NUVOTON ISD3900FYI

The ISD3900 is a multi-message ChipCorder featuring digital compression, comprehensive memory management, and integrated analog/digital audio signal paths. The message management feature is designed to make message recording simple and address-free as well as make code development easier for playback-only applications. The ISD3900 utilizes winbond 25X/25Q series flash memory to provide non-volatile audio record/playback for a two-chip solution. Unlike other ChipCorder series, the ISD3900 provides an I²S digital audio interface, faster digital recording, higher sampling frequency, and a signal path with SNR equivalent to 12bit resolution. The ISD3900 can take digital audio data via I²S or SPI interface. When I²S input is selected, it will replace the analog audio inputs and will support sample rates of 32, 44.1 or 48 kHz depending upon clock configuration. When SPI interface is chosen, the sample rate of the audio data sent must be one of the ISD3900 supported sample rates. The ISD3900 has built-in analog audio inputs, analog audio line driver, and speaker driver output. The two analog audio inputs to the device are: (1) AUXIN has a fixed gain configured by SPI command, and (2) ANAIN/ANAOUT has a fixed gain amplifier with the gain set by two external resistors. ANAIN/ANAOUT can also be used as a microphone differential input (ANAIN/ANAOUT becomes MIC+/MIC-) in conjunction with an automatic gain control (AGC) circuit configured by SPI command. Analog outputs are available in three forms: (1) AUXOUT is a single-ended voltage output; (2) AUDOUT can be configured as either a single-ended voltage output or a single-ended current output; (3) BTL (bridge-tied-load) is a differential voltage output.

• External Memory: support winbond 25X/25Q SpiFlash.
• The addressing ability of ISD3900 is up to 128Mbit, which is 64-minute recording time based on 8kHz/4bit ADPCM.
• Programming rate can go up to 1Mbits/second mainly limited by the flash memory write rate.
• Perform address-free recording: The ISD3900 allocates memory for new recording requests and upon completion, returns a start address to the host via SPI interface
• Store pre-recorded audio (Voice Prompts) using high quality digital compression
• Use a simple index based command for playback
• Execute pre-programmed macro scripts (Voice Macros) designed to control the configuration of the device and play back Voice Prompts sequences and message recordings.
• Seven record and playback sampling frequencies are available for a given master sample rate. For example, the record and playback sampling frequencies of 4, 5.3, 6.4, 8, 12.8, 16 and 32kHz are available when the device is clocked at a 32kHz master sample rate. For I²S operation, 32, 44.1 and 48kHz master sample rates are available with record and playback sampling frequencies scaling accordingly.
• Compression Algorithms:
  • For recording ADPCM: 2, 3, 4 or 5 bits per sample
  • µ-Law: 6, 7 or 8 bits per sample
  • Differential µ-Law: 6, 7 or 8 bits per sample
  • PCM: 8, 10 or 12 bits per sample. Each sampled value is stored as a code, offering no compression but preserving maximum resolution
  • For Pre-Recorded Voice Prompts
    • µ-Law: 6, 7 or 8 bits per sample
    • Differential µ-Law: 6, 7 or 8 bits per sample
    • PCM: 8, 10 or 12 bits per sample
    • Enhanced ADPCM: 2, 3, 4 or 5 bits per sample
    • Variable-bit-rate optimized compression. This allows best possible compression given a metric of SNR and background noise levels.
• Oscillator:
  • Internal oscillator with internal reference: 2.048 MHz with ±10% deviation
  • Internal oscillator with external resistor: 2.048 MHz with ±5% deviation when Rosc is 78.7kohm
  • External crystal or clock input
  • I²S bit clock input
  • Crystals and resonators support standard audio sampling rates of 2.048, 4.096, 8.192, 12.288 and 11.2896MHz
• Inputs:
  • AUXIN: Analog input with 2-bit gain control configured by SPI command
  • ANAIN/ANAOUT: Analog input with the gain set by two external resistors from ANAOUT to ANAIN, or Microphone differential input (ANAIN/ANAOUT becomes MIC+/MIC-)
  • Digital AGC: Automatic gain control of digitized data from the analog input
• Outputs:
  • PWM: Class D speaker driver to direct drive an 8Ω speaker or buzzer
  • AUDOUT: configurable as a current or voltage single-ended line driver
  • AUXOUT: a single-ended voltage output
  • BTL: a differential voltage output
• I/Os:
  • SPI interface: MISO, MOSI, SCLK, SSB for commands and digital audio data
  • I2S interface: I2S_CLK, I2S_WS, I²S._SDI, I²S._SDO for digital audio data
  • 8 GPIO pins (4 of the 8 GPIO pins share with I²S).
• Three 8-bit Volume Control set by SPI command for flexible mixing
  • VOLA: volume control for the digital audio data from I²S or analog inputs
  • VOLB: volume control for the digital audio data from decompression block or SPI
  • VOLC: master volume control for PWM, AUDOUT, AUXOUT and I²S outputs
• Operating Voltage: 2.7-3.