MX COM Inc MX806ADW, MX806AP Datasheet

DATA BULLETIN

MX806A

Audio Processor

1998 MX-COM, Inc. www.mxcom.com Tel: [phone] 744 5050 Fax: [phone] Doc. # 20480064.006

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

Features



Half-Duplex Audio Processor



Dynamic Control of Signal Levels



Performs Signal Conditioning and
Filtering requirements for both
Transmit and Receive



Three separate signal sections:

Input process
Main Process
Mixing and Output Drives



Low Power Operation



Member of DBS800 Family (C-BUS
Compatible)

C-BUS INTERFA CE

MIC. AMP

VOGAD AMP

HIGHPASS

FILTER

GAIN

SET

PRE-EMPHASIS

LIMITING

FILTERING

GAIN SETTING

MODULATION

MIXER AMP

VOGAD
SENSE

VOGAD
SENSE

OR

MAIN PROCESS

CLOCK

GENERAT OR

BUFFER

ATTENUAT OR

ATTENUAT OR

ATTENUAT OR

INPUT
PROCESS

DE-EMPHASIS

FILTER

OUTPUT DRIVES

#

#

#

#

#

## #

#

#

#

#

LOUDSPEAKER

AUDIO

MODULATION 2

OUT

MODULATION 1

OUT

TRANSMITTER

MODULATION

DRIVES

MOD

OUT

MOD

IN

MAIN

PROCESS

OUT

PRIMARY

AND

SECONDARY

AUDIO

INPUTS

Voice

Sub-Audio

Tone

MSK,etc.

COMMAND

DATA

SERIAL
CLOCK

CHIP

SELECT

VOGAD SENSE

CALIBRATION INPUT

TX

MIC IN

RX

AUDIO IN

XTAL/CLOCK

XTAL

TO EXTERNAL

AUDIO PROCESSES

EXTERNAL AUDIO

PROCESS IN

POWER
SUPPL Y

The MX806A LMR audio processor is intended too primarily to operate as the “Audio Terminal” or radio
systems using the DBS800 Digitally Integrated Baseband Subsystem.

The MX806A half-duplex device has signal paths and level setting elements that are configured and adjusted
by digital information sent from the radio microcontroller using C-BUS protocol. (C-BUS is the serial interface
for all DBS 800 ICs.)

The Signal Path is divided into three sections: Input Process, Main process, and Mixing and Output Drives.
If selected, signal level stability and output accuracy of the MX806A is maintained by a voltage-controlled gain

system using selectable signal-level detectors. Signal levels can be dynamically controlled to provide
“dynamic compensation” for factors such as temperature drift, VCO non-linearity, etc.

The MX806A audio stages can be completely disabled – or the whole IC can be placed into powersave mode,
leaving only clock and C-BUS circuitry active.

The MX806A may be used with a 5.0V power supply and is available in the following packages:
24-pin SOIC (MX806ADW), 24-pin PLCC (MX806ALH), and 24-pin PDIP (MX806AP).

Audio Processor 2 MX806A

1998 MX-COM, Inc. www.mxcom.com Tel: [phone] 744 5050 Fax: [phone] Doc. # 20480064.006

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....................................................................................................6

4 General Description.......................................................................................................7

4.1 Signal Path .......................................................................................................................... 7

4.2 VOGAD................................................................................................................................ 7

4.2.1 VOGAD Components Calculations – Figure 2 and Figure 5.....................................................8

4.3 Calibration Methods............................................................................................................. 8

4.3.1 TX Calibration: From Mic. In to Modulator Drives Out.............................................................8

4.3.2 RX Calibration: From RX Audio In to Audio Out......................................................................8

5 Controlling Protocol....................................................................................................10

5.1.1 Control Command – (Preceded by A/C 10H)..........................................................................11

5.1.2 Mode Command – (Preceded by A/C 11H)............................................................................12

5.1.3 Modulator Levels – (Preceded by A/C 12H) ........................................................................... 13

5.1.4 Volume Set – (Preceded by A/C 13H)....................................................................................15

6 Application Notes ........................................................................................................16

7 Performance Specifications........................................................................................17

7.1 Electrical Specifications..................................................................................................... 17

7.1.1 Absolute Maximum Limits.......................................................................................................17

7.1.2 Operating Limits......................................................................................................................17

7.1.3 Operating Characteristics .......................................................................................................18

7.1.4 Timing..................................................................................................................................... 21

7.2 Packages........................................................................................................................... 22

MXCOM, Inc. reserves the right to change specifications at any time without notice.

Audio Processor 3 MX806A

1998 MX-COM, Inc. www.mxcom.com Tel: [phone] 744 5050 Fax: [phone] Doc. # 20480064.006

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

1 Block Diagram

C-BUS INTERFACE

MIC. AMP

VOGAD AMP

HIGHPASS

FILTER

GAIN

SET

PRE-EMPHASIS

LIMITING

FILTERING

GAIN SETTING

MODULATION

MIXER AMP

VOGAD
SENSE

VOGAD
SENSE

OR

MAIN PROCESS

CLOCK

GENERATOR

BUFFER

ATTENUATOR

ATTENUATOR

ATTENUATOR

INPUT
PROCESS

DE-EMPHASIS

FILTER

OUTPUT DRIVES

#

#

#

#

#

## #

#

#

#

#

LOUDSPEAKER

AUDIO

MODULATION 2

OUT

MODULATION 1

OUT

TRANSMITTER

MODULATION

DRIVES

MOD

OUT

MOD

IN

MAIN

PROCESS

OUT

PRIMARY

AND

SECONDARY

AUDIO

INPUTS

Voice

Sub-Audio

Tone

MSK,etc.

COMMAND

DATA

SERIAL
CLOCK

CHIP

SELECT

VOGAD SENSE

CALIBRATION INPUT

TX

MIC IN

RX

AUDIO IN

XTAL/CLOCK

XTAL

TO EXTERNAL

AUDIO PROCESSES

EXTERNAL AUDIO

PROCESS IN

POWER
SUPPL Y

Figure 1: Block Diagram

Audio Processor 4 MX806A

1998 MX-COM, Inc. www.mxcom.com Tel: [phone] 744 5050 Fax: [phone] Doc. # 20480064.006

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 Signal Description

1

Xtal

The output of the 4.032MHz on-chip clock oscillator. External components are
required at this output when a Xtal is used. See Figure 2.

2 Xtal/Clock

The input to the on-chip 4.032MHz clock oscillator inverter. A 4.032MHz Xtal or
externally derived clock should be connected here. See Figure 2. This clock
provides timing for on-chip elements, filters, etc.

3 Serial Clock This is the ‘C-BUS’ serial Clock input. This clock, produced by the

microcontroller, is used for transfer timing of commands and data to and from the
MX805A. See Section 6 and Section 7.1.4.

4 Command Data This is the ‘C-BUS’ serial data input from the microcontroller. Command Data is

loaded to this device in 8-bit bytes, MSB (bit 7) first and LSB (bit 0) last,
synchronized to the Serial Clock. The Command/Data instruction is acted upon
at the end of loading the whole instruction. Command information is detailed in
Table 3 through Table 7. See Section 6 and Section 7.1.4.

5

CS

Select Chip . This is the ‘C-BUS’ data loading control function. This input is
provided by the microcontroller. Command Data transfer sequences are initiated,
completed or aborted by the

CS signal. See Section 6 and Section 7.1.4.

6 VOGAD OUT The error-voltage output of the selected VOGAD sensor. This output, with

external attack and decay setting components, should be connected as in Figure
2 and Figure 3, to the VOGAD In pin.

7 RX Audio In

The audio input to the MX806A from the radio receiver’s demodulator circuits.
This input, which requires AC coupling with capacitor C12, is selected via a
Control Command bit.

8 VOGAD In The gain control signal from the selected VOGAD sensor (VOGAD Out) to the

Input Process voltage-controlled amplifier. The required sensor is selected via a
Mode Command. The choice of two sensors enables gain control from either the
Input Process or an External Process. External attack and decay setting
components should be applied as recommended. See Figure 2 and Figure 3.

9V

BIAS

The output of the on-chip analog circuitry bias system, held internally at VDD/2.
This pin should be decoupled to V

SS

by capacitor C10. See Figure 2.

10 Mic In (+) The non-inverting input to the microphone Op-Amp. This input requires external

components for Op-Amp gain/attenuation setting as shown in Figure 2.

11 Mic In (-) The inverting input to the microphone Op-Amp. This input requires external

components for Op-Amp gain/attenuation setting as shown in Figure 2.

12 V

SS

Negative Supply (GND)

13 Mic Out The output of the Microphone Op-Amp, used with the Mic In (-) input to provide

the required gain/attenuation using external components as shown in Figure 2.
The external components shown are to assist in the use of this amplifier with
wither inverting or non-inverting inputs. During Powersave (Volume Command
this output is placed at V

SS

.)

14 Processed Audio In The input to the device from such external audio processed as Voice Store and

Retrieve or Frequency Domain Scrambling. This input, which requires AC
Coupling with capacitor C13, is selected by a Mode Command bit.

15

External Audio
Process

The buffered output of the Input Processing Stage. Its purpose is to further
external audio processing stages prior to re-introduction at the Processed Audio
In Pin.

16 Calibration Input A unique audio input to be used for dynamic balancing of the modulator drives for

measuring Deviation Limiter levels. A CUE (beep) input from the MX803 Audio
Tone Processor can be entered on this line. This audio input must be externally
biased. It is selected via a Mode Command bit.

17 Main Process Out The output of the Main Process stage. This output should be mixed with any

additional system audio inputs (Audio, Sub-Audio Signaling, MSK) in the on-chip
Modulation Summing Amplifier. External components shown in Figure 2 should
be used as required.

Audio Processor 5 MX806A

1998 MX-COM, Inc. www.mxcom.com Tel: [phone] 744 5050 Fax: [phone] Doc. # 20480064.006

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

Pin Signal Description

18 Sum In
19 Sum Out

The input and output terminals of the on-chip Modulation Summing Amplifier.
External components are required for input signals and gain/attenuation setting as
shown in Figure 2. For single-signal, no gain requirements, Main Process Out
may be linked directly to Modulation In.

20 Modulation In The final, composite modulating signal to VCO (Mod 1) and Reference (Mod 2)

Output Drives

21 Audio Output The processed audio signal output intended as a received audio (volume) output.

Though normally used in the RX mode, operation in TX is permitted. The output
level of this attenuator is controlled via a Volume Set command. During
Powersave this output is placed at V

SS

.

22 Modulation 1 Drive The drive to the radio modulator Voltage Controlled Oscillator (VCO) from the

composite audio summing stage.

23 Modulation 2 Drive The drive to the radio modulator Reference Oscillator from the composite audio

summing stage.
Note: These VCO output attenuators are individually adjustable using the
Modulator Level command. During Powersave these outputs are placed at V

SS

.

24 V

DD

Positive Supply. A single 5.0V regulated supply is required. Levels and voltages
within this Audio Processor are dependent upon this supply.

Table 1: Signal List

Audio Processor 6 MX806A

1998 MX-COM, Inc. www.mxcom.com Tel: [phone] 744 5050 Fax: [phone] Doc. # 20480064.006

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

3 External Components

1
2
3
4
5
6
7
8

9
10
11
12

24
23
22
21
20
19
18
17
16
15
14
13

MX806AJ

XTAL

XTAL/CLOCK

SERIAL CLOCK

COMMAND DA TA

CHIP SELECT

VOGAD OUT

RX AUDIO IN

VOGAD IN

MIC. IN (+)

MIC. IN (-)

V

BIAS

V

V

V

V

V

V

SS

SS

BIAS

DD

DD

DD

MODULATION 2 DRIVE
MODULATION 1 DRIVE
AUDIO OUT
MOD. IN
MIX OUT
MIX IN

CALIBRATION IN
EXTERNAL AUDIO PROCESS
PROCESSED AUDIO IN
MIC. OUT

MAIN PROCESS
OUT

EXTERNAL SIGNAL

AND

DATA INPUTS

SEE INSET 2

SEE INSET 1

C11

C13

C14

R8

R7

R9

R10

R11

R6

C12

R5

R12

R13

C8

C10

C9

MIC. OUT

C5

R4

C4

+

-

C2

R2

C1

R1

MIC. IN (+)

MIC. IN (-)

R3

C3

MX806AJ

MX806AJ

10

11

13

INSET 2

INSET 1

1

2

XTAL

XTAL/CLOCK

X1

C7

C6

Figure 2: Recommended External Components

Component Notes Value Tolerance Component Notes Value Tolerance

R1

10k



±10% C2

.47F

±20%

R2

10k



±10% C3 270pF ±20%

R3

20k



±10% C4 270pF ±20%

R4

20k



±10% C5

0.1F

±20%

R5

10k



±10% C6 33pF ±20%

R6

2.2M



±10% C7 5-65pF ±20%

R7

100k



±10% C8

1.0F

±20%

R8

100k



±10% C9

1.0F

±20%

R9

100k



±10% C10

1.0F

±20%

R10

100k



±10% C11 22pF ±20%

R11

100k



±10% C12

0.1F

±20%

R12

2.2M



±10% C13

0.01F

±20%

R13

470k



±10% C14

0.01F

±20%

C1

.47F

±20% X1 4.00MHz

Table 2: Recommended External Components

Audio Processor 7 MX806A

1998 MX-COM, Inc. www.mxcom.com Tel: [phone] 744 5050 Fax: [phone] Doc. # 20480064.006

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

Recommended External Component Notes:

1. Input Op-Amp gain/attenuation components (voltage gain = 6.0dB) are shown in Inset 1 is a differential
configuration to demonstrate the versatility of this input. Components for a single (+ or -) input may be
used.

2. Resistor values R7 to R11 (summation components) are dependent upon application and configuration
requirements.

3. Xtal circuit capacitors C6 (CD) and C7 (CG) shown in Inset 2 are recommended in accordance with MX­COM’s Crystal Oscillator Application Note. Circuit drive and drain resistors are incorporated on-chip.
Operation of any MX-COM IC without a Xtal clock input may cause device damage. To minimize damage
in the event of a Xtal/drive failure, you should install a current limiting device (resistor or fast-reaction
fuse) on the power-input (V

DD

).

4 General Description

The MX806A LMR audio processor is intended too primarily to operate as the “Audio Terminal” or radio
systems using the DBS800 Digitally Integrated Baseband Subsystem.

The MX806A half-duplex device has signal paths and level setting elements that are configured and adjusted
by digital information sent from the radio microcontroller using C-BUS protocol. (C-BUS is the serial interface
for all DBS 800 ICs.)

4.1 Signal Path

The Signal path is divided into three sections:

Input Process:

This stage has selectable TX/RX paths. Transmits voice signals pass through microphone
pre-amplifier, voltage controlled gain (VOGAD) and highpass filter stages. Received audio is de-emphasized.
This initial audio, after line-in gain adjustment, may be switched to external audio processes (such as
scrambling) or to the internal Main Process stages.

Main Process

: Conditioning for the input or external process signals is completed in this stage. It is

comprised of pre-emphasis, high and lowpass switched capacitor filters and a deviation limiter.

Mixing and Output Drives

: Main audio for transmission is mix with signaling and data from external sources
(other DBS 800 ICs) to provide the composite signal for the digitally adjustable transmitter modulation drives.
Received audio level is adjusted for output to loudspeaker circuitry.

If selected, signal level stability and output accuracy of the MX806A is maintained by a voltage-controlled gain
system using selectable signal-level detectors. Signal levels can be dynamically controlled to provide
“dynamic compensation” for factors such as temperature drift, VCO non-linearity, etc.

The MX806A audio stages can be completely disabled – or the whole IC can be placed into powersave mode,
leaving only clock and C-BUS circuitry active.

4.2 VOGAD

The overall Gain Control system of the MX806A consists of 2 selectable signal peak detectors whose output
is fed via external integrating components to adjust the gain of the Voltage Controlled Amplifier positioned in
the TX Input Process Path. The transmit input signals is presented to Peak Detector 1 or 2. The Peak
Detectors are enabled individually by a Mode Command. When the input signal exceeds the peak - to - peak
threshold of the detector, a 5-volt level is produced at the VOGAD Out pin. This level remains for as long as
the signal exceeds the threshold. The integrated level to the VOGAD In pin causes the Voltage Controlled
Amplifier gain to be reduced. As can be seen from Figure 3 and Figure 5, Peak Detector 1 allows control of
the audio level to the external audio process and Peak Detector 2 allows control of transmit deviation levels.