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ML2272x/ML2276x series

Speech synthesis LSI built-in speech-speed/pitch conversion  with 4M/8M/18M bit large scale P2ROM™



package dimension figure


ML2272x/ML2276x series is a speech synthesis LSI that enables adjustments of the speech playback speed and pitches. The LSI enables speech playback slowly without changing the pitch, or increase or reduce the pitch without changing the speed. This enables voice guidance that can be easily understood by the elderly and change of voice tone of the guidance that is output by the alarm device according to the degree of urgency.
By using P2ROM™ memory in the memory section, the turn-around time from fixing of speech data to shipment has been reduced significantly. The built-in amplifier enables speech playback simply by directly connecting a speaker.

Playback time (second)

(at 4bit ADPCM2 method) *When speech-speech/pitch conversion function is not used.
Part number Memory type ROM
Maximum playback time(s)
fs=4.0k fs=8.0k fs=16.0k
ML22725/ML22765 P2ROM 16M 1044 522 261
ML22724/ML22764 8M 520 260 130
ML22723/ML22763 4M 258 129 64


  • Speech-speed/pitch conversion function
  • Long-time playback of 1044 seconds in maximum
    Large memory size to handle the increase of incorporation of speech data and high quality speech
  • Built-in amplifier
  • Memory bank function
    The built-in memory can be divided, enabling a new way of using speech LSI such as increase of the number of playback phrases.
  • The use of P2ROM allows TAT to be significantly reduced.
  • Supports the development by evaluation board and special writer.
  • 3 products (with the capacities of 4M, 8M, and 16M bits) lined up
  • CPU IF: SPI(ML2272x),I2C(ML2276x)

Speech-Speed / Pitch Conversion Functions


*Sodiac is a trademark of AREX Co.

The speech-speed conversion function enables the settings of playback speed in 150 steps from 0.5 times to 2.0 times. In this case, the pitch is hardly affected by the playback speed.
The pitch conversion function enables the pitch settings at 40 levels within the range of ±1%. In this case, the playback speed is hardly affected by the pitch.
Sodiac of AREX is used for the speech-speed conversion/pitch conversion techniques.


  • Operation guidance
    for household electrical appliances
    • White home appliances
    • Cooking appliances
    • Air conditioners
  • House equipment
    • Water heater
    • Fire alarm
  • Security
    • Alarm and antitheft security system
  • On-vehicle applications
    • ETC/radar detector


Parameter Specification
Part number ML2272x/ML2276x series
Speech synthesis method 4bit ADPCM2
8bit non-linea PCM
8bit PCM, 16bit PCM
(can be specified for each phrase)
Sampling frequency
4.0k, 5.3k, 6.4k, 8.0k, 10.7k, 12.0k, 12.8k ,
16.0k ,21.3k ,24.0k, 25.6k ,32.0k, 48.0kHz
(Each phrase can be specified.)
Speaker amplifier output 0.7W(8&Omega, 5V)
Number of playback phrases Max.4,096 phrases(ML22725)
Speech speed conversion function Playback speed from 0.5times to 2.0times
Pitch conversion function ±20% (40 levels: 1% step range)
Other functions Volume control function, Repeat function, ROM edit function
Operating power supply voltage +2.7V to +5.5V
Clock frequency 4.096MHz
Operating temperature range -40°C to +85°C
Package 30pin plastic SSOP
(2-direction lead type, 0.65mm lead pitch)

Block Diagram

Block diagram

Typical Application Example