Datasheet MX315ADW, MX315AJ, MX315AP Datasheet (MX COM)

DATA BULLETIN

MX315A

CTCSS Encoder



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

Features Applications



Field Programmable Tone
Encoder



40 CTCSS Frequencies



Crystal-Controlled Frequency
Stability



Low Distortion Sinewave Output



Few External Components
Required



CMOS Low Power Requirements



Mobile Radio Base Stations & Repeater
Stations



Mobile Radios



Hand-Held Radios



Industrial Controls



Intercom Systems



Door-Entry Systems

Xtal/Clock

Clock

Generator

D0-D5

Xtal

Binary

Rate

Multiplier

TX Enable

TX Enable

V

DD

Programmed Clocks

TX Tone
Square
Wave

TX Tone

Sinewave

Output
Emitter

Follower

Enable

TX Tone Output

The MX315A is a monolithic CMOS tone encoder for sub-audible tone squelch systems, which provides three
additional frequencies over the earlier MX315A. These frequencies are 69.3, 97.4 and 206.5Hz. The tone
frequencies are derived from an input reference frequency. An on-chip inverter is provided to drive an
external crystal circuit.

Tone selection is achieved through six programming inputs and two control inputs (which allow either a logic
“1” or “0” to enable the device). A low distortion sinewave is generated at the TX Tone Output when the
MX315A is enabled. The emitter follower output stage can source 1mW directly into a 600 load (0dBm).

The MX315A is available in the following package styles: 16-pin SOIC (MX315ADW), 14-pin PDIP
(MX315AP) and 14-pin CDIP (MX315AJ).

CTCSS Encoder 2 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

CONTENTS

Section Page

1. Block Diagram................................................................................................................3

2. Signal List.......................................................................................................................4

3. External Components....................................................................................................5

4. Application .....................................................................................................................6

4.1 Interfacing and Electromagnetic Capability ......................................................................... 6

4.2 CTCSS Programming.......................................................................................................... 7

5. Performance Specification............................................................................................8

5.1 Electrical Performance ........................................................................................................ 8

5.1.1 Absolute Maximum Ratings....................................................................................................8

5.1.2 Operating Limits .....................................................................................................................8

5.1.3 Operating Characteristics.......................................................................................................8

5.2 Packaging............................................................................................................................ 9

MX•COM, Inc. reserves the right to change specifications at any time and without notice.

CTCSS Encoder 3 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

1. Block Diagram

Xtal/Clock

Clock

Generator

D0-D5

Xtal

Binary

Rate

Multiplier

TX Enable

TX Enable

V

DD

Programmed Clocks

TX Tone
Square
Wave

TX Tone

Sinewave

Output

Emitter

Follower

Enable

TX Tone Output

Figure 1: Device Block Diagram

CTCSS Encoder 4 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

2. Signal List

Pins Signal

J,P DW Name Type

Description

1 1 D3 input
2 2 D2 input
3 3 D1 input
4 4 D0 input
5 5 D4 input
6 6 D5 input

D0-D5 are tone select inputs with internal pull-up resistors.
The logic combination at these inputs determines the encoded
CTCSS tone. See Table 1. The input sequence is not latched
and may be changed at any time. A logic “1” will be
programmed if the input is open circuit, allowing the use of
SPST switches.

77 V

SS

power Negative Supply Voltage.

8 8 Xtal/Clock In input

This is the input to the CMOS inverter. It can be used in
conjunction with the Xtal output to form the active element in a
crystal oscillator circuit. Alternatively, a logic level 1MHz
frequency can be injected at this pin. However, the supply
voltage should never be applied without the input clock signal.

99

Xtal Output

output This is the output of the CMOS inverter. When used as a

crystal oscillator, track lengths and loading of this pin should be
minimized.

10 10 Internal Connection Do not use

11 N/C No Connection
12 N/C No Connection

11 13 TX Tone Output output

This is the tone output pin. It includes a low impedance emitter
follower stage for sourcing sinusoidal tone. The tone is
generated about a DC level of approximately V

DD

/2. The pin is

high impedance when not encoding.

12 14

TX Enable Input

input This logic input has an internal pull-up resistor. A logic “0” at

this pin enables the MX315A.

13 15 TX Enable Input input

This logic input has an internal pull-down resistor. A logic “1”
at this pin enables the MX315A.

14 16 V

DD

power Positive Supply Voltage.

Table 1: Signal List

CTCSS Encoder 5 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

3. External Components

MICROPHONE

VOICE BAND

FILTER

SUMMING

AMPLIFIER

TO

MODULATOR

TX TONE OUT

X1

1MHz

1M

33pF

PTT

12

9

8

XTAL/CLOCK

TX ENABLE

XTAL

4

3

215

6

11

D0

D1 D2D3D4

D5

V

SS

MX315AJ

Figure 2: External Components

R1 Note 1 1M



20%

C1 33pF



20%

X1 Note 2, 3 1MHz



0.19%

Table 2: Recommended External Components

Notes:

1. The 1M resistor is used to bias the internal CMOS inverter into its linear mode. A tolerance of ±20%
is acceptable.

2. “X1” is a parallel resonant crystal. A reference frequency of 1MHz ±0.19% is required to maintain a
tone accuracy within 0.5%.

3. For best results, a crystal oscillator design should drive the clock inverter input with signal levels of at
least 40% of V

DD

, peak to peak. Tuning fork crystals generally cannot meet this requirement. To

obtain crystal oscillator design assistance, consult your crystal manufacturer.

CTCSS Encoder 6 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

4. Application

The MX315A is dedicated to Continuous Tone-controlled Squelch Systems (CTCSS) in radio applications.
However, it can be used wherever encoding of low-frequency tones is required, such as intercoms, door-entry
systems and various industrial applications.

The performance of a CTCSS system can be degraded if speech frequencies in the signaling spectrum are
not removed prior to transmission. This can be accomplished by filtering the microphone signals to attenuate
frequencies below 250 Hz. Figure 2 illustrates the addition of TX Tone Output to the filtered microphone
signals prior to modulation. Figure 3 illustrates the TX Tone Output sequence and a typical spectral analysis.

Where two or more circuits are required to use a single oscillator (i.e. repeater applications), the signal at

Xtal

can be used to drive one additional Xtal/Clock input. Any further circuits can be driven from the buffered

Xtal

output of the second device.

The program code can be set on the D0-D5 inputs by hardwired logic levels or SPST switches to V

SS

, as

illustrated in Figure 2 (allowing the internal pull-up resistors to program a logic “1”).
The MX315A provides both a

TX Enable

input and a TX Enable input. Either input can be used to enable the
tone output, with the unused pin left open circuit (internal resistors establish a valid logic level and prevent
damage). Any configuration of PTT switch or TX signal can therefore be interfaced.

TX ENABLE

TX TONE

OUTPUT

RISE-TIME

ENVELOPE

D.C. GROUND D.C. GROUND

RELATIVE HARMONIC

LEVELS (dB)

FREQUENCY

0
10
20
30
40
50
60
70

FUNDAMENT AL

TX TONE SPECTRUM

f02f

0

3f

0

4f05f

0

6f

0

7f08f

0

Figure 3: Tone Encoding Sequence and Spectral Response

4.1 Interfacing and Electromagnetic Capability

The MX315A requires a clock of 1MHz, which is internally converted to logic level square waves.
Consideration should therefore be given to possible interference problems with RF or IF circuitry caused by
1MHz or its harmonics.

A decoupling capacitor can be used to reduce ripple on the power supply. This will reduce the level of
superimposed noise on the supply caused by internal switching transients (particularly at 1MHz and f

0

).

CTCSS Encoder 7 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

4.2 CTCSS Programming

Tone Programming Inputs

Nominal Frequency (Hz) MX315A Freq. (Hz)



fo (%)

D5 D4 D3 D2 D1 D0 Hex

67.0 67.06 +.10 1 1 1 1 1 1 3F

69.3 69.37 +.10 1 1 1 0 0 1 39

71.9 71.84 -.08 0 1 1 1 1 1 1F

74.4 74.33 -.10 1 1 1 1 1 0 3E

77.0 76.99 -.02 0 0 1 1 1 1 0F

79.7 79.65 -.06 1 1 1 1 0 1 3D

82.5 82.50 0.0 0 1 1 1 1 0 1E

85.4 85.34 -0.7 1 1 1 1 0 0 3C

88.5 88.62 +.14 0 0 1 1 1 0 0E

91.5 91.38 -.13 1 1 1 0 1 1 3B

94.8 94.88 +.08 0 1 1 1 0 1 1D

97.4 97.46 +.06 1 1 1 0 1 0 3A

100.0 99.87 -.13 0 0 1 1 0 1 0D

103.5 103.39 -.11 0 1 1 1 0 0 1C

107.2 107.17 -.03 0 0 1 1 0 0 0C

110.9 110.85 -.04 0 1 1 0 1 1 1B

114.8 114.80 0.0 0 0 1 0 1 1 0B

118.8 118.60 -.17 0 1 1 0 1 0 1A

123.0 123.12 +.10 0 0 1 0 1 0 0A

127.3 127.50 +.16 0 1 1 0 0 1 19

131.8 131.67 -.10 0 0 1 0 0 1 09

136.5 136.69 +.14 0 1 1 0 0 0 18

141.3 141.48 +.13 0 0 1 0 0 0 08

146.2 145.96 -.16 0 1 0 1 1 1 17

151.4 151.45 +.03 0 0 0 1 1 1 07

156.7 156.59 -.07 0 1 0 1 1 0 16

162.2 162.10 -.06 0 0 0 1 1 0 06

167.9 168.01 +.07 0 1 0 1 0 1 15

173.8 173.43 -.21 0 0 0 1 0 1 05

179.9 180.21 +.17 0 1 0 1 0 0 14

186.2 186.46 +.14 0 0 0 1 0 0 04

192.8 193.16 +.19 0 1 0 0 1 1 13

203.5 202.88 -.31 0 0 0 0 1 1 03

206.5 206.78 +.14 1 1 1 0 0 0 38

210.7 210.84 +.07 0 1 0 0 1 0 12

218.1 217.96 -.07 0 0 0 0 1 0 02

225.7 225.58 -.05 0 1 0 0 0 1 11

233.6 233.75 +.07 0 0 0 0 0 1 01

241.8 242.54 +.31 0 1 0 0 0 0 10

250.3 250.06 +.10 0 0 0 0 0 0 00
Test 4032 0.0 1 1 0 0 1 1 *33

* - or any invalid address

Table 3: CTCSS Tones

CTCSS Encoder 8 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

5. Performance Specification

5.1 Electrical Performance

5.1.1 Absolute Maximum Ratings

Exceeding these maximum ratings can result in damage to the device.

General Min. Max. Units

Supply Voltage -0.3 7.0 V

J / P /DW Packages

Total Allowable Device Dissipation at T

AMB

= 25°C 800 mW

Derating above 25°C 10 mW/°C above 25°C
Operating Temperature -30 +85 °C
Storage Temperature -55 +125 °C

5.1.2 Operating Limits

Correct operation of the device outside these limits is not implied.

Notes Min. Typ. Max. Units

V

DD

4.5 5.0 5.5 V
Operating Temperature -30 85 °C
Clock Note 1 1 MHz

Operating Limits Note:

1. “X1” is a parallel resonant crystal. A reference frequency of 1 MHz ±0.19% is required to maintain a
tone accuracy within 0.5%.

5.1.3 Operating Characteristics

For the following conditions unless otherwise specified:
V

DD

= 5.0V , T

AMB

= 25°C, Xtal Frequency = 1MHz

Notes Min. Typ. Max Units

Supply Current (operating) 1.5 4.5 mA
Input Impedance 1 500

k



Input Impedance 2 10

M



Logic Input “1” 3.5 V
Logic Input “0” 1.5 V
TX Output EMF 3 550 775 mV

RMS

TX Risetime 1 ms
TX Tone Output Load Current 5 mA
TX Distortion 3 2 5 %
Variation in Output Level Between Tones 3 0.1 dB

Operating Characteristics Notes:

1. Refers to D0, D1, D2, D3, D4, D5, TX Enable and

TX Enable

inputs

2. Refers to Xtal/Clock input

3. Any program tone and R

L

= 600, CL = 15pF. THD measurements are taken in the 0-6 kHz

bandwidth.

CTCSS Encoder 9 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

5.2 Packaging

PIN 1

A

B

ALTERNATIVE

PIN
LOCATION
MARKING

X

P

J

Y

C

K

H

E

L

T

W

Z

NOTE: All dimensions in inches (mm.)

Angles are in degrees

PackageTolerances

A
B
C
E
H

TYP.

MAX.MIN.

DIM.

J

P

X

W

T

Y

K
L

0.105 (2.67)0.093 (2.36)

0.419 (10.64)

45°

7°

0° 10°

0.050 (1.27)

0.041 (1.04)

0.413 (10.49)

0.299 (7.59)

0.050 (1.27)

0.016 (0.41)

0.390 (9.90)

0.020 (0.51)0.003 (0.08)

0.009 (0.23) 0.0125 (0.32)

0.013 (0.33) 0.020 (0.51)

0.395 (10.03)

0.286 (7.26)

Z

5°

5°

Figure 4: 16-pin SOIC Mechanical Outline: Order as part no. MX315ADW

PackageTolerances

B

A

PIN 1

E

Y

E1

T

NOTE: All dimensions in inches (mm.)

Angles are in degrees

A
B
C
E
E1
H

TYP. MAX.MIN.

DIM.

J
J1

P
T
Y

K
L

0.200 (5.06)

0.260 (6.60)

0.390 (9.91)

7°

0.150 (3.81)

0.810 (20.57)

0.135 (3.43)

0.100 (2.54)

0.121 (3.07)

0.300 (7.62)

0.290 (7.37) 0.325 (8.26)

0.015 (0.38) 0.070 (1.77)

0.015 (0.38) 0.023 (0.58)

0.040 (1.01) 0.065 (1.65)

0.056 (1.42) 0.064 (1.63)

0.740 (18.80)

0.240 (6.10)

0.008 (0.20) 0.015 (0.38)

K

H

J1

J

C

P

L

Figure 5: 14-pin PDIP Mechanical Outline: Order as part no. MX315AP

CTCSS Encoder 10 MX315A



1998 MXCOM, INC. www.mxcom.com tel: [phone] 744 5050 fax: [phone] Doc. # 20480054.006

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All Trademarks and service marks are held by there respective companies.

NOTE: All dimensions in inches (mm.)

Angles are in degrees

PackageTolerances

A
B

E
E1
F
H

TYP. MAX.MIN.

DIM.

J

P
T

K1

K
L

0.288 (7.32)

0.420 (10.67)

0.200 (5.08)

0.766 (19.46)

0.100 (2.54)

0.115 (2.92)

0.360 (9.14)

0.305 (7.75) 0.315 (8.00)

0.600 (15.24)

0.015 (0.38)

0.018 (0.46)

0.053 (1.35)

0.075 (1.91)

0.080 (2.03)

0.080 (2.03)

0.754 (19.15)

0.240 (6.10)

0.010 (0.254)

C

0.165 (4.19) 0.230 (5.84)

J1

0.060 (1.52)

E1

T

E

B

A

PIN 1

H

K

F

J

K1

P

L

C

J1

Figure 6: 14-pin CDIP Mechanical Outline: Order as part no. MX315AJ