µPD9903

7

2.

USE CAUTIONS

(1) Combined characteristics of the

µPC9903 and µPD7073

•

The

µPD9903 is designed to be used in combination with the µPC7073. Therefore, the first half of the electrical

specifications described below are ratings for the

µPD9903 as a discrete unit while the second half are

combined ratings with the

µPC7073.

•

Subscriber circuit constants that are determined by factors such as termination impedance are configured to

enable setting by external order parameters. Consequently, input of an order that is not suitable for the target

impedance may result in failure to obtain the required characteristics.

(2) Absolute maximum ratings

Application of voltage or current in excess of the absolute maximum ratings may result in damage. Be

especially cautious about surges, etc.

(3) Load of by-pass capacitor

Because the

µPC7073 and µPD9903 use several internal high-frequency operational amplifiers, high power

supply impedance can cause instability in these internal operational amplifiers (such as oscillation). To

0.1

µF) having superior high frequency characteristics as close as possible to the µPC7073’s power supply

(4) Addition of ACOM pin connection capacitor

The voltage of the ACOM pin between the

µPC7073 and µPD9903 is the reference voltage of the signal

source between the

µPC9903 and µPC7073. Superposing of noise on this pin may have adverse effects

on transmission characteristics. Therefore, make the wires between the ACOM pins of the two LSIs as short

µF) having superior high frequency

characteristics as close as possible to the pins.