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 VDD power supply voltage is independent of the DTMF output level. 6) There is little deviation in the frequency dividing for the DTMF output frequency. The maximum on the + side is + 0.15%, and on the - side is – 0.08%. Block diagram 163 Communication ICs FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) 164 BU8307CS / BU8307CF Communication ICs BU8307CS / BU8307CF FElectrical characteristics (unless otherwise noted, Ta = 25_C, VDD = 3.0V) 165 Communication ICs FElectrical AC characteristics (unless otherwise noted, Ta = 25_C, VDD = 3.0V) 166 BU8307CS / BU8307CF Communication ICs BU8307CS / BU8307CF Electrical characteristic curves 167 Communication ICs Measurement circuit 168 BU8307CS / BU8307CF Communication ICs BU8307CS / BU8307CF Circuit operation Keypad functions 0 to 9 These are numeric keys, and dial signals are 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 # is the first key to be pressed after going off-hook, the redial operakey switches the unit tion is executed. The from pulse mode to tone mode. When this key is pressed, a 3.6-second pause PA is generated. It also serves as a “break pause” key when redialing. T 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 opR erations. When redialing, it also serves as a “break pause” key. H Pressing this key initiates on-hook operation. 169 Communication ICs Key operations BU8307CS / BU8307CF : Off-hook : On-hook (1) Normal dialing D1 to Dn 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 D1 PA D2 to Dn Pressing the PA key automatically initiates a 3.6-second pause. Pauses can be stacked by simply pressing the PA 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 PA , T , or R key during the pause. Multiple causes being executed in succession can also be canceled by pressing the PA , T , or R key one time during the cumulative pause. (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 to 9 , PA and T . In tone mode, the following can be written to the redial memory 0 to 9 , , # , and PA . 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. 170 (4) Mode switching (mixed mode dialing) D1 to D i T (or ) Di+1 to Dn (MODEIN = H or Z) 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 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 automatically. 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 key is pressed 1 The input mode is reset, and the circuit goes to standby state in the pulse mode. If the MODEIN pin is LOW, however, the state is recognized as tone mode. 2 The line pointer is reset, enabling redialing. 3 After the H key has been pressed, other subsequent 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. Communication ICs BU8307CS / BU8307CF Circuit operation 171 Communication ICs 172 BU8307CS / BU8307CF Communication ICs BU8307CS / BU8307CF 173 Communication ICs 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 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 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 VSS. 174 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 confirmation 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 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. Communication ICs BU8307CS / BU8307CF 175 Communication ICs 176 BU8307CS / BU8307CF 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. To 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 Communication ICs Attached components 178 BU8307CS / BU8307CF Communication ICs BU8307CS / BU8307CF External dimensions (Units: mm) 179