Cirrus-logic CS6422 Manual do Utilizador Página 1

Preliminary Product InformationThis document contains information for a new product.Cirrus Logic reserves the right to modify this product without not

CS6422102. OVERVIEWThe CS6422 is a full-duplex speakerphone chip foruse in hands-free communications with telephonyquality audio. Common applications

CS642211of higher amplitude will clip the ADC input andwill result in poor echo canceller performance. SeeSection 4., “Design Considerations” for more

CS642212through the Microcontroller Interface. This gainstage allows gains of 0 dB, 6 dB, 9.5 dB, and 12 dBto be added prior to the ADC input. The def

CS642213STROBE pulses must be applied to latch the datainto the CS6422.Since the MCR is a shift register, the STROBE canbe run arbitrarily slowly with

CS6422143.3 Register 0b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0MicHDD GB RVol TSD ACC TSMde00001 0 10 0100 0 00 0A4 0 0Bits Name Function

CS6422153.3.1 MIC - MICROPHONE PREAMPLIFIER ENABLEThe microphone preamplifier described in Section 3.1.1, “Acoustic Interface” is enabled by default,

CS6422163.3.6 ACC - ACOUSTIC COEFFICIENT CONTROLThe coefficients of the AEC adaptive filters in the CS6422 are controlled by ACC. The default position

CS6422173.4 Register 1b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0THDet Taps TVol RSD NCC AuNECD 0 0 1 000 10 1010 0 00 02A 0 2Bits Name Func

CS6422183.4.1 THDET - TRANSMIT HALF-DUPLEX DETECTION THRESHOLDThe sensitivity of the speech detector controls channel switching and ownership in half-

CS6422193.5 Register 2b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0RHDet RSThd NseRmp HDly HHold TDSRmp RDSRmp IdlTx 0 1 0 000 00 00 00 0 0 0

CS64222TABLE OF CONTENTS1. CHARACTERISTICS AND SPECIFICATIONS ... 5ABSOLUTE MAX

CS6422203.5.1 RHDET - RECEIVE HALF-DUPLEX DETECTION THRESHOLDThe sensitivity of the speech detector controls channel switching and ownership in half-d

CS6422213.5.7 RDSRMP - RX DOUBLE-TALK SUPPRESSION RAMP RATEWhen “Rx Double-talk Suppression attenuation” (RDbtS, Register 3) is set to a non-zero valu

CS6422223.6 Register 3b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0TSAtt PCSen TDbtS RDbtS TSThd TSBias 0 1 1 000 0 000 00 00 000006Bits Name

CS6422233.6.1 TSATT - TRANSMIT SUPPRESSION ATTENUATIONThis parameter sets the amount of attenuation inserted into the transmit path when transmit supp

CS6422243.7 Register 4b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0AErle AFNse NErle NFNse RGain TGain 100000 00 00 00 00 000008Bits Name Func

CS6422253.7.1 AERLE - AEC ERLE THRESHOLDThe CS6422 will allow full-duplex operation when the ERLE provided by the AEC exceeds the value programmed at

CS6422263.8 Register 5b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0HwlD TDAPCDNPCDAPFDNPFDAECDNECD ASdt NSdt 1010000000000000000ABits Name Fun

CS6422273.8.1 HWLD - HOWL DETECTOR DISABLEThis is a diagnostic parameter that is normally set to ‘0’.In normal operation, the CS6422 will clear both t

CS6422283.8.6 AECD - ACOUSTIC ECHO CANCELLER DISABLESetting this bit to a ‘1’ disables the Acoustic Echo Canceller. The AEC is removed from the signa

CS6422293.9 ResetA hardware reset, initiated by bringing RST low forat least tRSTL and then high again, must be appliedafter initial power-on.When RST

CS642233.5.4 HDly - Half-Duplex Holdover Delay... 193.5.5 HHold - Hold in Half-D

CS6422303.11 Power SupplyThe pins AVDD (pin 1) and AGND (pin 2) powerthe analog sections of the CS6422, and DVDD (pin16) and DGND (pin 15) power the d

CS642231Figure 8 shows the suggested placement of decou-pling capacitors for the power supplies. Note thatthe trace length from the power pin to the c

CS6422324. DESIGN CONSIDERATIONSWhen designing the CS6422 into a system, it is im-portant to keep several considerations in mind.These concerns can be

CS642233room, when someone moves the speaker or the mi-crophone, or when someone drops a piece of paperon top of the speaker. So, the filter needs to

CS642234characteristics than white noise because of its qua-si-periodic nature.Research at Crystal has shown that quasi-periodicsignals cause the form

CS64223514), and the receive suppression speech detectorthreshold is set by RSThd (Register 2, bits 13 and12). The transmit speech detectors for both

CS642236Any signal greater than 30 dB below full-scale (a),is scaled down to 30 dB (b). This signal is thenscaled up +30 dB (the reference level) to p

CS642237Suppression may cause some modulation of theperceived background noise which may be distract-ing to some users. As a result, it may be desirab

CS642238loop (near-end speaker/mic to far-end speaker/mic)during a double-talk scenario (where both near-endand far-end parties are talking at the sam

CS642239The three pins that comprise the MicrocontrollerInterface are STROBE, DATA, and DRDY. Also,four extra clocks are required after DRDY isbrought

CS642244.1.4.3 Double-talk Attenuation ... 364.1.4.4 Noise Guard ...

CS642240speaker, the reflections reaching the microphoneshould present no more than 0.9 Vrms to the Acous-tic ADC. In fact, it is advisable to allow 6

CS6422414.3.2.2 Convergence TimeConvergence time is a measure of how quickly theadaptive filter can model the echo path. Fromcleared coefficients, the

CS6422425. PIN DESCRIPTIONSAnalog InterfaceAO - Acoustic Interface Output, Pin 3Analog voltage output for the acoustic side (near-end output/receive o

CS642243NI - Network Interface Input, Pin 17Input to the network side analog-to-digital converter (far-end input/receive input). This input expects as

CS642244MiscellaneousNC1 - No Connect, Pin 9Must be floating for normal operation.NC2 - No Connect, Pin 10Must be floating for normal operation.NC3 -

CS6422456. GLOSSARYEchoA signal that returns to its source after some delay.Network EchoEcho resulting from signal reflection due to an impedance mism

CS642246Adaptive FilterA digital FIR filter that adjusts its coefficients to match a transfer function, such as the echo pathbetween the speaker and m

CS6422477. PACKAGE DIMENSIONSINCHES MILLIMETERSDIM MIN NOM MAX MIN NOM MAXA 0.093 0.098 0.104 2.35 2.50 2.65A1 0.004 0.008 0.012 0.10 0.20 0.30b 0.013

CS642248 DS295F1ORDERING INFORMATION ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION* MSL (Moisture Sensitivity Level) as specified by IPC/JE

CS642251. CHARACTERISTICS AND SPECIFICATIONSABSOLUTE MAXIMUM RATINGSWARNING: Operation beyond these limits may result in permanent damage to the devic

CS64226ANALOG TRANSMISSION CHARACTERISTICS (TA = 25°C, DVDD = AVDD = 5 V, f XTAL =20.480 MHz, RVol=TVol=RGain=TGain= 0 dB, HDD=TSD=RSD=1, analog input

CS64227ANALOG TRANSMISSION CHARACTERISTICS (TA = -40°C to 85oC, DVDD = AVDD = 5 V, f XTAL =20.480 MHz, RVol=TVol=RGain=TGain= 0 dB, HDD=TSD=RSD=1, ana

CS64228SWITCHING CHARACTERISTICS Parameter Symbol Min Typ Max UnitsDigital input rise time trise1.0 µsRST low timetRSTL1.0 µsCLKI frequen

CS64229AVDDAGNDAPIAPOMBAOCLKOCLKISTROBEDATADRDYNINODGNDDVDD0.1 µF10 µF+0.1 µF10 µF+0.47 µF10 µF22pFNetworkLine OutNetwork Line InFrom Microcontrolle