Page 1
Communication ICs
Pulse / tone dialer for telephone set
BU8307CS / BU8307CF
The BU8307CS and BU8307CF are large scale integrated circuits with a pulse dialer and tone dialer integrated on a
single chip. These products are capable of dialing in either pulse or tone mode, and can redial up to 32 digits.
Applications
Telephones and cordless telephones
Features
1) The chip includes both a pulse and tone dialer, making it possible to dial in either pulse or tone mode.
2) A wide operating voltage range enables direct powering by line current. The voltage range guaranteed
for both pulse and tone dialing is 2.5V to 5.5V.
3) A built-in memory enables redialing of up to 32 digits.
Note: In tone mode, the memory itself uses one digit,
so please be aware that a maximum of 31 digits can
be redialed.
4) The chip conforms to the standards of Japan, Ameri-
ca, Canada, England, Korea, Taiwan, and Australia.
5) The V
6) There is little deviation in the frequency dividing for
DD power supply voltage is independent of the
DTMF output level.
the DTMF output frequency. The maximum on the +
side is + 0.15%, and on the - side is – 0.08%.
Block diagram
163
Page 2
Communication ICs BU8307CS / BU8307CF
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions (Ta = 25_C)
164
Page 3
Communication ICs BU8307CS / BU8307CF
FElectrical characteristics (unless otherwise noted, Ta = 25_C, VDD = 3.0V)
165
Page 4
Communication ICs BU8307CS / BU8307CF
FElectrical AC characteristics (unless otherwise noted, Ta = 25_C, VDD = 3.0V)
166
Page 5
Communication ICs BU8307CS / BU8307CF
Electrical characteristic curves
167
Page 6
Communication ICs BU8307CS / BU8307CF
Measurement circuit
168
Page 7
Communication ICs BU8307CS / BU8307CF
Circuit operation
Keypad functions
to 9 These are numeric keys, and dial signals are
0
sent when one of these keys is pressed.
, # In tone mode, when these keys are pressed,
the corresponding DTMF signals are sent. In
pulse mode, if the #
pressed after going off-hook, the redial operation is executed. The
from pulse mode to tone mode.
A When this key is pressed, a 3.6-second pause
P
is generated. It also serves as a “break pause”
key when redialing.
T
R
H
This is used to switch from pulse mode to tone
mode. It also serves as a “break pause” key
when redialing.
This is used in both redial and inhibit redial operations. When redialing, it also serves as a
“break pause” key .
Pressing this key initiates on-hook operation.
is the first key to be
key switches the unit
169
Page 8
Communication ICs BU8307CS / BU8307CF
Key operations : Off-hook
: On-hook
(1) Normal dialing
to
D
1
n
D
After going off-hook, the dial data from the key input is
written to the redial memory, and the dial signals are sent
based on the specified mode (pulse or tone). There is no
upper limit on the number of digits that can be dialed. Key
input can also be entered during dial output. To inhibit
subsequent redialing, press the R
key twice after the dial
signals have been sent.
(2) Access pause
to
1
A
2
D
P
n
D
D
Pressing the PA key automatically initiates a 3.6-second
pause. Pauses can be stacked by simply pressing the P
key the required number of times, each time being one
3.6-second pause.
During a pause, dialing input is allowed,just as during dial
signal transmission. When redialing, if a pause is being
executed, it can be canceled by pressing the P
key during the pause. Multiple causes being executed
R
A , T , or
in succession can also be canceled by pressing the P
, or R key one time during the cumulative pause.
T
(3) Redial
R
(MODEIN = H or Z)
#
Redial is only accepted if the redial key is pressed immediately after going off-hook. After going off-hook,
pressing the R
key in tone mode or the # key in pulse
mode causes the last number dialed to be redialed. Key
input is not accepted when a redial signal is being output.
After the redial digits have been transmitted, any number
of valid key inputs are accepted and transmitted. The redial memory holds up to 32 digits. Redial is inhibited if
more than 32 digits are dialed in pulse mode, or more
than 31 digits are dialed in tone mode. In pulse mode, the
following can be written to the redial memory : 0
P
A and T . In tone mode, the following can be written to
the redial memory 0
to 9 , , # , and PA.
to 9 ,
Further redialing is inhibited following completion of the
redial output by pressing the R
key twice in succession.
Note: In tone mode, because one digit of memory is
used to store the mode, the maximum number of
valid digits available for redialing is 31.
(4) Mode switching (mixed mode dialing)
to
1
T (or )
D
i
D
to
D
i+1
(MODEIN = H or Z)
D
n
Switching from pulse mode to tone mode can be done
only once when in an off-hook state. Setting the mode
switching pin to the pulse mode (MODEIN = HIGH or Z)
and pressing the T
(or ) key writes the data required
to switch to tone mode into memory.
In pulse mode, pressing the T
(or ) key while the dial
signal is being sent automatically inserts a 3.6-second
pause after all digits up to that key have been transmitted, and all subsequent dial signals are transmitted as
tones. In this case, the
signal is sent out as a DTMF
signal. Also, because the information required to switch
to the tone mode is written to the memory, mixed dialing
is possible when redialing. When doing this, the mode
A
setting will match that at the time of key input, regardless
of the position of the MODEIN pin.
(5) Hooking
H
This initiates the hooking operation. After the operation
has been completed, a hooking pause is inserted auto-
A ,
matically . If a dial signal is being transmitted when the H
key is pressed, the dial sequence is immediately interrupted, and the hooking operation is initiated. The hooking time can be selected as either 607ms or 84ms, depending on the setting of the LH/SH pin. Pressing the H
key initiates the following sequence: off-hook on-hook
(hooking time) off-hook pause (hooking pause time)
off-hook operation.
Internal state of the IC when the H
The input mode is reset, and the circuit goes to stand-
1
key is pressed
by state in the pulse mode.
If the MODEIN pin is LOW, however, the state is recognized as tone mode.
The line pointer is reset, enabling redialing.
2
After the H key has been pressed, other subsequent
3
key input is enabled. The hooking operation is not written
to the memory. While the hooking operation is in progress, the only key input which is not accepted is the H
key. All other key input is accepted.
170
Page 9
Communication ICs BU8307CS / BU8307CF
Circuit operation
171
Page 10
Communication ICs BU8307CS / BU8307CF
172
Page 11
Communication ICs BU8307CS / BU8307CF
173
Page 12
Communication ICs BU8307CS / BU8307CF
Pin descriptions
(1) ROW1 to ROW4 and COL1 to COL4
These are the keyboard input pins. They can be connected to a 3 4 (2 of 7) standard keypad, or a 4 4
keypad. Key input becomes valid by either shorting a
single ROW
single ROW
input and a single COL input, or setting a
and a COL input to LOW at the same time.
If two keys are pressed at the same time, the key input
is ignored. In tone mode, a single tone can be generated
by pressing two or more keys in the same row or column
of the ROW1
to ROW4 and CL1 to COL3 matrices. If the
two keys are not in the same row or column, the key input
will be ignored.
(2) HS
This is the hook switching input pin. When this pin is
LOW, the state is perceived as off-hook, and when HIGH
, as on-hook. The pin is set to the off-hook state during
a dial signal transmission, and to the on-hook state during memory hold.
(3) 67%/60%
This switches the dial pulse break ratio. In LOW state, the
ratio is 60%, and in HIGH state, 67%.
(4) MODEOUT
This is the output pin for the mode state. When the output
mode is set to the pulse mode, this pin is Z level, and
when the output mode is set to the tone mode, this pin is
LOW. It goes to Z level when on-hook. The output is Nch
open drain output.
(5) MODEIN
This is the input pin for the mode state. When LOW, the
tone mode is effective, and when Z, the pulse mode at
10pps is effective, and when HIGH, the pulse mode at
20pps is effective.
If the T
key is input, however, the mode switches to the
tone mode, even if this pin is HIGH or Z state.
If this pin is set to HIGH or LOW level by applying resistance, the resistance level should be 10kΩ or less.
(6) OSCIN and OSCOUT
These are the input and output pins for the internal oscillator. A crystal resonator or ceramic resonator
(CSA3.58MGU300AB or CST3.58MGWU300AB) is connected between OSCIN and OSCOUT. If CSA3.58
MGU300AB is connected, a CH-type 30 pF capacitor
should be connected between each of these pins and V
SS.
(7) KEYTONE
This is the pin which outputs keytones. It has a CMOS
output. When off-hook, this pin outputs a key-press confirmation tone for all valid key input in pulse mode, and
for valid input of the P
The output frequency f
KT is 34ms. When there is no output, this pin is LOW.
t
A , R , and H keys in tone mode.
KT is 1193Hz and the output time
(8) LH/SH
This pin switches the hooking time. When LOW, the
hooking time is 84ms, and when HGH, 607 ms.
(9) DTMF
In tone mode, this pin outputs the corresponding DTMF
signal when a key is pressed. It is LOW level except when
a DTMF signal is being sent. This has CMOS output. A
20kΩ resistor should be connected between this pin and
V
SS.
(10) MFMUTE
This goes LOW when a DTMF signal is sent. When there
is no output, and when on-hook, it goes to Z level. This
is Nch open drain output.
(11) DPMUTE
When a dial pulse is being sent, and when an on-hook sequence is in progress, this goes LOW. In tone mode,
when there is no output, and in on-hook state, this goes
to Z level. The output is Nch open drain output.
(12) DP
In pulse mode, this pin outputs the corresponding dial
pulse when a key is pressed. It goes to Z level for a contact make and to LOW level for a contact break. It remains at Z level unless a dial pulse is being output. The
output is Nch open drain output.
174
Page 13
Communication ICs BU8307CS / BU8307CF
175
Page 14
Communication ICs BU8307CS / BU8307CF
176
Page 15
Communication ICs BU8307CS / BU8307CF
Operation notes
The reset circuits in the IC could fail to operate properly,
depending on the way the supply voltage rises when
power is applied. T o avoid problems, we recommend adding a circuit to the HS pin, as shown in the diagram below. (There is no need for this circuit, however, if the HS
pin momentarily goes HIGH by some other means, for
example, by CPU control.)
Application example
177
Page 16
Communication ICs BU8307CS / BU8307CF
Attached components
178
Page 17
Communication ICs BU8307CS / BU8307CF
External dimensions (Units: mm)
179
Loading...