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Details, datasheet, quote on part number:FX806ALG
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Datasheet text preview:
FX806A AUDIO PROCESSOR
CHIP SELECT POWER SUPPLY C-BUS INTERFACE CALIBRATION INPUT PRIMARY and SECONDARY AUDIO INPUTS ------ Voice. Sub-/Audio Tone. FFSK. etc. SERIAL CLOCK COMMAND DATA MAIN PROCESS OUT SUM OUT MOD. IN
#
MODULATION 1 OUT ATTENUATOR
#
(TX) MIC. IN MIC. & VOGAD AMPS LOW & HIGHPASS FILTERS
VOGAD SENSE
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VOGAD SENSE
#
VOGAD SENSE
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#
TRANSMITTER MODULATION DRIVES
# #
GAIN SET
INPUT PROCESS
#
PRE-EMPHASIS LIMITING FILTERING GAIN SETTING
(RX) AUDIO IN
DE-EMPHASIS FILTER
XTAL/CLOCK CLOCK XTAL GENERATOR
BUFFER ATTENUATOR
To EXTERNAL AUDIO PROCESSES
EXTERNAL AUDIO PROCESS IN
Fig.1 FX806A Audio Processor
Brief Description
Intended primarily to operate as the "Audio Terminal" of Radio Systems using the DBS 800 Digitally-integrated Baseband System, the FX806A is a PMR Audio Processor which meets EIA and CEPT audio specifications. Using a unique filter line-up, the FX806A offers lower distortion versus modulation level figures than conventional filter/limiter configurations. The FX806A is a half-duplex device whose signal paths and level-setting elements are dynamically configured and adjusted by digital information sent from the Radio µController using "C-BUS" hardware and software protocol. Figure 5 shows a complete functional block diagram of the FX806A signal paths which can be viewed as 3 sections: q Input Process Selectable transmit or receive input paths. The transmit path with low-noise input and VOGAD amplifiers and bandpass filtered stages provides good signalto-noise performance at low input levels and minimum distortion for high-drive modulation signals. De-emphasis is software selectable at the Rx Audio Input for FM or PM radio configurations. This initial audio, after in-line gain adjustment, is available for switching to either external audio processes (such as scrambling) or internally to the Main Process stages. q Main Process Conditioning for Input or External Process signals with gain/pre-emphasis, high and lowpass switched capacitor filters and a transmitter deviation limiter. The Main Process Output may be switched to VBIAS. q Summation and Output Drives Main "voice audio" from the Main Process is combined with signalling and data from other DBS 800 facilities, to provide the composite (in and outband) signal for the digitally adjustable Transmitter Modulation Drives. Received audio is level (volume) adjusted for output to loudspeaker circuitry. Signal-level stability and therefore output accuracy, of the FX806A is maintained by a voltage-controlled gain system (VOGAD) with specific gain sensors that are selected automatically by the Internal/External Mode Command. The VOGAD system permits high deviation with low distortion. This is achieved by reducing the path gain (and so reducing the distortion introduced by the Peak Deviation limiter) when the input signal is large. Signal levels can be controlled to provide `dynamiccompensation' for such factors as temperature drift, VCO non-linearity, etc. FX806A audio output stages can be completely disabled or the whole microcircuit placed into a "Powersave" mode, leaving only clock and "C-BUS" circuitry active. The FX806A is a low-power, 5-volt CMOS integrated circuit and is available in 24-pin DIL cerdip and 24-pin/lead plastic SMD packages.
Publication D/806A/3 July 1994
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#
#
#
ATTENUATOR MODULATION 2 OUT
MAIN PROCESS
MODULATION SUMMING AMP
OUTPUT DRIVES
# indicates logic control
#
LOUDSPEAKER AUDIO
Pin Number Function
FX806A J/LG/LS
1
Xtal: The output of the on-chip clock oscillator. External components are required at this output when a Xtal circuit is employed. See Figure 2, INSET 2.
2
Xtal/clock: The input to the on-chip clock oscillator inverter. A Xtal or externally derived clock should be connected here. See Figure 2, INSET 2. This clock provides timing for on-chip elements, filters etc.
3
Serial Clock: The "C-BUS," serial data loading clock input. This clock, produced by the µController, is used for transfer timing of Command Data to the Audio Processor. See Timing diagrams and System Support Document.
4
Command Data: The "C-BUS," serial data input from the µController. Command Data is loaded to this device in 8-bit bytes, MSB (B7) first, and LSB (B0) 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 Tables 1, 2, 3, 4 and 5. See Timing diagrams and System Support Document.
5
Chip Select (CS): The "C-BUS," data loading control function. This input is provided by the µController. Command Data transfer sequences are initiated, completed or aborted by the CS signal. See Timing diagrams and System Support Document.
6
VOGAD Out: The output of the relevant VOGAD sensor. This output, with external attack and decay setting components, should be connected as in Figures 2 and 3, to the VOGAD In pin.
7
Rx Audio In: The audio input to the FX806A from the radio receiver's demodulator circuits. This input, which requires to be a.c. coupled with capacitor C12, is selected by 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. VOGAD operation is enabled via a Mode Command (Bit5). Individual sensors, automatically selected, permit gain control from either the Input Process or an external process. External attack and decay setting components should be applied as recommended in Figures 2 and 3.
9
VBIAS: The output of the on-chip analogue circuitry bias system, held internally at VDD/2. This pin should be decoupled to VSS by a 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, INSET 1.
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, INSET 1.
12
VSS: Negative supply rail (GND).
2
Pin Number Function
FX806A J/LG/LS
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 either inverting or non-inverting inputs. During Powersave (Volume Command) this output is placed at VSS.
14
Processed Audio In: The input to the device from such external audio processes as Voice Store and Retrieve or Frequency Domain Scrambling. This input, which requires to be a.c. coupled with a capacitor, C13, is selected by a Mode Command bit.
15
External Audio Process: The buffered output of the Input Processing stage. For further external audio processing prior to re-introduction at the Processed Audio In pin.
16
CALibration Input: A unique input, intended to be used for dynamic balancing of the modulator drives and for measuring Deviation Limiter levels. A CUE (beep) input from the FX803 Audio Tone Processor can be entered on this line. This input is selected via a Mode Command bit (11H) and is self-biased.
17
Main Process Out: The output of the Main Process stage. This output is summed with additional system inputs as required (Audio, Sub-Audio Signalling, FFSK See System Overview) in the on-chip Modulation Summing Amplifier. External components as shown in Figure 2 should be used as required.
18
19
Sum In: The input and output terminals of the on-chip Modulation Summing Amplifier. External components are required for input signals, with gain/attenuation setting as shown in Figure 2. For single-signal, no-gain requirements, Main Process Out may be linked directly to Modulation In. Sum Out:
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 VSS.
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 Levels command. During Powersave these outputs are placed at VSS.
24
VDD: Positive supply rail. A single, stable +5 volt supply is required. Levels and voltages within the Audio Processor are dependant upon this supply.
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