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Nuvoton ISD1900SY

16-64 seconds speech recording IC

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Key Features
  • Wider operating voltage from 2.4 to 5.5V
  • Higher sampling frequency from 4kHz to 12kHz
  • Converts MIC+ to ANAIN & feeds it to the speakers
  • Record/playback switch
  • level or edge recording
  • Edge-trigger, toggle on/off
  • level playback or looping playback
  • LED output for recording
  • NORM (Address Trigger): variable message duration
  • MODE: (Direct Trigger): fixed message duration

The ISD1900 ChipCorder range from Nuvoton is a single chip, multiple message record / playback IC with dual operating modes (address trigger and direct trigger) with a wide operating voltage ranging from 2.4V to 5.5V.

3 variants are available in the ISD1900 family which are either 16, 32 or 64 seconds at 8 KHz. The sampling frequency can be selected from 4 - 12 KHz via an external resistor, which also determines the duration from 10.6 - 128 seconds. Although these ICs are design mostly for standalone applications, it can be used in conjustion with a microcontroller if necessary.

The two operation modes are address trigger and direct trigger. While in address trigger mode, both record and playback operations are manipulated according to the start address and end address specified through the start address and end address pins. However, in direct trigger mode, the device can configure the memory up to as many as eight equal messages, ending upon the fixed message configuration settings. With the record or playback feature being pre-selected, each message can be randomly accessed via its message control pin.

The device has a selectable differential microphone input with AGC feature or single ended analogue input, Anain, under feed-through mode. Its differential class D PWM speaker driver can directly drive a typical speaker or buzzer.



  • The ISD1900 is a multiple messages record/playback device with two operational modes:
    • Address Mode
    • Direct Mode
  • Supply voltage: 2.4V to 5.5V
  • External resistor, Rosc, selects sampling frequency and duration.
  • Sampling Frequency 12 kHz 8 kHz 6.4 kHz 5.3 kHz 4 kHz
    Rosc 53.3Ω 80 KΩ 100 KΩ 120 KΩ 160 K
    ISD1916 10.6 sec 16 sec 20 sec 24 sec 32 sec
    ISD1932 21.3 sec 32 sec 40 sec 48 sec 64 sec
    ISD1964 42.6 sec 64 sec 80 sec 96 sec 128 sec
  • Mic+/Mic-: differential microphone inputs.
  • AGC: automatic gain control for microphone preamp circuit.
  • FT: feed-through the Analn signal to the speaker outputs while Analn is converted from MIC+.
  • When both FT and recording are active, device will record Analn signal into memory with Analn signal output to speak simultaneously.
  • SP+/SP-: Class-D PWM differential speaker drivers or single-ended voltage output, depending on the derivative selected.
  • LED: LED is on during recording.
  • Automatically power down after each operation cycle.
  • Temperature option: -40°C to +85°C (Industrial)
  • Packaging: available in SOIC only
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