General Description
The HT812D0 is a single chip LOG-PCM voice synthesizer LSI with 2.8-second voice capacity at 6kHz sampling rate. The chip when triggered drives a speaker through an external transistor with a current switch D/A converter output. Negligible current will be consumed in the standby state.

Features
• Operating voltage: 2.4V~5.0V
• Directly drives an external transistor
• Low standby current (1µA Typ. for VDD=3V)
• Minimal external components
• 124 words table ROM for key functions
• Programmable silence length and end-pulse width (minimal end-pulse width is 330µs at a 6kHz sampling rate)
• 2.8-second voice capacity
• Controllable volume
• FLAG1 options:
    – End-pulse output
    – 3Hz flash
    – 6Hz flash
    – Voice output indication
    – Busy output
• FLAG2 options:
    – 3Hz flash
    – 6Hz flash
    – Busy output
• Four keys
• Key options:
    – Stop key: KEY4
    – Random (only for KEY1)
    – Sequential (only for KEY1)
    – Repeat (for all KEYs, under retriggerable condition)
    – Key debounce time (for all KEYs): 700µs, 22ms, 45ms, 180ms (based on a sampling rate of approximately 6kHz)
    – One shot (for all KEYs)
    – Level-trigger
    – Pull-high resistance (for all KEYs)
• Section options:
    – Retriggerable
    – Non-retriggerable

Applications
• Toys
• Alarm clocks
• Public address system
• Alert & warning system
• Sound effect generators