MC34118 LINEAR INTEGRATED CIRCUIT
VOICE SWITCHED SPEAKER-PHONE CIRCUIT
DESCRIPTION
As a voice switched speaker-phone integrated circuit, the UTC
MC34118 includes the necessary amplifiers, attenuators, level
detectors and control algorithm.
To form the UTC MC34118’s internal circuit, there is an internal
microphone amplifier with adjustable gain and mute control,
internal transmit and Receive attenuators (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.
The dial tone can be pretended from being attenuated by the receive
background noise monitor circuit by a dial tone detector. There are
also two line driver amplifiers which can be used to form a hybrid
network in conjunction with an external coupling transformer. A
high-pass filter can be used for other filtering functions, and
especially to filter out 60Hz noise in the receive channel.
The UTC MC34118 which requiring typically 5mA may be operated from
a power supply, or it can be powered from the telephone line.
FEATURES
* Attenuator gain range: 52dB (between Transmit and Receive)
* For line-powered applications : 3~6.5V low voltage operation
* For improved sensitivity :4-point signal sensing
* For Transmit and Receive paths: background noise monitors
* External resistors set microphone amplifier gain
* Mute function included
* Chip disable: active or standby operation
* During dial tone presence: dial tone detector to inhibit receive
idle mode
ORDERING INFORMATION
| Ordering Number | Package | Packing |
| Normal | Lead Free Plating | Halogen Free |
| MC34118-D28-T | MC34118L-D28-T | MC34118G-D28-T | DIP-28 | Tube |
| MC34118-E28-T | MC34118L-E28-T | MC34118G-E28-T | SDIP-28 | Tube |
| MC34118-S28-T | MC34118L-S28-T | MC34118G-S28-T | SOP-28 | Tube |
| MC34118-S28-R | MC34118L-S28-R | MC34118G-S28-R | SOP-28 | Tape Reel |
ABSOLUTE MAXIMUM RATING (Ta=25°С,Voltages referred to pin 22)
| PARAMETER | SYMBOL | RATINGS | 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 | °С |
Note: Absolute maximum ratings are those values beyond which the
device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional
device operation is not implied.
BLOCK DIAGRAM
TYPICAL APPLICATION CIRCUIT
