ST3917A ST3917B SPEECH - TONE/PULSE DIALER - LED INDICATOR .. . . . . . SPEECH CIRCUIT 2 TO 4 WIRES CONVERSION PRESENT THE PROPER DC PATH FOR THE LINE CURRENT AND THE FLEXIBILITY TO ADJUST IT ANDALLOWPARALLEL PHONE OPERATION SYMMETRICAL HIGH IMPEDANCE MICROPHONE INPUTS SUITABLE FOR DYNAMIC, ELECTRET OR PIEZOELECTRIC TRANSDUCER ASYMMETRICAL EARPHONE OUTPUT SUITABLE FOR DYNAMIC TRANSDUCER LINE LOSS COMPENSATION FIXED INTERNALLY BY A.G.C. INTERNAL MUTING TO DISABLE SPEECH DURING DIALING AND EXTERNAL MUTING TO DISABLE TRANSMIT AMPLIFIER DURING CONVERSATION MODE LED INDICATOR EITHER FOR KEYBOARD ILLUMINATION (OR ON-LINE INDICATION) DURING DIALING AND CONVERSATION OR FOR TONE MODE INDICATION, THROUGH MU/MFI PIN . .. .. . . . . . DIALER CIRCUIT STORE UP TO 32 DIGITS FOR LAST NUMBER REDIAL BUFFER, LNR IS INHIBITED IF THERE ARE MORE THAN 32 DIGITS STORED ALLOWMIXED MODE DIALING IN PULSE MODE PACIFIER TONE PROVIDES AUDIBLE INDICATION OF VALID KEY PRESSED IN A BUZZER OR/AND IN THE EARPHONE TIMED PABX PAUSE / 10PPS PULSE RATE MAKE/BREAK RATIO : 40/60 (ST3917A) AND 33/67 (ST3917B) 4 SELECTABLE OPTIONS ON FLASH DURATION AND SOFTSWITCH INHIBITION IN ONE OF THE OPTION WITH 100ms FLASH TIMING 2 SELECTABLE OPTIONS : TRANSMIT MUTE TOGETHER WITH LED FOR KEYBOARD ILLUMINATION OR LED FOR TONE MODE INDICATION CONTINUOUS TONE FOR EACH DIGIT UNTIL KEY RELEASE USES INEXPENSIVE 3.579545MHz CERAMIC RESONATOR POWERED FROM TELEPHONE LINE, LOW OPERATING VOLTAGE FOR LONG LOOP APPLICATION July 1996 DESCRIPTION The device consists of the speech and the dialer functions. It provides the DC line interface circuit that terminates the telephone line, analog amplifier for speech transmission and necessary signals for either DTMF and pulse dialing. When mated with a tone ringer, a complete telephonecan be producedwith just two ICs. TheDClineinterfacecircuit developsits ownlinevoltage acrossthedeviceandit is adjustableby externalresistor to suit different country’s specification. A built-in LED driver can deliver excess line current to external LED indicator(s) during dialing and speech mode. The LED(s) can be used either for keyboard illumination purpose or for tone mode indication during softswitch and mixed mode dialing by connecting MU/MFI pin to VDDandGND oranyrowrespectively.The LEDcurrent is limited to 17mA (typical). The speech network provides the two to four wires interface,electronic switchingbetweendialingandspeechand automaticgain control on transmit and receive. The dialing network buffers up to 32 digits into the LND memorythatcan be laterredialedwith asinglekeyinput. Users can store all 13 signalling keys and access several unique functions with single key entries. These functions include : Pause, Last Number Dialled (LND), Softswitch and Flash. (see Figure 1). The FLASH key simulates a hookflash to transfercalls or to activate other special features provided by the PABX or central office. The PAUSE key stores a timed pause in the number sequence. Redial is then delayed until an outside line can be accessed or some other activities occur before normal signalling resumes. A LND key automatically redials the last number dialed. Adedicatedpin MU/MFI is used to select the muting for transmit amplifier and lighted dial LED for keyboard illumination or a LEDindicator for tonemode indication. The SEL pin allows selection of any one of the four possible Flash duration options. DIP28 (Plastic Package) ORDER CODES : ST3917AN - ST3917BN SO28 (Plastic Package) ORDER CODES : ST3917AD - ST3917BD 1/16 ST3917A - ST3917B C1 1 28 R1 C2 2 27 R2 C3 3 26 R3 SEL 4 25 R4 OSC 5 24 MU/MFI PULSE 6 23 VDD MODE/PT 7 22 GDTMF HKS 8 21 MIC+ GND 9 20 MIC- RXOUT 10 19 GTX GRX 11 18 REG RXIN 12 17 LN IREF 13 16 ILINE VCC 14 15 LED PIN DESCRIPTION 1 2 3 Flas h 4 5 6 Tone /P ulse 7 8 9 P a us e * 0 # LND C1, C2, C3, R4, R3, R2, R1 (Keyboard inputs, Pins 1, 2, 3, 25, 26, 27, 28) The device interfaces with either the standard 2 of 8 with negative common or the single contact (Form A) keyboard. Column 4 of the keypad is connecting to ground. A valid keypad entry is either a single Row connected to a single Column or GND simultaneously presented to both a single Row and a single Column. In its quiescent or standby state, during normal off-hook operation, the Rows are initialized at logic level 1 (VDD) and the columns are initialized at logic level 0 (GND). Pulling any row input low enables the on chip oscillator. Keyboard scanning then begins. 2/16 3917-02.EPS Figure 1 : Keyboard Configuration Scanning consists of Rows and Columns alternately switching high through on chip pullups. After both a Row and Column keys have been detected, the debounce counter is enabled and any noise (bouncing contacts, etc) is ignored for a debounce period (TKD) of 32ms. At this time, the keyboard is sampled and if both the Row and Column information are valid, the information is buffered into the LND location. In the tone mode, if two or more keys in the same row or if two or more keys in the same column are depressed a single tone will be output. The tone will correspond to the common row or common column for which the two keys were pushed. This feature is for test purposes, and single tone will not be redialed. Also in the tone mode, the output tone is continuous in the manual dialing as long as the key is pushed. The output tone duration follows the Table 1. When redialing in the tone mode, each DTMF output is 90ms duration, and the tone separation (inter signal delay) is 90ms. Table 1 : Output Tone Duration Key Push Time, T Tone Output T < 32ms No output, ignored by the device 32ms < T < 90ms + Tkd 90ms duration T > 90 ms + Tkd Output duration = T - tkd 3917-01.EPS PIN CONNECTIONS ST3917A - ST3917B PIN DESCRIPTION (continued) SEL (Input, Pin 4) This is an option selectable pin for four Flash duration. The four options are summarised in the table 2. For option 1, softswitch feature is inhibited. It means redialed by the LND key in pulse mode will not repeat the softswitch and subsequent digits, only pulse digits are dialed out. Table 2 : Options Selectable for Flash Duration Options SEL Flash (ms) Softswitch 1 VDD 100 Inhibited 2 GND 600 Enable 3 Any Row 300 Enable 4 Any Col 100 Enable OSC (Input, Pin 5) Only one pin is needed to connect the ceramic resonator to the oscillator circuit. The other end of the resonator is connected to GND. The nominal resonator frequency is 3.579545MHz and any deviation from this standard is directly reflected in the Tone output frequencies. The ceramic resonator provides the time reference for all circuit functions. A ceramic resonator with tolerance of ±0.25% is recommended. PULSE (Output, Pin 6) This is an output consisting of an open drain Nchannel device. During on-hook, pulse output pin is in high impedance and once off-hook, it will be pulled high by external resistor. MODE/PT (Input, Pin 7) Input (MODE). MODE determines the dialer’s default operating mode. When the device is powered up or the hookswitch input is switched from onhook (VDD) to off-hook (GND), the default determines the signalling mode. A VDD connection defaults to tone mode operation and a GND connection defaults to pulse mode operation. When dialing in the pulse mode, a softswitch feature will allow a change to the tone mode whenever the * or softswitch key (TONE) is depressed. Subsequent * key inputs will cause the DTMF code for an * to be dialed. The softswitch will only switch from pulse to tone. The phone will be in pulse mode only after returning to on-hook and back to offhook. Redialed by the LND key will repeat the softswitch unless the softswitch redial feature is inhibited. Output (PT). Pacifier Tone Output. In pulse mode, all valid key entries activate the pacifier tone. In tone mode, any non DTMF entry (FLASH, PAUSE, LND, TONE) activates the pacifier tone. The pacifier tone provides audible feedback, confirmingthat the key has been properly entered and accepted. It is a 500Hz square wave activated upon acceptance of valid key input after the 32ms debounce time. The square wave terminates after 75ms typically or when the valid key is no longer present. The pacifier tone signal is simultaneously sent to the earphone and the buzzer. The buzzer can be removed without affecting this function. The resistor value set on MODE/PT pin determines the level of the pacifier tone in the earphone. HKS (Input, Pin 8) This is the hookswitch input to the device. It is a CMOS input with a high pull up internal resistance and must be switched high or open for on-hook operation and low for off-hook operation. A transition on this input causes the on-chip logic to initialize, terminating any operation in progress at the time. The signalling mode defaults to the mode selected at MODE/PT pin. Figures 2, 3 and 4, 5 illustrate the timing for this pin. GND (Pin 9) GND is the negative line terminal of the device.This is the voltage reference for all specifications. RXOUT, GRX, RXIN (Pins 10, 11 and 12) The receive amplifier has one input RXIN and a non inverting output RXOUT. Amplification from RXIN to RXOUT is typically 31dB and it can be adjusted between 21dB and 41dB to suit the sensitivity of the earphone used. The amplification is proportional to the external resistor connected between GRX and RXOUT. For the hearing impaired, a specific application to offer 17dB additional gain at 3kHz is permitted. IREF (Pin 13) An external resistor of 3.6kΩ connected between IREF and GND will set the internal current level. Any change of this resistor value will influence the microphone gain, DTMF gain, earphone gain and sidetone level. VCC (Pin 14) VCC is the positive supply of the speech network. It can be stabilized by a decoupling capacitor between VCC and GND. The VCC supply voltage may also be used to supply external peripheral circuits. 3/16 ST3917A - ST3917B PIN DESCRIPTION (continued) LED (Output, Pin 15) When the MU/MFI pin is connected to either VDD or GND, the LED connected to the LED pin, which functions as a keyboard illumination or off-hook indicator, will light up when the telephone is offhook. When the MU/MFI pin is connected to anyrow pins, the LED connected to LED pin functions as a tone mode indicator. From minimum operating line current up to 20mA, ILN-ICC is sourced into the LED with a maximum current limit of 18mA. For line current more than 20mA, this sourced current is limited at 18mA (typical). ILINE (Pin 16) A recommended external resistor of 20Ω is connected between ILINE and GND. Changing this resistor value will influence the microphone gain, DTMF gain, sidetone, maximum output swing on LN and the DC characteristics, especially in the low voltage region. LN (Pin 17) LN is the positive line terminal of the device. REG (Pin 18) The internal voltage regulator has to be decoupled by a capacitor from REG to GND. The DC characteristics can be changed with an external resistor connected between LN and REG or between REG and ILINE. GTX, MIC-, MIC+ (Pins 19, 20, 21) The device has a symmetrical microphone inputs. The amplification from microphone inputs to LN is 51dB at 15mA line current and it can be adjusted between 43 and 51dB. The amplification is proportional to the external resistor connected between GTX and REG. 4/16 GDTMF (Pin 22) When the DTMF input is enabled, the microphone inputs and the receive amplifier input will be muted and the dialing tone will be sent on the line. The voltage amplification from GDTMF to LN is 40dB. Final output level on the LN can be adjusted via the external resistor connected between GDTMF and GND through a decoupling capacitor. A confidence tone is sent to the earphone during tone dialing. The attenuation of the confidence tone from LN to RXOUT is -32dB typically. The level of the confidence tone in the earphone can be increased by adjusting the resistor connected between GDTMF and GRX pins, the possible range is 20dB. VDD (Pin 23) VDD is the positive supply for the dialing circuit and it must meet the maximum and minimum voltage requirements. MU/MFI (Input, Pin 24) A logic low input to this pin will disable the transmit amplifier of the speech circuit. MUTE efficiency is greater than 60dB. An open circuit to this pin will enable the transmit amplifier. In this case, LED is used for keypad lighting. A connection to any row will disable the transmit mute function and the LED connected to the LED pin is used for tone mode indication. Table 3 : Logic of MU/MFI Pin Indicator MU/MFI Pin Transmit Muting LED at Pin 15 OPEN Active Lighted Dial Indicator GND Muted Lighted Dial Indicator Any Row Not Available Tone Mode Indicator 3917-03.EPS C14 CMF IREF VCC MIC- MIC+ RMF GDTMF R14 C10 20 21 22 13 14 R15 C8 gm gm k IREF K IREF IREF ST3917A/B D12 + 19 RGTX GTX 23 VDD 16 ILINE V1 LN 17 R21 R20 ILINE/ILED CONTROL 15 LED 18 C20 REG Ri2 Ri1 PULSE 12 R24 C11 RXIN I1 GND K IREF K IREF R25 gm gm LN 9 RAM REDIAL DTMF GENERATOR LOGIC + DAC MUTE PULSE INTERFACE 6 8 7 OSCILLATOR KEYBOARD INTERFACE 4 SEL HKS MODE 10 11 5 24 RXOUT GRX OSC 8 7 0 5 4 * 2 1 + # 9 6 3 C9 RGRX 3.58MHz Ceramic MU/MFI Ci Ri Secret LND Pause Tone/Pulse Flash LB LA ST3917A - ST3917B BLOCK DIAGRAM 5/16 ST3917A - ST3917B Symbol VLN ILN VDD VI Toper Tstg Ptot Parameter Positive Line Voltage Continuous Line Current Logic Voltage Maximum Voltage on PULSE, SEL, HKS, MODE, Ri, Ci, MU/MFI and OSC Pins Operating Temperature Storage Temperature Total Power Dissipation Value 12 140 7 GND(-0.3) VDD(+0.3) Unit V mA V V -25, +70 -40, +125 700 °C °C mW 3917-01.TBL ABSOLUTE MAXIMUM RATINGS ELECTRICAL CHARACTERISTICS (ILN = 10mA to 120mA, f = 1kHz, Tamb = 25°C, VDD = 3V ; unless otherwise specified) VLN Parameter Line Voltage (see Figure 6) Test Conditions ILN = 4mA ILN = 15mA ILN = 120mA ILN = 15mA, RA = 68kΩ ILN = 15mA, RB = 39kΩ Min. Typ. 3.15 3.50 2.60 3.60 3.20 4.10 VDD Logic Voltage (see Figure 6) Tone mode Pulse mode IDD Supply Current into VDD (see Figure 6) VDD = 3V ICC Supply Current into VCC (see Figure 6) ILN = 15mA 1.3 ILED Supply Current to LED (see Figure 6) ILN = 10 - 20mA ILN = 20 - 120mA ILNICC VMR Memory Retention Voltage (see Figure 7) VDD = 3V IMR Memory Retention Current (see Figure 7) VDD = 3V IS Off-Hook Standby Current (see Figure 6) VDD = 3V IPL Pulse Output Sink Current (see Figure 6) VOUT = 0.5V IPO Pacifier Tone Sink/Source Current (see Figure 6) VIL HKS, Mode, Keyboard Inputs Low VIH HKS, Mode, Keyboard Inputs High GTX Transmit Gain (see Figure 9) AGTX Transmit Gain Variation (see Figure 9) 2.50 2.00 Tone mode Pulse mode VOUT = 0.5V(Sink) VOUT = 2.5V(Source) ILN = 15mA, VMIC = 2mVRMS RGTX = 43kΩ RGTX = 27kΩ Transmit Distortion (see Figure 9) ILN = 15mA, VLN = 1VRMS Transmit Noise (see Figure 9) ILN = 15mA, VMIC = 0V ZMIC Microphone Input Impedance (see Figure 8) DTMF Gain (see Figure 10) DTMF Confidence Tone Attenuation (see Figure 10) VDTMF DTMF level on the line (see Figure 10) High Frequency Group Low Frequency Group PEI Pre-emphasis (see Figure 10) DIS DTMF Output Distortion (see Figure 10) 6/16 V V V V V 6.00 6.00 V V 900 600 µA µA mA 24 1.5 100 1 µA 250 µA 1 3 mA 1.00 0.60 3.00 1.00 mA mA 49.5 43 R DTMF = 2.25kΩ, C DTMF = 22nF V V 51 45 -8 52.5 47 dB dB 0 dB -4 -8 dB dB 2 -72 50 R DTMF = 2.25kΩ, C DTMF = 22nF mA mA V 0.7xVDD VMIC = 2mVRMS ILN = 15mA, RGTX = 68kΩ ILN = 60mA, RGTX = 68kΩ NTX CDTMF 10 Unit 2.70 3.85 7.00 3.70 4.70 0.3xVDD DTX GDTMF 600 300 Max. 64 % dBmp 80 kΩ 37 39 41 dB -34 -31.5 -29 dB -8 -10 -6 -8 -4 -6 dBm dBm 2 3 dB 5 8 % 1 3917-02.TBL Symbol ST3917A - ST3917B ELECTRICAL CHARACTERISTICS (continued) (ILN = 10mA to 120mA, f = 1kHz, Tamb = 25°C, VDD = 3V ; unless otherwise specified) ZDTMF Parameter Receive gain (see Figure 11) GRX AGRX Receive Gain Variation (see Figure 11) Receive Distortion (see Figure 11) D RX Test Conditions DTMF Attenuation Pin Impedance VINP = 4mVRMS, R E = 300Ω, RGRX=100kΩ ILN = 15mA ILN = 60mA Min. Typ. Max. Unit 25 32 39 kΩ 29.5 23.0 31.0 25.0 32.5 27.0 dB dB 10 dB -20 VINP = 4mVRMS, R E = 300Ω, ILN = 15MA RGRX = 10KΩ RGRX = 300kΩ -20 +10 dB dB ILN = 15mA, RGRX=100kΩ RE = 150Ω, VEAR = 0.25VRMS RE = 300Ω, VEAR = 0.45VRMS RE = 450Ω, VEAR = 0.55VRMS 2 2 2 % % % N RX Receive Noise (see Figure 11) ILN = 15mA, RE = 300Ω R GRX = 100kΩ, VINP = 0V 200 µV ZOUT Receive Output Impedance (see Figure 11) ILN = 15mA 35 Ω VPT Pacifier Tone Level on Earphone (see Figure 11) ILN = 15mA RP = ∞ RP = 430kΩ 60 600 mVRMS mVRMS Keyboard Interface Keypad Debounce Time Keypad Scan Frequency Keypad Pullup Resistance Keypad Pulldown Resistance See Figures 4 and 5 32 250 100 500 ms Hz kΩ Ω Tone Mode Tone Output Rise Time Tone Signalling Rate Presignal Delay Intersignal Delay Tone Output Duration See Figures 2 and 3 Pulse Mode Pacifier Tone Duration Pacifier Tone Frequency Pulse Rate Break Time : ST3917A ST3917B Make Time : ST3917A ST3917B Interdigital Pause Predigital Pause : ST3917A ST3917B See Figures 4 and 5 TKD FKS KRU KRD TRIS TR TPSD TISD TDUR TPT FPT PR TB TM IDP PDP 5 90 90 ms 1/sec ms ms ms 75 500 10 60 67 40 33 820 50 43 ms Hz PPS ms ms ms ms ms ms ms 5.55 40 Option Selectable Symbol Parameter Option 1 SEL = VDD Option 2 SEL = GND Option 3 SEL = ROW Option 4 SEL = COL Unit tFLASH Timed Hook Flash (see Figures 2 and3) 100 600 300 100 ms Notes : 1. 2. 3. 4. All inputs unloaded. Quiescent mode (oscillator off). Pulse output sink current for VOUT = 0.5V at VDD = 3V. Pacifier tone sink current for VOUT = 0.5V, source current for VOUT = 2.5V at VDD = 3V. Memory retention voltage is the point where memory is guaranteed but circuit operation is not. Proper memory retention is guaranteed if either the minimum IMR is provided or the minimum VMR. The design does not have to provide both the minimum current and voltage. 5. Option 1 is with softswitch inhibition. 7/16 3917-02.TBL Symbol ST3917A - ST3917B DEVICE OPERATION During on-hook all keypad inputs are high impedance internally and it requires very low current for memory retention.At anytime,row inputs are initialized at logic level 1 and column inputs are initialized at logic level 0 at off-hook. The circuit verifies that a valid key has been entered by alternately scanning the Row and Column inputs. If the input is still valid following 32ms of debounce,the digit is stored into memory, and dialing begins after a pre-signal delay of approximately 40ms measured from the initial key closure. Output tone duration is shown in Table 1. The device allows manual dialing of an indefinite number of digits, but if more than 32 digits are dialed, LND will be inhibited. Table 4 : DTMF Output Frequencies (Hz) Key Input Std Frequency Output Frequency % in Deviation Row 1 Row 2 Row 3 Row 4 Column 1 Column 2 Column 3 697 770 852 941 1209 1336 1477 699.1 766.2 847.4 948 1215.9 1331.7 1471.9 +0.31 -0.49 -0.54 +0.74 +0.57 -0.32 -0.35 Last Number Dialed Off-Hook LND Last number redialing is accomplished by entering the LND key at off-hook or after the FLASH key, the subsequent LND keys pressed will be ignored. Sequence Digit Emitted OFF-HO OK, D1, D2, ON-HOOK D1, D2 OFF-HOO K, LND, LND, ON-HOOK D1, D2 OFF-HOO K, D3, D4, LND, ON-HOOK D3, D4 OFF-HO OK, LND, ON-HOOK D3, D4 Last Number Dialed Inhibition Last number redialing by LND key is inhibited if there are more than 32 digits stored. Last Number Dialed Cascading Digits dial after the LND will cascade into the LND buffer for the next redialing. In cascade operation, the keyboard is inhibited upon pressing the LND key, the LND output must be completed before acceptance of any key entry. Sequence Digit Emitted OFF-HO OK, D1, D2, ON-HOOK Normal Dialing D D D ... Normal dialing is straight forward, all keyboard entries will be stored in the buffer and signalled in succession. Hook Flash D Flash D ... Hook flash may be entered into the dialed sequence at any point by keying in the function key, FLASH. When a FLASH key is pressed, no further key inputs will be accepteduntilthe hookflashfunctionhasbeen dialed.The key inputfollowing aFLASH will be stored as the initial digit of the new number (overwriting the numberdialed beforethe FLASH) unless it is another FLASH. FLASHkey pressed immediatelyafterhookswitch or LND will not clear the LND buffer unless digits are entered following the FLASH key. Flash LND not cleared LND Flash LND not cleared LND Flash D1 D2 LND buffer will contain D1, D2 8/16 D1, D2 OFF-HOO K, LND, D3, D4, ON-HOOK D1, D2, D3, D4 OFF-HO OK, LND, ON-HOOK D1, D2, D3, D4 Pause Off-Hook D Pause D ... A pause may be entered into the dialed sequence at any point by keying in the special function key, PAUSE. Pause inserts a 3.1 seconds (Tone mode) or 3.4 seconds (Pulse mode) delay into the dialing sequence. The total delay, including predigit and post digit pauses as shown in Table 5. Table 5 : Special Function Delays Delay (second) Function First / Auto SOFTSWITCH First Auto 0.2 1 PAUSE First Auto 2.6 3.4 Pulse Tone 3.0 3.1 Each delay shown in Table 5 represents the time required from the time the special function key is depressed until a new digit is dialed. The time is considered ”FIRST” key if all previous inputs have been completely dialed. The time is considered ”AUTO” if in redial, or if previous digits dialing is still in progress. ST3917A - ST3917B DEVICE OPERATION (continued) Led Indicator / Tone Mode Indication the LED will light up to indicate the switch to tone mode or tone dialing. The LED will turn off only when the telephone goes on-hook or is reset by the Flash key Examples : Pulse mode a) OFF-HOOK (LED is off) <Pulse> D1, D2 (LED remains off),”*” <Tone> (LED turns on), D3, D4 ON-HOOK or Flash (LED turns off) b) OFF-HOOK (LED is off) <Pulse> LND <Pulse> D1, D2 (LED remains off), ”*” <Tone> (LED turns on) D3, D4, ON-HOOK or Flash (LED turns off) - At Pulse mode, after off-hook, LED is off during pulse dialing. When switching the Tone/Pulse mechanical switch to Tone mode, LED will turn on. Example : Pulse mode OFF-HOOK (LED is off) <Pulse> D1, D2 Switch ”Tone/Pulse” mechanical switch to Tone mode (LED turns on) <Tone> D3, D4, ON-HOOK (LED turns off) The function of the LED for Tone mode indicator is described in the timing waveform in Figures 2, 3, 4 and 5. When the MU/MFI (Pin 24) is connected to any row of the keypad input, the LED connected to Pin 15 (LED) becomes a Tone mode indicator. The LED indicator is used in the following conditions : - At Tone mode, LED will light up at off-hook. The LED will turn off only when the telephone goes on-hook. Example : Tone mode OFF-HOOK (LED turns on) <TONE> D1, D2, D3 ON-HOOK (LED turns off) OFF-HOOK (LED turns on) <TONE> LND ON-HOOK (LED turns off) - At Pulse mode after off-hook, LED is off during pulse dialing. When dialing is followed by the ”*” or ”TONE” softswitch key depressed, the LED will light up immediately at the softswitch after pulse dialing is completed to indicate the signalling mode change from pulse to tone. After returning to on-hook and back to off-hook, the device will be in pulse mode and then LED is turned off. Redialing from LND memory buffer will repeat the softswitch, i.e. mixed mode redialing, Figure 2 : Tone Mode Timing with Lighted Dial LED (Pin 24 to VDD or GND) Keybo ard Inp ut * 1 Dial Se que nc e FLAS H 3 3 : Debounce Time ENTE R ENTER E NTER ENTER 1 * FLASH 3 3 Keybo ard S c an KE YBOARD S CAN 3 DTMF Outpu t (P in 17) 3 LED ON OFF 3917-04.EPS Tflas h P ULS E Outpu t ON 9/16 ST3917A - ST3917B Figure 3 : Tone Mode Timing with Tone Indicator (Pin 24 to any row) Keyb oard Input * 1 Dial Se quenc e FLASH 3 3 : Debounce Time ENTER ENTER ENTER ENTER 1 * FLASH 3 3 Keyb oard Sc an KEYBOARD SCAN 3 DTMF Outpu t (P in 17) 3 LED ON OFF 3917-05.EPS Tflas h P ULSE Outpu t ON Figure 4 : Pulse Mode Timing with Lighted Dial LED (Pin 24 to VDD or GND) Keyb oa rd Inp ut * 1 Dial S equ enc e FLAS H 3 3 : De bounce Time ENTER ENTE R E NTER ENTE R 1 * FLASH 3 3 Keyb oa rd S ca n KEYBOARD S CAN 3 DTMF Outp ut (P in 17) 3 LED ON OFF 3917-06.EPS Tflas h P ULSE Outp ut ON Figure 5 : Pulse Mode Timing with Tone Indicator Using ”*” or ”Tone” Key Keyb oa rd Inp ut * 1 Dia l Se qu en ce FLASH LND 3 : De bounce Time E NTER ENTE R ENTER E NTER 1 * FLAS H LND 3 Keyb oa rd S ca n KEYBOARD S CAN 3 DTMF Outp ut (Pin 17) 3 LED 10/16 OFF ON OFF ON 3917-07.EPS Tflas h P ULSE Outp ut ST3917A - ST3917B Figure 6 : Test VDD Row Col IPL 3.58MHz mA Pulse ST3917A/B 1 C1 R1 2 8 1 2 3 FLASH 2 C2 R2 2 7 4 5 6 TONE/P ULSE 3 C3 R3 2 6 7 8 9 PAUSE 4 S EL R4 2 5 # OSC MU/MFI 2 4 * 0 5 6 P ULSE 7 MODE/PT 8 HKS 9 GND VDD 2 3 100kΩ S W2 Tone + LND SECRET RDTMF GDTMF 2 2 470nF CDTMF S W1 MIC+ 2 1 1 0 RXOUT RGRX 1 F MIC- 2 0 1 F RGTX 1 1 GRX + GTX 1 9 10 F Re IDD 4.7 F 100pF 100pF 1 2 RXIN 3.9kΩ + VLN REG 1 8 RA 1 3 IREF LN 1 7 1 4 VCC ILINE 1 6 + LED 100 F 100 F RB ILED 130kΩ ILN LED 1 5 600Ω 20Ω 390Ω 3.9kΩ ICC 3917-08.EPS 390Ω 100nF 620Ω Figure 7 : Test VMR Row Col 470kΩ 3.58MHz P ulse Tone S T3917A/B 1 C1 R1 2 8 1 2 3 FLASH 2 C2 R2 2 7 4 5 6 TONE/P ULSE 3 C3 R3 2 6 7 8 9 PAUSE 4 S EL R4 2 5 # OS C MU/MFI 2 4 * 0 5 6 P ULSE 7 MODE/PT 8 HKS 9 GND VDD 2 3 100kΩ S W2 + RDTMF 470nF CDTMF 1 0 RXOUT 11 MIC+ 2 1 MIC- 2 0 GRX 1 F 1 F RGTX GTX 1 9 10 F Re LND SECRET GDTMF 2 2 S W1 RGRX IMR + 4.7 F 100pF 3.9kΩ + 100pF 12 RXIN 13 IREF LN 1 7 VCC ILINE 1 6 REG 1 8 LED 14 130kΩ 100 F LED 1 5 20Ω 390Ω 3.9kΩ 3917-09.EPS 390Ω 100nF 620Ω 11/16 ST3917A - ST3917B Figure 8 : Test Row Col 470kΩ 3.58MHz P ulse S T3917A/B 1 C1 R1 28 1 2 3 FLASH 2 C2 R2 27 4 5 6 TONE/P ULSE 3 PAUSE C3 R3 26 7 8 9 4 S EL R4 25 # OS C MU/MFI 24 * 0 5 6 P ULSE 7 MODE/PT 8 HKS 9 GND VDD 23 100kΩ SW2 Tone RDTMF GDTMF 22 470nF S W1 CDTMF Imic 1.2 Imic 1.2V MIC- 2 0 1 1 GRX RGTX + GTX 1 9 10 F Re Zmic = MIC+ 21 1 0 RXOUT RGRX + LND S ECRET 4.7 F 100pF 100pF 1 2 RXIN 3.9kΩ REG 1 8 1 3 IREF LN 1 7 1 4 VCC ILINE 1 6 LED + 130kΩ 100 F LED 1 5 20Ω 390Ω 3.9kΩ 3917-10.EPS 390Ω 100nF 620Ω Figure 9 : Test VDD Row Col 3.58MHz P ulse Tone C1 R1 2 8 1 2 3 FLASH 2 C2 R2 2 7 4 5 6 TONE/P ULSE 3 C3 R3 2 6 7 8 9 PAUSE 4 S EL R4 2 5 # 5 OSC MU/MFI 2 4 * 0 6 P ULSE 7 MODE/PT 8 HKS 9 GND VDD 2 3 100kΩ S W2 + 470nF CDTMF 1 0 RXOUT MIC+ 2 1 MIC- 2 0 1 1 GRX GTX = 20 log 1 F 1 F RGTX GTX 1 9 10 F Re RDTMF GDTMF 2 2 SW1 RGR X LND S ECRET VLN Vmic Vmic + 4.7 F 100pF 3.9kΩ + 1 2 RXIN 100pF VLN REG 1 8 1 3 IREF LN 1 7 1 4 VCC ILINE 1 6 + LED 100 F 130kΩ ILN 100 F LED 1 5 20Ω 600Ω 390Ω 390Ω 100nF 12/16 620Ω 3.9kΩ 3917-11.EPS 470kΩ S T3917A/B 1 ST3917A - ST3917B Figure 10 : Test VDD Row Col 470kΩ 3.58MHz P ulse ST3917A/B 1 C1 R1 2 8 1 2 3 FLASH 2 C2 R2 2 7 4 5 6 TONE/P ULSE 3 C3 R3 2 6 7 8 9 P AUSE 4 S EL R4 2 5 # OSC MU/MFI 2 4 * 0 5 6 P ULSE VMF VDD 2 3 100kΩ 7 MODE/PT 8 HKS 9 GND S W2 Tone 470nF CDTMF MIC+ 2 1 1 0 RXOUT RGR X MIC- 20 1 1 GRX GDTMF = 20 log 1 F 1 F RGTX CDTMF = 20 log Re VLN VMF Vear VLN + GTX 19 10 F Vear RDTMF GDTMF 2 2 S W1 + LND SECRET 4.7 F 100pF 3.9kΩ + 100pF 1 2 RXIN VLN REG 18 1 3 IREF LN 17 1 4 VCC ILINE 16 + LED 100 F 130kΩ ILN 100 F LED 15 600Ω 20Ω 390Ω 3.9kΩ 3917-12.EPS 390Ω 100nF 620Ω Figure 11 : Test VDD Row Col 470kΩ 3.58MHz P ulse Tone S T3917A/B 1 C1 R1 2 8 1 2 3 FLASH 2 C2 R2 2 7 4 5 6 TONE/P ULSE 3 C3 R3 2 6 7 8 9 PAUSE 4 SEL R4 2 5 # 5 OS C MU/MFI 2 4 * 0 6 PULSE 7 MODE/P T 8 HKS 9 GND VDD 2 3 100kΩ S W2 470nF CDTMF 10 RGRX RXOUT Re MIC+ 2 1 MIC- 2 0 1 1 GR X GRX= 20 log Vear Vinp 1 F 1 F RGTX GTX 1 9 10 F Vear RDTMF GDTMF 2 2 S W1 + LND SECRET + 4.7 F 100pF 3.9kΩ + 1 2 RXIN 100pF VLN REG 1 8 1 3 IREF LN 1 7 1 4 VCC ILINE 1 6 + LED 100 F 130kΩ 100 F ILN LED 1 5 20Ω 390Ω 3.9kΩ 100nF 3917-13.EPS 390Ω Vinp 620Ω 13/16 ST3917A - ST3917B TYPICAL APPLICATION 2S A1013 100kΩ 3.3k Ω 150k Ω 10V 5.6kΩ BF393 10Ω HKS1 A 10MΩ Options 1 C1 2 S T3917A/B R1 28 1 2 3 FLASH C2 R2 27 4 5 6 TONE/PULSE 3 C3 R3 26 7 8 9 P AUSE 4 S EL R4 25 # LND 5 OS C * 0 6 P ULSE 7 MODE/PT 8 HKS 9 GND B Ce ramic 1 F 2.2k Ω 3 24kΩ 4 6 5 MU/MFI 24 100kΩ P ulse VDD 23 3.3kΩ GDTMF 22 HKS2 4.7 F + + 470nF 10nF 10 RXOUT 100kΩ MIC+ 21 Microphone MIC- 20 11 GRX + GTX 19 Earphone 7 Buzzer 2 DTMF 10 F 8 L3240 100nF 1 SE CRE T 3.58MHz 12 RXIN 3.6kΩ REG 18 13 IRE F LN 17 14 VCC ILINE 16 10 F 47kΩ LED 15 Zside tone 14/16 620Ω 4.7nF 3.9kΩ 3917-14.EPS + 20 Ω + BAT42 100 F 5.6V 470 F 100nF LED ST3917A - ST3917B PM-DIP28.EPS PACKAGE MECHANICAL DATA 28 PINS - PLASTIC PACKAGE a1 b b1 b2 D E e e3 F I L Min. Millimeters Typ. 0.63 0.45 0.23 Max. Min. 0.31 0.009 1.27 2.54 33.02 0.012 1.470 0.657 0.598 0.100 1.300 14.1 4.445 3.3 Max. 0.050 37.4 16.68 15.2 Inches Typ. 0.025 0.018 0.555 DIP28.TBL Dimensions 0.175 0.130 15/16 ST3917A - ST3917B PM-SO28.EPS PACKAGE MECHANICAL DATA 28 PINS - PLASTIC PACKAGE Dimensions Millimeters Typ. 0.1 0.35 0.23 Max. 2.65 0.3 0.49 0.32 Min. Inches Typ. 0.004 0.014 0.009 0.5 Max. 0.104 0.012 0.019 0.013 0.020 o 45 (Typ.) 17.7 10 18.1 10.65 0.697 0.394 1.27 16.51 7.4 0.4 0.713 0.419 0.050 0.65 7.6 1.27 0.291 0.016 0.299 0.050 o 8 (Max.) Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No licence is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without noti ce. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. 1996 SGS-THOMSON Microelectronics - All Rights Reserved Purchase of I2C Components of SGS-THOMSON Microelectronics, conveys a license under the Philips I2C Patent. Rights to use these components in a I2C system, is granted provided that the system confo rms to the I2C Standard Specifications as defined by Philips. SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. 16/16 SO28.TBL A a1 b b1 C c1 D E e e3 F L S Min.