ISD1420S

Overview

The ISD1420S is a single-chip voice record and playback device from the ISD1400 series, manufactured by Nuvoton Technology Corporation. It utilizes Multi-Level Storage (MLS) technology to store analog audio signals directly in non-volatile memory without digitization or compression. The component supports a nominal recording duration of 20 seconds with a sampling frequency of 6.4 kHz and a filter passband of 2.6 kHz. It operates on a single +5V supply (4.5V to 5.5V) and features an internal oscillator, microphone preamplifier with Automatic Gain Control (AGC), and a Class D PWM speaker driver capable of driving loads as low as 16 Ω. Available in 28-lead PDIP and SOIC packages, it offers zero-power message storage with 100-year retention.

Feature Summary

• Direct analog storage using patented Multi-Level Storage (MLS) technology for natural voice reproduction without digital compression.
• Integrated automatic power-down mode that reduces standby current to approximately 1 µA after record or playback cycles.
• Fully addressable architecture allowing multiple messages via eight address pins, supporting up to 160 distinct segments.
• Built-in operational modes including message cueing, looping, consecutive addressing, and EOM marker deletion.

Applications

• Short-duration messaging systems requiring push-button operation
• Voice annotation devices and educational aids
• Security alarm announcements and industrial warning systems
• Consumer electronics with simple voice feedback requirements

Procurement Notes

Verify the specific ordering suffix to confirm package type, as the ISD1420S designation may correspond to either the 28-PDIP or 28-SOIC variant depending on manufacturer documentation. Confirm temperature range specifications, as commercial versions operate from 0°C to 70°C while industrial versions support -40°C to 85°C. Ensure compatibility with existing design constraints regarding the single +5V supply requirement and direct drive speaker impedance limits.

Selection Notes

Select the ISD1420S when a fixed 20-second recording duration is required without external clock precision needs. Choose this component over higher-speed variants if lower sampling rates are acceptable for speech-only applications. Consider the ISD1416 if a shorter 16-second duration allows for a higher 8.0 kHz sampling rate. Evaluate the need for external clocking via the XCLK pin if strict timing stability beyond the internal oscillator's tolerance is necessary for the application environment.

Part Context

The ISD1420S belongs to the Winbond/Nuvoton ISD1400 ChipCorder series, which introduced direct analog storage solutions for short-duration voice applications. This series distinguishes itself from digital voice ICs by eliminating ADC/DAC conversion stages, thereby reducing component count and cost. The ISD1420 specifically targets the 20-second market segment, offering a balance between recording time and audio fidelity suitable for standard voice communications.

Replacement Considerations

The ISD1420PY is a pin-compatible alternative within the same series, differing primarily in package style (PDIP vs. potentially other variants). For longer durations, the ISD1416 offers 16 seconds at a higher sampling rate. Direct replacements for different voltage ranges or digital interfaces require redesigning the control logic and power supply circuits, as the ISD1400 series relies on specific analog input/output characteristics.