HT8950/HT8950A

Rev. 1.10

4

November 16, 2006

Functional Description

The HT8950/HT8950A are single chip LSIs designed for

voice modulation. These devices provide seven steps to

shift the frequency of an input voice signal up and down.

The chips are also equipped with two special effects; Vi-

brato and Robot.

The HT8950/HT8950A include a built-in amplifier, 8-bit

A/D converter and current output type of 8-bit D/A con-

verter in addition to a built-in SRAM. The brightness of

the LED indicator changes with the volume of the input

voice signal.

Power on Initial

The HT8950/HT8950A enter the Robot state right after

power is initially switched on.

Robot State

The system goes into the Robot state after the ROB pin

is triggered or power is turned on. In this mode, an input

voice can be converted into a robot voice.

Vibrato

An output voice will be generated with a vibrato effect

when the VIB pin is triggered, regardless of what state

the system is in. The vibrato effect is toggle activated. In

other words, when a voice output is playing with a vi-

brato effect, this effect can be eliminated by retriggering

the VIB pin. The rate of vibrato effect can be changed by

adjusting the resistance of the external resistor between

the OSC2 and FVIB pins.

Voice Modulation

The HT8950/HT8950A provide an 8-bit A/D and D/A

converters with a sampling rate of 8kHz, ensuring a high

quality voice output and with a high S/N ratio. The chips

include seven steps to shift the frequency of an input

signal. The voice modulation is selected and deter-

mined by the SW0~SW2 inputs.

Input

Step Mode

Speed

Ratio

SW2

SW1

SW0

111

Controlled by TGU and

TDG

Notes

1

1

0

UP3

2

1

0

1

UP2

8/5

1

0

0

UP1

4/3

0

1

1

NORMAL

1

0

1

0

DN1

8/9

0

0

1

DN2

4/5

0

0

0

DN3

2/3

Notes: The TGU switch increments by one step mode,

and the TGD switch, on the other hand, decrements by

one step mode, step by step as shown:

pin is triggered, regardless of what state the system is

in.

ter the VIB pin is triggered, regardless of what state

the system is in.

LED Indicator

The HT8950/HT8950A provide a LAMP pin to drive an

external LED. The brightness of the LED changes with

the volume of the input voice signal.

*

R O B O T

T G U

T G D

D N 3

T G U

T G D

D N 2

T G U

T G D

D N 1

T G U

T G D

N O R M A L

T G U

T G D

U P 1

T G U

T G D

U P 2

T G U

T G D

U P 3

T G U

T G D