CS8900A-CQZ View Datasheet(PDF) - Cirrus Logic

Part Name

Description

Manufacturer

CS8900A-CQZ

Crystal LAN™ Ethernet Controller

Cirrus Logic 

CS8900A

Crystal LAN™ Ethernet Controller

8.5 10BASE-T WIRING

CS8900A

TXD + Rt

TXD -

Rt

68 pF

0.01 µF

1: 2

RXD+

+

- RXD-

0.01 µF

1:1

Rr

Rr

TD +

1

TD -

2

RJ45

RD +

3

RD -

6

• If a center tap transformer is used on the RXD+ and RXD- inputs, replace the pair of Rr re-

sistors with a single 2xRr resistor.

• The Rt and Rr resistors are ±1% tolerance.

• The CS8900A supports 100, 120, and 150 Ω unshielded twisted pair cables. The proper val-

ues of Rt and Rr, for a given cable impedance, are shown below:

Cable Impedance (Ω)

100

120

150

Rt (Ω)

24.3

30.1

37.4

Rr (Ω)

49.9

60.4

75

• Note: for 3.3V operation the turns ratio on TXD+ and TXD- is 1:2.5, rt is 8Ω for 100Ω cable

and the 68pF cap changes to 560pF.

CIRRUS LOGIC PRODUCT DATASHEET

132

DS271F4

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