U3761MB-T Datasheet, PDF (6/27 Pages) ATMEL Corporation – Universal Telephone IC - All Functions Integrated

Pin Description
Pin Symbol Function
15
MICO
Transmit pre-amp output which is normally capacitively
coupled to Pin TIN
Configuration
MICO
VI
1V
16K
PD
16
VL
Positive supply voltage input to the device. The current
through this pin is modulated by the transmit signal.
VL
RDC
16 V
PD
PD
An external resistor (1 W) is required from this pin to GND to
control the DC input impedance of the circuit. It has a
17
RDC
nominal value of 39 W for low-voltage operation. Values up
to 100 W may be used to increase the available transmit
AGC
output voltage swing at the expense of low-voltage
operation.
RDC
VL
PD
PD
18
TIN
Input to the line output driver amplifier. Transmit AGC
applied to this stage.
This internal voltage bias line must be connected to VL via
19
V_I
an external resistor which dominates the AC input
impedance of the circuit and should be 680 W for an 600-W
input impedance or 1.2 kW for a 900-W input impedance.
1V
5.6K
TIN
16 V
PD
VI
16 V
PD
6 U3761MB-T
4744A–CORD–09/03