HOLTEK HT8950

HT8950
Voice Modulator
Features
•
•
•
•
•
•
Operating voltage: 2.4~4.0V
On-chip SRAM
Robot function
Vibrato function
8kHz sampling rate
7-step level shifting
•
•
•
•
•
8-bit A/D and D/A converters
LED indicator with voice level
Push button selection or electronic mode
Few external components required
16-pin/18-pin DIP package
•
•
•
Audio system
Speech system
Telephone system
Applications
•
•
•
Toys
Mixers
Recorders
General Description
SW0, SW1 and SW2 for electronic direct selection and ROB, TGD, TGU and VIB for push
button selection.
The HT8950 is a single chip CMOS LSI voice
modulator. It provides 7 steps to shift the frequency of an input voice, producing a dramatical change in the output.
The HT8950 includes a built-in microphone amplifier with an internal bias, an 8-bit A/D converter, a built-in SRAM as well as a current
output type 8-bit D/A converter. The 8-bit A/D
and D/A converters with a sampling rate of
8kHz ensures a high quality and high S/N ratio
output voice. The chip provides an LED indicator which flashes with the volume of the input
voices. It is offered in a 16-pin or 18-pin DIP
package.
The HT8950 provides two special effects: Vibrato and Robot. The Vibrato effect is generated
by alternating the frequency of an input signal
up and down at a rate of 8Hz. The Robot function, on the other hand, converts an input voice
into a Robot voice. Both effects can be selected
depending on which pin is triggered, either
ROB or VIB. For the output frequency level
shifting, the chip provides 7 steps which can be
selected from the two groups of pins namely,
1
5th May ’98
HT8950
Pin Assignment
Block Diagram
2
5th May ’98
HT8950
Unit: µm
Pad Coordinates
Pad
No.
X
Y
Pad
No.
X
Y
1
2
3
4
5
6
7
8
9
–957.0
–957.0
–957.0
–957.0
–957.0
–957.0
–962.0
–161.5
200.5
720.5
423.5
210.0
–87.0
–299.5
–596.5
–815.0
–747.5
–747.5
10
11
12
13
14
15
16
17
18
732.0
984.0
956.5
956.5
956.5
530.5
345.50
–33.50
–287.50
–774.0
–675.0
–400.0
374.5
671.5
765.5
765.5
765.5
765.5
Chip size: 2350 × 2080 (µm)2
∗ The IC substrate should be connected to VSS in the PCB layout artwork.
Pin Description (18 Pin Version)
Pin No.
Pin Name I/O
Internal
Connection
Description
1
SW0
I
Pull-High
Function setting pin (for electronic setting)
2
SW1
I
Pull-High
Function setting pin (for electronic setting)
3
SW2
I
Pull-High
Function setting pin (for electronic setting)
4
VSS
I
—
Negative power supply (GND)
5
AO
O
—
Internal amplifier output
6
AIN
I
—
Internal amplifier input (inverted)
7
VDD
O
—
Positive power supply
8
LAMP
O
NMOS
Lamp output (brightness changes with voice volume)
Open Drain
9
AUDIO
O
PMOS
Audio output
Open Drain
10
Vref
I
—
Internal amplifier reference voltage
11
TS
I
—
For IC test only
12
Fvib
O
—
Vibrato frequency control
13
OSC2
O
—
Oscillator output
14
OSC1
I
—
Oscillator input
15
VIB
I
Pull-High
Switch to Vibrato mode (toggle)
3
5th May ’98
HT8950
Pin No.
Pin Name I/O
Internal
Connection
Description
16
TGU
I
Pull-High
Switch to Upward step mode
17
TGD
I
Pull-High
Switch to Downward step mode (internal pull-high)
18
ROB
I
Pull-High
Switch to Robot mode (internal pull-high)
Absolute Maximum Ratings*
Supply Voltage ................................. –0.3V to 6V
Storage Temperature................. –50°C to 125°C
Input Voltage................. VSS–0.3V to VDD+0.3V
Operating Temperature............... –20°C to 70°C
*Note: These are stress ratings only. Stresses exceeding the range specified under “Absolute Maximum Ratings” may cause substantial damage to the device. Functional operation of this
device at other conditions beyond those listed in the specification is not implied and prolonged
exposure to extreme conditions may affect device reliability.
(Ta=25°C)
Electrical Characteristics
Symbol
Parameter
Test Conditions
VDD
Conditions
—
Min.
Typ.
Max.
Unit
2.4
3.0
4.0
V
—
2.0
10
mA
—
—
580
mV
mA
VDD
Operating Voltage
—
IOP
Operating Current
3V
VIN
Input Signal
3V
ILAMP
Lamp Sink Current
3V
VOL=1.3V
5.0
9.5
—
AV
OPA Gain Value
3V
Open loop
—
2000
—
IO
Audio Output Voltage
3V
During silence
—
–1.0
—
mA
VIH
“H” Input Voltage
—
—
0.7VDD
—
—
V
VIL
“L” Input Voltage
—
—
—
—
0.3VDD
V
fOSC
Oscillating Frequency
3V
—
512
—
kHz
No load,
fOSC=640kHz
—
ROSC=47kΩ
4
5th May ’98
HT8950
Functional Description
the frequency of an input signal. The voice
modulation is selected and determined by the
SW0~SW2 inputs.
The HT8950 is a single chip LSI designed for
voice modulation. It provides 7 steps to shift the
frequency of an input voice signal up and down.
The chip is also equipped with two special effects; Vibrato and Robot.
Input
Step Mode
SW2 SW1 SW0
The HT8950 includes a built-in amplifier, 8-bit
A/D converter and current output type of 8-bit
D/A converter in addition to a built-in SRAM.
The brightness of an LED indicator changes
with the volume of the input voice signal.
Power on initial
The HT8950 enters 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.
Speed
Ratio
1
1
1
Controlled by TGU
Notes
and TDG
1
1
0
UP3
2
1
0
1
UP2
8/5
1
0
0
UP1
4/3
0
1
1
NORMAL
0
1
0
DN1
8/9
0
0
1
DN2
4/5
0
0
0
DN3
2/3
1
Notes: The TGU switch elevates by one step
mode, and the TGD switch, on the other hand,
falls one step mode step by step as shown:
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 vibrato 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 Fvil pins.
• The system changes to the Robot state after
the ROB pin is triggered, regardless of what
state the system is in.
• A voice output is accompanied with a vibrato
effect after the VIB pin is triggered, regardless of what state the system is in.
LED indicator
The HT8950 provides a LAMP pin to drive an
external LED. The brightness of LED changes
with the volume of the input voice signal.
Voice modulation
The HT8950 provides an 8-bit A/D and a D/A
converters with a sampling rate of 8kHz, ensuring a voice output of high quality and with a
high S/N ratio. The chip includes 7 steps to shift
5
5th May ’98
HT8950
Application Circuits
16-pin version with an LM386 power amplifier and a 6V power supply
6
5th May ’98
HT8950
18-pin version with an LM386 power amplifier and a 6V power supply
7
5th May ’98
HT8950
16-pin version with a transistor output stage and a 6V power supply
8
5th May ’98
HT8950
18-pin version with a transistor output stage and a 6V power supply
9
5th May ’98
HT8950
16-pin version with a TDA2822 power amplifier and a 6V power supply
10
5th May ’98
HT8950
18-pin version with a TDA2822 power amplifier and a 6V power supply
11
5th May ’98