Datasheet MX128DW, MX128P Datasheet (MX COM)

DATA BULLETIN

MX128

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

Cordless Telephone Scrambler

Features Applications



Full-Duplex Audio Processing



On-Chip Filters



Carrier Rejection >55dB



Uses IF (10.24 MHz) Clock



Requires No Extra Crystal



Excellent Audio Quality



Low Voltage 3.3V/5.0V Operation



ECPA* Qualified Voice Protection



Battery Powered Portability



Cordless Telephones



Wireless PBXs

+

RX Path

TX Path

V

BIAS

Inversion

Carrier

The MX128 is a full-duplex frequency inversion scrambler designed to provide secure conversations for 46/49 MHz cordless telephone users. The RX and TX audio paths consist of the following:

1. A switched-capacitor balanced modulator with high baseband and carrier rejection.

2. A 3.3 kHz inversion carrier (injection tone).

3. A 3100 Hz lowpass filter.

4. Input op-amps with externally adjustable gain.

The MX128 uses mixed signal CMOS switched-capacitor filter technology and operates from a single supply in the range of 3.0V to 5.5V. The inversion carrier's frequency and filter switching clock are generated on-chip using an external 10.24 MHz or 3.58/3.6864 MHz crystal or clock input (selectable).

The MX128 is available in the following package styles: 16-pin SOIC (MX128DW) and 16-pin PDIP (MX128P).

Cordless Telephone Scrambler 2 MX128

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

CONTENTS

Section Page

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

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

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

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

4.1 Application Notes.................................................................................................................... 6

5. Performance Specification......................................................................................7

5.1 Electrical Performance ........................................................................................................... 7

5.2 Packaging............................................................................................................................. 10

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

Cordless Telephone Scrambler 3 MX128

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

1. Block Diagram

+

-

+

CLOCKS

AND

LOGIC

RX GAIN AMP

OUT

RXIN

12 11

2 1

15

14

6

5

4

8

9

16

13

V

BIAS

V

DD

V/2

DD

V

SS

XT AL/CLOCK

CLR

10.24/3.58 MHz

CLOCK SELECT

XT AL

TXIN

TX GAIN AMP

OUT

RX CHANNEL

TX CHANNEL

212 kHz

3.3 kHz

RXOUT

TXOUT

0V

V

BIAS

V

BIAS

Figure 1: Device Block Diagram

Cordless Telephone Scrambler 4 MX128

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

2. Signal List

Pin No. Signal Type Description

1

Xtal

output

This is the output of the clock oscillator inverter

2 Xtal/Clock input A 10.24 MHz, 3.58/3.6864 MHz, or an externally derived clock

signal is injected at this pin. See Figure 3

4 TXOUT output This is the analog output of the transmit channel. It is internally

biased at V

DD

/2

5 TX Gain Ampout output This is the output pin of the transmit channel gain adjusting op-

amp. See Figure 4 for gain setting components

6 TXIN input This is the analog signal input to the transmit channel. This input

is to a gain adjusting op-amp whose gain is set by internal

components. See Figure 4. 8VSSpower Negative supply (GND) 9V

BIAS

output This is an internally generated bias voltage output (VDD/2)

11 RXIN input This is the analog signal input to the receive channel. This input is

to a gain adjusting op-amp whose gain is set by internal

components. See Figure 4.

12 RX Gain Ampout output This is the output pin of the receive channel gain adjusting op-

amp. See Figure 4 for gain setting components

13 RXOUT output This is the analog output of the receive channel. It is internally

biased at V

DD

/2

14 CLR A logic 1 on this input selects the invert mode. A logic 0 selects

the clear (not inverted) mode

15 Clock Select Selects either 10.24 or 3.58/3.6864 MHz clock frequency. A logic

“1” selects 10.24 MHz, and a logic “0” selects 3.58/3.6864 MHz.

This input is internally pulled high

16 V

DD

power Positive supply of 3.0V to 5.5 V

3, 7, 10 N/C No internal connections

Cordless Telephone Scrambler 5 MX128

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

3. External Components

MX128

INSET

SEE INSET

BELOW

SEE INSET

BELOW

1 2 3 4 5 6 7 8

16 15 14 13 12 11 10

9

16 15 14 13 12 11 10

9

XTAL

XTAL/CLOCK

N/C

TXOUT

TX GAIN AMP OUT

TXIN

N/C

XTAL

XTAL/CLOCK

N/C

TXOUT

TX GAIN AMP OUT

TXIN

N/C

R

X

C

SS

1

2

3

1

DD

BIAS

V

DD

V CLK SEL CLR RXOUT RX GAIN AMP OUT RXIN N/C V

XTAL/CLOCK

XTAL

1

2

MX128

SEE

FIG. 4

SEE

FIG. 4

SEE

FIG. 4

SEE

FIG. 4

}

V

10.24 MHz 3.58/3.6864 MHz

R1

1.0M



10%

R1

1.0M



10%

C1 0.47µF



20%

C1 0.47µF



20%

C2 22.0pF



20%

C2 33.0pF



20%

C3 22.0pF



20%

C3 47.0pF



20%

X1 10.24 MHz X1 Note 1 3.58/3.6864 MHz

Figure 2: Recommended External Components

External Components Note:

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

DD

peak - peak. Tuning fork crystals generally cannot meet this requirement. To obtain

crystal oscillator design assistance, consult your crystal manufacturer.

Cordless Telephone Scrambler 6 MX128

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

4. Application

12

120pF

100k

RXIN

RXOUT

11

13

.1uF

150pF

5

120pF

100k

TXIN

TXOUT

6

4

.1uF

RF AMP

RF

AMP

AF

AMP

AF AMP

HYBRID TRANSFORMER

TELEPHONE LINE

DE-EMP

PREEMP

CODE DETECT

CODE ENCODE

MODULATOR

FM

DETECTOR

IF

AMP

P

m

BASE

12

120pF

100k

RXIN

RXOUT

11

13

.1uF

5

120pF

100k

TXIN

TXOUT

6

4

.1uF

RF AMP

RF

AMP

AF

AMP

MIC.

AF AMP

SPKR

DE-EMP

PREEMP

CODE DETECT

CODE ENCODE

MODULATOR

KEYPAD

FM

DETECTOR

IF

AMP

DTMF

Generation

P

PORTABLE

MX128

Note: Components shown set a gain of 0dB.

Figure 3: Block Diagram of a Typical Application of the MX128 (Cordless Phone)

4.1 Application Notes

Formulas for calculating the carrier frequency, upper cutoff frequency and lower cutoff frequency with clock select pin high are as follows:

Carrier Frequency = (3.2995kHz / 10.24MHz) * XTAL frequency Upper Cutoff Frequency = (2.800kHz / 10.24MHz) * XTAL frequency Lower Cutoff Frequency = (400Hz / 10.24MHz) * XTAL frequency

Formulas for calculating the carrier frequency, upper cutoff frequency and lower cutoff frequency with clock select pin low are as follows:

Carrier Frequency = (3.2995kHz / 3.415MHz) * XTAL frequency Upper Cutoff Frequency = (2.800kHz / 3.415MHz) * XTAL frequency Lower Cutoff Frequency = (400Hz / 3.415MHz) * XTAL frequency

Cordless Telephone Scrambler 7 MX128

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

5. Performance Specification

5.1 Electrical Performance

Absolute Maximum Ratings

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

General Min. Max. Units

Supply Voltage (VDD - VSS) -0.3 7.0 V Voltage on any pin to V

SS

-0.3 VDD + 0.3 V

Current

V

DD

-30 30 mA

V

SS

-30 30 mA

Any other pin -20 20 mA

P/DW Packages

Total Allowable Power Dissipation at T

AMB

= 25°C 800 mW max.

Derating above 25°C 10 mW/°C above 25°C Operating Temperature -40 85 °C Storage Temperature -55 125 °C

Operating Limits

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

Notes Min. Max. Units

Supply (VDD - VSS)3.05.5V Operating Temperature -40 85 °C Clock Frequency 10.24 MHz

Cordless Telephone Scrambler 8 MX128

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

Operating Characteristics

For the following conditions unless otherwise specified: V

DD

= 3.3V at T

AMB

= 25°C Clock Frequency = 10.24MHz Audio Level 0dB ref. @ 1kHz = (V

DD

-1) x 150mV

RMS

e.g. VDD = 3.3V 0dB = 345mV

RMS.

Notes Min. Typ. Max Units

Static Values

Supply Current 2.0 3.0 mA Input Impedance

Digital 2 100

k



Amplifiers 2 1.0 10.0

M



Output Impedance (RXOUT, TXOUT) 1.0

k



Input Logic 1 Voltage 1 70% V

DD

Input Logic 0 Voltage 1 30% V

DD

Dynamic Values

Analog Signal Input Levels -16.0 3 dB Analog Output Noise 4 2.5 5.0 mV

RMS

Clear Mode

Passband -3dB Cutoff Frequencies

Low 300 Hz High 3000 Hz

Passband Ripple (300-3000Hz)

RX Channel 0 3.6 dB TX Channel 0 2.9 dB

Passband Ripple (500-2750Hz)

RX Channel 0 2.2 dB TX Channel 0 2.0 dB

Filter Attenuation at 3.3 kHz

RX Channel 30 dB TX Channel 30 dB

Filter Attenuation at 3.6 kHz

RX Channel 45 dB TX Channel 45 dB

Passband Gain (@1kHz ref.)

RX Channel -1.5 0.5 dB

TX Channel -1.5 0.5 dB Switched-Capacitor Filter Sampling 211.066 kHz Carrier Frequency 3298 Hz

Invert Mode Combined TX and RX Response

Passband -3dB Cutoff Frequencies

Low 400 Hz

High 2800 Hz Passband Gain -3 0.5 dB Distortion (@1kHz) 3 1.75 2.75 % Passband Gain (@1kHz ref.) 5 -2.5 -1.5 0 dB Low Frequency Roll-off (<200 Hz) 12 dB/octave

Cordless Telephone Scrambler 9 MX128

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

Notes Min. Typ. Max Units

Invert Mode Single Channel Response

Unwanted Modulation Products 3

RX Channel -40 dB

TX Channel -40 dB Carrier Breakthrough 3

RX Channel -55 dB

TX Channel -55 dB Baseband Breakthrough 3

RX Channel -40 dB

TX Channel -40 dB

Operating Characteristics Notes:

1. Batch sampled only

2. By characterization only

3. Measured with Input Level 0dB

4. Short circuit RX or TX input, measure noise at corresponding analog output, in 30KHz bandwidth

5. Op Amp gain 0dB

6. Clear mode only

Cordless Telephone Scrambler 10 MX128

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their 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°

Figure 4: 16-pin SOIC Mechanical Outline: Order as part no. MX128DW

PackageTolerances

NOTE: All dimensions in inches(mm.)

Angles are in degrees

TYP. MAX.MIN. A B C E

E1

H

DIM.

J

J1

P Y

T

K

L

0.200 (5.06)

0.262 (6.63)

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)

0.008 (0.20) 0.015 (0.38)

0.014 (0.35) 0.023 (0.58)

0.040 (1.02) 0.065 (1.65)

0.056 (1.42) 0.064 (1.63)

0.740 (18.80)

0.240 (6.10)

B

A

PIN 1

E

Y

E1

T

K

H

J1

J

C

P

L

Figure 5: 16-pin PDIP Mechanical Outline: Order as part no. MX128P

Datasheet MX128DW, MX128P Datasheet (MX COM)

Specifications and Main Features

Frequently Asked Questions

User Manual