Page 1
ST3917A
ST3917B
SPEECH - TONE/PULSE DIALER - LED INDICATOR
SPEECH CIRCUIT
.
2 TO4 WIRESCONVERSION
.
PRESENTTHEPROPERDC PATH FOR THE LINE
CURREN T AND THE FLEXIBILITY TO ADJUST IT
ANDALLOWPARALLELPH ONEOP ERATION
.
SYMMETRICAL HIGH IMPEDANCE MICROPHON E INPUTS SUIT ABLE FOR DYNAM IC ,
ELECTRET OR PIEZOELECTRIC TRANSDUCER
.
ASYMMETRICAL EARPHONE OUTPUT SUITABLEFOR DYNAMIC TRANSDUCER
.
LINE LOSS COMPENSATION FIXED INTERNALLYBYA.G.C.
.
INTERNAL MUTING TO DISABLE SPEECH
DURING DIALING AND EXTERNAL MUTING
TO DISABLE TRANSMIT AMPLIFIER DURING
CONVERSATIONMODE
.
LEDIND IC A T OREIT H E RFORKEYBOAR DILLUMINATION (OR ON-LINE INDICATION) DURING
DIALING AND CONVERSATION OR FOR TONE
MODE INDICATION, THROUGH MU/MFI PIN
DIALER CIRCUIT
.
STOREUP TO 32 DIGITS FOR LAST NUMBER
REDIAL BUFFER, LNR IS INHIBITED IF THERE
AREMOR ETH AN32DIGITSSTORED
.
ALLOWMIXED MODE DIALINGIN PULSE MODE
.
PACIFIER TONE PROVIDES AUDIBLE INDICATIONOF VALID KEY PRESSEDIN A BUZZER OR/AND IN THEEARPHONE
.
TIMEDPABX PAUSE/ 10PPSPULSE RATE
.
MAKE/BREAK RATIO : 40/60 (ST3917A) AND
33/67(ST3917B)
.
4 SELECTABLE OPTIONS ON FLASH DURATION AND SOFTSWITCH INHIBITION IN ONE
OF THE OPTIONWITH100msFLASHTIMING
.
2 SELECTABLE OPTIONS : TRANSMIT MUTE
TOGETHERWITHLEDFORKEYBOAR DILLU M INATIONOR LED FOR TONE MODE INDICATION
.
CONTINUOUS TONE FOR EACH DIGIT UNTIL
KEYRELEASE
.
USES INEXPENSIVE 3.579545MHz CERAMIC
RESONATOR
.
POWERED FROM TELEPHONE LINE, LOW
OPERATINGVOLTAGE FOR LONG LOOP APPLICATION
DESCRIPTION
Thedev iceconsis tsof thespeechand the dialerfunction s .It providesthe DCline interfacecircuit thattermi nates the telephoneline, analog ampli f i erfor speech
transmis sion and necessary signals for either DTMF
and pulse dialing. When mated with a tone ringer, a
comp letetelepho necanbeproduc edwithjusttwoICs.
TheDClineinterfacecircuitdev elopsi t sow nlinevoltage
acro s sthedeviceanditisadjus t ablebyexternalres istor
to suit different countr y ’s speci f icatio n. A built - i n LED
drivercan deliverexcessline currentto externalLED
indic ator(s) duri ng dialing and speech mode. The
LED(s) can be used either for keyboard illumination
purposeor fortonemodeindication duringsoftswitch
andmixedmodediali ngby connec tingMU/MFI pi nto
VDDandGNDoranyrowr es pect ively.TheLEDcurrent
is limited to17mA(typical).
The speechnetworkprovidesthetwo to four wires interface,electronicswitchingbetweendialingandspeechand
automaticgaincontrolontransmi tandr eceive.
Thediali ngnetwor kbuffersupto32digitsintotheLND
memorythatcanbelaterredi aledwithasi ngleke yinput.
Users can store all 13 signalling keys and acc es s
seve r aluniquefunct ionswit hsingl ekeyentries.T hes e
functionsinclude:Pause,LastNum be rDial led (LN D) ,
Softs w i tch andF l as h.( s eeFigure1).
TheFLASHkeys i mulatesahookflashto transfercalls
or to activateother specialfeaturesprovidedby the
P ABXor centraloffice.
ThePAUSE keystoresa timed pauseinthenumber
sequence. Redialis then delayeduntil an outs i deline
canbeaccessedorsom eotheractivitie soccurbefore
normal signalling resumes. A LND key autom atically
redialsthela st number dial ed.
Adedic atedpinMU/MFI isus edtoselectthemutingfor
transmit ampl i f ier and lighted dial LED for keyboar d
illuminati onoraLEDindicato rforto nemodeindic ation.
TheSEL pin allows selection of any one of the four
poss i ble Flashdurationopti ons.
DIP28
(Plastic Package)
ORDER CODES :
ST3917AN - ST3917BN
ST3917AD - ST3917BD
SO28
(Plastic Package)
ORDER CODES :
July 1996
1/16
Page 2
ST3917A - ST3917B
PIN CONNECTIONS
C1
C2
C3
SEL
OSC
PULSE
MODE/PT
HKS
GND
RXOUT
GRX
RXIN
I
REF
V
1
2
3
4
5
6
7
8
9
10
11
12
13
14
CC
28
27
26
25
24
23
22
21
20
19
18
17
16
15
R1
R2
R3
R4
MU/MFI
V
DD
GDTMF
MIC+
MIC-
GTX
REG
LN
ILINE
LED
PIN DESCRIPTION
Figure 1 : KeyboardConfiguration Scanning consists of Rows and Columns alter-
natelyswitching highthroughonchippullups.After
123
456
Flash
Tone/Pulse
botha Row andColumnkeyshavebeen detected,
the debounce counter is enabled and any noise
(bouncingcontacts,etc)is ignored for a debounce
period(TKD) of 32ms. At thistime,the keyboardis
789
Pause
sampledandifboth the Row and Column information are valid, the information is buffered into the
0#
*
C1, C2, C3, R4, R3, R2, R1
(Keyboardinputs,Pins 1, 2, 3, 25,26, 27, 28)
The deviceinterfaces with eitherthe standard 2 of
8 with negative common or the single contact
(Form A) keyboard. Column 4 of the keypad is
connectingto ground.
LND
LNDlocation.
3917-02.EPS
In the tone mode,if two or more keysin thesame
rowor if two or more keys inthe samecolumnare
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
featureisfortestpurposes,and singletonewillnot
be redialed.Also in the tonemode,theoutputtone
is continuous in the manual dialing as long as the
keyispushed. Theoutputtonedurationfollowsthe
A valid keypad entry is either a single Row connected to a single Columnor GNDsimultaneously
presented to both a single Row and a single Column. In its quiescent or standby state,during normal off-hookoperation,the Rows are initializedat
logic level 1 (V
) and the columns are initialized
DD
at logic level 0 (GND). Pulling any row input low
enables the on chip oscillator.Keyboardscanning
then begins.
Table 1. When redialing in the tone mode, each
DTMF outputis90ms duration,and thetoneseparation(inter signal delay) is90ms.
Table 1 : Output ToneDuration
Key Push Time, T Tone Output
T < 32ms
32ms < T < 90ms + Tkd
T > 90 ms + Tkd
Nooutput,ignoredbythe device
90ms duration
Output duration = T - tkd
3917-01.EPS
2/16
Page 3
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
1V
2 GND 600 Enable
3 Any Row 300 Enable
4 Any Col 100 Enable
DD
100 Inhibited
OSC (Input, Pin 5)
Only one pin is needed to connect the ceramic
resonatorto the oscillatorcircuit. Theother end of
the resonator is connected to GND. The nominal
resonatorfrequencyis 3.579545MHzand any deviationfromthisstandardis directly reflectedin the
Tone output frequencies. The ceramic resonator
providesthe timereferencefor all circuitfunctions.
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
pulledhigh by externalresistor.
MODE/PT(Input, Pin 7)
Input (MODE). MODE determinesthe dialer’s default operatingmode.Whenthedevice is powered
up or the hookswitch input is switched from onhook (V
mines the signalling mode. A V
) to off-hook (GND), the default deter-
DD
connection
DD
defaults to tone mode operation and a GND connectiondefaults to pulse mode operation.
When dialing in the pulse mode, a softswitch featurewillallowa changetothe tonemodewhenever
the * or softswitchkey (TONE) is depressed. Subsequent * key inputs willcausethe DTMF codefor
an * to be dialed. The softswitch will only switch
frompulseto tone.Thephonewillbe inpulsemode
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,
ST3917A - ST3917B
all valid key entries activate the pacifier tone. In
tonemode,anynonDTMF entry (FLASH,PAUSE,
LND, TONE) activates the pacifier tone. The pacifiertoneprovidesaudiblefeedback,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.
Thesquarewaveterminatesafter75mstypicallyor
whenthevalidkeyisnolongerpresent.Thepacifier
tonesignal is simultaneouslysentto the earphone
and the buzzer.The buzzer can be removedwithoutaffectingthis function.Theresistorvalueseton
MODE/PTpin determines the level of the pacifier
tone in theearphone.
HKS (Input, Pin8)
This is the hookswitch input to the device. It is a
CMOSinput with a high pull up internal resistance
and must be switched high or open for on-hook
operationand low for off-hook operation. A transitionon this input causestheon-chiplogictoinitialize, 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
illustratethe timing for this pin.
GND (Pin 9)
GNDisthenegativelineterminalofthedevice.This
isthe voltagereferencefor all specifications.
RXOUT, GRX, RXIN (Pins 10, 11and 12)
ThereceiveamplifierhasoneinputRXINandanon
inverting output RXOUT. Amplification from RXIN
to RXOUTis typically31dBand 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
specificapplicationto offer17dBadditionalgainat
3kHzis permitted.
I
(Pin 13)
REF
An external resistor of 3.6kΩ connectedbetween
IREF and GND will set the internal current level.
Anychangeof this resistor value will influence the
microphone gain, DTMF gain, earphone gain and
sidetonelevel.
VCC(Pin14)
VCCis the positivesupplyof the speechnetwork. It
can be stabilized by a decoupling capacitor between V
alsobe usedtosupplyexternalperipheralcircuits.
andGND. The VCCsupplyvoltagemay
CC
3/16
Page 4
ST3917A - ST3917B
PIN DESCRIPTION (continued)
LED (Output,Pin 15)
When the MU/MFI pin is connected to either V
or GND,theLED connectedto the LED pin,which
functions as a keyboard illumination or off-hook
indicator, will light up when the telephone is offhook.
WhentheMU/MFIpinisconnectedto anyrow pins,
the LED connectedto LED pin functionsasa tone
mode indicator.
Fromminimum operating line current up to 20mA,
I
LN-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).
DD
GDTMF(Pin22)
Whenthe DTMF input is enabled,the microphone
inputsandthereceiveamplifier input will be muted
and the dialing tone will be sent on the line. The
voltage amplification from GDTMF to LN is 40dB.
Finaloutputlevelon the LN canbeadjustedviathe
external resistor connectedbetween GDTMF and
GNDthrougha decouplingcapacitor.Aconfidence
tone is sent to the earphone during tone dialing.
Theattenuation of the confidence tone from LN to
RXOUT is -32dB typically. The level of the confidence tone in the earphone can be increased by
adjustingthe resistor connected between GDTMF
and GRX pins, the possiblerange is 20dB.
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 andtheDCcharacteristics,especiallyinthe low
voltageregion.
LN (Pin 17)
LN is the positive line terminal of the device.
REG (Pin 18)
The internalvoltageregulatorhas to bedecoupled
by a capacitorfrom REGto GND.TheDC characteristics can be changed with an external resistor
connectedbetweenLN and REGor betweenREG
and ILINE.
GTX,MIC-, MIC+ (Pins 19, 20, 21)
The devicehas a symmetricalmicrophoneinputs.
The amplification from microphoneinputs to LN is
51dB at 15mAline current and it can be adjusted
between43 and51dB.Theamplificationisproportional to the external resistor connected between
GTX and REG.
VDD(Pin23)
VDDis the positive supplyforthe dialingcircuit and
it must meet the maximum and minimum voltage
requirements.
MU/MFI (Input, Pin 24)
Alogic lowinput to this pin willdisablethetransmit
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
usedfor keypadlighting.
A connection to any row will disable the transmit
mute function and the LED connectedto the LED
pin is used for tonemode indication.
Table 3 : Logicof MU/MFI Pin Indicator
MU/MFI
Pin
OPEN Active Lighted Dial Indicator
GND Muted LightedDial Indicator
Any Row Not Available Tone Mode Indicator
Transmit
Muting
LED at Pin 15
4/16
Page 5
BLOCK DIAGRAM
ST3917A - ST3917B
LA
LB
Flash
Tone/Pulse
123
456
Ri
MODEHKSSELPULSELNLED
4678
RAM
REDIAL
PULSE
INTERFACE
LND
Pause
0#
*
789
Ci
24
KEYBOARD
INTERFACE
MUTE
Secret
OSC
MU/MFI
5
OSCILLATOR
DTMF
GENERATOR
LOGIC + DAC
Ceramic
3.58MHz
Ri1
GRX
11
gm
RGRX+C9
RXOUT
10
REF
KI
Ri2
gm
REF
KI
I1
9
12
LN
R24 R25
C20 C11
R15
15 1723
CONTROL
ILINE/ILED
R21
R20RGTX
16 1819
V1
DD
V
GTX ILINE REG RXIN GND
+
C8
D12
IREF
REF
KI
gm
gm
kI
REF
ST3917A/B
13
REF
I
R14
22
GDTMF
RMFCMF
MIC+
20
21
MIC-
C14
3917-03.EPS
5/16
V
C10
14
CC
Page 6
ST3917A - ST3917B
ABSOLUTEMAXIMUM RATINGS
Symbol Parameter Value Unit
V
V
T
T
P
ELECTRICALCHARACTERISTICS
(I
LN
Symbol Parameter Test Conditions Min. Typ. Max. Unit
V
V
I
V
I
G
A
D
N
Z
G
C
V
DIS DTMF Output Distortion (see Figure 10) 5 8 %
Positive Line Voltage Continuous 12 V
LN
I
Line Current 140 mA
LN
Logic Voltage 7V
DD
V
Maximum Voltage
I
on PULSE, SEL, HKS, MODE, Ri, Ci, MU/MFI and OSC Pins
Operating Temperature -25, +70 °C
oper
Storage Temperature -40, +125 °C
stg
Total Power Dissipation 700 mW
tot
=10mA to 120mA, f = 1kHz, T
Line Voltage (see Figure 6) ILN= 4mA
LN
Logic Voltage (see Figure 6) Tone mode
DD
Supply Current into VDD(see Figure 6) VDD= 3V Tone mode
I
DD
Supply Current into VCC(see Figure 6) ILN= 15mA 1.3 mA
I
CC
Supply Current to LED (seeFigure 6) ILN= 10 - 20mA
LED
Memory Retention Voltage(see Figure7) VDD= 3V 1.5 V
MR
MemoryRetentionCurrent (seeFigure 7) VDD=3V 1 µA
MR
Off-Hook StandbyCurrent (see Figure6) VDD= 3V 100 250 µA
IS
Pulse Output Sink Current (see Figure6) V
I
PL
Pacifier Tone Sink/Source Current
I
PO
(see Figure 6)
HKS, Mode, Keyboard Inputs Low 0.3xV
V
IL
HKS, Mode, Keyboard Inputs High 0.7xV
V
IH
Transmit Gain (see Figure 9) V
TX
Transmit Gain Variation (see Figure 9) ILN= 15mA,
GTX
Transmit Distortion (see Figure 9) ILN= 15mA, VLN=1V
TX
Transmit Noise (see Figure 9) ILN= 15mA, V
TX
Microphone Input Impedance
MIC
(see Figure 8)
DTMF Gain (see Figure 10) R
DTMF
DTMF Confidence Tone Attenuation
DTMF
(see Figure 10)
DTMFlevel ontheline (seeFigure10)
DTMF
P
High FrequencyGroup
Low Frequency Group
Pre-emphasis (see Figure 10) 1 2 3 dB
EI
=25°C,VDD= 3V ; unless otherwise specified)
amb
= 15mA
I
LN
= 120mA
I
LN
= 15mA, RA = 68kΩ
I
LN
= 15mA, RB = 39kΩ
I
LN
Pulse mode
Pulse mode
= 20 - 120mA 10
I
LN
= 0.5V 1 3 mA
OUT
V
= 0.5V(Sink)
OUT
= 2.5V(Source)
V
OUT
= 2mV
MIC
ILN= 15mA, R
I
LN
V
MIC
R
GTX
R
GTX
DTMF
C
DTMF
R
DTMF
C
DTMF
RMS
= 68kΩ
RMS
GTX
GTX
= 68kΩ
= 60mA, R
= 2mV
= 43kΩ
= 27kΩ
RMS
= 0V -72 dBmp
MIC
= 2.25kΩ,
= 22nF
= 2.25kΩ,
= 22nF -8
GND(-0.3) VDD(+0.3) V
2.70
3.15
3.50
3.85
7.00
2.60
3.60
2.50
2.00
1.00
0.60
DD
3.20
4.10
600
300
I
LN
I
CC
3.00
1.00
3.70
4.70
6.00
6.00
900
600
24
DD
49.543514552.5
47
-8
0dB
-4
-8
2%
50 64 80 kΩ
37 39 41 dB
-34 -31.5 -29 dB
-10
-6
-8
-4
-6
dBm
dBm
3917-01.TBL
V
V
V
V
V
V
V
µA
µA
mA
mA
mA
mA
V
V
dB
dB
dB
dB
3917-02.TBL
6/16
Page 7
ST3917A - ST3917B
ELECTRICALCHARACTERISTICS (continued)
(I
=10mA to 120mA, f = 1kHz, T
LN
Symbol Parameter Test Conditions Min. Typ. Max. Unit
Z
G
A
D
N
Z
V
DTMF Attenuation Pin Impedance 25 32 39 kΩ
DTMF
Receive gain (see Figure 11) V
RX
Receive Gain Variation (see Figure11) V
GRX
Receive Distortion (see Figure 11) ILN= 15mA, R
RX
Receive Noise (see Figure 11) ILN= 15mA, RE= 300Ω
RX
Receive Output Impedance
OUT
(see Figure 11)
Pacifier Tone Level on Earphone
PT
(see Figure 11)
Keyboard Interface
TKD
FKS
KRU
KRD
Keypad DebounceTime
Keypad Scan Frequency
Keypad Pullup Resistance
Keypad PulldownResistance
Tone Mode
TRIS
TR
TPSD
TISD
TDUR
Tone Output Rise Time
Tone Signalling Rate
Presignal Delay
Intersignal Delay
Tone Output Duration
Pulse Mode
TPT
FPT
PR
TB
Pacifier Tone Duration
Pacifier Tone Frequency
Pulse Rate
Break Time : ST3917A
ST3917B
TM
Make Time : ST3917A
ST3917B
IDP
PDP
Interdigital Pause
Predigital Pause : ST3917A
ST3917B
=25°C,VDD= 3V ; unless otherwise specified)
amb
= 4mV
INP
= 300Ω,R
R
E
= 15mA
I
LN
= 60mA
I
LN
= 4mV
INP
= 300Ω,ILN= 15MA
R
E
= 10KΩ
R
GRX
= 300kΩ
R
GRX
= 150Ω,V
R
E
RE= 300Ω,V
RE= 450Ω,V
= 100kΩ,V
R
GRX
RMS
RMS
,
GRX
,
GRX
EAR
EAR
EAR
=100kΩ
=100kΩ
= 0.25V
= 0.45V
= 0.55V
=0V
INP
RMS
RMS
RMS
ILN= 15mA 35 Ω
ILN= 15mA
= ∞
R
P
= 430kΩ
R
P
See Figures 4 and 5
See Figures 2 and 3
See Figures 4 and 5
29.5
23.0
-20
40
31.0
25.0
32.5
27.0
10 dB
-20
+10
2
2
2
200 µV
60
600
mV
mV
32
250
100
500
5ms
5.55
1/sec
90
90
75
500
10
PPS
60
67
40
33
820
50
43
dB
dB
dB
dB
%
%
%
ms
Hz
kΩ
Ω
ms
ms
ms
ms
Hz
ms
ms
ms
ms
ms
ms
ms
RMS
RMS
3917-02.TBL
Option Selectable
Symbol Parameter
t
FLASH
Notes : 1. All inputs unloaded. Quiescent mode (oscillator off).
Timed Hook Flash (see Figures 2 and3) 100 600 300 100 ms
2. Pulseoutput sink current for V
3. Pacifier tone sink current for V
4. Memory retention voltage is the point where memory is guaranteed but circuit operation is not. Proper memory retention is
guaranteed if either the minimum I
current and voltage.
5. Option 1 iswith softswitchinhibition.
= 0.5V atVDD= 3V.
OUT
= 0.5V, source currentfor V
OUT
is provided or the minimum VMR. The design does not have to provide both the minimum
MR
Option 1
SEL = V
Option 2
SEL = GND
DD
= 2.5V at VDD= 3V.
OUT
Option 3
SEL = ROW
Option 4
SEL = COL
Unit
7/16
Page 8
ST3917A - ST3917B
DEVICEOPERATION
During on-hook all keypad inputs are high impedance internallyand it requiresvery low current for
memoryretention.At anytime,rowinputsareinitializedatlogiclevel1andcolumninputsareinitialized
at logiclevel 0 at off-hook. The circuitverifies that
a validkey has been entered by alternately scanning the Row and Column inputs.If the input is still
validfollowing32msofdebounce,thedigitisstored
into memory, and dialing begins after a pre-signal
delay of approximately40ms measured from the
initial keyclosure.Outputtonedurationisshown in
Table1.
The device allows manual dialing of an indefinite
number of digits, but if more than 32 digits are
dialed, LND will be inhibited.
Table4 : DTMF Output Frequencies(Hz)
Key Input
Row 1
Row 2
Row 3
Row 4
Column 1
Column 2
Column 3
Std
Frequency
697
770
852
941
1209
1336
1477
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 ...
Hookflashmaybeenteredintothedialedsequence
at any point by keying in the function key, FLASH.
Whena FLASHkeyis pressed,nofurtherkeyinputs
willbeaccepteduntilthehookflashfunctionhasbeen
dialed.ThekeyinputfollowingaFLASHwillbestored
as theinitial digit of thenew number (overwriting the
numberdialedbeforetheFLASH)unlessitisanother
FLASH.FLASHkeypressedimmediatelyafterhookswitch or LND will not clear the LND bufferunless
digitsare enteredfollowingthe FLASHkey.
Flash
LND notcleared
LND Flash
LND notcleared
LND Flash D1 D2
LND bufferwill contain D1, D2
Output
Frequency
699.1
766.2
847.4
948
1215.9
1331.7
1471.9
%in
Deviation
+0.31
-0.49
-0.54
+0.74
+0.57
-0.32
-0.35
Last Number Dialed
Off-Hook LND
Last number redialing isaccomplished by entering
the LNDkey atoff-hookor aftertheFLASHkey,the
subsequentLND keys pressed will be 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 key is inhibited if
there are more than 32 digits stored.
Last Number Dialed Cascading
Digitsdial after the LND will cascade into the LND
buffer for the next redialing.In cascadeoperation,
the keyboard is 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-Hook D Pause D ...
Apause may be entered into the dialed sequence
at any point by keying in the special function key,
PAUSE.Pause insertsa3.1seconds(Tonemode)
or 3.4seconds(Pulse mode) delay into the dialing
sequence. The total delay, including predigit and
post digit pauses as shown in Table5.
Table 5 : Special Function Delays
Function First / Auto
SOFT-
SWITCH
PAUSE First
First
Auto
Auto
Delay (second)
Pulse Tone
0.2
1
2.6
3.4
3.0
3.1
Each delay shown in Table5 represents the time
required from the time the special function key is
depresseduntila newdigit 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 previousdigits
dialingis still in progress.
8/16
Page 9
DEVICEOPERATION (continued)
Led Indicator/ ToneMode Indication
WhentheMU/MFI(Pin24)is connectedtoanyrow
of the keypad input, the LED connectedto Pin 15
(LED) becomes a Tonemode indicator.
The LEDindicator is used in the following conditions :
- At Tonemode, 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(LEDturnson) <TONE> LND
ON-HOOK(LED turns off)
- At Pulse mode after off-hook, LED is off during
pulsedialing. When dialing isfollowed by the ”*”
or ”TONE” softswitchkeydepressed,theLEDwill
light up immediately at the softswitch after pulse
dialing is completed to indicate the signalling
modechange from pulseto tone.
After returning to on-hook and back to off-hook,
the device will be in pulse mode andthen LED is
turnedoff.RedialingfromLNDmemory bufferwill
repeat the softswitch, i.e. mixed mode redialing,
the LEDwill light up to indicatetheswitch to tone
mode or tone dialing. The LED will turn off only
when the telephone goes on-hook or is reset by
the Flashkey
Examples :
Pulsemode
a) OFF-HOOK (LED is off) <Pulse> D1, D2
(LED remains off),”*” <Tone> (LED turns on),
D3, D4
ON-HOOKor Flash(LEDturns off)
b) OFF-HOOK (LED is off) <Pulse> LND
<Pulse>D1,D2 (LEDremainsoff),”*” <Tone>
(LED turns on) D3, D4,
ON-HOOKor Flash(LEDturns off)
- At Pulse mode, after off-hook, LED is off during
pulsedialing.When switching the Tone/PulsemechanicalswitchtoTonemode,LED will turnon.
Example :
Pulsemode
OFF-HOOK (LED is off) <Pulse> D1, D2 Switch
”Tone/Pulse” mechanical switch to Tone mode
(LEDturnson) <Tone> D3,D4,
ON-HOOK (LED turns off)
The function of the LEDfor Tonemodeindicatoris
describedin the timing waveform in Figures 2,3, 4
and 5.
Figure2 : ToneMode Timing with Lighted Dial LED (Pin24 to VDDor GND)
ST3917A - ST3917B
Dial Se que nce
Keyboard
Input
Keyboard
Scan
DTMF
Outp ut
(Pin 17)
PULSE
Outp ut
LED
1
FLAS H 3 3 : Debounce Time
*
ENTE R ENTER ENTER ENTER
1 FLASH
3
*
KEYBOARD SCAN
3
Tflash
OFFON
3
3
ON
3917-04.EPS
9/16
Page 10
ST3917A - ST3917B
Figure3 : ToneMode Timing with ToneIndicator(Pin 24to anyrow)
1
Dial Se quenc e
Keyboard
Input
Keyboard
Sca n
DTMF
Output
(Pin 17)
PULSE
Output
ENTER ENTER ENTER ENTER
3
FLASH 3 3 :Debounce Time
*
1 FLASH
*
KEYBOARD S CAN
3
Tflas h
3
3
LED
OFFON
Figure4 : Pulse Mode Timing with Lighted Dial LED (Pin24 to VDDor GND)
1
Dial Sequenc e
Keyboard
Input
Keyboard
Scan
DTMF
Outp u t
(Pin 17)
PULSE
Outp u t
LED
ENTER ENTER ENTER ENTE R
3
FLAS H 3 3 : Debounc e Time
*
1 FLASH
*
KEYBOARD SCAN
3
3
Tflash
ONOFFON
Figure5 : Pulse Mode Timing with Tone IndicatorUsing ”*” or ”Tone” Key
1
Dial Sequence
Keyboard
Input
Keyboard
Scan
DTMF
Output
(Pin 17)
PULSE
Output
ENTER ENTER ENTER ENTER
3
FLASH 3 : Debounce TimeLND
*
1 FLASH
*
KEYBOARD SCAN
3
3
Tflash
ON
3917-05.EPS
3
3917-06.EPS
LND
10/16
LED
OFF
OFFON
ON
3917-07.EPS
Page 11
Figure6 : Test
Re
V
DD
Row
Col
IPL
Tone
100nF
ST3917A - ST3917B
ST3917A/B
1
C1
C2
2
C3
3
SEL
4
5
SW1
F
OSC
6
PULSE
MODE/PT
7
HKS
8
GND
9
10
RXOUT
11
GRX
12
RXIN
13
I
REF
+
14
V
CC
620
Ω
3.58MHz
mA
100kΩPulse
SW2
RGRX
+
10
F
100pF
3.9kΩ
100
I
CC
MU/MFI
V
GDTMF
MIC+
MIC-
GTX
REG
ILINE
LED
R1
R2
R3
R4
LN
DD
20
28
27
26
25
24
23
22
CDTMF
21
20
19
18
17
16
15
Ω
123
456
789
*
RDTMF
1
F
1
F
RGTX
100pF
I
LED
390
390Ω
0#
Ω
FLASH
TONE/P ULSE
PAUSE
LND
SECRE T
470nF
+
F
4.7
RA
LED
RB 130k
3.9k
Ω
I
DD
V
LN
+
100
F
Ω
600Ω
I
LN
Figure7 : Test
Re
V
MR
Row
Col
470k
Pulse
Tone
100nF
3917-08.EPS
ST3917A/B
1
C1
2
C2
C3
3
SEL
4
5
Ω
SW1
F
OSC
6
PULSE
7
MODE/P T
8
HKS
GND
9
10
RXOUT
11
GRX
12
RXIN
13
I
REF
+
14
V
CC
620
Ω
Ω
3.58MHz
100k
SW2
RGRX
+
10
F
100pF
3.9kΩ
100
MU/MFI
V
GDTMF
MIC+
MIC-
GTX
REG
ILINE
LED
R1
R2
R3
R4
LN
DD
20
28
27
26
25
24
23
22
CDTMF
21
20
19
18
17
16
15
Ω
123
456
789
*
RDTMF
F
1
1
F
RGTX
100pF
390
390
0#
Ω
Ω
FLASH
TONE/PULSE
PAUSE
LND
SECRET
470nF
+
F
4.7
LED
3.9k
Ω
130k
I
MR
Ω
11/16
3917-09.EPS
Page 12
ST3917A - ST3917B
Figure8 : Test
Figure9 : Test
Re
Row
Col
Pulse
Tone
100nF
470k
10
ST3917A/B
1
C1
C2
2
3
C3
4
SEL
5
Ω
SW1
Ω
F
OSC
PULSE
6
7
MODE/P T
HKS
8
GND
9
10
RXOUT
11
GRX
12
RXIN
13
I
REF
+
14
V
CC
620
Ω
Ω
3.58MHz
100k
SW2
RGRX
+
F
100pF
3.9k
100
MU/MFI
V
GDTMF
MIC+
MIC-
GTX
REG
ILINE
LED
R1
R2
R3
R4
LN
DD
20
28
27
26
25
24
23
22
CDTMF
21
20
19
18
17
16
15
Ω
123
456
789
*
RDTMF
RGTX
100pF
390
390
0#
Ω
Ω
FLASH
TONE/P ULSE
PAUSE
LND
S ECRET
470nF
Imic
+
F
4.7
LED
3.9k
Ω
Zmic =
1.2V
130k
1.2
Imic
Ω
3917-10.EPS
12/16
Re
V
DD
Row
Col
470k
Pulse
Tone
100nF
ST3917A/B
1
C1
2
C2
3
C3
SEL
4
OSC
100k
3.9k
100
Ω
SW1
Ω
5
6
PULSE
MODE/P T
7
HKS
8
9
GND
RXOUT
10
11
GRX
12
RXIN
13
I
REF
+
14
V
CC
F
620
Ω
Ω
3.58MHz
SW2
RGRX
+
10
F
100pF
R1
R2
R3
R4
MU/MFI
V
GDTMF
MIC+
MIC-
GTX
REG
LN
ILINE
LED
DD
20
28
27
26
25
24
23
22
CDTMF
21
20
19
18
17
16
15
Ω
123
456
789
*
RDTMF
F
1
1
F
RGTX
100pF
390
390
0#
Ω
Ω
FLASH
TONE/P ULSE
PAUSE
LND
S ECRET
470nF
Vmic
+
F
4.7
LED
3.9k
Ω
GTX = 20 log
130k
Ω
100
V
Vmic
600
LN
V
LN
+
F
I
Ω
LN
3917-11.EPS
Page 13
Figure10 : Test
ST3917A - ST3917B
V
DD
ST3917A/B
1
Ω
SW1
C1
C2
2
C3
3
4
SEL
5
OSC
PULSE
6
7
MODE/PT
8
HKS
GND
9
10
RXOUT
11
GRX
12
RXIN
13
I
REF
+
14
V
CC
F
620
Ω
Row
Col
470k
Ω
3.58MHz
Pulse
Tone
V
10
Re
ear
100k
SW2
RGRX
+
F
100pF
3.9kΩ
100
100nF
R1
R2
R3
R4
MU/MFI
V
GDTMF
MIC+
MIC-
GTX
REG
LN
ILINE
LED
DD
20
28
27
26
25
24
23
22
CDTMF
21
20
19
18
17
16
15
Ω
123
456
789
0#
*
V
MF
RDTMF
F
1
1
F
RGTX
100pF
390
390
Ω
Ω
FLASH
TONE/PULSE
PAUSE
LND
SECRET
470nF
+
F
4.7
LED
3.9k
Ω
GDTMF = 20 log
CDTMF = 20 log
100
130kΩ
600
V
LN
V
MF
Vear
V
LN
V
LN
+
F
I
Ω
LN
Figure11: Test
3917-12.EPS
V
DD
ST3917A/B
1
Ω
SW1
Ω
F
C1
2
C2
3
C3
SEL
4
OSC
5
6
PULSE
MODE/PT
7
HKS
8
9
GND
RXOUT
10
11
GRX
12
RXIN
13
I
REF
+
14
V
CC
620
Ω
Row
Col
470k
Ω
3.58MHz
Pulse
Tone
10
V
Re
ear
100k
SW2
RGRX
+
F
100pF
3.9k
100
100nF
V
inp
R1
R2
R3
R4
MU/MFI
V
GDTMF
MIC+
MIC-
GTX
REG
LN
ILINE
LED
DD
20
28
27
26
25
24
23
22
CDTMF
21
20
19
18
17
16
15
Ω
123
456
789
0#
*
RDTMF
F
1
1
F
RGTX
100pF
390
390
LED
Ω
Ω
FLAS H
TONE/P ULSE
PAUSE
LND
SECRET
470nF
+
F
4.7
3.9k
Ω
GRX= 20 log
130k
Ω
V
ear
V
inp
V
LN
+
10
0
F
I
LN
13/16
3917-13.EPS
Page 14
ST3917A - ST3917B
TYPICALAPPLICATION
2SA1013
A
B
100nF
10
Ω
1 F
1
8
2
7
3
6
L3240
45
Ω
24k
HKS1
Ω
2.2k
Buzzer
10 F
100kΩ
150kΩ
5.6k
10M
+
Ω
Ω
BF393
Options
Ω
3.3k
DTMF
Pulse
4.7 F
Earphone
3.58MHz
+
10V
Ceramic
100k
Ω
HKS2
100k
Ω
3.6k
Ω
1
2
3
4
5
6
7
8
9
10
11
12
13
14
ST3917A/B
C1
C2
C3
SEL
OSC
PULSE
MODE/PT
HKS
GND
RXOUT
GRX
RXIN
I
REF
V
CC
R1
R2
R3
R4
MU/MFI
V
GDTMF
MIC+
MIC-
GTX
REG
LN
ILINE
LED
28
123
27
456
26
789
25
24
23
DD
22
21
20
19
18
17
16
15
0#
*
3.3k
Ω
10nF
47k
Ω
SECRET
TONE/PULSE
470nF
Microphone
10 F
+
FLASH
PAUSE
LND
Zside tone
14/16
5.6V
+
470 F
100nF
BAT42
LED
+
100 F
620
Ω
4.7nF
3.9k
Ω
20Ω
3917-14.EPS
Page 15
PACKAGE MECHANICALDATA
28 PINS- PLASTICPACKAGE
ST3917A - ST3917B
Dimensions
Min. Typ. Max. Min. Typ. Max.
Millimeters Inches
a1 0.63 0.025
b 0.45 0.018
b1 0.23 0.31 0.009 0.012
b2 1.27 0.050
D 37.4 1.470
E 15.2 16.68 0.598 0.657
e 2.54 0.100
e3 33.02 1.300
F 14.1 0.555
I 4.445 0.175
L 3.3 0.130
PM-DIP28.EPS
DIP28.TBL
15/16
Page 16
ST3917A - ST3917B
PACKAGE MECHANICALDATA
28 PINS- PLASTICPACKAGE
Dimensions
Min. Typ. Max. Min. Typ. Max.
Millimeters Inches
A 2.65 0.104
a1 0.1 0.3 0.004 0.012
b 0.35 0.49 0.014 0.019
b1 0.23 0.32 0.009 0.013
C 0.5 0.020
c1 45
o
(Typ.)
D 17.7 18.1 0.697 0.713
E 10 10.65 0.394 0.419
e 1.27 0.050
e3 16.51 0.65
F 7.4 7.6 0.291 0.299
L 0.4 1.27 0.016 0.050
S8
Information furnished is believedto be accurateand reliable. However, SGS-THOMSON Microelectronicsassumes no responsibility
for the consequences of use of such information nor for anyinfringement of patents or other rights of third partieswhich may result
from itsuse. No licence is granted byimplication or otherwise under any patent or patentrights ofSGS-THOMSON Microelectronics.
Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all
information previously supplied. SGS-THOMSON Microelectronics products arenot authorized foruse as critical components inlife
support devices or systems without express written approval of SGS-THOMSON Microelectronics.
1996 SGS-THOMSON Microelectronics - All Rights Reserved
Purchase of I
2
I
C Patent. Rights to use these components in a I2C system, is granted provided that the system conforms to
Australia - Brazil -Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea- Malaysia - Malta - Morocco
The Netherlands - Singapore - Spain - Sweden - Switzerland- Taiwan - Thailand - UnitedKingdom -U.S.A.
2
C Components ofSGS-THOMSON Microelectronics, conveys a licenseunder the Philips
2
the I
C Standard Specifications as defined by Philips.
SGS-THOMSON Microelectronics GROUP OF COMPANIES
o
(Max.)
PM-SO28.EPS
SO28.TBL
16/16
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