Datasheet MC14497P Datasheet (Motorola)

MC14497MOTOROLA

1

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

The M C14497 is a P CM remote c ontrol transmitter realized in C MOS
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 d ecoder device w hich is compatible with the MC14497.
Typically, the decoding resides in MCU software.

• 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

BLOCK DIAGRAM

17

E1

2

E2

1

E3

16

E4

15

E5

14

E6

10

E7

11

E8

ENCODER

7–BIT

SR

SEQUENCE

CONTROL

3–BIT

LATCH

OUTPUT

CONTROL

DIVIDER

÷

10/12

MUX

SCANNER

DIVIDER

÷

32

DIVIDER

÷

16

OSC

STANDBY

7
6
5
4

FK3

E9

3

FK1

A4 A3 A2 A1

9

V

DD

18

8

IN OUT

12 13

500 kHz CERAMIC

RESONATOR

KEYBOARD

Order this document

by MC14497/D



SEMICONDUCTOR TECHNICAL DATA



P SUFFIX

PLASTIC DIP

CASE 707

ORDERING INFORMATION

MC14497P Plastic DIP

PIN ASSIGNMENT

A3

E9

E2

E3

V

SS

SIGNAL OUT

A1

A2

A4 E5

E4

E1

V

DD

E7

E8

OSC

in

OSC

out

E614

15

16

17

18

10

11

12

13

5

4

3

2

1

9

8

7

6

18

1

 Motorola, Inc. 1995

SAME AS IN DL136/D R3

MC14497 MOTOROLA
2

MAXIMUM RATINGS (Voltages referenced to V

SS

)

Parameter

Symbol

Value

Unit

DC Supply Voltage V

DD

– 0.5 to + 18 V

Input Voltage, All Inputs V

in

– 0.5 to VDD + 0.5 V
DC Current Drain per Pin I 10 mA
Operating Temperature Range T

A

– 40 to + 85 °C

Storage Temperature Range T

stg

– 65 to + 150 °C

ELECTRICAL CHARACTERISTICS (T

A

= 0 to 70°C; all Voltages Referenced to VSS)

Characteristic

Symbol V

DD

Min Max Unit

Supply Voltage V

DD

— 4.0 10.0 V

Supply Current

Idle
Operation

I

DD

10
10

—
—

50

5

µA

mA

Output Current — Signal

VOH = 3.0 V Source
VOL = 0.5 V Sink

I

OH

I

OL

4
4

– 900

120

—
—

µA

Output Current — Scanner

VOH = 3.0 V Source
VOL = 0.5 V Sink

I

OH

I

OL

4
4

– 30

245

—
—

µA

Output Current — Oscillator

VOH = 3.0 V Source
VOL = 0.5 V Sink

I

OH

I

OL

4
4

– 300

245

—
—

µA

Input Current — Oscillator

Operation
Idle, VIL = 0.5 V

I

in

10

4

± 2

30

± 80

—

µA

Input Current — Encoder

VIH = 9.0 V
VIL = 0.5 V

I

in

10

4

– 15

—

—

– 60

µA

Input Voltage — Encoder V

IH

V

IL

V

IH

V

IL

10
10

4
4

9

—

3

—

—

1.2
—

1.0

V

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 V

out

be constrained to the range

VSS ≤ (Vin or V

out

) ≤ VDD.

MC14497MOTOROLA

3

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

f

1

f

1

“0”

“1”

Figure 1. AM Coding

AM

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

f

2

f

3

“0”

“1”

Figure 2. FSK Coding

f

2

f

3

FSK

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

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

*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. T o 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 MOTOROLA
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PIN DESCRIPTIONS

E1 – E8
Row Inputs (Pins 1, 2, 10, 11, 14, 15, 16, 17)

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.

E9
Row Input (Pin 3)

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.

A1 – A4
Scanner Outputs (Pins 4 – 7)

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).

OSCin, OSC

out

Oscillator Input and Oscillator Output (Pins 12, 13)

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.

SIGNAL OUT
Signal Output (Pin 8)

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.

Figure 3. 64–Key Keyboard

E1a

E1

E2a

E2

E3a

E3

E4a

E4

E5a

E5

E6a

E6

E7a

E7

E8a

E8

17

2

1

16

15

14

10

11

9 18

V

SS

V

DD

3 13

12

A1

7

A2

6

A3

5

A4

4

FK2 FK1

E9

C1 C2

NOTE: Maximum key contact

resistance = 1 kΩ.

Figure 4. Transmitted Waveforms and Timing (Not Drawn to Scale)

START BIT A B C D E F

f2 f3f3f2f3f2f3f2f3

f1 f1 f1 f1f1 f1

INSTRUCTION

FSK

AM

ONE WORD

DEBOUNCE

KEY WORD

20 ms

9 ms

99 ms

MC14497MOTOROLA

5

Figure 5. Scanner Output Timing Diagram

A1

A2

A3

A4

KEY RELEASEDKEY DOWN

DEBOUNCE

Figure 6. Typical Application Circuit

KEYBOARD

9 12 13

1 k

Ω

100

Ω

18

8

100

Ω

0.1

Ω

C1 C2

1500 µF 9 V

1N4001

MC14497

*

*Visible Indicator

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.

MC14497 MOTOROLA
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AGC BURST START BIT A B C D E F

f4 f4 f4 f4 f4 f4 f4

540

µ

s

2.84 ms
540

µ

s

1.155 ms 1.1 ms
540

µ

s

590

µ

s

540

µ

s

590

µ

s

540

µ

s

590

µ

s

1.16 ms
540

µ

s

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 0 0 0 0 0 0 E8 A4 32 1 0 0 0 0 0 E8a A4
1 0 0 1 E1 A4 33 0 0 1 E1a A4
2 0 1 0 E2 A4 34 0 1 0 E2a A4
3 0 1 1 E3 A4 35 0 1 1 E3a A4
4 1 0 0 E4 A4 36 1 0 0 E4a A4
5 1 0 1 E5 A4 37 1 0 1 E5a A4
6 1 1 0 E6 A4 38 1 1 0 E6a A4
7 1 1 1 E7 A4 39 1 1 1 E7a A4
8 0 0 1 0 0 0 E8 A1 40 1 0 1 0 0 0 E8a A1

9 0 0 1 E1 A1 41 0 0 1 E1a A1
10 0 1 0 E2 A1 42 0 1 0 E2a A1
11 0 1 1 E3 A1 43 0 1 1 E3a A1
12 1 0 0 E4 A1 44 1 0 0 E4a A1
13 1 0 1 E5 A1 45 1 0 1 E5a A1
14 1 1 0 E6 A1 46 1 1 0 E6a A1
15 1 1 1 E7 A1 47 1 1 1 E7a A1
16 0 1 0 0 0 0 E8 A3 48 1 1 0 0 0 0 E8a A3
17 0 0 1 E1 A3 49 0 0 1 E1a A3
18 0 1 0 E2 A3 50 0 1 0 E2a A3
19 0 1 1 E3 A3 51 0 1 1 E3a A3
20 1 0 0 E4 A3 52 1 0 0 E4a A3
21 1 0 1 E5 A3 53 1 0 1 E5a A3
22 1 1 0 E6 A3 54 1 1 0 E6a A3
23 1 1 1 E7 A3 55 1 1 1 E7a A3
24 0 1 1 0 0 0 E8 A2 56 1 1 1 0 0 0 E8a A2
25 0 0 1 E1 A2 57 0 0 1 E1a A2
26 0 1 0 E2 A2 58 0 1 0 E2a A2
27 0 1 1 E3 A2 59 0 1 1 E3a A2
28 1 0 0 E4 A2 60 1 0 0 E4a A2
29 1 0 1 E5 A2 61 1 0 1 E5a A2
30 1 1 0 E6 A2 62 1 1 0 E6a A2
31 0 1 1 1 1 1 E7 A2 Not

Transmitted

1 1 1 1 1 1 E7a 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.

MC14497MOTOROLA

7

PACKAGE DIMENSIONS

P SUFFIX
PLASTIC DIP
CASE 707–02

MIN MINMAX MAX

MILLIMETERS INCHES

DIM

22.22

6.10

3.56

0.36

1.27

1.02

0.20

2.92

23.24

6.60

4.57

0.56

1.78

1.52

0.30

3.43

0

°

0.51

0.875

0.240

0.140

0.014

0.050

0.040

0.008

0.115

0.915

0.260

0.180

0.022

0.070

0.060

0.012

0.135

15

°

1.02

2.54 BSC

7.62 BSC

0.100 BSC

0.300 BSC

0

°

0.020

15

°

0.040

A
B
C
D
F
G
H

J
K
L
M
N

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.

1 9

1018

B

A

H

F

G

D

SEATING
PLANE

N

K

M

J

L

C

MC14497 MOTOROLA
8

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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/D

*MC14497/D*

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