1893YI-10LF IDT, 1893YI-10LF Datasheet - Page 32

• Manufacturer Part Number: 1893YI-10LF
• Description: Ethernet ICs 3.3V 10/100 BASE TX INTEGRATED PHYCEIVER
• Manufacturer: IDT

Specifications of 1893YI-10LF

• Rohs: yes
• Part # Aliases: ICS1893YI-10LF

6.5.1
ICS1893 Rev C 6/6/00
Twisted-Pair Transmitter Interface
The twisted-pair transmitter driver uses an H-bridge configuration, which requires that the transmit
transformer not have a choke on the chip side. ICS suggests any of the following for the H-bridge:
•
•
•
Figure 6-1
•
•
•
Note:
1. If the transmit transformer has a choke, put a choke on the RJ-45 side. Do not put a choke on the
2. Keep all TX traces as short as possible.
3. When making board traces, 50 -characteristic impedance is desirable
4. Include a 0
Figure 6-1. ICS1893 Transmit Twisted Pair
ICS1893
Halo TG22S012ND transformer
Transpower HB617-LP transformer
Pulse 68517 transformer, which can be turned around to move the choke windings to the RJ-45 side
Two 61.9
form a network that connects across both the transformer and the ICS1893 TP_TXP and TP_TXN pins.
The ICS1893 supplies the power to the transformer. (No VDD connection is required.)
The ICS1893 TP_CT pin is connected directly to the transformer transmit center tap connection and is
bypassed to ground with a 100-pF capacitor. The transformer center tap must not connect to the
resistor/inductor network.
TP_TXN 6
ICS1893 side of the transformer for the transmit windings.
connection.)
TP_TXP 5
ICS1893 Data Sheet - Release
TP_CT 3
shows the design for the ICS1893 twisted-pair transmitter interface.
Ideally, for these traces Z
1% resistors are in series, with a 120-nH 5% inductor between them. These components
resistor in series with TP_CT. (Some systems work better without the TP_CT
Copyright © 2000, Integrated Circuit Systems, Inc.
All rights reserved.
61.9
61.9
120 nH
0
o
1%
1%
System Ground Plane
= 50 .
32
Center
Tap
1:1
100 pF
Chassis Ground Plane
75
0.1 F
Separate Ground Plane
Chapter 6 Interface Overviews
To RJ-45
June, 2000