CS8403A-CS 查看數據表（PDF） - Cirrus Logic

零件编号

产品描述 (功能)

生产厂家

CS8403A-CS

96 kHz Digital Audio Transmitter

Cirrus Logic 

CS8403A CS8404A

APPENDIX A: RS422 DRIVER

INFORMATION

The RS422 drivers on the CS8403A and CS8404A

are designed to drive both the professional and con-

sumer interfaces. The AES/EBU specification for

professional/broadcast use calls for a 110 Ω source

impedance and a balanced drive capability. Since

the transmitter impedance is very low, a 110 Ω re-

sistor should be placed in series with one of the

transmit pins. (A 110 Ω resistor in parallel with the

transformer would, with the receiver impedance of

110 Ω, provide a 55 Ω load to the part which is too

low.) The specifications call for a balanced output

drive of 2-7 volts peak-to-peak into a 110 Ω load

with no cable attached. Using the circuit in Figure

A1, the output of the transformer is short-circuit

protected, has the proper source impedance, and

provides a 5 volt peak-to-peak signal into a 110 Ω

load. Lastly, the two output pins should be attached

to an XLR connector with male pins and a female

shell, and with pin 1 of the connector grounded.

CS8403A/4A

TXP

110 Ω

XLR

TXN

1

Figure A1. Professional Output Circuit

In the case of consumer use, the specifications call

for an unbalanced drive circuit with an output im-

pedance of 75 Ω and a output drive level of

0.5 volts peak-to-peak ±20% when measured

across a 75 Ω load using no cable. The circuit

shown in Figure A2 only uses the TXP pin and pro-

vides the proper output impedance and drive level

using standard 1% resistors. The connector for con-

sumer would be an RCA phono socket. This circuit

is also short circuit protected.

The TXP pin may be used to drive TTL or CMOS

gates as shown in Figure A3. This circuit may be

CS8403A/4A

TXP

TXN

374 Ω

90.9 Ω

RCA

Phono

Figure A2. Consumer Output Circuit

used for optical connectors for digital audio since

they are usually TTL compatible. This circuit is

also useful when driving multiple digital audio out-

puts since RS422 line drivers have TTL interfaces.

CS8403A/4A

TXP

TTL or

CMOS Gate

TXN

Figure A3. TTL/CMOS Output Circuit

The transformer should be capable of operating

from 1.5 to 14 MHz, which is the audio data rate of

25 kHz to 108 kHz after biphase-mark encoding.

Transformers provide isolation from ground loops,

60Hz noise, and common mode noise and interfer-

ence. One of the important considerations when

choosing transformers is minimizing shunt capaci-

tance between primary and secondary windings.

The higher the shunt capacitance, the lower the iso-

lation between primary and secondary, and the

more coupling of high frequency energy. This en-

ergy appears in the form of common mode noise on

the receive side ground and has the potential to de-

grade analog performance. Therefore, for best per-

formance, shielded transformers optimized for

minimum shunt capacitance should be used. The

following are a few typical transformers:

Pulse Engineering

Telecom Products Group

7250 Convoy Ct.

San Diego, CA 92111

30

DS239PP1

Share Link: