BU8307CS Datasheet, PDF (12/17 Pages) Rohm – Pulse / tone dialer for telephone set

Communication ICs
FPin descriptions
(1) ROW1 to ROW4 and COL1 to COL4
These are the keyboard input pins. They can be con-
nected to a 3 4 (2 of 7) standard keypad, or a 4 4
keypad. Key input becomes valid by either shorting a
single ROW input and a single COL input, or setting a
single ROW 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 dur-
ing 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 resis-
tance, the resistance level should be 10kΩ or less.
(6) OSCIN and OSCOUT
These are the input and output pins for the internal oscilla-
tor. A crystal resonator or ceramic resonator
(CSA3.58MGU300AB or CST3.58MGWU300AB) is con-
nected 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 VSS.
BU8307CS / BU8307CF
(7) KEYTONE
This is the pin which outputs keytones. It has a CMOS
output. When off-hook, this pin outputs a key-press con-
firmation tone for all valid key input in pulse mode, and
for valid input of the PA , R , and H keys in tone mode.
The output frequency fKT is 1193Hz and the output time
tKT is 34ms. When there is no output, this pin is LOW.
(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
VSS.
(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 se-
quence 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 con-
tact make and to LOW level for a contact break. It re-
mains at Z level unless a dial pulse is being output. The
output is Nch open drain output.
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