HT85XXX 데이터 시트보기 (PDF) - Holtek Semiconductor

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HT85XXX

Green Voice

Holtek Semiconductor 

PCM/ADPCM synthesizer

The HT85XXX family contains a PCM and

ADPCM synthesizer. The synthesizer offers a

wide range of sampling rates from 4kHz to

24kHz for PCM synthesis and 4kHz to 16kHz

for ADPCM synthesis. The sampling rate of the

synthesizer can be changed by writing a control

value to the sampling rate register. It also sup-

ports a small variety of 100Hz. For a higher

performance sound quality, the PCM coding is

required. But for a longer recording capacity,

the ADPCM coding is recommended.

The capability of the voice sampling rate for

various voice compression format.

fOSC

PCM8

m-law

PCM

AD4

4M

12kHz 11kHz 8kHz

5M

15kHz 14kHz 10kHz

6M

18kHz 16kHz 12kHz

8M

24kHz 22kHz 16kHz

Oscillator configuration

The HT85XXX series provides an RC oscillator

for the system clock. The system oscillator

stops in the standby state so as to reduce power

consumption.

HT85XXX

For the oscillator circuit, an external resistor is

required between OSC and VSS. The oscillator

frequency is typically 4MHz for an external re-

sistor of 240kW. The RC type of oscillator offers

the most cost-effective solution, although the

frequency of the oscillation may vary with tem-

perature and the chip itself due to process vari-

ation.

ROSC

fOSC

HT84EVA

HT84P00

4M

180kW

240kW

IC

240kW

5M

150kW

210kW 210kW

6M

120kW

180kW 180kW

8M

91kW

150kW 150kW

Mask options

The following options have to be defined to en-

sure a proper system functioning:

· Pull-high resistor: 33kW/98kW (3V)

· Key debounce time: 0ms~255ms (fOSC=4MHz)

6

August 24, 2000

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