TEMIC U3750BM

U3750BM
TELEFUNKEN Semiconductors
One Chip Telephone Circuit
Description
TELEFUNKEN microelectronic’s one chip telephone
circuit, U 3750 BM, is BICMOS integrated circuit that
performs all the speech and line interface functions
required in an electronic telephone set, the tone ringer, the
pulse and DTMF dialling with redial, a keyboard interface with the possibility to interface with an external
microcontroller using the internal serial bus, and a power
supply for peripherals.
Features
D Adjustable dc slope characteristic
D Adjustable automatic line length receiving and sending gain control (not used in DTMF) with the
possibility of fixed gain (PABX)
D
D
D
D
D Four ringing tones adjustable without external
components
D Internal speed up circuit permits a faster charge of
VCC and VRAM capacitors
Adjustable dynamic impedance
D Logic bounce elimination
Stabilized power supply for peripherals
D Pulse dialling 66/33 or 60/40 or DTMF dialling select-
Confidence level during pulse and DTMF dialling
Receiving amplifier for dynamic or piezo-electric ear
pieces
D High-impedance microphone inputs (80 kW in
symmetrical and 40 kW in asymmetrical) suitable for
dynamic, magnetic, piezo-electric or electret microphone
D Dynamic limiting in sending (anticlipping) prevents
distortion of line signal and sidetone
D Ringing balanced output in HVMOS for higher power
capability
able by programming pin
D Adjustable flashing duration
D Pause function
D Confidence tone (440 Hz)
D Last number redial up to 23 digits
D Standard low-cost ceramic 455 kHz
D Binary data input in serial mode
D Test-mode capability
Benefits
D Low number of external components
D High quality through one chip solution
Rev. A1: 16.07.1996
1 (20)
U3750BM
TELEFUNKEN Semiconductors
Block Diagram
2 (20)
Rev. A1: 16.07.1996
U3750BM
TELEFUNKEN Semiconductors
Pin Description
Pin
1
2
3
4
Symbol
C4
C3
FLASH
DC/FV
5
6
7
8
9
10
11
12
13
14
OL
RESET
TEEIN
SHEN
NC
VRAM
VCC
VL
OSCAB
EC
15
16
17
18
19
20
21
TESTR
GND
NC
AGA
IREF
SELF
RGAB
22
MIC1
Rev. A1: 16.07.1996
Function
Keyboard input
Keyboard input
Flashing selection
Dialling selection (33/66 pulse,
40/60 pulse or DTMF)
Open line output
Output reset
Test pins
Test pins
Not connected
RAM and internal logic supply
Power supply for peripherals
Line voltage
Test pin
Extra current for peripherals or
can be used to dissipate power
for high line current applications.
Test pin
Ground
Not connected
Line length AGC adjustment
Bias adjustment
Electronic self input
DC characteristic slope
adjustment
Microphone input
Pin
23
24
25
26
27
Symbol
MIC2
ZAC
EM/FILT
MOD
EM/MF
28
ACL
29
30
31
32
33
34
35
36
37
38
E2
E1
NC
REC
ZAL
OUT1
OUT2
VIR
CK
PAIR
39
BEAT
40
41
42
43
44
MF
C1
C2
C6
C5
Function
Microphone input
Dynamic impedance adjustment
First sending stage output
Modulator output
Second sending stage input and
DTMF input
Anticlipping time constant
adjustment
Receiver output
Receiver output
Not connected
Receiver input
Sidetone network
Buzzer output
Buzzer output
Ringing supply
Ceramic input (455 KHz)
Adjustment between two pairs of
ringing frequencies
Beat adjustment of each pair of
ringing frequencies
DTMF output
Keyboard inputs
Keyboard inputs
Keyboard inputs
Keyboard inputs
3 (20)
U3750BM
TELEFUNKEN Semiconductors
Application Circuit
Absolute Maximum Ratings
See application circuit
Parameters
DC line voltage
Pin 36
DC line current
Pin 36
Conversation line voltage Pin 12
Pulse duration, t = 20 ms
Conversation line current Pin 12
Power dissipation, Tamb = 55°C
Junction temperature
Ambient temperature range
Storage temperature range
4 (20)
Symbol
VIR
IR
VL
VL
IL
Ptot
Tj
Tamb
Tstg
Value
35
30
15
17
150
1
125
–25 to +55
–55 to +155
Unit
V
mA
V
V
mA
W
°C
°C
°C
Rev. A1: 16.07.1996
U3750BM
TELEFUNKEN Semiconductors
Thermal Resistance
Parameters
Junction ambient
Symbol
RthJA
Value
70
Unit
K/W
Electrical Characteristics
f = 1 kHz, fclock = 455 kHz, RE = 20 kW, Tamb = 25°C,
unless otherwise specified, Q (Resonance factor) = 3100,
L1 = 6.1 mH, C1 = 21 pF, CO = 268.5 pF, R1 = 5.5 W. All
resistances are specified at 1%, all capacitance at 2%.
Parameters
Line voltage normal
Line voltage operation
Stabilized voltage
Test Conditions / Pins
IL = 8 mA
IL = 15 mA
IL = 28 mA
IL = 60 mA
figure 3
IL = 8 mA, ICC = 0.6 mA
IL 28 mA, ICC = 2.1 mA
figure 3
w
Symbol
VL
VCC
Min.
2.9
4.1
6.4
12.3
Typ.
2.0
3.3
2.5
3.5
3.7
47
39.5
–6
48
41
–7
49
42.5
–8
dB
–73
–68
dBmp
4.5
Max.
3.6
4.9
7.3
13.7
Unit
V
V
Transmission
Sending gain
VMI = 2 mVRMS (note 1)
IL = 28 mA (GS max)
IL = 60 mA (GS min)
AGC
IL = 28 to 60 mA
figure 3
Psophometric sending noise VMI = 0, IL = 28 mA
figure 3
Attenuation gain during
VMI = 2 mVRMS,
dialing
IL = 28 mA
figure 3
Microphone input
figure 3
impedance (Pins 22–23)
Common mode rejection
IL = 28 mA
ratio
figure 3
From transmission to
IL = 28 to 60 mA
dialing mode
figure 3, Pin 25
Dynamic limiter
CACL = 470 nF,
(anticlipping)
RACL = 6.8 MW
IL = 20 mA
Output voltage swing
IL 28 mA,
(peak-to-peak value)
VMI = 8 mVRMS
figure 3
Overdrive dynamic range
IL 28 mA
figure 3
Line distortion (on 600 W)
IL 28 mA
VMI = 4.6 mVRMS
VMI = 8 mVRMS
VMI = 80 mVRMS
figure 3
w
w
w
Rev. A1: 16.07.1996
GS
DGS
AS
63
70
CMRR
Step
dB
120
kW
80
dB
–100
3.0
+100
2.5
3.6
mV
Vpp
4.2
5
dB
3
5
5
%
5 (20)
U3750BM
Parameters
Available current
Reception
Receiving gain
GR = VR/VL
AGC
Psophometric receiving
noise
Receiving distortion
Receiver output impedance
Receiver output offset
Sidestone (VR/VM)
Z line matching impedance
Ringer
Turn on voltage
Turn off voltage
Current consumption
without load
Output voltage swing
Output tone frequencies
TELEFUNKEN Semiconductors
Test Conditions / Pins
Close switch S4
IL = 28 mA
IL = 60 mA
figure 3
Pin 14
VL = 0.3 VRMS
IL = 28 mA (GR max)
IL = 60 mA (GR min)
IL = 28 to 60 mA
figure 4
VL = 0V, IL = 28 mA
figure 4
Pin 29–30
IL = 15 mA, VR = 2.8 Vpp
IL = 28 mA, VR = 5.5 Vpp
IL = 60 mA, VR = 5.0 Vpp
figure 4
VR = 50 mVRMS,
IL = 28 mA
figure 4
Pin 29–30
IL = 28 mA
figure 4
Pin 29–30
IL = 28 mA
figure 3
VL = 0.3 VRMS
IL = 28 and 60 mA
figure 4
Measured at pin VIR
figure 5
figure 5
VIR = 18 V
Load = 10 kW
figure 5
Pin 38 grounded
Pin 38 open
Sweep frequencies
Leakage current
6 (20)
Pin 39 grounded
Pin 39 open
VIR = 30 V
IIL at VIL = 0 V
Pins 38 and 39
figure 5
Symbol
GR
DGR
Min.
Typ.
7.0
35
8
40
10
2.5
–6
11
4
–7
45
VON
VOFF
VOUT
9.5
Unit
mA
12
5.5
–8
dB
–65
dBmp
3
3
3
%
85
W
+650
mV
36
40
dB
660
750
W
16
18.0
V
1.5
V
mA
65
–650
580
Max.
10.5
1.2
VIR–2
Vp
1458
1166
547
438
4.0
9.1
Hz
Hz
5
mA
Rev. A1: 16.07.1996
U3750BM
TELEFUNKEN Semiconductors
Parameters
Test Conditions / Pins
DTMF generation Pin 4 grounded
Tone frequency accuracy
VRAM = 3.5 V
(confidence tone included)
Low group tone level
(Note 2)
(depends on external
Measured on 600 W
components)
IL = 28 mA
figure 3
High group tone level
(Note 2)
(depends on external
Measured on 600 W
components)
IL = 28 mA
figure 3
Preemphasis (depends on
(Note 2)
external components)
Measured on 600 W
IL = 28 mA
figure 3
DTMF distortion (depends (Note 2 and note 3)
on external components)
Measured on 600 W
IL = 28 mA,
300 < f < 3400 Hz
figure 3
DTMF transmission time
DTMF interdigit time
Transmission mute tmMF
Confidence tone
Only by serial bus
FCT frequency
Tone level (depends on
Measured on 600 W
external components)
IL = 25 mA
figure 3
Symbol
Min.
Typ.
–0.4
tMF
tIMF
Max.
Unit
+0.25
%
–10
–8
–6
dBm
–8
–6
–4
dBm
1
2
3
dB
3.5
%
82.4
89.2
171.6
ms
ms
ms
80.2
89.2
169.4
440.9
–9
Hz
dBm
Note 1: sending gain: GS = VL/VMI with the values of
RAG1 and RAG2 (figure 3) so the maximum gain
is at 28 mA and the minimum gain is at 60 mA.
Note 2: For DTMF measurements, close switches S1 and
S3 and select each group of frequencies on the
keyboard.
Note 3: The level of each harmonic on line is under the
limited curve given below with the filter components value chosen for the test.
Figure 1
Rev. A1: 16.07.1996
7 (20)
U3750BM
TELEFUNKEN Semiconductors
dBm ( 600W )
–30
–40
–50
–60
0.1
1
10
100
1000
f ( kHz )
93 7831 e
Figure 2
DTMF distortion
Figure 3 Test circuit
8 (20)
Rev. A1: 16.07.1996
U3750BM
TELEFUNKEN Semiconductors
Figure 4 Test circuit
Figure 5 Test circuit
S5 (Pin 38)
S6 (Pin 39)
Pair of Frequencies (Hz)
ON
ON
OFF
OFF
ON
OFF
ON
OFF
1458/1166
1458/1166
547/438
547/438
Rev. A1: 16.07.1996
Sweep Frequency
(Hz)
4
9.1
4
9.1
9 (20)
U3750BM
TELEFUNKEN Semiconductors
Electrical Characteristics of Logical Part
fclock = 455 kHz (other specifications as under electrical characteristics)
Parameters
VRAM
Speed-up off threshold
Speed-up on threshold
Logic operating voltage in
normal mode
IRAM
Oscillator on
Leakage
Inputs: C1, C2, C3, C4,
C5, C6, DC/FV, FLASH
Keyboard pins: C1, C2,
C3, C4, C5, C6
Internal pull down
Output current
FLASH, DC/FV
Internal pull-up current
IPV
Leakage current
Timing and frequency
Reset time tr (see figure 6
and 7)
Clock start-up time ton
Time line break generating
a reset: tlb
Debounce time, te
RESET output (with 390 W
series)
Output low current
Output high current
OL output
Output low current
Output high current
MF output
High impedance
CK Input
Low input leakage
High input leakage
10 (20)
Test Conditions / Pins
IL = 8 mA
IL = 15 to 70 mA
Symbol
VSOFF
VSON
Min.
2.4
1.9
Typ.
2.75
2.2
2.5
3.5
VRAM = 3.5 V
Input voltage low, VIL
Input voltage high, VIH
Max.
2.9
2.3
800
300
0.2
VRAM
0.8
VRAM
Unit
V
V
V
V
mA
mA
V
V
VIL = 3.5 V
VIH = 0 V
15
0.8
50
2.5
mA
mA
VIL = 0 V
VIH = 3.5 V
0.5
5
1
mA
mA
In mode 60/40
In mode 66/33 and DTMF mode
30
33
5
290
319
14
15.4
In mode 60/40
In mode 66/33 and DTMF mode
In mode 60/40
In mode 66/33 and DTMF mode
24
26.4
ms
ms
ms
300
330
34
37.4
ms
ms
ms
ms
VOL = 2.5 V
VOL = 0.5 V
IOL
IOH
0.25
0.25
1.2
1.2
mA
mA
VOL = 0.5 V
IOL
IOH
2
1
20
4
mA
mA
150
200
200
150
0.5
350
550
550
350
mA
mA
mA
mA
mA
1
1
mA
mA
VOHI = 1.4 V
FL = L, FH = H, VOH = 3.5 V
FB = L, FH = H, VOH = 0 V
FB = H, FH = L, VOH = 3.5 V
FB = H, FH = L, VOH = 0 V
VIL = 0.5 V
VIL = 3.0 V
Rev. A1: 16.07.1996
U3750BM
TELEFUNKEN Semiconductors
Parameters
Serial bus (see figure 12)
Pulse width clock
Pulse width enable signal
Set-up time data to clock
Hold time data from clock
Enable time
Time between two transmissions
Pulse dialing (OL)
Dialing pulse frequency
Test Conditions / Pins
Symbol
Min.
twl, twh
tel, teh
tset up
2
2
0
100
0
900
te
tRRN
In mode 60/40 (Pin 4 tied to
RESET)
In mode 66/33 (Pin 4 not
connected)
TOL
Dialing pulse period
Break time
tb
Make time
tm
tIDOL
Interdigit time
Transmission mute:
tmol = (tm + tb) @ n + tm1
n pulses dialling
Flash pulse
Flash pulse duration
Transmission mute
Pause time
Rev. A1: 16.07.1996
Pin 3 to GND Pin 4 to RESET
Pin 3 to GND Pin 4 to NC
Pin 3 to GND Pin 4 to GND
Pin 3 to NC Pin 4 to RESET
Pin 3 to NC Pin 4 to NC
Pin 3 to NC Pin 4 to GND
Pin 3 to RESET Pin 4 to RESET
Pin 3 to RESET Pin 4 to NC
Pin 3 to RESET Pin 4 to GND
In mode 60/40
In mode 66/33
In mode DTMF
In mode 60/40
In mode 66/33
In DTMF mode
tfl
tmfl
Tp
Typ.
Max.
Unit
ms
ms
ms
ms
ms
ms
10
Hz
10.11
Hz
100
98.9
60
66
40
33
ms
ms
ms
ms
ms
ms
ms
ms
ms
830
813
[n@100
+ 30]
[[email protected]
+ 22]
833
816.5
(n@100)
+ 32
([email protected])
+ 24.2
89.5
98.5
102.5
239.5
263.5
274.0
109.5
120.5
125.0
830
813
846
92
101
105
242
266
277
112
123
128
832
815.5
848.5
3116
3075
3012
3118
3077
3110
ms
ms
ms
11 (20)
U3750BM
TELEFUNKEN Semiconductors
Power-on Reset and Pin RESET
Pin RESET
To avoid undefined states of the device when it is powered
on, an internal reset clears the control logic. When the
power supply rises above the internal reference level, the
pin RESET goes to high during trt. After a line break
longer than tlb, a reset is generated. A short line break
(< tlb) does not affect the reset. Power on reset timings
(t > tlb).
It is the power on reset output.
1)
VRAM > VSON at t = 0 . . . . . . . . . a)
Trt = Tr + T on . . . . . . . . . . . . . . . . . . . . . . b)
In test mode, it permits to force the IC U 3750 BM in
permanent DTMF dialing by applying a negative voltage
(test schematic figure 3).
Data Acquisition
Input data is derived from any standard matrix keyboard
(15 keys) or from a remote microcontroller.
Keyboard
The keyboard is connected to the IC by six pins, (see
figure 8). Its matrix is triangular.
a)
b)
Figure 6
2)
VRAM < VSON at t = 0 . . . . . . . . . a)
Trt = T (VRAM to VS off) + Tr + T on . . . . b)
Figure 8
Keyboard inputs to the U 3750 BM
Internal pull down resistors (typical value: 120 kW) are
connected to the inputs Ci.
A push button is made by a short-circuit of two pins
among the six.
Entries are scanned every 12 ms or 13.2 ms and go to the
logical state 1 during this scanning.
a)
The scanning is inhibited as soon as a calibrated linebreak is produced at the OL output.
The scanning-cycle has eight phases: six of them are
reserved for the scanning of the six pins, the two others are
kept for the reset of the logic keyboard (T0) and the
acquisition (T7).
A push button is valid, if it is unique and if it’s pressed
long enough (see table of pressed and released push
buttons).
b)
Figure 7
12 (20)
Every acquisition time, T7, the input code is decoded into
5 bits (with or without a pressed push button). The microprocessor can read it as soon as the logic keyboard has set
a flag, tested about every 800 ms and which indicates that
a pushbutton has been correctly detected.
Rev. A1: 16.07.1996
U3750BM
TELEFUNKEN Semiconductors
Table 2 The scanning principle
Keyboard clock
Ti except T0, T1, T7
T1
T0 or T7
Scanning cycle
2 ms
2 ms
1.956 ms
22 ms
12 ms
2.2 ms
2.2 ms
2.156 ms
22 ms
13.2 ms
T0:
reset of the logic keyboard
T7:
acquisition of the code present at the keyboard
Scanning
Push button
Figure 9 The scanning principle
Rev. A1: 16.07.1996
13 (20)
U3750BM
TELEFUNKEN Semiconductors
Timing of a Push Button
The information from a pressed push button or released push button is taken into account if it is still present during
at least two sampling times, T7.
Table 3 Timing of a push button
Clock Keyboard 2 ms, 2.2 ms
Minimum time – push button on
Minimum time – push button off
Min.
14
15.4
24
26.4
Typ.
24
26.4
24
26.4
Max.
34
37.4
34
37.4
Unit
ms
ms
ms
ms
The entries are debounced on both the leading and trailing edges for 34 ms or 37.4 ms according to the value of the
keyboard clock, and so the time remains less than 40 ms. At this time the information can be processed. If the information is still present after more than 40 ms, it is only taken one time.
Serial Bus
The remote microcontroller is connected to the IC by 4 pins: C2, C3, C4, C5 (see figure 10).
Figure 10 Connection of the microcontroller to the U3750BM
C2 transmits the data, C3 the clock, C4 the enable signal, and C5 indicates the state of the dialer:
C5 = 0, dialer is busy
C5 = 1, dialer is free
Data is serially shifted in a 5-bit register during the positive going transition of the clock pulse. The positive going
transition of the enable signal validates the transmission.
14 (20)
Rev. A1: 16.07.1996
U3750BM
TELEFUNKEN Semiconductors
Figure 11 Timing of the serial bus
Code Entries Table
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
Rev. A1: 16.07.1996
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
0
1
0
1
*
1
2
3
4
5
6
7
8
9
0
A
B
C
D
#
16
R flash
Redial
Confidence tone
Micro inhibition
Pause
23
15 (20)
U3750BM
TELEFUNKEN Semiconductors
Dialer
The IC includes a dialing circuit for either pulse dialing
or dual tone multifrequency dialing. The dialer transmits
the codes decoded by the logic keyboard on the outputs
OL and MF.
Mode Selection
The choice of dialing is made by the tri-state-level on the
DC/FV Pin
FV DC = Z
FV DC
tied to pin RESET
FV DC = 0
on the dialing. The code A is filtered and corresponds to
eleven pulses.
Dialing
As soon as the code is detected by the logic keyboard and
written in RAM, it can only be loaded in the dialer if the
dialer is not occupied and a pause is not generated.
pulse dialing in 66/33 ms
Pulse Dialing
pulse dialing in 60/40 ms
DTMF dialing calibrated
The output which provides control signals for proper
timing in pulse dialing is pin, OL. The dialling starts with
a make time (see figure 12).
When the circuit is in pulse mode, it is possible to change
over to DTMF dialing with the “ * ” key. The code “ * ” is
sent in line. The circuit returns in pulse mode after a reset
condition or after a flash pulse (see figure 14).
Dialing Codes
The dialing codes are the numeric keys 0 to 9, and the non
numeric keys A, B, C, D, *, #. All are stored in RAM. The
codes A, B, C and D can be only transmitted by the serial
bus. In pulse dialing, the code #, B, C and D have no effect
Dual tone Multifrequency Dialing
The output pin, MF, provides the multifrequency signal
to transmit in line. This signal results from the sum of two
frequency pulses modulated and requires a filter to compose a dual sine wave. The frequencies are chosen in a low
group and a high group. Table 3 shows the frequency
tolerance of the output tones for DTMF signalling. In
manual dialing or in redial, output tone is timed with a
fixed duration.
Table 4 Frequency tolerance of the output tones for DTMF signaling
Standard
Frequency
Hz
Low Group
697
770
852
941
High Group
1209
1336
1477
1633
Tone Output
Frequency
Hz
Frequency Deviation
%
Hz
697.8
768.6
848.9
940.1
+0.12
–0.18
–0.37
–0.10
+0.85
–1.42
–3.12
–0.92
1210.1
1338.2
1477.3
1636.7
+0.09
+0.17
+0.02
+0.22
+1.11
+2.23
+0.27
+3.69
Tone output frequency when using a 455 kHz ceramic.
16 (20)
Rev. A1: 16.07.1996
TELEFUNKEN Semiconductors
U3750BM
Figure 12 Timing diagram for pulse dialing
Figure 13 Timing diagram for DTMF dialing
Figure 14 Timing diagram for mixed mode dialing
Rev. A1: 16.07.1996
17 (20)
U3750BM
TELEFUNKEN Semiconductors
Flash Control
Microphone Inhibition
Detecting a “R” code produces either a short timed line
break (< 200 ms ) or long timed line break (>200 ms) at
the OL output.
Like the confidence tone, it is a flip flop function activated through the serial bus by the code 21 (in decimal).
For the duration of the flash, it is not possible to take
information from the keyboard.
Organization
Flash signifies that the circuit executes a particular work
as a dialing, a redial, or a pause function, and the code “R”
is lost and not used.
The flash pulse resets the read address counter and does
not erase the data storage, so later redial is possible.
The flash duration is programmed by the FLASH pin
(Pin 3) and depends on the selection of the tri-state-level
pin (Pin 4).
Mutes (transmission mute and dialing mute) become
active high from the beginning of the line break. Timings
explains this.
According to these timings and what has previously been
said, a second pulse flash could only follow the first one
810 ms or 850 ms later.
Consequently the “R” entry remains inhibited during a
time less than 1 second.
Pause Function
A pause separates the dial sequence. It is used for waiting
for a dial tone.
A pause code takes one position in the RAM like a digit.
However, if the circuit executes a pause and if another
pause code is entered, the storage of the second one does
not occur. Furthermore, the pause running is aborted.
Duration of the pause is given in electrical characteristics
for the following configuration: digit, pause, digit, and
consequently takes into account the interdigit.
Particular Functions
After the reset, the particular functions are cleared. The
state of the circuit is no confidence tone, no microphone
inhibition.
Confidence Tone Output
When the data entries are derived from the serial bus, a
pulse frequency modulation corresponding to a 440 Hz
sine wave can be generated on the output MF by transmitting the confidence tone code which is 20 (in decimal).
The function confidence tone is a flip-flop function.
18 (20)
RAM
The RAM is 32 words of 5 bits and is organized in two
parts: one for the data storage and the other for the
working RAM.
Safeguard
The safeguard is guaranteed by an external capacitor. If
VRAM decreases under the data retention supply voltage,
the redial function is forbidden. After the reset of the
circuit, a test is executed on VRAM in order to ensure the
redial validity.
Data storage
Storage, overflow and erasing are realized through three
address counters. The written address counter (P1) points
out the location where the code will be stored. At each
storage, P1 is incremented by one. As each code is
recalled from the RAM for line dialing, the read address
counter (M1) is incremented by one to select the RAM
location of the next code to be recalled.
Consequently, the difference between the contents of P1
and of M1 represents the number of codes that have been
written into the RAM but not yet converted into line
dialing.
The third counter (P2) gives the real capacity of the redial
register.
Redial features
Capacity
If more than 23 codes are entered into the RAM memory,
overflow results and the excess codes replace the data in
the lower numbered RAM locations. In this event, automatic redial is no longer possible.
Storage
Storage pertains to the dialing codes 0 to 9, *, #, pause,
A, B, C and D. It is independent of the dialing mode (pulse
dialing or DTMF dialing).The storage generally contains
the last digits transmitted.
Use of redial
The use of redial is always possible except if the content
of the RAM is empty (P2 = 0). This happens when the
RAM supply is not high enough , when an overflow
occurred, or when previously an erroneous use of the
redial occurred (start of manual dialing not equal to the
content of the RAM).
Rev. A1: 16.07.1996
U3750BM
TELEFUNKEN Semiconductors
If the redial is ordered after a manual dialing the redial is
executed according to the digits already transmitted in
line.
The redial is effective if the comparison digit-by-digit of
all digits is correct. It is not produced if the comparison
is incorrect or if the number of digits exceeded the last
capacity of the redial. During redial, entry codes are
accepted.
Procedure with *
Storage does not pertain to the “*” code and the codes
entered after it when the manual dialing starts with a
numeric code or A, B, C, D, #, or pause codes. If the
dialing starts with the “*” code, all codes can be stored.
Note: the “#” code is treated for storage like a number.
Procedure with flash
The flash pulse does not reset the content of the RAM.
Example: 1 2 3 R
Redial µ å 1 2 3 R 1 2 3
Redial µ å 1 2 3
Erasing redial
The erasing is possible through the serial bus with the
decimal codes 16 and 23. There is not much difference
between these two codes: code 16 always erases the
redial, code 23 inhibits a later redial if it is transmitted
after or before dialing codes. The following examples
illustrates this.
Transmitted Codes
123
16
Redial µ
123
Redial µ
123
Redial µ
123
Redial µ
123
Redial µ
123
Redial µ
On Line
123
–nothing
23
16
4µ
23
4µ
R
16 µ
R
23 µ
123
–
1234
4
1234
–
123R
–
123R
123
Special Case
When the overflow flag is set and when the written
address counter becomes equal to the read address
counter, the codes are not stored.
Dimensions in mm
Package: PLCC 44
Rev. A1: 16.07.1996
19 (20)
U3750BM
TELEFUNKEN Semiconductors
Ozone Depleting Substances Policy Statement
It is the policy of TEMIC TELEFUNKEN microelectronic GmbH to
1. Meet all present and future national and international statutory requirements.
2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems
with respect to their impact on the health and safety of our employees and the public, as well as their impact on
the environment.
It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as
ozone depleting substances ( ODSs).
The Montreal Protocol ( 1987) and its London Amendments ( 1990) intend to severely restrict the use of ODSs and
forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban
on these substances.
TEMIC TELEFUNKEN microelectronic GmbH semiconductor division has been able to use its policy of
continuous improvements to eliminate the use of ODSs listed in the following documents.
1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively
2 . Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental
Protection Agency ( EPA) in the USA
3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C ( transitional substances ) respectively.
TEMIC can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain
such substances.
We reserve the right to make changes to improve technical design and may do so without further notice.
Parameters can vary in different applications. All operating parameters must be validated for each customer
application by the customer. Should the buyer use TEMIC products for any unintended or unauthorized
application, the buyer shall indemnify TEMIC against all claims, costs, damages, and expenses, arising out of,
directly or indirectly, any claim of personal damage, injury or death associated with such unintended or
unauthorized use.
TEMIC TELEFUNKEN microelectronic GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany
Telephone: 49 ( 0 ) 7131 67 2831, Fax number: 49 ( 0 ) 7131 67 2423
20 (20)
Rev. A1: 16.07.1996