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MC34018L-D28-T View Datasheet(PDF) - Unisonic Technologies

Part Name
Description
View to exact match
MC34018L-D28-T
UTC
Unisonic Technologies UTC
MC34018L-D28-T Datasheet PDF : 8 Pages
1 2 3 4 5 6 7 8
MC34018
LINEAR INTEGRATED CIRCUIT
„ PIN DESCRIPTION(Cont.)
PIN NO.
15
16
17
18
19
20
21
22
23
24
25
26
27
28
PIN NAME
DESCRIPTION
SKO
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
V+
inductor is used to prevent loading ac line signals. The required V+ voltage is 6.0V to 11V
(7.5V nominal) at 7.0mA.
AGC
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 110kΩ.
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
CS logic "0".Input impedance is nominally 140k ohms. The input voltage should not exceed
11V.
SKI Input to the speaker amplifier. Input impedance is nominally 20kΩ.
A 5.4V regulated output which powers all circuits except the speaker amplifier output stage.
VCC can be used to power external circuitry such as a microprocessor(3.0mA max.) A filter
VCC capacitor is required. The UTC MC34018 can be powered by a separate regulated supply
by connecting V+ and VCC to a voltage between 4.5V and 6.5V while maintaining CS at a
logic "1".
An output voltage equal to approximately VCC/2 which series as an analog ground for the
VB
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.
GND Ground pin for the IC(except the speaker amplifier)
XDC
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).
VLC
ACF
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.
RXO
RXI
Receive attenuator Output. Normally this pin is ac coupled to the input of the speaker
amplifier.
Receive attenuator Input. Input impedance is nominally is 5.0kΩ.
RRX
A resistor to ground determines the nominal gain of the receive attenuator. The receive
channel gain is directly proportional to the RRX resistance.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
3 of 8
QW-R108-006,C
 

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