SM8230A
Tone Dialer with Built-in Piezo Driver
OVERVIEW
The SM8230A is a dual-tone signal generator LSI developed for DTMF (dual tone multi-frequency) dialing. It
features a built-in piezo-electric speaker driver for direct connection to a piezo-electric buzzer. The DTMF fre-
quencies can be set to correspond to the DTMF standards of any country. The output level is also adjustable
under software control. These features, combined with its small package and low power dissipation, make the
SM8230A a very use device to use.
FEATURES
I
I
I
PINOUT
(Top view)
I
I
I
I
3-line serial interface to external CPU
2 independent, adjustable frequency outputs
Piezo driver for direct connection to a piezo-elec-
tric buzzer
4 system clock frequencies selectable
(480kHz, 960kHz, 1.92MHz, 3.84MHz)
2.6 to 3.3V supply voltage
Low current consumption
• 3.0mA (max) operating current
• 1µA (max) standby current
Package: 8-pin plastic SOP
SD
SCL
OE
VSS
1
8
VDD
BZH
BZL
4
5
CLK
ORDERING INFORMATION
Device
SM8230AS
Package
8-pin SOP
PACKAGE DIMENSIONS
(Unit: mm)
Peripheral
4.4
±
0.2
6.2
±
0.3
5.2
±
0.3
0.15
−
0.05
+ 0.10
0.4
±
0.1
0.05
±
0.05
1.5
±
0.1
1.27
0 to 10
0.4
±
0.2
SEIKO NPC CORPORATION —1
SM8230A
BLOCK DIAGRAM
VDD
Programmable
Counter
High Group
ROM
D/A
Converter
Output
Control
BZH
SD
SCL
OE
LATCH
SELECTOR
CLK
VSS
Programmable
Counter
Low Group
ROM
D/A
Converter
Output
Control
BZL
PIN DESCRIPTION
Number
1
2
3
4
5
6
7
8
Name
SD
SCL
OE
VSS
CLK
BZL
BZH
VDD
I/O
I
I
I
–
I
O
O
–
Serial data input
Serial data transfer clock input.
(For valid transfer, OE must stay LOW for 16 clock cycles.)
DTMF output enable/serial data transfer select input.
Serial data transfer is selected when LOW.
Ground
System clock input. The clock can be set to one of four frequencies (480kHz,
960kHz, 1.92MHz, 3.84MHz).
DTMF low-frequency group analog output
DTMF high-frequency group analog output
Supply voltage
Description
SEIKO NPC CORPORATION —2
SM8230A
SPECIFICATIONS
Absolute Maximum Ratings
V
SS
= 0V
Parameter
Supply voltage range
Input voltage range
Output voltage range
Storage temperature range
Power dissipation
Symbol
V
DD
V
IN
V
OUT
T
stg
P
D
Rating
−0.3
to 7.0
V
SS
−
0.3 to V
DD
+ 0.3
V
SS
−
0.3 to V
DD
+ 0.3
−55
to 125
250
Unit
V
V
V
°C
mW
Recommended Operating Conditions
V
SS
= 0V
Rating
Parameter
Supply voltage range
Operating temperature
Symbol
V
DD
T
opr
Condition
min
2.6
−20
typ
3.0
25
max
3.3
70
V
°C
Unit
DC Characteristics
V
DD
= 2.6 to 3.3V, V
SS
= 0V, Ta =
−20
to 70°C
Rating
Parameter
Symbol
Condition
min
Operating current consumption
Standby current consumption
Input voltage (all inputs)
Input leakage current
BZH/BZL tone output voltage
BZH/BZL tone output adjustment step
BZH/BZL tone output absolute error
BZH/BZL tone output impedance
I
DD
I
ST
V
IH
V
IL
I
IL
V
BZO
D
RES
D
LIN
Z
OUT
V
ZBO
levels
V
DD
= 3.0V, Ta = 25°C,
f
CLK
= 480kHz
V
DD
= 3.3V, OE = LOW
HIGH-level input
LOW-level input
HIGH/LOW-level input
0dB output level
–
–
1.1
V
SS
−1
0.86V
DD
–
−1
100
typ
1.5
–
–
–
–
0.93V
DD
1.0
–
150
max
3
1
V
DD
0.6
1
1.0V
DD
–
1
200
µA
Vp-p
dB
dB
Ω
mA
µA
V
Unit
SEIKO NPC CORPORATION —3
SM8230A
AC Characteristics
V
DD
= 2.6 to 3.3V, V
SS
= 0V, Ta =
−20
to 70°C
Rating
Parameter
Symbol
∆f
DIS
t
CLK
t
CLKL
t
CLKH
t
SUOE
t
HDOE
t
SCL
t
SCLL
t
SCLH
t
SUD
t
HDD
Between SD and SCL
100
–
–
ns
SCL input waveform
Between OE and SCL
100
1
400
400
100
–
–
–
–
–
–
–
–
–
–
ns
µs
ns
ns
ns
CLK input waveform
Condition
min
Tone output frequency error
Tone distortion
1
CLK cycle time
CLK LOW-level pulsewidth
CLK HIGH-level pulsewidth
OE setup time
OE hold time
SCL cycle time
SCL LOW-level pulsewidth
SCL HIGH-level pulsewidth
Input data setup time
Input data hold time
f
CLK
= 3.84MHz,
no deviation
BZH/BZL
–
–
250
100
100
100
typ
–
5
–
–
–
–
max
0.37
10
–
–
–
–
%
%
ns
ns
ns
ns
Unit
1. Ta =
−10
to 70°C, THD + N (10Hz to 500kHz), no load
System clock input timing
CLK
t
CLKL
t
CLK
Serial data transfer timing
t
CLKH
OE
SCL
SD
1
DATA(b15)
2
DATA(b14)
16
DATA(b0)
t
SUD
t
SUOE
t
SCLH
t
HDD
t
SCL
t
SCLL
t
HDOE
SEIKO NPC CORPORATION —4
SM8230A
FUNCTIONAL DESCRIPTION
Serial Interface
Data is transferred in 16-bit units by writing commands over a 3-line serial interface comprising OE (output
enable), SCL (serial clock) and SD (serial data input). Note that data transfer is unidirectional; no data is output
from the SM8230A. The operating sequence is described below.
Port
Serial Clock
OE
SCL
SD
CLK
BZH
R
CPU
Serial Data
(Clock)
SM8230
BZL
Piezo Buzzer
Figure 1. Serial interface connection example
Command transfer
Data can be transferred when OE goes LOW. Data is transferred in 16-bit units in sync with the rising edge of
the SCL clock.
Note that when OE is LOW and both SD and SCL are tied LOW, the current consumption is less than 1µA
(standby mode).
The internal states are undefined when power is first applied.
DTMF analog signal output
Data transfer stops and DTMF analog signal output starts when OE goes HIGH, as shown in figure 2.
OE
1
SCL
2
3
4
5
6
Serial data transmission
Piezo buzzer
output
7
8
b8
9
b7
10
b6
11
b5
12
b4
13
b3
14
b2
15
b1
16
b0
LSB
b15 b14 b13 b12 b11 b10 b9
SD
BZL
BZH
0
MSB
0
CK1 CK0 FH1 FH0 GH3 GH2 GH1 GH0 FL1 FL0 GL3 GL2 GL1 GL0
Low frequency
group output
High frequency
group output
Figure 2. Serial data transfer timing
SEIKO NPC CORPORATION —5
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