3.4
VDD_IO33 Referenced to IOVSS 3.2 3.3 3.4
DVDD Referenced to DVSS 1.05 1.1 1.15
Main Clock - 12 13 MHz
I2C SCL Clock Frequency Full Speed - 100 400 KHz
Analog input maximum signal range Full Scale, Gain GID* = 0 dB, boost gain GIM* = 0 dB 0 0.53 2.12 Vpeak
Output load resistace (Rl) Differential configuration 16 Ω
Output load capacitance 200 pF
Operating Temperature -20 80 °C

# Electrical Characteristics, Audio ADC inputs

Condition: - 40°C to +100°C, AVDD=3.3Vm DVDD=1.1V. Input sine wave with a frequency of 1 kHz, measurement bandwidth 20 Hz - Fs/2 for Fs < 48 kHz, measurement bandwidth 20 Hz - 20 kHz for Fs = 48 kHz to 192 kHz, normal mode, capacitor-less input configuration, unless otherwise specified.
Parameter Test condition Min. Typ. Max. Unit
Input level Full Scale, Gain GID* = 0 dB, boost gain GIM* = 0 dB 2.12 Vpp
Full Scale, Gain GID* = 0 dB, boost gain GIM* = 20 dB 0.212 Vpp
THD+N 1 kHz sine wave @ Full Scale -3 dB and gain GID* = 0 dB, boost gain GIM* = 0 dB, normal mode and low power mode 88 dB
Dynamic Range A-weighted, 1 kHz sine wave, normal mode 106.5 dB
A-weighted, 1 kHz sine wave, low power mode 103.5 dB
SNR A-weighted, 1 kHz sine wave, with activation of the SNR optimizer feature 106 dB
A-weighted, 1 kHz sine wave, gain GID* = 0 dB, boost gain GIM* = 0 dB, normal mode 94.5 dB
A-weighted, 1 kHz sine wave, gain GID* = 0 dB, boost gain GIM* = 0 dB, low power mode 90.5 dB
PSRR 100 mVpp 1 kHz sinewave is applied to AVD, input data is 0 and gain GID* = 0 dB, boost gain GIM* = 0 dB 90 dB
Input referred noise A-weighted, 1 kHz sine wave @ Full Scale and gain GID* = 0 dB, boost gain GIM* = 20 dB, normal mode 3.6 uVrms
A-weighted, 1 kHz sine wave @ Full Scale and gain GID* = 0 dB, boost gain GIM* = 20 dB, low power mode 5 uVrms
Channel separation 1 kHz sine wave @ Full Scale on one channel, no signal on the other channel and gain GID* = 0 dB, boost gain GIM* = 0 dB 108 dB
Inter-channel phase mismatch 1 kHz sine wave @ Full Scale on two channels and gain GID* = 0 dB, boost gain GIM* = 0 dB, input bypass capacitor inter-channel mismatch = 10% max, master mode 0.1 °
Gain range Boost gain GIM* when activated -2 24 dB
Digital gain GID* -64 63 dB
Gain step GIM* @1kHz 2 dB
GID* @1kHz 1 dB
Gain accuracy GIM* @1kHz -1 1 dB
GID* @1kHz -0.5 0.5 dB
Input impedance (differential configuration) Boost gain GIM* = 20 dB Includes 10 pF for ESD, bonding and package pins capacitances 20 pF
Input impedance (single-ended configuration) Boost gain GIM* = 20 dB Includes 10 pF for ESD, bonding and package pins capacitances 20 pF
Polarity AIP*-AIN* to DIL/R 1

# Electrical Characteristics, Audio DAC Outputs

Condition: - 40°C to +80°C, AVDD=3.3Vm DVDD=1.1V. Input sinewave with a frequency of 1kHz, measurement bandwidth 20Hz-20kHz, unless otherwise specified.
Parameter Test condition Min. Typ. Max. Unit
Output level Full Scale, gain GOL/R = +6 dB, GODL/R = 0 dB, 10 kOhms load 5.6 Vpp
Full Scale, gain GOL/R = +5 dB, GODL/R = 0 dB, 128 Ohms load 4.99 Vpp
Full Scale, gain GOL/R = +3 dB, GODL/R = 0 dB, 32 Ohms load 3.96 Vpp
Full Scale, gain GOL/R = 0 dB, GODL/R = 0 dB, 16 Ohms load 2.8 Vpp
Output power 200 Ohms load 19.6 mW
16 Ohms load 60 mW
SNR A-weighted, 1 kHz sine wave @ Full Scale, gain GOL/R = +6 dB, GODL/R = 0 dB, 10 kOhms load 110 dB
Dynamic Range A-weighted, 1 kHz sine wave @ Full Scale, gain GOL/R = [-10 +6] dB, GODL/R = 0 dB, 10 kOhms load 110 dB
Idle Noise A-weighted with no signal, gain GOL/R=-10dB, GODL/R = 0 dB, 10k Ohms load -104.9 dBV
THD+N 1 kHz sine wave @ Full Scale -1 dB, gain GOL/R = +6 dB, GODL/R = 0 dB, 10 kOhms load 87 dB
1 kHz sine wave @ Full Scale -1 dB, gain GOL/R = +5 dB, GODL/R = 0 dB, 128 Ohms load 85 dB
1 kHz sine wave @ Full Scale -1 dB, gain GOL/R = 0 dB, GODL/R = 0 dB, 16 Ohms load 79 dB
PSRR 100 mVpp 1 kHz is applied to AVD, input data is 0 and gain GOL/R = 0 dB, GODL/R = 0 dB, 10 kOhms load capacitor inter-channel mismatch = 10% max, master mode 90 dB
100 mVpp 1kHz is applied to VDDAO, input data is 0 and gain GOL/R = 0 dB, GODL/R = 0 dB, 10 kOhms load 70 dB
Analog gain Gain GOL/R -19 12 dB
Digital gain Gain GODL/R -31 32 dB
Gain step GOL/R, GODL/R @1 kHz 1 dB
Gain accuracy GOL/R, GODL/R @1 kHz -0.5 0.5 dB
Pop-up Noise Active <-> Inactive, 10 kOhms load -60 dBV
Active <-> Inactive, 16 Ohms load -60 dBV
Output load
resistance (Rl)		 32 ohms
Output load
capacitance (Cp)		 200 pF

# Electrical Characteristics, Analog Microphone Interface

Condition: - 20°C to +80°C, AVDD=3.3Vm DVDD=1.1V. Input sine wave with a frequency of 1 kHz, measurement bandwidth 20 Hz - Fs/2 for Fs \< 48 kHz, measurement bandwidth 20 Hz - 20 kHz for Fs = 48 kHz to 192 kHz, normal mode
Parameter Test conditionsMin. Typ Max. Unit
Micbias ouput level 2.5 V
Micbias output current
Current per MICBIAS output		 2 mA
Micbias output current
Total current for all MICBIAS outputs		 4 mA
VREG output level 2.35 2.5 2.65 V
VCAP output level 1.9 2 2.1 V

# Digital microphone interface to decimating filter output path

Condition: Input sine wave with a frequency of 1 kHz, MCLK = 12 MHz or 13 MHz, DMIC_CLK = Fmclk/4, measurement bandwidth 20 Hz - Fs/2 for Fs = 8 to 32 kHz, measurement bandwidth 20 Hz - 20 kHz for Fs = 44.1 kHz to 192 kHz, unless otherwise specified.
Parameter Test condition Min. Typ. Max. Unit
Input level Full Scale max value, Gain GID* = 0 dB 85.6 %
Full Scale min value, Gain GID* = 0 dB 14.4 %
SNR A-weighted,1kHz sinewave @Full Scale and gain GIDL, GIDR = 0 dB 100 dB
Dynamic Range A-weighted, 1 kHz sine wave @ Full Scale -60 dB and gain GID* = 0 dB 100 dB
THD+N 1kHz sinewave @Full Scale-1dB and gain GIDL, GIDR = 0 dB 90 dB
Digital gain Gain GID* when activated -64 63 dB
Gain step GID* @1 kHz 1 dB
Gain accuracy GID* @1 kHz -0.25 1 0.25 dB

# Voice detection on digital microphone interface

Parameter Test condition Min. Typ. Max. Unit
Detection Latency Detection results based on MIWOK≠CTM r1.0, Far-Field configuration, Power Level Sensitivity set to 5 dB, within 60% truncation of the first phoneme 25.7 ms
VDV (Voice Detected as Voice) 93.5 %
NDV (Noise Detected as Voice) 7 %
VTE (Voice Trigger Efficiency) 93.25 %
Detection Latency Detection results based on MIWOK≠CTM r1.0, Far-Field configuration, Power Level Sensitivity set to 5 dB, within 60% truncation of the first phoneme 25.7 ms
VDV (Voice Detected as Voice) 98.5 %
NDV (Noise Detected as Voice) 7 %
VTE (Voice Trigger Efficiency) 95.75 %
VDV (Voice Detected as Voice) Detection results based on MIWOK≠CTM r1.0, Far-Field configuration, Power Level Sensitivity set to 5 dB, within the word length 100 %
Minimum Absolute Detection Threshold -80 dBFS
Power Level Sensitivity 0 31 dB
Power Level Sensitivity programmable step 1 dB

# Electrical Characteristics, LDO

Parameter Test condition Min. Typ. Max. Unit
Operating Temperrature Junction temperature -40 100 °C
Input voltage Range, VAVDPWR 2.7 5.5 V
Output voltage 3.3 V
Output voltage Accuracy ±3 %
Maximum Output Current,IMAX 100 mA
Dropout voltage,VDROPOUT IOUT =IMAX 380 mV
PSRR(Power Supply Rejection Ratio) @ DC -45 -30 dB
no-load current ILOAD= 0 mA 40 uA

# System Block Diagram

# Theory of Operation

# DSP core

A powerful Cadence HiFi3 DSP core handles system control and audio digital signal processing. Following figure shows the HiFi3 architecture.

The following table shows the key features and configuration of the HiFi3 DSP core:

Item Specification Comment
Core Cadence HiFi3
32 bit instruction As system controller and audio signal processing
Processor Clock Up to 200 MHz
MAC Single-cycle MAC
FPU Vector FPU, half-precision
SIMD Full type of operation
MIPS 600 MIPS max 3 slots in HiFi3
I-RAM 256KB Local zero-wait RAM for instruction
D-RAM 256KB Local zero-wait RAM for data
I-Cache 16 KB 4 cache way, 64 Byte cache line
D-Cache 32 KB 4 cache way, 64 Byte cache line
Bus protocol AHB-lite 32-bit data width
Timer 3 timers

# Interrupt description

HiFi3 supports 32 interrupts which are listed in the following table with priority, where higher-level number means higher priority.

Configurable IRQ Num Function Interrupt (default) Priority Comments
0 USB IRQ USB 4
1 USBDMA 4
2 ADC CODEC_IRQADC12 4 ADC DMIC1/2 or AMIC1/2 interrupt
3 CODEC_IRQADC34 4 ADC DMIC3/4 interrupt
4 CODEC_IRQADC56 4 ADC DMIC5/6 interrupt
5 CODEC_IRQADC78 4 ADC DMIC7/8 interrupt
6 CODEC_IRQADC9A 4 ADC DMIC9/A interrupt
7 DAC CODEC_IRQDAC 4 DAC interrupt
8 SW interrupt_0 SOFTWARE_INT_0 4 SW interrupt 0
9 I2S-1 I2S-1 IRQ 4 I2S-1 word clock interrupt
10 I2S-2 I2S-2 IRQ 4 I2S-2 word clock interrupt
11 I2S-3 I2S-3 IRQ 4 I2S-3 word clock interrupt
12 DMAC DMAC-IRQ 4 DMAC interrupt
13 Maestro (PMU) Maestro-IRQ 4 Maestro interrupt
14 Codec Codec-IRQ 4 Codec interrupt on AIAS lock event and headphone output short-circuit detection
15 Codec-IRQ-WT 4 Codec interrupt for VAD
16 I2C-1 I2C-1 IRQ 3 I2C-1 IRQ
17 I2C-2 I2C-2 IRQ 3 I2C-2 IRQ
18 UART UART IRQ 3
Timer Timer0-IRQ 3 Hifi3 own timer
19 GPIO678 GPIO6-IRQ 3 Group to one IRQ
GPIO7-IRQ 3
GPIO8-IRQ 3
20 RTC RTC-IRQ 2 RTC interrupt
21 Watchdog Watchdog-IRQ 2 watchdog interrupt (32KHz)
22 GPIO9ABCDEF GPIO9-IRQ 2 Group to one IRQ
GPIO10-IRQ 2
GPIO11-IRQ 2
GPIO12-IRQ 2
GPIO13-IRQ 2
GPIO14-IRQ 2
GPIO15-IRQ 2
23 USB_Sleep USB_Sleep_IRQ 1 USB skep mode
DSP SW interrupt DSP_SW_IRQ 1 Software IRQ from HiFi3
Timer Timer1-IRQ 1 Hii3 own timer
Trmer2-IRQ 1 Hifi3 own timer
24 ADC ADC-IRQ 1 ADC IRQ with eoc signal
25 PWM Interrupt PWM_IRQ 1 PWM Interrupt
26 SW interrupt_1 SOFTWARE_INT_1 1 SW interrupt 1
Profiling Profing_IRQ 1 Profing interrupt

# System bus structure

The following figure shows the multi-layer bus matrix: HiFi3, DMA, and USB HS are masters, while ROM, SPI Flash controller, Codec data, BQ filter, and peripherals are slaves. IRAM and DRAM are TCM type SRAM with 1 cycle operation. 64KB ROM is used for system boot. The Hardware BQ filter is connected on the AHB bus.

AHB and AHP peripherals:

# Data processing flow

There are two typical data flow cases. The left figure shows the USB audio data flow with the HiFi3 core. This is the application case for USB headset. The right figure shows the I2S data flow with the HiFi3 core. This is the application case for Bluetooth headset and beamforming voice command products.

# DMA

DMA controller is connected to the AHB bus. Data are transferred between RAM, Flash controller, and I2S through the DMA controller. USB controller has a master mode DMA to control data transfer between DRAM and USB FIFO. The following figure shows the DMA function implementation.

DMA is an AHB-Central DMA Controller core that transfers data from a source peripheral to a destination peripheral over one or more AHB bus, which consists of:

  • DMA hardware request interface

  • Up to six channels

  • FIFO per channel for source and destination

  • Arbiter

  • AHB master interface

  • AHB slave interface

The following figure shows the DMA block diagram:

# Startup, Initialization, and Power

One single power supply comes either from the USB host device VBUS, or from Li-ion battery. The on-chip Power Management Unit (PMU) provides all necessary supply voltage to all functional blocks with low power consumption.

Codec module can provide MIC bias for external microphones, 2.5V LDO for audio analog output. PMU supports power-on-reset (POR), brown-out-detect (BOD), and OVP/OCP/ULP protection. PMU can be set via APB bus to work in active mode, sleep mode, and power-down mode.

The following figure shows the power tree architecture, includes:

  • Single power input from 3.3V to 5.5V

  • One DC-DC regulator for Core and digital: 1.1V

  • One Always-on ultra-low-power LDO for sleep-mode: 1.1V

  • One DC-DC regulator for Codec analog part: 3.3V

  • One LDO generate 3.3V power for other analog parts

  • One LDO generate 3.3V power for digital IO

# Power-Up Sequence

The startup sequence is described in above figure. POR sends out the general reset signal, and Maestro sets all regulators into the right states.

# Reset Network

The following figure shows reset network. There are 4 kinds of reset signal from different function blocks. Reset 1 is generated by POR and BOR, the other 3 kinds of reset signal may come from POR/BOR, hardware reset, software reset, o_sus_done or o_sus_fail.

# Audio Codec

Audio codec includes the following function blocks:

One stereo Analog to Digital Converter (ADC) and additional analog circuit:

Two single-ended or differential analog inputs with boost gain, which can be used either for line-in or mic-in application in capless configuration

  • The two-stage gain for record path: an analog boost gain from -2 dB to +24 dB with 2 dB step and a digitally programmable gain from -64 to +63 dB with 1 dB step.
  • Ten mono or five stereo digital microphone interfaces with programmable DMIC clock frequency.

One stereo Digital to Analog Converter (DAC) and additional analog circuit:

  • One stereo differential capless headphone and line output.
  • Two dedicated mono differential line output

Built-in power regulation:

  • One low noise linear voltage regulator to supply part of the analog circuits.
  • Two microphone biasing outputs for driving up to two microphones.

Signal processing function:

  • An Automatic Gain/Level Control (AGC) enables a self-adaptive recording of the sound level during recording.
  • A Wind Noise Filter (WNF), a programmable high pass filter feature enabling to reduce wind noise during recording in a windy environment or an open window vehicle.
  • A digital WhisperTrigger for digital microphones which wake-up the chip when voice activity is detected.
  • An Audio Interface Adaptive Synchronizer (AIAS) system enables to synchronize automatically the input data if the mean sample frequency is close to a standardized value (up to 3% difference).

Its main features include:

  • One stereo 24-bit/192Ksps ADC and One stereo 24-bit/192Ksps DAC
  • Low BOM capacitor-less input and output
  • Up to 10 digital microphone interfaces with programmable DMIC clock frequency and support of low power mode
  • 24 to 16-bit signed linear PCM format, support sampling rate of 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48, 88.2, 96, 176.4, 192kHz
  • Embedded low noise linear regulator for high resilience to power supply noise
  • Low power operating mode on the ADC path
  • Reduction of audible glitches systems:
    • Soft mute mode
    • Zero-crossing gain change
  • Automatic Gain/Level Control (AGC) with SNR optimizer feature
  • Programmable Wind Noise Filter (WNF)
  • WhisperTrigger, voice activity detection for digital microphone
  • Slave mode interface on DAC with AIAS automatic data rate synchronization
  • Slave mode interface on ADC with AIAS automatic data rate synchronization

# Clocking and Sampling Rates

# Clock Generation and Management

The above figure shows crystal oscillator circuit and crystal equivalent circuit. Only the crystal (XTAL) and the capacitances CX1 and CX2 need to be connected externally on XTAL-In and XTAL-Out. The oscillator has also a bypass mode that an external clock is connected directly to the XTAL-In pin.

To get the best performance, it's very critical to select a matching crystal for on-chip oscillator. The load capacitance CL, series resistance Rs, and drive level DL are important parameters to consider while choosing the crystal. Rf is the feedback resistor for the crystal to start oscillation. After selecting the proper crystal, the external load capacitor CX1 and CX2 values can be generally calculated by the following equation:

CX1=CX2= CL -- (Cpad + Cparasitic)

Where:

CL：Crystal load capacitance per terminal

Cpad: Pad capacitance of the XTAL-In and XTAL-Out pins

Cparasitic: Parasitic or stray capacitance of the external circuit.

Following table lists the electrical characteristics of the crystal oscillator:

Description Symbol Min. Typ. Max. Unit
Frequency range (crystal mode) Fref 24 MHz
Frequency range (bypass mode) Fref 24 MHz
Frequency accuracy -20 20 ppm
Cycle-to-cycle Jitter CCJ -10 10 ps
Output Duty Cycle t-do 40 50 60 %
Equivalent Series Resistance 40 Ω
CL 8 pF
Rf 1 MΩ
Total Power (unloaded) IDD TBD mA

# Core Clock

The clock generation module includes PLL which generates clock to HiFi3 Core, Codec, USB, I2S, SPI, and other interfaces.

There are two reference oscillators. An on-chip 32kHz RC oscillator is used during power-up and low power mode. An external 24MHz crystal oscillator provides reference clocks in active mode.

Codec master clock is 12MHz, the USB master clock is 24MHz, the system clock can be up to 200MHz.

Following table lists clock requirements:

Clock Active mode (max MHz) Sleep mode (MHz) Duty-cycle
CPU/AHB 200 0 45%-55%
APB1 50 0 45%-55%
APB2 100 0
Flash 108 0 45%-55%
JTAG External 0 45%-55%
Codec 12 0 45%-55%
USB 24 0 45%-55%
I2S 24 0 45%-55%
PLL ref clk 24 0 45%-55%

# Sampling Rates

Sampling frequency and main clock frequency:

Parameter Description Min. Typ. Max. Unit
Fs Sampling frequency in normal mode 8 192 kHz
Fs Sampling frequency in low power consumption mode (ADC only) 8 16 kHz
Fmclk Main clock frequency 12 or 13 MHz
Dmclk Main clock duty cycle 0.45 0.5 0.55 -

The relation between MCLK, DMIC_CLK frequencies, and available Fs:

Clock division ratio (DMIC_RATE) DMIC-CLK: frequency (Fdmic≠clk) for Fmclk=12Mhz DMIC-CLK: frequency (Fdmic≠clk) for Fmclk=13Mhz Available Fs (kHz)
16 750 kHz 812.5 kHz 8, 11.025, 12, 16
12 1 MHz 1.08 MHz 8, 11.025, 12, 16
5 2.4 MHz 2.6 MHz 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48, 88.2, 96, 176.4, 192
4 3.0 MHz 3.25 MHz 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48, 88.2, 96, 176.4, 192

# PLL

The following figure shows the PLL architecture where the typical reference clock is 24MHz.

Following table lists the signals for PLL operation:

Signal Usage Limitation
DIVR[4:0] Reference Divider Value
 (binary value + 1 : 00000 = ÷1)		 Both REF and post-divide REF must be within the specified range
DIVF[6:0] Feedback Divider Value
(binary value + 1 : 0000000 = ÷1)		 VCO must be within the specified range
DIVQ[2:0] Output Divider Value (2^ binary value)
001 = ÷2        100 = ÷16
010 = ÷4        101 = ÷32
011 = ÷8        110 = ÷64
FSE Chooses between internal and external input paths:
0 = FB pin input
1 = internal feedback
RANGE [2:0] PLL Filter Range
000=BYPASS      100=26-42MHz
001=Reserved     101=42-68MHz
010=10-16MHz    110=68-110MHz
011=16-26MHz    111=110-200MH		 This sets the PLL loop filter to work with the post-reference divider frequency. Choose the highest valid range for best jitter performance, or optimize with post-silicon characterization.

Following table lists PLL key parameters:

Description Symbol Min. Typ. Max. Unit
Input Frequency Fref 24 MHz
VCO Frequency Fvco 1000 2000 MHz
Output Frequency Fout 20 1000 MHz
Output Duty Cycle t-do 45 55 %
Maximum Lock Time t-lock 50 µs
Reset Time t-reset 1 µs
Maximum Long Term Jitter LTJ ±1% Divided-Ref Period
Maximum Cycle to Cycle Jitter CCJ ±1% Output Period
Total Power (unloaded) IDD 2 mA

# Control Ports

# USB Port

SNC8508 provides a full functional USB controller with integrated PHY, which supports USB2.0 and USB Audio Class Specification Rev1.0 and 2.0 compliance.

Item Unit Specification Comment
USB standard 2.0 full speed and high speed, device
VBUS voltage V 5.0/3.3
Interface type Type-C/Micro USB

# I2C/UART

Item Quantity Unit Specification Comment
UART 1 bps Up to 3M TX and RX
I2C 2 kbps Up to 400K

# I2S

There are two I2S interfaces, which are specified in the following table.

Item Unit Specification Comment
Interface number 3 I2S interface, with word clock, bit clock, data-in, data-out
Word clock kHz Up to 192 8, 16, 32, 44.1, 48, 88.2, 96, 176.4, 192
Data width bits 16/20/24
Format Standard, left-justified, right-justified

I2S pins are GPIO reusable pins. GPIO mappings are described in the following table, where CLK is the bit clock, WS is the word clock, SDI is the input data, SDO is the output data.

I2S-1 I2S-2
I2S1_clk GPIO0 I2S2_clk GPIO4
I2S1_ws GPIO1 I2S2_ws GPIO5
I2S1_sdi GPIO2 I2S2_sdi GPIO6
I2S1_sdo GPIO3 I2S2_sdo GPIO7

# Auxiliary ADC (SAR ADC)

Two 12-bit SAR ADC can be used for headset button detection, battery monitor, or other analog sensor input measurement.

Parameters Min. Typ. Max. Unit
Resolution 12 Bits
ENOB 11 Bits
Sampling rate 5 Msps
Channel TBD
AVDD-aux-ADC 3.3 V
DVDD-aux-ADC 1.1 V
Input voltage range 0 3.3 V
INL accuracy -2 2 LSB
DNL accuracy -1 1 LSB
Offset -2 2 LSB
Gain error -1 1 %
Hardware conversion time 1 us

# eFuse

There is one OTP memory of 256-bits which is organized as 32-bit by 8. This is a one-time programmable electrical fuse with random access interface. The electrical fuse is a type of non-volatile memory which can be fabricated in standard CMOS logic process.

Pin name Signal type Description
CSB Input Active-low chip select in low power standby mode
STROBE Input High to turn ‘ON’ the array for read or program access
LOAD Input High to turn ‘ON’ sense amplifier and load data into latch
Q7~Q0 Output Data output
VDDQ Input High voltage for fuse programming, ground for read
A7~A0 Input Address pins
PGENB Input Program enable (active low)
VDD Supply Core supply voltage
VSS Supply Ground

Key features：

  • Programming condition:

    • VDDQ: 2.5V±10%

    • VDD: 1.1V±10%

    • Temperature: 125℃~-40℃

    • Program time: 10us±1us

  • Read condition:

    • VDDQ: 0V or floating

    • VDD: 0.81V~1.21V

    • Temperature: 125℃~ -40℃

  • Asynchronous signal interface

# Outline Dimensions

BGA80 dimension information:

# Ordering Guide

Part Number
Type
 Package Size
Packing
MoQ
SNC8508 BGA-80L 4.5mm*6.2mm*1.2mm
X: 0.5mm, Y: 0.4mm Pitch		 Tape&Reel 3K