ETC NT95089

NT95089
Tone Dialer
Features
„ Wide operating voltage range: 2.5V - 10V
„ Optimum use with a constant operating supply voltage
„ TV
„
(typically 3.5V )
amplitude stability of ±1.5dB within the
suggested operating temperature range
Device power may be derived directly from telephone
lines or from small batteries
Low total harmonic distortion
„ Tone
„
„
„
„
crystal standard (3.58MHz) is used to derive all
frequencies, providing high accuracy and stability
Specifically designed for electronic telephone
applications
Interfaces directly with a standard push-button
telephone keyboard with common terminal
Dual tone/single tone capability
General Description
The NT95089 DTMF generator is specifically designed
for applications requiring a fixed supply operating voltage
and a high stability tone output, making it ideal for
electronic telephone applications. The NT95089
interfaces directly to a standard push-button telephone
keyboard (common terminal connected to VSS) and
operates directly from telephone lines. All necessary
dual-tone frequencies are derived from the widely-used
TV crystal standard, providing high accuracy and
stability. The required sinusoidal waveform for individual
tones is digitally synthesized on the chip, resulting in a
waveform with low total harmonic distortion. A voltage
reference which is stable over the operating temperature
range is generated on the chip; this reference is used to
regulate the dual tone frequency levels to ensure that
they
meet
recommended
telephone
industry
specifications.
Pin Configuration
Keyboard Assignments
1
1
2
3
A
R1
4
5
6
B
R2
7
8
9
C
R3
*
0
#
D
R4
C1
C2
C3
C4
NT95089
Block Diagram
Absolute Maximum Ratings*
*Comments
Power Supply Voltage (VDD - VSS) . . . . -0.3V to +10.5V
Input Voltage (VIN). . . . . . . . . . . . . -0.3V to VDD + 0.3V
Maximum Power Dissipation (at 25°C). . . . . . . . 500mW
Operating Temperature. . . . . . . . . . . . . . -20°C to +70°C
Storage Temperature. . . . . . . . . . . . . . -55°C to +150°C
Stresses above those listed under "Absolute Maximum
Ratings" may cause permanent damage to this device.
These are stress ratings only. Functional operation of
this device at these or any other conditions above those
indicated in the operational sections of this specification
is not implied or intended. Exposure to the absolute
maximum rating conditions for extended periods may
affect device reliability.
DC Electrical Characteristics (TOP = 25°C, FOSC = 3.579MHz, unless otherwise specified.)
Parameter
Symbol
Min.
VDD1
2.5
Typ.
Max.
Unit
10
V
Operating Voltage
VDD2
1.6
10
2
V
Conditions
Valid key input
(tone output mode)
AKD outputs vary with key
input (non-tone output
mode)
Test
CKT.
B
NT95089
DC Electrical Characteristics (continued)
Parameter
Symbol
Min.
IDD1
Typ.
Max.
Unit
1.0
1.4
mA
Supply Operating
Current
6.6
10
mA
VDD = 10V, one key input,
all outputs unloaded
ISD1
1
20
µA
VDD = 3V, no key input,
all outputs unloaded
ISD2
AKD Output Sink
Current
IOL
AKD Output off Leadage
Current
IOH
Row & Column Input
Current (Pull-up)
VDD = 3V, one key input,
all outputs unloaded
IDD2
Standby Current
Input Voltage Range
Conditions
5
0.5
B
A
µA
VDD = 10V, no key input,
all outputs unloaded
mA
VDD = 3V, VOL = 0.5V
C
10
µA
VDD = 10V
C
100
1
1
Test
CKT.
VIH
0.8
1
VDD
VIL
0
0.2
VDD
IIH
30
90
150
µA
VDD = 3V, VIH = 0V
-
IIH
100
300
500
µA
VDD = 10V, VIH = 0V
-
760
830
900
mVP-P
VDD = 2.5V, RL = 10KΩ
2028
2200
2380
mVP-P
VDD = 10V, RL = 100KΩ
550
600
650
mVP-P
VDD = 2.5V, RL = 10KΩ
1520
1650
1780
mVP-P
VDD = 10V, RL = 100KΩ
1
2
3
dB
1
5
%
Single Column Tone
Output Amplitude
VOC
Single Row Tone
Output Amplitude
VOR
Pre-Emphasis
Twist
Distortion
DIS%
-
B
B
B
VDD = 5V, * Note
B
IOH1
0.13
0.31
mA
VDD = 3V, VOH = 2.5V,
one key input
C
IOH2
0.42
1.1
mA
VDD = 10V, VOH = 9.5V,
one key input
C
Oscillator Output
Drive Current
3
NT95089
DC Electrical Characteristics (continued)
Parameter
Max.
Unit
Min.
Typ.
Conditions
IOL1
0.21
0.52
mA
VDD = 3V, VOH = 0.5V,
one key input
C
IOL2
0.8
2.1
mA
VDD = 10V, VOH = 0.5V,
one key input
C
Oscillator Output
Sink Current
Input/Output
Capacitance
Test
CKT.
Symbol
C1/01
12
16
pF
VDD = 3V
-
C1/02
10
14
pF
VDD = 10V
-
Note:
DIS% =
100 * (V 12 + V 2 2 +...+ VN 2 )1/2
(VIL2 + VIH 2 )1/2
1. V1. . . . Vn are the intermodulations or the harmonic frequencies in the 500Hz to 3400Hz band.
2. VIL and VIH are the individual frequency components of the DTMFsignal.
AC Characteristics
Parameter
Symbol
Min.
Typ.
Max.
Unit
Conditions
VDD = 3.0V - 10.0V
Oscillator Start up Time
TSTART
2
5
ms
Tone Output Rise Time
TR
2
5
ms
TPDP
0
0
ms
Pre-Digit Pause
Frequency Tolerance of the Output Tones for DTMF Signaling
R/C
Spec.
Actual
Error(%)
Unit
R1
697
699.2
+0.32
Hz
R2
770
766.27
-0.48
Hz
R3
852
847.54
-0.64
Hz
R4
941
948.09
-0.75
Hz
C1
1,209
1,216
+0.58
Hz
C2
1,336
131.8
-0.33
Hz
C3
1,477
1,472
-0.34
Hz
C4
1,633
1,645
+0.73
Hz
4
Conditions
FOSC = 3.579MHZ
NT95089
Pin Description
Pin No.
Designation
Description
1
6
VDD
VSS
2
CE
Chip enable input
The chip enable input has an internal pullup to VDD. When this input is
left unconnected or connected to VDD, the NT95089 operates normally.
When this input is connected to VSS, tone generation is inhibited;
however, all other chip functions continue to operate normally.
3 - 5, 9
11 - 14
C1 - C4
R4 - R1
Keyboard inputs
Internal pullup resistors are present on the row and column inputs
(20KΩ - 10KΩ); low levels on a particular row and column input
correspond to a key entry.
The NT95089 interfaces with the standard push-button telephone
keyboard (see Figure 1).(Keyboard common terminal must be connected
to VSS).
7
8
OSCI
OSCO
Oscillator input
Oscillator output
The NT95089 contains an oscillator circuit with the necessary parasitic
capacitances and feedback resistor on chip, making it necessary to
connect only a standard 3.58MHz TV crystal across the OSCI and
OSCO terminals to implement the oscillator function. The oscillator is
enabled whenever a row input is activated.
10
AKD
Any key down output
The AKD output consists of an open drain N-channel device. When no
keys are pressed, the AKD output is open. When a key is pressed, the
AKD output = VSS.
15
STI
Single tone inhibit input
The STI input is used to inhibit the generation of tones other than dual
tones. It has an internal pull-down to VSS. When this input is left
unconnected or connected to VSS, the SINGLE TONE mode is disabled.
When this input is connected to VDD, single as well as dual tones may
be generated as follows:
DUAL TONE mode: When one row and one column are selected, a dual
tone output consisting of an appropriate low group tone and high group
tone is generated. If two digit keys that are not in the same row or same
column are pressed, the dual tone mode is disabled and no output is
provided.
SINGLE TONE mode: Low group tones can be generated by pressing
two digit keys in the appropriate row. High group tones can be generated
by pressing two digit keys in the appropriate column, i.e., selecting the
appropriate column input and pressing two row inputs in that column.
Positive power supply input
Negative power supply input
The NT95089 is designed to operate within a range of 2.5V to 10.0V.
5
NT95089
Pin Descriptions (continued)
Pin No.
Designation
Description
16
TONE
DTMF signal output
The NT95089 uses a Johnson counter and resistor ladder network (see
block diagram) to synthesize the two desired frequencies in sinewaves.
The ladder network is then used to mix the two. The NT95089 uses a
bipolar NPN transistor, connected as emitter follower, to allow proper
impedance transformation and at the same time preserve signal level
Functional Description
Crystal Specification
DTMF Generator
Standard TV color burst crystals have a much tighter
tolerance specification than is necessary for tone
generation applications. Because the required tolerance
specification for this type of application is more relaxed,
lower-cost crystals can be used. Crystals with the
following specifications are suggested for use with the
NT95089:
Frequency: 3.58MHz ± 0.02%.
RS ≤ 100Ω, LM = 96 mH, CM = 0.02pF, CH = 5pF, CL =
12pF.
The NT95089 has a well designed, digitally-synthesized
sinewave with an 8-level, 16-segment structure. (See
Figure 2.)
Reference Voltage
The structure of the reference voltage employed in the
NT95089 is shown in Figure 3. It has the following
characteristics:
a) V is proportional to the supply voltage. Output tone
amplitude, which is a function of (VDD - VREF),
increases with supply voltage. (Figure 4).
b) The temperature coefficient of VREF is low due to a
single VBE drop. Use of a resistor divider also
contributes to providing an accuracy of better than
10%. As a result, tone amplitude variations over
temperature and unit to unit differences are held to
less than ±1.0dB.
c) Resistor values in the divider network are chosen so
that VREF is above the VBE drop of the tone output
transistor even at the low end of the supply voltage
range. This eliminates tone output clipping at low
supply voltage and improves distortion performance.
AKD Output Structure
N-CHANNEL OPEN DRAIN OUTPUT
6
NT95089
C2
1
2
3
4
5
6
R1
R2
7
8
9
*
0
#
R3
R4
COMMON
(CONNECT TO V S S)
C3
C1
R O N (Contact Resistance)
1 KΩ
MECHANICAL
LINKAGE
Figure 1. Standard Telephone Push-Button Keyboard
(1) R1 Single Tone
(2) C1 Single Tone
Figure 2. DTMF Waveforms
7
(3) DTMF
NT95089
×ÅÅ
©¹­ ¹¹±ª
¹±±
ÂÌÅ
ÕÐÏÆ ÂÎÑÍÊÕÖÅÆ î× ©óîôª
¸±±
ÑÆÂÌ ÕÐÏÆ
ÂÎÑÍÊÕÖÅÆ
©×ÅÅ®×ÓÆǪ
´¯·ÌΩ Ó²
·¯ºÌΩ Ó³
µÌΩ Ó´
×ÓÆÇ
·±±
©ÔÍÐÑÆ» ²²±îװת
¶±±
µ±±
´±±
©´­´²±ª
´
µ
¶
·
¸
¹
º
²±
ÔÖÑÑÍÚ ×ÐÍÕÂÈÆ ©×ÐÍÕÔª
Figure 3. Structure of the Reference Voltage
Figure 4. Typical Single Tone Output Amplitude
vs. Supply Voltage (RL = 10K)
Timing Waveform
CE
KEY INPUT
TONE
AKD
OSC
T START
8
NT95089
Application Circuit (for reference only)
ON- HOOK
L1
ON- HOOK
SPEECH
NETWORK
L2
RINGER
NETWORK
150 Ω
C2
Q1
pin 4
ô
22K
.0047 F
250V
12V
100 Ω
1
1
2
3
4
5
6
16
R1
NT95089
10
R2
pin 13
7
8
9
*
0
#
6
15
7
8
R3
R4
pin 11
COMMON
(CONNECT TO V
C3
pin 5
C1
pin 3
R O N (Contact Resistance)
1K
3.579 MHz
XTAL
SS )
MECHANICAL
LINKAGE
Ω
Standard Telephone Push Button Keyboard
9
AKD
NT95089
Test Circuits
(A)
(B)
(C)
Ordering Information
Part No.
Package
NT95089
16L DIP
10
NT95089
Package Information
DIP 16L Outline Dimensions
unit: inches/mm
D
9
1
8
E1
16
E
A1
A2
Base Plane
Seating Plane
L
A
C
S
B
α
e1
B1
Symbol
Dimensions in inches
Dimensions in mm
A
0.175 Max.
4.45 Max.
A1
0.010 Min.
0.25 Min.
A2
0.130±0.010
3.30±0.25
B
0.018 +0.004
-0.002
0.46 +0.10
-0.05
B1
0.060 +0.004
-0.002
1.52 +0.10
-0.05
C
0.010 +0.004
-0.002
0.25 +0.10
-0.05
eA
D
0.750 Typ. (0.770 Max.)
E
0.300±0.010
19.05 Typ. (19.56 Max.)
7.62±0.25
E1
0.250 Typ. (0.262 Max.)
6.35 Typ. (6.65 Max.)
e1
0.100±0.010
2.54±0.25
L
0.130±0.010
3.30±0.25
α
0° ~ 15°
0° ~ 15°
eA
0.345±0.035
8.76±0.89
S
0.040 Max.
1.02 Max.
Notes:
1. The maximum value of dimension D includes end flash.
2. Dimension E1 does not include resin fins.
3. Dimension S includes end flash.
11