ET- 34018 LINEAR INTEGRATED CIRCUIT VOICE SWITCHED SPEAKERPHONE CIRCUIT DESCRIPTION The Contek KGM34018 speaker-phone integrated circuit incorporates the necessary functions to produce a high quality hands-free speaker-phone system. The applications include household and office speaker-phones, intercom systems, hand free kit for mobile phones, and others SOP-28 FEATURES *All necessary level detection and attenuation controls for a hand-free telephone included. *Background noise level monitoring with long time constant. *Background sound level compensation for transmit and DIP-28 receive levels as well as the background level. *Wide operating dynamic range through signal compression. *On-chip voltage regulators illuminate external regulators for lining operation. *Power audio amplifier for typical 100mW output (into 25 ohms)with peak limiting for speaker to minimize distortion. *Chip Select pin for active/stand by operation. *Volume control function for external volume control. *Standard 28-pin plastic DIP and SOP package. ABSOLUTE MAXIMUM RATINGS(Ta=25 PARAMETER C,Voltages referred to pin 22) V+ terminal Voltage (pin 16) CS (pin 18 Speaker amplifier Ground(pin 14) VLC(pin 24) Storage temperature RECOMMENDED OPERATION CONDITIONS PARAMETER V+ Terminal Voltage (pin 16) CS (pin 18) Vcc (pin 20) VLC(pin 24) Receive Signal(pin 27) Microphone Signal(pin 9) Speaker Amplifier Ground (pin 14) Ambient Temperature 1 VALUE UNIT +12,-1.0 +12,-1.0 V V +3.0,-1.0 +VCC,-1.0 -65 ~ +150 V V C VALUE UNIT +6.0 to +11 0 to +11 V V 0 to 3.0 0.55VB to VB 0 to 250 0 to 5.0 -10 to +10 -20 to +60 mA V mVrms mVrms mVdc C BEIJING ESTEK ELECTRONICS CO.,LTD ET- 34018 Internal Block Diagram TRANSMIT CHANNEL MIC TRANSMIT OUTPUT TRANSMIT ATTENUATOR MIC AMP TRANSMIT LEVEL DETECTOR SIGNAL/NOISE DETECTOR TRANSMIT/ RECEIVE COMPARATOR ATTENUATOR CONTROL SIDE TONE SIDE TONE RECEIVE LEVEL DETECTOR PEAK LIMITER SPEAKE R AMP RECEIVE ATTENUATOR RECEIVE INPUT RECEIVE CHANNEL VCC REGULATOR SPE AKE R DC INPUT TELEPHONE LINE Contek ENABLE INPUT RECEIVE VOLUME CONTROL Fig 1 PIN CONFIGURATIONS PIN 1 2 NAME RR RTX 3 4 TXI TXO 5 TLI 6 TLO 7 RLI 8 RLO 9 MCI 10 11 MCO CP1 12 CP2 13 XDI 14 SKG 15 SKO 16 V+ 17 AGC 18 CS 19 20 21 SKI VCC VB 22 GND DESCRIPTION A resistor to ground provides a reference current for the transmit and receive attenuators A resistor to ground determines the nominal gain of the transmit attenuator ,the transmit channel gain is inversely proportional to RTX resistance. Input to the transmit attenuator. Input resistance is nominally 5.0k ohms. Output of the transmit attenuator. The TXO output signal drivers the input of transmit level detector, as well as the external circuit which drivers the telephone line. Input of the transmit level detector. An external resistor ac coupled to The TLI pin sets the detection level. Decreasing this resistor increases the sensitivity to transmit channel signals. Output of the transmit level detector. The external resistor and capacitor set the time the comparator will hold the system in the transmit mode after speech ceases. Input of the receive level detector. An external resistor ac coupled to The RLI pin sets the detection level. Decreasing this resistor increases the sensitivity to receive channel signals Output of the receive level detector. The external resistor and capacitor set the time the comparator will hold the system in the receive mode after speech ceases Microphone amplifier input. Input impedance is nominally 10k ohms and the dc bias voltage is approximately equal to VB Microphone amplifier output. The MIC amp gain is internally set at 34dB(50V/V) A parallel resistor and capacitor connected between this pin and VCC holds a voltage corresponding to the background noise level. The transmit detector compares the CP1 voltage with the speech signal from A capacitor at this pin peak detects the speech signals for comparison with the background noise level held at CP1. Input to the transmit detector system. The microphone amplifier output is ac coupled to the XDI pin through an external resistor High current ground pin for the speaker amplifier output stage. The SKG voltage should be within 10mV of the ground voltage at pin 22 Speaker amplifier output. The SKO pin will source and sink up to 100mA when ac coupled to the speaker. The speaker amplifier gain is internally set at 34dB(50V/V). Input DC supply voltage. V+ can be powered from Tip and Ring if an ac decoupling inductor is used to prevent loading ac line signals. The required V+ voltage is 6.0V to 11V(7.5V nominal ) at 7.0mA A capacitor from this pin to VB stabilizes the speaker amplifier gain control loop, and additionally controls the attack and decay time of this circuit. The gain control loop limits the speaker amplifier input to prevent clipping at SKO. The internal resistance at AGC pin is nominally 110k ohms. Digital chip select input. When at a logic "0" (<0.7V) the VCC regulator is enabled. When at a logic "1" (>1.6V),the chip is in the standby mode drawing 0.5mA.An open CS pin is a logic "0". Input Impedance is nominally 140k ohms. The input voltage should not exceed 11V Input to the speaker amplifier. Input impedance is nominally 20k ohms A 5.4V regulated output which powers all circuits except the speaker amplifier output stage An output voltage equal to approximately VCC/2 which series as an analog ground for the speakerphone system. Up to 1.5mA of external load current may be sourced from VB. Output impedance is 250 ohms. A filter capacitor is required Ground pin for the IC(except the speaker amplifier) 2 BEIJING ESTEK ELECTRONICS CO.,LTD ET- 34018 (continued) PIN NAME 23 XDC 24 VLC 25 ACF 26 27 28 RXO RXI RRX DESCRIPTION Transmit detector output. A resistor and capacitor at his pin hold the system in the transmit mode during pauses between words or phrases. When the XDC pin voltage decays to ground, the attenuators switch from the transmit mode to idle mode. The internal resistor at XDC is nominally 2.6k ohms(see fig.1). Volume control input>connecting this pin to the slider of a variable resistor provides receive mode volume control. The VLC pin voltage should be less than or equal to VB Attenuator control filter. A capacitor connected to this pin reduces noise transient as the attenuator control switches level of attenuation Output of the receive attenuator. Normally this pin is ac coupled to the input of the speaker amplifier Input of the receive attenuator. Input impedance is nominally is 5.0k ohms A resistor to ground determines the nominal gain of the receive attenuator. The receive channel gain is directly proportional to the RRX resistance ELECTRICAL CHARACTERISTICS(referred to fig. 1) PARAMETER SUPPLY VOLTAGES SYMBOL V+ Supply Current IV+ V+=11V, Pin 18=0.7V V+=11V, Pin 18=1.6V VCC Voltage (V+=7.5V) Line Regulation (6.5V<V+<11V) Output Resistance (ICC=3mA) VB Voltage(V+=7.5V) Output Resistance (I B=1.7mA) ATTENUATORS Receive Attenuator Gain (1.0kHz) Rx Mode, Pin 24= VB, Pin 27 = 250Mvrms Range (Rx to Tx Modes) Idle Mode, Pin 27= 250mVrms RXO Voltage (Rx Mode) Delta RXO Voltage (Switch from Rx to Tx Mode) RXO Sink Current (Rx mode) MIN UNIT 9.0 800 5.9 150 20 300 3.3 mA A Vdc MV ohms mV Vdc ohms 4.9 GRX 2.0 6.0 10 dB GRX GRI VRXO VRXO 40 -20 1.8 44 -16 2.3 48 -12 3.2 100 dB dB mV mV 2.5 IRXOL 75 ITXOH 1.0 TXO Input Resistance ACF Voltage (VCC-Pin 25 Voltage) Rx Mode Tx Mode Idle Mode RTXI VACF 3.5 5.4 65 6.0 80 2.9 250 MAX Vcc VccLN RoVcc Vccsat Vb Rovb TXO Source Current (Tx mode) SPEAKER AMPLIFIER Speaker Amp Gain (pin 19 = 20mVrms) SKI Input Resistance SKO Voltage ( Pin 19 =Cap couple to GND) SKO High Voltage ( Pin 19 = 0.1V, -60mA Load at Pin 15) SKO Low Voltage (pin 19=0.1V, +60mA Load at Pin 15) MICROPHONE AMPLIFIER Microphone Amp Gain ( Pin 9 = 10mVrms,1KHz) Microphone Amp Input Resistance LOGAMPS RLO Leakage Current (Pin 8 = VB+1.0V) TLO Leakage Current (Pin 6 = VB+1.0V) Transmit-Receive Switching Threshold (Ratio of ITLI to IRLI - at 20 A - to Switch Tx-Rx Comparator) TRANSMIT DETECTOR XDC Voltage Idle Mode Tx Mode CP2 Current Source Distortion Rx Mode RXI to SKO (pin 27 = 10mVrms,1KHz) Tx Mode MCI to TXO (Pin 9 = 5mVrms,1KHz) TYP A 5.0 3.0 mA 8.0 k 150 6.0 75 GSPK RSKI VSKO 33 15 2.4 VSKOH 5.5 mV mV mV 34 22 3.0 35 37 3.6 dB k Vdc Vdc VSKOL 600 mV GMCI 32.5 34 35 dB RMCI 6.5 10 16 k 2.0 2.0 A A ILKRLO ILKTLO ITH 25 VXDC ICP2 5.0 0 4.0 10 Vdc Vdc 13 A RXD 1.5 % TXD 2.0 % Note 1:V+=7.5V, CS =0.7V except where noted. Note 2:Rx mode:pin7=-100 A, pin5=+100 A, except where noted Tx mode: pin 5,13=-100 A, pin 7=+100 A, pin 11=0V. Idle mode: Pin 5=-100A, pin 7,13=+100 A Note 3:Current into a pin designed as + ,current out of a pin designed -; Note 4:Voltage referred to pin 22,Tamb=25 C 3 BEIJING ESTEK ELECTRONICS CO.,LTD ET- 34018 TEMPERATURE CHARACTERISTICS(-20 TO +60 C ) PARAMETER V+ Supply Current ( V+ 11V,Pin 18 = 0.7V ) V+ Supply Current(V+ 11V,Pin 18 = 1.6V ) VCC Voltage( V+ = 7.5V ) Attenuator Gain ( Max and Min Setting ) Delta RXO,TXO Voltage Speaker AMP Gain Microphone AMP Gain Microphone Amp Input Resistance Tx-Rx Switching Threshold (20 A) PIN TYP CHANGE UNIT 16 16 20 -0.2 -0.4 +0.1 +-0.003 +-0.24 +-0.001 +-0.4 +0.4 +-0.2 %/ C %/ C %/ C dB/ C %/ C dB/ C dB/ C %/ C nA/ C 4,26 15,19 9,10 9 5,7 S1 0.01μF 22kΩ 1000μF 4700pF 4700pF 47kΩ 2.2kΩ 33kΩ 10μF 47kΩ 0.1μF 470kΩ 0.068μF 15kΩ R 8.2kΩ 6.8kΩ 8.2kΩ 8.2kΩ 0.01μF 0.01μF 2.7kΩ 47kΩ T 470kΩ 68kΩ Hook Switch 0.05μF 470kΩ 220kΩ 0.01μF 4.7kΩ 47kΩ Vcc 0.05μF MIC 2kΩ 0.1μF 10 ΤXΙ ΜCΟ 9 MCI 15 SKO 14 SKG 13 XDΙ 4 0.1μF 0.068μF 1.0μF 4.7μF 100kΩ 4.7kΩ 3 0.068μF 0.1μF S2 0.068μF VB 3.3kΩ 47μF 3.3kΩ 5 11 25 17 16 18 7 TXO TLI CP1 ACF AGC V+ CS RLI 27 RTX RR RRX RXO SKI CP2 XDC TLO 1 28 26 19 12 23 6 RXI 47μF 2 4.3kΩ VB 47μF 30kΩ 18kΩ 0.01μF 91kΩ 20kΩ Volume Control 47μF 24kΩ 200kΩ RLO GND 8 2.2MΩ 22 2.2MΩ 1.0μF 20 1.0μF Vcc 21 4.7μF VB 24 4.7μF VLC 0.05μF Speaker Fig 2 - Basic Line powered Speakerphone 4 BEIJING ESTEK ELECTRONICS CO.,LTD