Functional Description

The HT8658/HT8659 are single chip LSIs with

an external DRAM (dynamic random access

memory). They are designed for applications on

recording sounds. The recording length is de-

cided by the data rate along with the size of an

external memory. The type as well as amount of

DRAM, operation mode and sampling rate are

determined by the connection of the AS0~AS6

pins. The HT8658/8659 provide 2 audio out-

puts. One is filtered by an internal low pass

filter for the sake of improving sound quality in

addition to minimizing external required com-

ponents. The other is non-filtered and a voice

signal can be filtered with an external circuit to

decide the audio cut-off frequency as well as

band width. The two chips have the same func-

tions except the reset time as shown:

Name

Reset Time (Minimum)

HT8658

4 seconds

HT8659

2 seconds

Initial setting of operation mode

The HT8658/HT8659 load the statuses of the

AS0~AS6 pins into a mode register after power

is initially turned on or the system is reset.

These pins are internally built with pull-high

resistors so that all inputs with “1” are the

default value of the mode register. External

pull-low resistors which are tied to the AS0~

AS6 pins defines the operation mode of the ICs

as shown in the following table:

AS0

AS1

AS2

AS3

AS4

AS5

AS6

Function Description

0

1

1

0

0

0

1

1

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

Data rate: 32K bps

Data rate: 22K bps

Data rate: 16K bps

Data rate: 11K bps

X

X

X

X

X

X

X

X

0

1

0

1

0

0

1

1

X

X

X

X

X

X

X

X

X

X

X

X

DRAM chip number: 4 pcs

DRAM chip number: 3 pcs

DRAM chip number: 2 pcs

DRAM chip number: 1 pcs

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

1

0

1

0

X

X

X

X

1

1

0

0

Operation mode: Normal mode

Operation mode: Auto play back mode

Operation mode: Not applicable

Operation mode: Not applicable

X

X

X

X

X

X

X

X

X

X

1

0

X

X

DRAM type: 256Kb

DRAM type: 1Mb

Notes: 1.“0” connects an external pull-low resistor to ASn, where n=0~6.

2.“1” connects no external pull-low resistor to ASn, where n=0~6.

3.“X” means don’t car.

HT8658/HT8659

5

26th Sep ’96