ST3917 ,SPEECHfeatures provided by the. PABXor central office.ALLOWMIXED MODE DIALINGIN PULSE MODEThe PAUSE key s ..
ST3917A ,SPEECHfeatures provided by the. PABX or central office.ALLOW MIXED MODE DIALING IN PULSE MODEThe PAUSE ke ..
ST3917A/ ,SPEECHfeatures provided by the. PABX or central office.ALLOW MIXED MODE DIALING IN PULSE MODEThe PAUSE ke ..
ST3917B ,SPEECHST3917AST3917BSPEECH - TONE/PULSE DIALER - LED INDICATORSPEECH CIRCUIT DESCRIPTIONThe device consis ..
ST3917B ,SPEECHST3917AST3917BSPEECH - TONE/PULSE DIALER - LED INDICATORSPEECH CIRCUIT DESCRIPTIONThe device consis ..
ST3DV520EQTR ,MUX/DEMUX for 4 differential channel LVDS and DDCApplicationsmultiplexer/demultiplexer low R bidirectional ONswitch used to switch between multiple ..
STM809MWX6F ,RESET CIRCUITLogic Diagram (STM811/812)V(For STM810)CCAI07833Figure 5. SOT143-4 Connections(1)MR STM811/812 RST ..
STM809RWX6F ,320mW; I(o): 20mA; V(cc): -0.3 to +7.0V; reset circuitAbsolute Maximum Ratings . . . . . . . 10DC and AC PARAMETERS . 11Table 4. Operating and ..
STM809SWX6F ,320mW; I(o): 20mA; V(cc): -0.3 to +7.0V; reset circuitSTM809, STM810STM811, STM812Reset Circuit
STM809TWX6F ,320mW; I(o): 20mA; V(cc): -0.3 to +7.0V; reset circuitLogic Diagram (STM809/810) . . . . . . 4Figure 3.
STM810LWX6F ,320mW; I(o): 20mA; V(cc): -0.3 to +7.0V; reset circuitBlock Diagram . . 4Figure 7. Hardware Hookup . . . . . . . 5OPERATION . . . . ..
STM810MWX6F ,RESET CIRCUITLogic Diagram (STM811/812) . . . . . . 4Table 2. Signal Names . . 4Figure 4. SOT23-3 Co ..
ST3917
SPEECH
ST3917A
ST3917BSPEECH- TONE/PULSE DIALER- LED INDICATOR
July 1996
SPEECH CIRCUIT.2 TO4 WIRES CONVERSION.PRESENTTHE PROPERDC PATH FOR THE LINE
CUR RENT AND THE FLEXIBILITY TO ADJUSTIT
ANDALLOWPARALLELPH ONEOPERATION.SYMMETRICAL HIGH IMPEDANCE MICRO-
PHONE INPUTS SUITABLE FOR DYNAMIC,
ELECTRET OR PIEZOELECTRIC TRANSDUCER.ASYMMETRICAL EARPHONE OUTPUT SUIT-
ABLE FOR DYNAMIC TRANSDUCER.LINE LOSS COMPENSATION FIXED INTER-
NALLY BY A.G.C..INTERNAL MUTING TO DISABLE SPEECH
DURING DIALING AND EXTERNAL MUTING DISABLE TRANSMIT AMPLIFIER DURING
CONVERSATION MODE.LED INDICATOR EITHER FOR KEYBOARDILLU-
MINATION (OR ON-LINE INDICATION) DURING
DIALING AND CONVERSATION OR FOR TONE
MODE INDICATION, THROUGH MU/MFI PIN
DIALER CIRCUIT.STORE UP TO32 DIGITS FOR LAST NUMBER
REDIAL BUFFER, LNRIS INHIBITEDIF THERE
ARE MORE THAN32 DIGITS STORED.ALLOWMIXEDMODE DIALINGIN PULSEMODE.PACIFIER TONE PROVIDES AUDIBLE INDI-
CATION OF VALID KEY PRESSEDINA BUZZ- OR/ANDIN THE EARPHONE.TIMED PABX PAUSE/ 10PPS PULSE RATE.MAKE/BREAK RATIO: 40/60 (ST3917A) AND
33/67 (ST3917B).4 SELECTABLE OPTIONS ON FLASH DURA-
TION AND SOFTSWITCH INHIBITIONIN ONE THE OPTION WITH 100ms FLASH TIMING.2 SELECTABLE OPTIONS: TRANSMIT MUTE
TOGETHER WITH LED FORKEYBOARDILLUMI-
NATION OR LED FOR TONEMODE 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 AP-
PLICATION
DESCRIPTIONThe device consistsof the speech and the dialer func-
tions.It providesthe DC line interfacecircuit that termi-
nates the telephone line, analog amplifierfor speech
transmission and necessary signalsfor either DTMF
and pulse dialing. When mated witha tone ringer,a
completetelephonecan beproducedwith just twoICs.
TheDClineinterfacecircuit developsits ownlinevoltage
acrossthedeviceanditisadjustablebyexternalresistor suit different country’s specification.A built-in LED
driver can deliver excess line currentto external LED
indicator(s) during dialing and speech mode. The
LED(s) can be used eitherfor keyboard illumination
purposeor fortonemode indication during softswitch
and mixed mode dialingby connectingMU/MFI pinto
VDDandGNDoranyrowrespectively.TheLEDcurrent
islimited to17mA(typical).
The speechnetwork providesthetwoto fourwires inter-
face,electronic switchingbetweendialingandspeechand
automaticgaincontrolontransmitandreceive.
The dialing network buffersup to32digits intothe LND
memorythatcanbelaterredialedwithasinglekeyinput.
Users can storeall 13 signalling keys and access
severaluniquefunctionswith singlekey entries.These
functionsinclude: Pause, Last NumberDialled (LND),
SoftswitchandFlash.(see Figure1).
TheFLASH keysimulatesahookflash totransfercallsto activate other special features providedby the
PABXor central office.
The PAUSE key storesa timed pausein the number
sequence. Redialis then delayeduntilan outsideline
canbe accessedor someother activitiesoccur before
normal signalling resumes.A LND key automatically
redials thelast numberdialed.
AdedicatedpinMU/MFI isused toselectthe mutingfor
transmit amplifier and lighted dial LED for keyboard
illuminationora LEDindicatorfor tonemodeindication.
The SEL pin allows selectionof any oneof the four
possible Flash durationoptions.
DIP28(Plastic Package)
ORDER CODES:ST3917AN- ST3917BN
SO28(Plastic Package)
ORDER CODES:ST3917AD- ST3917BD
1/16
PULSE
MU/MFI
MIC+
MIC-
GTX
MODE/PT
OSC
SEL
HKS
RXOUT
GNDDD
GDTMF
GRX
RXIN
IREF
VCC
ILINE
LED
REG
3917-01.EPS
PIN CONNECTIONS
PIN DESCRIPTION
C1, C2, C3, R4, R3, R2, R1(Keyboard inputs, Pins1,2,3, 25, 26, 27, 28)
The device interfaces with either the standard2of with negative commonor the single contact
(FormA) keyboard. Column4of the keypadis
connectingto ground. valid keypad entryis eithera single Row con-
nectedtoa single Columnor GND simultaneously
presentedto botha single Row anda single Col-
umn.Inits quiescentor standby state, during nor-
mal off-hookoperation, the Rows are initializedat
logic level1 (VDD) and the columns are initialized logic level0 (GND). Pulling any row input low
enables theon chip oscillator. Keyboard scanning
then begins.
789 0#
Flash
Tone /Pulse
Pause
LND
3917-02.EPS
Figure1: Keyboard Configuration Scanning consistsof Rows and Columns alter-
nately switching high throughon chip pullups.After
botha Row and Column keys have been detected,
the debounce counteris enabled and any noise
(bouncing contacts, etc)is ignoredfora debounce
period (TKD)of 32ms.At this time, the keyboardis
sampled andif both the Row and Column informa-
tion are valid, the informationis buffered into the
LND location. the tone mode,if twoor more keysin thesame
roworif twoor more keysin the same column are
depresseda single tone will be output. The tone
will correspondto the common rowor common
columnfor which the two keys were pushed. This
featureisfor test purposes, and single tone will not redialed. Alsoin the tone mode, theoutput tone continuousin the manual dialingas longas the
keyis pushed. The output tone duration follows the
Table1. When redialingin the tone mode, each
DTMF outputis 90ms duration,and the tone sepa-
ration(inter signal delay)is 90ms.
Table1: Output Tone Duration
Key Push Time,T Tone Output< 32ms
32ms
90ms+ Tkd output, ignoredbythe device
90ms duration
Output duration=T-tkd
ST3917A- ST3917B
2/16
SEL (Input, Pin4)
Thisis an option selectable pin for four Flash
duration. The four options are summarisedin the
table2.
For option1, softswitch featureis inhibited.It
means redialedby the LND keyin pulse mode will
not repeat the softswitch and subsequent digits,
only pulse digits are dialed out.
Table2: Options Selectablefor Flash Duration
Options SEL Flash (ms) Softswitch
1VDD 100 Inhibited GND 600 Enable Any Row 300 Enable Any Col 100 Enable
OSC (Input, Pin5)
Only one pinis neededto connect the ceramic
resonatorto the oscillator circuit. The other endof
the resonatoris connectedto GND. The nominal
resonator frequencyis 3.579545MHzand any de-
viation from this standardis directly reflectedin the
Tone output frequencies. The ceramic resonator
provides the time referenceforall circuit functions. ceramic resonator with toleranceof ±0.25%is
recommended.
PULSE (Output, Pin6)
Thisis an output consistingof an open drainN-
channel device. During on-hook, pulse output pinin high impedance and once off-hook,it willbe
pulled highby external resistor.
MODE/PT (Input, Pin7)
Input (MODE). MODE determines the dialer’s de-
fault operatingmode. When the deviceis poweredor the hookswitch inputis switched from on-
hook (VDD)to off-hook (GND), the default deter-
mines the signalling mode.A VDD connection
defaultsto tone mode operation anda GND con-
nection defaultsto pulse mode operation.
When dialingin the pulse mode,a softswitch fea-
ture will allowa change tothe tonemode whenever
the*or softswitchkey (TONE)is depressed. Sub-
sequent* key inputs will cause the DTMF codefor*to be dialed. The softswitch will only switch
from pulseto tone.The phone willbein pulsemode
only after returningto on-hook and backto off-
hook. Redialedby the LND key will repeat the
softswitch unless the softswitch redial featureis
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 paci-
fier tone providesaudiblefeedback,confirmingthat
the key has been properly entered and accepted.isa 500Hz square wave activated upon accep-
tanceof valid key input after the 32ms debounce
time.
Thesquare wave terminatesafter 75mstypicallyor
when thevalidkeyisnolonger present.The pacifier
tone signalis simultaneouslysentto the earphone
and the buzzer. The buzzercanbe removed with-
out affecting this function.The resistor value seton
MODE/PT pin determines the levelof the pacifier
tonein the earphone.
HKS (Input, Pin8)
Thisis the hookswitch inputto the device.Itisa
CMOS input witha high pullup internal resistance
and must be switched highor open for on-hook
operationand low for off-hook operation.A transi-
tionon this input causes the on-chip logicto initial-
ize, terminating any operationin progressat the
time. The signalling mode defaultsto the mode
selectedat MODE/PT pin. Figures2,3 and4,5
illustrate the timingfor this pin.
GND (Pin9)
GNDis thenegative lineterminalof the device.This the voltage referenceforall specifications.
RXOUT, GRX, RXIN (Pins 10,11 and 12)
Thereceive amplifierhas one input RXIN anda non
inverting output RXOUT. Amplification from RXIN RXOUTis typically 31dB andit canbe adjusted
between 21dB and 41dBto suit the sensitivityof
the earphone used. The amplificationis propor-
tionalto the external resistor connected between
GRX and RXOUT. For the hearing impaired,a
specific applicationto offer 17dB additional gainat
3kHzis permitted.
IREF (Pin 13) external resistorof 3.6kΩ connected between
IREF and GND will set the internal current level.
Any changeof this resistor value will influence the
microphone gain, DTMF gain, earphone gain and
sidetone level.
VCC (Pin 14)
VCCis the positive supplyof the speech network.It
can be stabilizedbya decoupling capacitor be-
tween VCC and GND. The VCC supply voltage may
alsobe usedto supply external peripheral circuits.
PIN DESCRIPTION (continued)
ST3917A- ST3917B
3/16
LED (Output, Pin 15)
When the MU/MFI pinis connectedto either VDD GND, the LED connectedto the LED pin, which
functionsasa keyboard illuminationor off-hook
indicator, will light up when the telephoneis off-
hook.
Whenthe MU/MFI pinis connectedto anyrow pins,
the LED connectedto LED pin functionsasa tone
mode indicator.
From minimum operating line currentupto 20mA,
ILN-ICCis sourced into the LED witha maximum
current limitof 18mA. For line current more than
20mA, this sourced currentis limitedat 18mA
(typical).
ILINE (Pin 16) recommended external resistorof 20Ωis con-
nected between ILINE and GND. Changing this
resistor value will influence the microphone gain,
DTMF gain, sidetone, maximum output swingon and theDC characteristics, especiallyin the low
voltage region. (Pin 17)is the positive line terminalof the device.
REG (Pin 18)
The internal voltage regulator hastobe decoupleda capacitor from REGto GND. The DC charac-
teristics can be changed withan external resistor
connected betweenLN and REGor between REG
and ILINE.
GTX, MIC-, MIC+ (Pins 19, 20, 21)
The device hasa symmetrical microphone inputs.
The amplification from microphoneinputsto LNis
51dBat 15mAline current andit canbe adjusted
between43 and 51dB. The amplificationis propor-
tionalto the external resistor connected between
GTX and REG.
GDTMF (Pin 22)
When the DTMF inputis enabled,the microphone
inputs and the receive amplifier input willbe muted
and the dialing tone will be senton the line. The
voltage amplification from GDTMFto LNis 40dB.
Final output levelon the LN canbe adjustedvia the
external resistor connected between GDTMF and
GNDthrougha decouplingcapacitor.A confidence
toneis sentto the earphone during tone dialing.
The attenuationof the confidencetone from LNto
RXOUTis -32dB typically. The levelof the confi-
dence tonein the earphone can be increasedby
adjustingthe resistor connected between GDTMF
and GRX pins, the possible rangeis 20dB.
VDD (Pin 23)
VDDis the positive supplyfor the dialing circuit and must meet the maximum and minimum voltage
requirements.
MU/MFI (Input, Pin 24) logic low inputto this pin will disable the transmit
amplifierof the speech circuit. MUTE efficiencyis
greater than 60dB. An open circuitto this pin will
enable the transmit amplifier.In this case, LEDis
usedfor keypad lighting. connectionto any row will disable the transmit
mute function and the LED connectedto the LED
pinis usedfor tone mode indication.
Table3: Logicof MU/MFI Pin Indicator
MU/MFI
Pin
Transmit
Muting LEDat Pin15
OPEN Active Lighted Dial Indicator
GND Muted Lighted Dial Indicator
Any Row Not Available Tone Mode Indicator
PIN DESCRIPTION (continued)
ST3917A- ST3917B
4/16
111422MIC+
MIC-
REF
REF
GDTMF
Ri2
REF
REF
Ri1
GRX RXOUT
RGRX
ILINE/ILEDCONTROL
IREF
REF
DTMF
GENERATORLOGIC
DAC
MUTE
OSCILLATOR
KEYBOARDINTERFACE
PULSE
INTERFACE
RAM
REDIAL
MODE
HKS
SEL
PULSE
LED
OSCMU/MFICiRi
Flash
Tone/Pulse
Pause
LND
3.58MHz
Ceramic
RMF
CMF
C14
R14
C10
ST3917A/B
D12
R15 LB
R20
RGTX
R21
C20
C11
GTX
ILINE
REG
RXIN
GND
R24
R25
Secret
3917-03.EPS
BLOCK DIAGRAM
ST3917A- ST3917B
5/16
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
VLN Positive Line Voltage Continuous 12 V
ILN Line Current 140 mA
VDD Logic Voltage 7V Maximum Voltage PULSE, SEL, HKS, MODE,Ri,Ci, MU/MFI and OSC Pins
GND(-0.3) VDD(+0.3) V
Toper Operating Temperature -25, +70 °C
Tstg Storage Temperature -40, +125 °C
Ptot Total Power Dissipation 700 mW
3917-01.TBL
ELECTRICAL CHARACTERISTICS
(ILN= 10mAto 120mA,f= 1kHz, Tamb =25°C, VDD= 3V; unless otherwise specified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
VLN Line Voltage (see Figure6) ILN= 4mA
ILN= 15mA
ILN= 120mA
ILN= 15mA,RA= 68kΩ
ILN= 15mA,RB= 39kΩ
VDD Logic Voltage (see Figure6) Tone mode
Pulse mode
IDD Supply Current into VDD (see Figure6) VDD=3V Tone mode
Pulse mode
ICC Supply Current into VCC (see Figure6) ILN= 15mA 1.3 mA
ILED Supply Currentto LED (see Figure6) ILN=10- 20mA
ILN=20- 120mA 10
ILN-
ICC 24
VMR MemoryRetention Voltage(see Figure7) VDD=3V 1.5 V
IMR Memory Retention Current (see Figure7) VDD =3V 1 μA Off-Hook StandbyCurrent (seeFigure6) VDD=3V 100 250 μA
IPL Pulse Output Sink Current (see Figure6) VOUT= 0.5V 1 3 mA
IPO Pacifier Tone Sink/Source Current
(see Figure6)
VOUT= 0.5V(Sink)
VOUT= 2.5V(Source)
VIL HKS, Mode, Keyboard Inputs Low 0.3xVDD V
VIH HKS, Mode, Keyboard Inputs High 0.7xVDD V
GTX Transmit Gain (see Figure9) VMIC= 2mVRMS
ILN= 15mA, RGTX= 68kΩ
ILN= 60mA, RGTX= 68kΩ
AGTX Transmit Gain Variation (see Figure9) ILN= 15mA,
VMIC= 2mVRMS
RGTX= 43kΩ
RGTX= 27kΩ
0dB
DTX Transmit Distortion (see Figure9) ILN= 15mA, VLN =1VRMS 2%
NTX Transmit Noise (see Figure9) ILN= 15mA, VMIC=0V -72 dBmp
ZMIC Microphone Input Impedance
(see Figure8) 64 80 kΩ
GDTMF DTMF Gain (seeFigure 10) RDTMF= 2.25kΩ,
CDTMF= 22nF 39 41 dB
CDTMF DTMF Confidence Tone Attenuation
(see Figure 10)
-34 -31.5 -29 dB
VDTMF DTMF levelonthe line (see Figure10)
High Frequency Group
Low Frequency Group
RDTMF= 2.25kΩ,
CDTMF= 22nF -8
dBm
dBm
PEI Pre-emphasis (see Figure10) 1 2 3 dB
DIS DTMF Output Distortion (see Figure 10) 5 8 %
3917-02.TBL
ST3917A- ST3917B
6/16
Symbol Parameter Test Conditions Min. Typ. Max. Unit
ZDTMF DTMF AttenuationPin Impedance 25 32 39 kΩ
GRX Receivegain (see Figure 11) VINP= 4mVRMS,= 300Ω,RGRX=100kΩ
ILN= 15mA
ILN= 60mA
AGRX Receive Gain Variation (see Figure11) VINP= 4mVRMS,= 300Ω,ILN= 15MA
RGRX= 10KΩ
RGRX= 300kΩ
+10 dB
DRX Receive Distortion (see Figure 11) ILN= 15mA, RGRX=100kΩ= 150Ω,VEAR= 0.25VRMS= 300Ω,VEAR= 0.45VRMS= 450Ω,VEAR= 0.55VRMS
NRX ReceiveNoise (see Figure11) ILN= 15mA,RE= 300Ω
RGRX= 100kΩ,VINP =0V
200 μV
ZOUT Receive Output Impedance
(see Figure 11)
ILN= 15mA 35 Ω
VPT Pacifier Tone Levelon Earphone
(see Figure 11)
ILN= 15mA=∞= 430kΩ
mVRMS
mVRMS
TKD
FKS
KRU
KRD
Keyboard Interface
Keypad Debounce Time
Keypad Scan Frequency
Keypad Pullup Resistance
Keypad Pulldown Resistance
See Figures4 and5
500Ω
TRIS
TPSD
TISD
TDUR
Tone Mode
Tone Output Rise Time
Tone Signalling Rate
Presignal Delay
Intersignal Delay
Tone Output Duration
See Figures2 and3
5ms
1/sec
TPT
FPT
IDP
PDP
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 Figures4 and5
PPS
Option Selectable
Symbol Parameter Option1
SEL= VDD
Option2
SEL= GND
Option3
SEL= ROW
Option4
SEL= COL Unit
tFLASH Timed Hook Flash (see Figures2 and3) 100 600 300 100 ms
Notes:1. Allinputs unloaded.Quiescent mode (oscillator off). Pulseoutput sink currentfor VOUT= 0.5VatVDD=3V. Pacifier tone sink currentfor VOUT= 0.5V, source currentfor VOUT =2.5VatVDD=3V. Memory retention voltageisthe point where memoryis guaranteedbut circuit operationis not. Proper memory retentionis
guaranteedif eitherthe minimumIMRis providedorthe minimum VMR. The design doesnot haveto provide boththe minimum
currentand voltage. Option1is with softswitch inhibition.
3917-02.TBL
ELECTRICAL CHARACTERISTICS (continued)
(ILN= 10mAto 120mA,f= 1kHz, Tamb =25°C, VDD= 3V; unless otherwise specified)
ST3917A- ST3917B
7/16
DEVICE OPERATION
During on-hookall keypad inputs are high imped-
ance internally andit requires very low currentfor
memory retention.At anytime,rowinputsare initial-
ized atlogiclevel1 and column inputsare initialized logic level0at off-hook. The circuit verifies that valid key has been enteredby alternately scan-
ning the Row and Column inputs.If the inputis still
validfollowing 32msof debounce,the digitisstored
into memory, and dialing begins aftera pre-signal
delayof approximately 40ms measured from the
initial key closure. Outputtone durationis shownin
Table1.
The device allows manual dialingof an indefinite
numberof digits, butif more than 32 digits are
dialed, LND willbe inhibited.
Table4: DTMF Output Frequencies(Hz)
Key Input Std
Frequency
Output
Frequency
%in
Deviation
Row1
Row2
Row3
Row4
Column1
Column2
Column3
+0.31
+0.74
+0.57
Normal DialingDD...
Normal dialingis straight forward, all keyboard
entries willbe storedin the buffer and signalledin
succession.
Hook Flash FlashD...
Hook flash maybe enteredinto the dialed sequence any pointby keyingin the function key, FLASH.
Whena FLASHkeyis pressed,no further key inputs
willbe accepteduntilthe hookflashfunctionhasbeen
dialed.ThekeyinputfollowingaFLASHwillbe stored the initial digitof the new number (overwriting the
numberdialedbeforetheFLASH) unlessitis another
FLASH.FLASHkeypressedimmediatelyafterhook-
switchor 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
Last Number Dialed
Off-Hook LND
Last number redialingis accomplishedby entering
the LND key atoff-hookor after the FLASH key, the
subsequent LND keys pressed willbe ignored.
Sequence Digit Emitted
OFF-HOOK, D1, D2, ON-HOOK D1,D2
OFF-HOOK, LND, LND, ON-HOOK D1,D2
OFF-HOOK, D3, D4, LND, ON-HOOK D3,D4
OFF-HOOK, LND, ON-HOOK D3,D4
Last Number Dialed Inhibition
Last number redialing by LND keyis inhibitedif
there are more than32 digits stored.
Last Number Dialed Cascading
Digits dial after the LND will cascade into the LND
bufferfor the next redialing.In cascade operation,
the keyboardis inhibited upon pressing the LND
key, the LND output must be completed before
acceptanceof any key entry.
Sequence Digit Emitted
OFF-HOOK, D1, D2, ON-HOOK D1,D2
OFF-HOOK, LND, D3, D4, ON-HOOK D1, D2, D3,D4
OFF-HOOK, LND, ON-HOOK D1, D2, D3,D4
Pause
Off-HookD PauseD... pause maybe entered into the dialed sequence any pointby keyingin the special function key,
PAUSE. Pause insertsa 3.1 seconds (Tone mode) 3.4 seconds (Pulse mode) delay into the dialing
sequence. The total delay, including predigit and
post digit pausesas shownin Table5.
Table5: Special Function Delays
Function First/ Auto Delay (second)
Pulse Tone
SOFT-
SWITCH
First
Auto
PAUSE First
Auto
Each delay shownin Table5 represents the time
required from the time the special function keyis
depressed untila new digitis dialed.
The timeis considered”FIRST” keyifall previous
inputs have been completely dialed. The timeis
considered ”AUTO”ifin redial,orif previousdigits
dialingis stillin progress.
ST3917A- ST3917B
8/16
