CONTEK MC34118 Datasheet

MC34118 LINEAR INTEGRATED CIRCUIT

VOICE SWITCHED SPEAKER­PHONE CIRCUIT

DESCRIPTION

The Contek MC34118 voice switched speaker-phone
integrated circuit incorporates the necessary amplifiers,
attenuators, level detectors and control algorithm to form the
heart of a high quality hands-free speaker-phone system. It
includes a microphone amplifier with adjustable gain and
mute control. Transmit and Receive attenuators which
operate in a complementary manner, level detectors at both
input and output of both attenuators, and background noise
monitors for both the transmit and receive channels. A dial
tone detector prevents the dial tone from being attenuated by
the receive background noise monitor circuit. Also two line
driver amplifiers which can be used to form a hybrid network
in conjunction with an external coupling transformer. A high­pass filter can be used to filter out 60Hz noise in the receive
channel, or for other filtering functions. A chip disable pin
permits powers down the entire circuit to converse power on
long loops where loop current is at a minimum. The Contek
MC34118 may be operated from a power supply, or it can be
powered from the telephone line, requiring typically 5mA. The
Contek MC34118 can be interfaced directly to TIP and
RING( through a coupling transformer) for stand-alone
operation, or it can be used in conjunction with a handset
speech network and/or other features of a feature phone.

FEATURES

*Improved attenuator gain range: 52dB between Transmit

and Receive
*Low voltage operation for line-powered applications(3~6.5V)
*4-point signal sensing for improved sensitivity
*Background noise monitors for both Transmit and Receive

paths

SOP-28

DIP-28

*Microphone amplifier gain set by external

Resistors-Mute function included
*Chip disable for active/standby operation
*On board filter pinned-out for user defined

function

*Dial tone detector to inhibit receive idle mode

during dial tone presence

ABSOLUTE MAXIMUM RATINGS(Ta=25 C,Voltages referred to pin 22)

PARAMETER SYMBOL VALUE UNIT

Supply Voltage Vcc -1~7 V
Voltage at Pin 3 V3 -1~Vcc+1 V
Voltage at Pin 12( mute) V12 -1~Vcc+1 V
Voltage at Pin 13( VLC) V13 -1~Vcc+0.5 V
Voltage at Pin 9, Pin 21, and Pin 2 V9, 21, 2 -0.5~Vcc+0.5 V
Storage temperature Tstr -65~150 C

Contek Microelectronics Co.,Ltd.

CONTEK

http://www.contek-ic.com E-mail:[e-mail]

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MC34118 LINEAR INTEGRATED CIRCUIT

RECOMMENDED OPERATION CONDITIONS

PARAMETER SYMBOL VALUE UNIT

Supply Voltage V4 3.5~6.5 V
Voltage at Pin 3 V3 0~Vcc V
Voltage at Pin 12( MUTE) V12 0~Vcc V
Voltage at Pin 13( VLC) V13 0.3*VB~VB V
IVB Current( Pin 15) IVB 500 mA
Attenuator Input Signal Voltage at Pin 9, Pin 21 V9, V21 350 Mvrms
Load Current
@RXO, TXO(Pin8, Pin 22)
@MCO(Pin 10)
@HTO-, HTO+(Pin 6, Pin5)
Ambient Operating Temperature Topr -20~60 C

BLOCK DIAGRAM

Contek

0~+-2
0~+-1

0~+-0.5

mA

CONTEK

Contek Microelectronics Co.,Ltd.

http://www.contek-ic.com E-mail:[e-mail]

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MC34118 LINEAR INTEGRATED CIRCUIT

PIN CONFIGURATIONS

PIN NAME DESCRIPTION

1 FO Filter Output. Output impedance is less than 50 ohms.
2 FI Filter Input. Input impedance is greater than 1 M ohms.
3 CD Chip Disable. A logic low (<0.8V) sets normal operation. A logic high (>2V) disable the IC to converse

4 Vcc A supply voltage of +2.8V to +6.5V is required at 5mA. As Vcc falls from 3.5V to 2.8V, an AGC circuit

5 HTO+ Output of the second hybrid amplifier. The gain is internally set at -1 to provide a differential output, in

6 HTO- Output of the first hybrid amplifier. The gain of the amplifier is set by external resistors.
7 HTI Input and summing node for the first hybrid amplifier. DC lever is about equal to VB.
8 TXO Output of the transmit attenuator. DC level is about VB.

9 TXI Input of the transmit attenuator. Maximum signal level is 350 mVrms. Input impedance is 10KW.
10 MCO Output of the microphone amplifier. The gain of the amplifier is set by external resistors.
11 MCI Input of the summing node of the microphone. DC lever is VB.
12 MUT Mute input. A logic low (<0.8V) sets normal operation. A logic high (>2V) mutes the microphone

13 VLC Volume control input. When VLC=VB, the receive attenuator is at maximum gain when in the receive

14 CT The RC at this pin sets the response time for the circuit to switch modes.
15 VB N output voltage=Vcc/2. This voltage is a system AC ground and biases the volume control. A filter

16 CPT The RC at this pin sets the time constant for the transmit background side.
17 TLI2 Input to the transmit level detector on the microphone/ speaker side.
18 TLO2 Output to the transmit level detector on the microphone/ speaker side, and input to the transmit

19 RLO2 Output of the receive level detector on the microphone/ speaker side
20 RLI2 Input to the receive level detector on the microphone/ speaker side
21 RXI Input to the receive attenuator and dial tone detector. Maximum input level is 350mVrms. Input

22 RXO Output of the receive attenuator. DC level is VB.
23 TLI1 Input to the transmit level detector on the line side.
24 TLO1 Output to the transmit level detector on the line side, and input to the transmit background monitor.
25 RLO1 Output of the receive level detector on the line side.
26 RLI1 Input to the receive level detector on the line side.
27 CPR The RC at this pin sets the time constant for the receive background monitor.
28 GND Ground pin for the entire IC.

power. Input impedance is nominally 90 K ohms.

reduces the receive attenuator gain by 25dB( when in the receive mode).

conjunction with HTO-, to the hybrid transformer.

amplifier without affecting the rest of the circuit. Input impedance is 90 K ohms.

mode. When VLC=0.3dB, the receive gain is down 35dB. Does not effect the transmit modes.

capacitor is required.

background monitor.

impedance is 10KW.

CONTEK

Contek Microelectronics Co.,Ltd.

http://www.contek-ic.com E-mail:[e-mail]

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MC34118 LINEAR INTEGRATED CIRCUIT

ELECTRICAL CHARACTERISTICS(referred to fig. 1)

PARAMETER SYMBOL TEST

CONDITIONS

SUPPLY VOLTAGES
V+ Supply Current

Vcc=6.5V, CD=0.8V

Vcc=6.5V, CD=2V
CD Input Resistance RCD Vcc=VCD=6.5V 50 90 kW
CD Input Voltage(High) VCDH 2 Vcc V
CD Input Voltage VCDL 0.8 V
VB Output Voltage VB Vcc=3.5V

VB Output Resistance ROVB IVB=1mA 400 W
VB Power Supply Rejection Ratio PSRR CVB=220mF,

ATTENUATORS
Receive Attenuator Gain(f=1kHz, VLC =VB)
Rx Mode, RXI=150mVrms GRX Vcc=5V 4 6 8 dB
Rx Mode, RXI=150mVrms GRX Vcc=3.5V 4 6 8 dB
Gain Change DGRX1 Vcc=3.5V vs.

AGC Gain Change DGRX2 Vcc=3.5V vs.

Idle Mode, RXI=150mVrms GRXI -22 -20 -17 dB
Rx to Tx Mode Range DGRX3 49 52 54 dB
Volume Control Range VCR 27 35 dB
RXO DC Voltage VRXO Rx Mode VB V
DRXO DC Voltage DVRXO Rx to Tx Mode +-10 +-150 mV
RXO High Voltage VRXOH Iout=-1mA,

RXO Low Voltage VRXOL Iout=+1mA,

RXI Input Resistance RRXI RXI<350mVrs 7 10 14 kW
TRANSMIT ATTENUATOR GAIN(f=1kHz)
Tx Mode, TXI=150mVrms GTX 468 dB
Idle Mode, TXI=150mVrms GTXI -22 -20 -17 dB
Tx to Rx Mode Range DGTXI 49 52 54 dB
TXO DC Voltage VTXO Tx VB V
DTXO DC Voltage DVTXO Tx to Rx Mode +-30 +-150 mV
TXO High Voltage VTXOH Iout=-1mA,

Icc

Vcc=5V 1.8

f=1kHz

Vcc=5V

Vcc=5V

RXI=V

B+1.5V

RXI=V

B-1V,

Output Measured

with Respect to

V

B

TXI=V

B+1.5V

MIN TYP MAX UNIT

5.5

600

1.3

2.1 2.4

54 dB

-0.5 0 +0.5 dB

-25 -15 dB

3.7 V

-1.5 -1 V

3.7 V

8

800

mA

mA

V

CONTEK

Contek Microelectronics Co.,Ltd.

http://www.contek-ic.com E-mail:[e-mail]

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