HOLTEK HT8656A

HT8656
Talking Back
Features
•
•
•
•
•
Operating voltage: 4.5V~5.5V
ADM algorithm
DRAM selection:
– 64K
– 256K
Sampling rate selection:
– 32Kb
– 16Kb
Auto stop recording
– 0.5 seconds silence is detected
– Recording capacity is full
•
•
•
•
•
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Built-in 2-stage microphone amplifier
Built-in DRAM refresh circuit
Voltage type D/A output
Current type D/A output
Auto record and playback
Auto power-off
Low power consumption
•
Games
Applications
•
•
Toys
Education
General Description
The HT8656 provides a recording capacity of 2
seconds for DRAM of 64K and 8 seconds for
DRAM of 256K at a 32Kb sampling rate and
double recording capacity at a 16Kb sampling
rate. A higher sampling rate will result in
sounds of better quality but sacrifice the recording time, and vice versa.
The HT8656 is a single chip CMOS LSI for
talking back applications using an ADM algorithm. Functions of the IC consist of recording/playing as well as auto power off. It starts
recording when a sound input is detected, and
stops to play back when silence lasts 0.5 seconds during recording. The auto power off function is activated once a REC/PLAY cycle has
been implemented 64 times or an interval of
silence exceeds 2 minutes.
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HT8656
Pin Assignment
Block Diagram
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HT8656
Pad Coordinates
Chip size: 3276.6 × 3530.6 (µm)2
* The IC substrate should be connected to VDD in the PCB layout artwork.
Unit: µm
Pad No.
X
Y
Pad No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
–1488.19
–1488.19
–1488.19
–1488.19
–1488.19
–1488.19
–1488.19
–1488.19
–1396.75
–1170.43
–964.69
–399.03
–145.29
1033.27
1239.01
1613.92
1277.87
906.53
653.80
–355.60
–635.51
–937.26
–1378.46
–1615.19
–1615.19
–1615.19
–1615.19
–1615.19
–1615.19
–1615.19
16
17
18
10
20
21
22
23
24
25
26
27
28
29
3
X
Y
1488.19 –1615.19
1488.19
–377.19
1488.19
–124.71
1488.19
130.30
1488.19
384.05
1488.19
651.51
1488.19
1089.41
1488.19
1363.73
1436.88
1615.19
1226.57
1615.19
973.84
1615.19
723.65
1615.19
473.20
1615.19
–1052.83 1615.19
5th May ’98
HT8656
Pin Description
Pin No.
Pin Name I/O
Internal
Connection
Description
1, 2
A6, A7
O
CMOS
DRAM address output
3~8
A5~A0
O
CMOS
DRAM address output
9
RASB
O
CMOS
DRAM row address strobe
10
WRB
O
CMOS
DRAM write enable
11
DATA
I/O
CMOS
DRAM data input/output
12
A8
O
CMOS
DRAM address output
13
CASB
O
CMOS
DRAM column address strobe
14
OSC2
O
—
Oscillator output
15
OSC1
I
—
Oscillator input
16
LEDB
O
LED indicator:
NMOS
Idle: LED is turned on
Open Drain Record: LED flashes
Play: LED is turned off
17
START
O
NMOS
System start pin
Open Drain
18
MOTOR
O
CMOS
19
VSS
I
—
Negative power supply (GND)
20
BIAS
I
—
For internal AMP bias de-coupling
21
AIN1
I
—
Internal AMP first stage input (inverted)
22
AO1
O
—
Internal AMP first stage output
23
AIN2
I
—
Internal AMP second stage input (inverted)
24
IOUT
(8656A)
O
—
Voltage type audio output for an external power AMP
24
IOUT
(8656B)
O
—
Current type audio output for an external transistor
25
VDD
I
—
Positive power supply
26
TESTB
I
Pull-High
For IC test only
27
16KB
I
Pull-High
32Kbps/16Kbps sampling rate selection:
Open/high: 32Kbps
Low: 16Kbps
28
MS
I
Pull-High
64K/256K DRAM size selection:
Open/high: 64K
Low: 256K
Motor drive output (active high) when playing back
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HT8656
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
4.5
—
5.5
V
—
1.5
3.0
mA
—
600
800
µA
VDD
Operating Voltage
—
IDD
Operating Current
5V
ISTB
Standby Current
5V
IO
Max. AUD Source Current
5V
VOH=0.6V
–1.5
–3.0
—
mA
IOL
MOTOR Source Current
5V
VOH=4.5V
–1
–3.5
—
mA
IOL
LED Sink Current
5V
VOL=0.5V
3.0
5.0
—
mA
VIH
“H” Input Voltage
—
—
0.7VDD
—
VDD
V
VIL
“L” Input Voltage
—
—
0
—
0.3VDD
V
VOUT
Max. VOUT Output Voltage
5V
RL>50kΩ
—
1.5
—
VP-P
fOSC
Oscillating Frequency
5V
ROSC=43kΩ
—
640
—
kHz
No load,
fOSC=640kHz
—
Functional Description
The HT8656 is a single chip LSI with an external DRAM. It is designed for talking back applications. The recording length of the IC is
determined by the data rate along with the size
of an external memory. Sounds coming from an
external microphone are coded through an internal ADM algorithm and saved in an external
memory until the memory is full or an interval
of silence lasts over 0.5 seconds. Once recording
is terminated, the IC will play back the recorded
sounds automatically.
Record function
The HT8656 provides two kinds of sampling
rate and DRAM size selection to determine the
recording capacity. The recording capacity is
determined as shown on the following table.
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HT8656
DRAM Type
(MS)
Sampling
Rate
(16KB)
Recording
Capacity
64Kb
32Kb
2 seconds
64Kb
16Kb
4 seconds
256Kb
32Kb
8 seconds
256Kb
16Kb
16 seconds
switched off when a REC/PLAY cycle has been
implemented 64 times or an interval of silence
lasts over 2 minutes.
Recording starts whenever a sound input is
detected. It then stops once a 0.5 seconds silence is detected or the recording capacity is
full. After that, talking back comes into play.
Motor
The HT8656 provides a motor driving pin. The
motor is turned on during playing but off once
talking back is terminated.
Play function
The HT8656 stops to play back the recorded
sounds when an interval of silence lasts 0.5
seconds during recording. Its sampling rate is
the same as the rate of recording sounds.
LED
The LED pin displays the status of the HT8656.
LED is switched ON when the IC is in the
standby state. Its intensity varies inversely
with the sound volume when the IC is in the
recording state. In the playing state, the LED is
switched OFF.
Power control
The HT8656 provides a START pin for power
control. The START pin is of high impedance
and switch Q is turned off initially. After the
START pin is triggered, it will remain at a low
level and switch Q is turned on. The START pin
is of high impedance and the chip’s power is
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HT8656
Flowchart
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HT8656
Application Circuits
LM386 output
• Dice form
* The IC substrate should be connected to VDD in the PCB layout artwork.
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HT8656
• Package form
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HT8656
two transistor output
• Dice form
* The IC substrate should be connected to VDD in the PCB layout artwork.
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HT8656
• Package form
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