General Description
The HT81003 is a Mask ROM type. The HT81003 is a single-chip voice synthesizer LSI with 3-second voice capacity at 5kHz sampling rate. The chip when triggered drives a speaker through an external transistor with a PWM output. Negligible current is consumed in the standby state.

Features
• Operating voltage: 2.4V~5V
• Directly drives an external transistor
• PWM function directly driver speaker
• Low standby current (1A typ. for VDD=3V)
• Minimal external components
• 240 notes table ROM for key functions
• Programmable silence length and end-pulse width (minimal end-pulse width is 1.3ms at 8kHz sampling rate)
• 3-sec voice capacity (based on a 5kHz sampling rate)
• Controllable volume
• FLAG1 options
   - End-pulse output
   - 3Hz, 3HzB flash
   - 6Hz, 6HzB flash
   - Busy output
   - OFF
• FLAG2 options
   - 3Hz flash
   - 6Hz flash
   - Busy output
   - OFF
• 2 keys
• Key options
   - Sequential/Directed
   - Repeat (KEY2)
   - STOP key (KEY2)
   - Key debounce time: 1.2ms, 22ms, 45ms (based on a 8kHz sampling rate)
   - One shot/Normal
   - Pull-high resistance: 0, 50kΩ, 100kΩ, 200kΩ
• Section options
   - Retriggerable
   - Non-retriggerable
• Dice form or 16-pin DIP package

Applications
• Leisure products
• Alarm clocks
• Public address system
• Alert and warning system
• Sound effect generators