HT9201A/B
Simple Tone Dialer
Features
•
•
•
Patent Number: 113235(R.O.C.), 5424740(U.S.A.)
•
•
Operating voltage: 2.0V~5.5V
Low standby current
4
×
4 keyboard matrix
3.58MHz crystal or ceramic resonator
Four flash key times selectable for the
HT9201B
General Description
The HT9201A/B tone dialers are CMOS LSIs
designed for telecommunication systems. The
HT9201A is for mute output whereas the
HT9201B is for flash output. Both dialers pro-
vide good performance for regular DTMF dial-
ing with low distortion output and minimal ex-
ternal components.
Selection Table
Function
Item
HT9201A
HT9201B
√
—
√
√
F1,F2,F3,F4
MUT E
XM E
UT
Fla T im (m
sh
e s)
—
600/
300/
200/
90
A,B,C,D
DT M O
F utput
√
—
Package
16 DIP
16 DIP
Pin Assignment
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3rd Dec ’97
HT9201A/B
Keyboard Information
Block Diagram
Pin Description
Pin Name
I/O
Internal
Connection
Description
These pins form a 4
×
4 keyboard matrix which can perform
keyboard input detection and dialing specification setting
functions. When the chip is in the standby mode the column
group (C1~C4) remains low whereas the row group (R1~R4) is
set high for key input detection.
An inexpensive single contact 4
×
4 keyboard can be used as an
input device. Pressing a key connects a single column to a
single row, and actuates the system oscillator which result in
a dialing signal output. If more than two keys are pressed at a
time, no response occurs. The key-in debounce time is 20ms.
Refer to the keyboard information for keyboard arrangement.
C1~C4
R1~R4
I/O
CMOS
IN/OUT
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3rd Dec ’97
HT9201A/B
Internal
Connection
Pin Name
I/O
Description
X1
I
X2
O
The system oscillator consists of an inverter, a bias resistor
and the necessary load capacitor on chip. Connecting a
standard 3.579545MHz crystal or ceramic resonator to the X1
OSCILLATOR
and X2 terminals can implement the oscillator function. The
oscillator is turned off in the standby mode, and is actuated
whenever a keyboard entry is detected.
XMUTE is an NMOS open drain structure pulled to VSS
during dialing signal transmission. Otherwise, it is an open
circuit. XMUTE is used to mute the speech circuit when
transmitting the dial signal.
The output is low when no keypad input is entered and it
becomes high during dialing sequence. The timing diagram is
shown in the operation timing.
This pin is a CMOS output structure from which the chip
receives the flash key (F1~F4) signals to break the telephone
line for a flash time.
For IC chip test only
Positive power supply, 2.0V~5.5V for normal operation
Negative power supply
XMUTE
O
NMOS OUT
MUTE
O
CMOS OUT
FLASH
O
CMOS OUT
CMOS IN
Pull-High
—
—
TEST
VDD
VSS
I
I
I
Approximate internal connection circuits
Absolute Maximum Ratings*
Supply Voltage ............................... –0.3V to 6V
Input Voltage ............... V
SS
–0.3V to V
DD
+0.3V
Storage Temperature ............... –50
°
C to 125
°
C
Operating Temperature ............. –20
°
C to 75
°
C
*Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent
damage to the device. These are stress ratings only. Functional operation of this device at
these or any other conditions above those indicated in the operational sections of this
specification is not implied and exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
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3rd Dec ’97
HT9201A/B
Electrical Characteristics
Symbol
V
DD
I
DD
I
STB
V
IL
V
IH
I
XMO
I
OLXM
I
OH1
I
OL1
T
DB
F
OSC
(Ta=25
°
C)
Parameter
Operating Voltage
Operating Current
Standby Current
Input Low Voltage
Input High Voltage
XMUTE Leakage Current
XMUTE Sink Current
—
Test Conditions
V
DD
Conditions
Min.
2
Typ.
—
0.6
—
—
—
—
—
—
400
20
Max.
5.5
2
1
0.2V
DD
V
DD
1
—
–40
—
—
Unit
V
mA
µ
A
2.5V
Keypad entry
No load
—
—
V
SS
0.8V
DD
—
1
–4
200
—
2.5V No load, no entry
—
—
—
—
—
V
XMUTE
=12V
No entry
V
V
µ
A
2.5V V
XMUTE
=0.5V
mA
µ
A
µ
A
Keypad Pin Source Current 2.5V V
OH
=0V
Keypad Pin Sink Current
Key-in Debounce Time
System Frequency
2.5V V
OL
=2.5V
—
—
F
OSC
=3.5795MHz
ms
Crystal=3.5795MHz 3.5759 3.5795 3.5831 MHz
(F
OSC
=3.5795MHz, Ta=25
°
C)
Tone Mode Electrical Characteristics
Symbol
V
TDC
I
TOL
V
TAC
R
L
A
CR
THD
Parameter
V
DD
DTMF Output DC Level
DTMF Sink Current
DTMF Output AC Level
DTMF Output Load
Column Pre-emphasis
DTMF Signal Distortion
—
Test Conditions
Conditions
—
Min.
0.45V
DD
0.1
0.12
5
1
—
Typ.
—
—
0.155
—
2
–30
Max.
0.7V
DD
—
0.18
—
3
–23
Unit
V
mA
Vrms
k
Ω
dB
dB
2.5V V
DTMF
=0.5V
—
Row group, R
L
=5k
Ω
2.5V THD
≤
–23dB
2.5V Row group=0dB
2.5V R
L
=5k
Ω
V1
2
+
V2
2
+ …
+
Vn
Vi
2
+
Vh
THD (Distortion) (dB) = 20 log
(
√
2
⁄
√
2
)
Vi, Vh: Row group and column group signals
V1, V2, ... Vn: Harmonic signals (BW=300Hz~3500Hz)
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3rd Dec ’97
HT9201A/B
Functional Description
Keyboard matrix
•
F1, F2, F3, F4
C1~C4 and R1~R4 form a keyboard matrix. The
keyboard arrangement for each of the HT9201
series are shown in the
Keyboard Information
.
Tone frequency
The flash keys can be selected with different
flash times as shown in the following table.
Flash time selection table
Tone
Name
R1
R2
R3
R4
C1
C2
C3
C4
Output
Frequency (Hz)
Specified
697
770
852
941
1209
1336
1477
1633
Key
% Error
+0.29%
–0.52%
–0.59%
+0.74%
+0.50%
–0.30%
–0.34%
+0.73%
F1
F2
F3
F4
Keyboard operation
Flash Time (ms)
600
300
200
90
Actual
699
766
847
948
1215
1332
1472
1645
Note: % Error does not contain the crystal frequency
drift
Key definition
•
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
∗
, #, A, B, C, D keys
These are the dialing number input keys for
normal operation.
Timing Diagrams
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3rd Dec ’97
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