MOTOROLA MC14497

Order this document
by MC14497/D
SEMICONDUCTOR TECHNICAL DATA
P SUFFIX
PLASTIC DIP
CASE 707
The MC14497 is a PCM remote control transmitter realized in CMOS
technology. Using a dual–single (FSK/AM) frequency bi–phase modulation, the
transmitter is designed to work with the MC3373 receiver. Information on the
MC3373 can be found in the Motorola Linear and Interface Integrated Circuits
book (DL128/D).
There is not a decoder device which is compatible with the MC14497.
Typically, the decoding resides in MCU software.
18
1
ORDERING INFORMATION
MC14497P
• Both FSK/AM Modulation Selectable
• 62 Channels (Up to 62 Keys)
• Reference Oscillator Controlled by Inexpensive Ceramic Resonator:
Maximum Frequency = 500 kHz
• Very Low Duty Cycle
• Very Low Standby Current: 50 µA Maximum
• Infrared Transmission
• Selectable Start–Bit Polarity (AM Only)
• Shifted Key Mode Available
• Wide Operating Voltage Range: 4 to 10 V
• See Application Notes AN1016 and AN1203
Plastic DIP
PIN ASSIGNMENT
E3
1
18
VDD
E2
2
17
E1
E9
3
16
E4
A4
4
15
E5
A3
5
14
E6
A2
6
13
OSCout
A1
7
12
OSCin
SIGNAL OUT
8
11
E8
VSS
9
10
E7
BLOCK DIAGRAM
VDD
KEYBOARD
E1
E2
E3
E4
E5
E6
E7
E8
17
2
1
16
15
14
10
11
A4 A3 A2 A1
E9
18
MUX
8
OUTPUT
CONTROL
ENCODER
7–BIT
SR
3
SEQUENCE
CONTROL
3–BIT
LATCH
DIVIDER
÷ 10/12
STANDBY
7
6
5
4
DIVIDER
÷ 32
SCANNER
DIVIDER
÷ 16
OSC
FK3
IN
FK1
9
12
OUT
13
500 kHz CERAMIC
RESONATOR
SAME AS IN DL136/D R3

Motorola, Inc. 1995
MOTOROLA
MC14497
1
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
MAXIMUM RATINGS (Voltages referenced to VSS)
Parameter
DC Supply Voltage
Input Voltage, All Inputs
DC Current Drain per Pin
Operating Temperature Range
Storage Temperature Range
Symbol
Value
Unit
VDD
– 0.5 to + 18
V
Vin
– 0.5 to VDD + 0.5
V
I
10
mA
TA
– 40 to + 85
°C
Tstg
– 65 to + 150
°C
This device contains circuitry to protect the
inputs against damage due to high static
voltages or electric fields; however, it is advised that normal precautions be taken to avoid
application of any voltage higher than maximum rated voltages to this high–impedance
circuit. For proper operation it is recommended
that Vin and Vout be constrained to the range
VSS ≤ (Vin or Vout) ≤ VDD.
ELECTRICAL CHARACTERISTICS (TA = 0 to 70°C; all Voltages Referenced to VSS)
Symbol
VDD
Min
Max
Unit
Supply Voltage
VDD
—
4.0
10.0
V
Supply Current
Idle
Operation
IDD
10
10
—
—
50
5
µA
mA
Characteristic
µA
Output Current — Signal
VOH = 3.0 V
VOL = 0.5 V
Source
Sink
IOH
IOL
4
4
– 900
120
—
—
Output Current — Scanner
VOH = 3.0 V
VOL = 0.5 V
Source
Sink
IOH
IOL
4
4
– 30
245
—
—
Output Current — Oscillator
VOH = 3.0 V
VOL = 0.5 V
Source
Sink
IOH
IOL
4
4
– 300
245
—
—
10
4
±2
30
± 80
—
10
4
– 15
—
—
– 60
10
10
4
4
9
—
3
—
—
1.2
—
1.0
µA
µA
Input Current — Oscillator
Operation
Idle, VIL = 0.5 V
Iin
Input Current — Encoder
VIH = 9.0 V
VIL = 0.5 V
Iin
Input Voltage — Encoder
VIH
VIL
VIH
VIL
MC14497
2
µA
µA
V
MOTOROLA
CIRCUIT OPERATION
The transmitter sends a 6–bit, labelled A (LSB) to F (MSB),
binary code giving a total of 64 possible combinations or
code words. All of these channels are user selectable, except the last two (where channel 63 is not sent while channel
62 is automatically sent by the transmitter at the end of each
transmission as an “End of Transmission” code).
In either mode, FSK or AM, the transmitted signal is in the
form of a bi–phase pulse code modulation (PCM) signal. The
AM coding is shown in Figure 1.
BIT–n
f1
to make an intermediate keyboard with between 32 and 64
keys.
The other two switches in the Block Diagram (FK1 and
FK2) change the modulation mode. Closing FK1 changes
the modulation from FSK to AM and the start–bit polarity.
Closing FK2 changes the start–bit to a logical 0.
The full range of options available is illustrated in Table 1.
Table 1.
Start
Bit
Modulation
Bit–F
Channels
E9 = Open
1
FSK
0
0 – 31
E9 = A1 (FK1)
1
AM
0
0 – 31
E9 = A2 (FK2)
0
FSK
0
0 – 31*
E9 = A3 (FK3)
1
FSK
1
32 – 61
E9 = A1 • A2
0
AM
0
0 – 31
E9 = A1 • A3
1
AM
1
32 – 61
E9 = A2 • A3
0
FSK
1
32 – 61*
E9 = A1 • A2 • A3
0
AM
1
32 – 61
“0”
AM
f1
“1”
Figure 1. AM Coding
In the AM mode, f1 is a train of pulses at the modulating
frequency of 31.25 kHz for a reference frequency of 500 kHz.
In the FSK mode, two modulating frequencies are used as
shown in Figure 2.
BIT–n
f2
f3
f3
f2
“0”
FSK
“1”
Figure 2. FSK Coding
In this mode, f3 is 50 kHz and f2 is 41.66 kHz for a reference frequency of 500 kHz.
The keyboard can be a simple switch matrix using no external diodes, connected to the four scanner inputs (A1 – A4)
and the eight row input (E1 – E8). Under these conditions,
only the first 32 code words are available since bit–F is always at logical 0. However, a simple 2–pole changeover
switch, in the manner of a typewriter “shift” key (switch FK3 in
the Block Diagram) can be used to change the polarity of
bit–F to give access to the next full set of 32 instructions.
An alternative method of accessing more than 32 instructions is by the use of external diodes between the address
inputs (see Figure 3). These have the effect of producing
“phantom” address inputs by pulling two inputs low at the
same time, which causes bit–F to go high (i.e., to logical 1).
By interconnecting only certain address inputs it is possible
MOTOROLA
* Not allowed.
One of the transmitter’s major features is its low power
consumption (in the order of 10 µA in the idle state). For this
reason, the battery is perpetually in circuit. It has in fact been
found that a light discharge current is beneficial to battery
life.
In its active state, the transmitter efficiency is increased by
the use of a low duty cycle which is less than 2.5% for the
modulating pulse trains.
While no key is pressed, the circuit is in its idle state and
the reference oscillator is stopped. Also, the eight address input lines are held high through internal pull–up resistors.
As soon as a key is pressed, this takes the appropriate address line low, signaling to the circuit that a key has been selected. The oscillator is now enabled. If the key is released
before the code word has been sent, the circuit returns to its
idle state. To account for accidental activation of the transmitter, the circuit has a built–in reactive time of approximately
20 ms, which also overcomes contact bounce. After this
delay, the code word will be sent and repeated at 90 ms intervals for as long as the key is pressed. As soon as the key is
released, the circuit automatically sends channel 62, the
“End of Transmission” (EOT) code. The transmitter then returns to its idle state.
The differences between the two modulation modes are illustrated in Figure 4. However, it should be noted that in the
AM mode, each transmitted word is preceded by a burst of
pulses lasting 512 µs. This is used to set up the AGC loop in
the receiver’s preamp. In the FSK mode, the first frequency
of the first bit is extended by 1.5 ms and the AGC burst is
suppressed. In either mode, it is assumed that the normal
start–bit is present.
MC14497
3
PIN DESCRIPTIONS
VSS
E1
E1 – E8
Row Inputs (Pins 1, 2, 10, 11, 14, 15, 16, 17)
17
VDD
18
9
E1a
Under idle conditions, these inputs are held high by internal pull–up resistors. As soon as a key is pressed, a logical 0
on that particular line signals to the circuit that a key has
been selected. After a delay of 20 ms, the internal register is
loaded with the code word for the key selected.
E2
2
E2a
E3
E9
Row Input (Pin 3)
1
E3a
This is a special programming input and when connected
to the appropriate scanner output via a diode, it will modify
the transmitted output according to Table NO TAG.
In Table NO TAG, the figures in brackets (FK1, etc.) refer
to the switches shown in the Block Diagram and Figure 3. If
only one option is required, the diode may be omitted. The
connections shown in Table NO TAG may be made in any
combination.
Although E9 is a row input, forcing this line low will not activate the circuit.
E4
16
E4a
E5
15
E5a
E6
A1 – A4
Scanner Outputs (Pins 4 – 7)
14
E6a
Under idle conditions, these outputs are held low, logical 0.
When a key is pressed, the circuit is activated and the oscillator will start and release the outputs (see Figure 5).
E7
E7a
OSCin, OSCout
Oscillator Input and Oscillator Output (Pins 12, 13)
E8
A1
7
A2
6
A3
5
A4
4
SIGNAL OUT
Signal Output (Pin 8)
FK2
3
FK1
13
12
E9
This output provides the modulating signal ready to drive
the modulation amplifier. If required, the transmitter can be
used as a keyboard encoder for direct use with a receiver. In
this case, the AM option is selected, the output inverted, and
fed directly to the receiver’s signal input pin.
A
11
E8a
These pins are designed to operate with a 500 kHz ceramic resonator or a tune LC circuit. It is important that a ceramic
resonator and not a filter be used here, as the oscillator frequency cannot be guaranteed if a ceramic filter is used.
START BIT
10
C1
NOTE: Maximum key contact
resistance = 1 kΩ .
C2
Figure 3. 64–Key Keyboard
B
C
D
E
F
INSTRUCTION
FSK
AM
f3
f1
f2
f1
KEY WORD
f3
f1
f2
f3
f2
f1
f3
f2
f1
f3
f1
ONE WORD
DEBOUNCE
9 ms
20 ms
99 ms
Figure 4. Transmitted Waveforms and Timing (Not Drawn to Scale)
MC14497
4
MOTOROLA
KEY DOWN
KEY RELEASED
DEBOUNCE
A1
A2
A3
A4
Figure 5. Scanner Output Timing Diagram
1500 µF
100 Ω
9V
0.1 Ω
1N4001
100 Ω
*
18
1 kΩ
MC14497
KEYBOARD
9
12
8
13
* Visible Indicator
C1
C2
C1 and C2 are sized per the ceramic resonator supplier’s recommendation.
Ceramic Resonator Suppliers:
1. Morgan Matrox, Inc., Bedford, OH, 216/232–8600
2. Radio Materials Co., Attica, IN, 317/762–2491
Motorola cannot recommend one supplier over another and in no way suggests that this is a
complete listing of ceramic resonator suppliers.
Figure 6. Typical Application Circuit
MOTOROLA
MC14497
5
AGC BURST
START BIT
f4
A
f4
2.84 ms
1.155 ms
540
µs
B
C
D
E
f4
f4
f4
f4
1.1 ms
590
µs
590
µs
590
µs
540
µs
540
µs
540
µs
F
f4
1.16 ms
540
µs
540
µs
NOTES:
1. f4 = 28.4 kHz.
2. Indicated time durations are approximated.
Figure 7. AM Mode Transmitted Wavetrain with 455 kHz Oscillator
Table 2. Transmitted Codes
Code Word
Keyboard
Code Word
Keyboard
Channel
F
E
D
C
B
A
In
Out
Channel
F
E
D
C
B
A
In
Out
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
1
0
1
1
0
0
1
1
1
1
1
0
1
1
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
Not
Transmitted
0
1
A4
A4
A4
A4
A4
A4
A4
A4
A1
A1
A1
A1
A1
A1
A1
A1
A3
A3
A3
A3
A3
A3
A3
A3
A2
A2
A2
A2
A2
A2
A2
A2
1
0
E8
E1
E2
E3
E4
E5
E6
E7
E8
E1
E2
E3
E4
E5
E6
E7
E8
E1
E2
E3
E4
E5
E6
E7
E8
E1
E2
E3
E4
E5
E6
E7
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
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
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
E8a
E1a
E2a
E3a
E4a
E5a
E6a
E7a
E8a
E1a
E2a
E3a
E4a
E5a
E6a
E7a
E8a
E1a
E2a
E3a
E4a
E5a
E6a
E7a
E8a
E1a
E2a
E3a
E4a
E5a
E6a
E7a
A4
A4
A4
A4
A4
A4
A4
A4
A1
A1
A1
A1
A1
A1
A1
A1
A3
A3
A3
A3
A3
A3
A3
A3
A2
A2
A2
A2
A2
A2
A2
A2
NOTE: Although the “a” suffix applies to a phantom input when using
a keyboard with up to 64 keys, the coding is identical with a
32–key keyboard when switch FK3 is closed.
MC14497
6
MOTOROLA
PACKAGE DIMENSIONS
P SUFFIX
PLASTIC DIP
CASE 707–02
18
NOTES:
1. POSITIONAL TOLERANCE OF LEADS (D),
SHALL BE WITHIN 0.25 (0.010) AT MAXIMUM
MATERIAL CONDITION, IN RELATION TO
SEATING PLANE AND EACH OTHER.
2. DIMENSION L TO CENTER OF LEADS WHEN
FORMED PARALLEL.
3. DIMENSION B DOES NOT INCLUDE MOLD
FLASH.
10
B
1
9
A
L
C
N
F
H
MOTOROLA
D
G
SEATING
PLANE
K
M
J
DIM
A
B
C
D
F
G
H
J
K
L
M
N
MILLIMETERS
MIN
MAX
22.22 23.24
6.10
6.60
3.56
4.57
0.36
0.56
1.27
1.78
2.54 BSC
1.02
1.52
0.20
0.30
2.92
3.43
7.62 BSC
15°
0°
0.51
1.02
INCHES
MIN
MAX
0.875 0.915
0.240 0.260
0.140 0.180
0.014 0.022
0.050 0.070
0.100 BSC
0.040 0.060
0.008 0.012
0.115 0.135
0.300 BSC
0°
15°
0.020 0.040
MC14497
7
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the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit,
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MC14497
8
◊
*MC14497/D*
MC14497/D
MOTOROLA