SH7619_09 Datasheet, PDF (719/860 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7619 Series

Section 22 Ethernet Physical Layer Transceiver (PHY)
(5) Terminations
To reduce signal reflections caused by impedance mismatches, provide damper or terminating
resistance at the end-points of signal nets. Damper resistance should be placed close to the signal
source, while terminating resistance should be placed at the farthest end-points of their nets. The
distance from the signal source or farthest end-point must be shorter than 12.7 mm (0.5 inch).
22.14.2 Guidelines for Layout
Since the signals of the PHY are analog signals with high frequencies and small amplitudes, they
are susceptible to digital noise. So, routing and placement must be done with extra care.
An example of connection with a pulse transformer (RJ45) is shown in figure 22.10. The codes
such as C1 and R2 in the following explanation are the part numbers indicated in figure 22.10.
(1) Example of Connection with a Pulse Transformer (RJ45)
PVCC
SH_TxP
SH_TxM
SH_RxP
SH_RxM
R3
CN1
R2
R1
C1 1 2
6.8nF/16V
R4*
1 _{TD+ (TX+)}
3
2
4
TCT (NC)
TD- (TX-)
RD+ (RX+)
6
5
7
RCT (NC)
RD- (RX-)
NC
Note:
R5*
12
8
GND (FG)
C3
C4
Pulse transformer
equivalent to TLA-6T718
6.8nF/16V
PVSS PVSS
PVSS
C2
PVCC: Analog power supply
PVSS: Analog ground
* R4, R5: Please set the terminating resistance as 50 ohm, summing up with both side of the magnetic
(even if the magnetic is in the RJ45 connector).
Figure 22.10 Example of Connection with a Pulse Transformer (RJ45)
Rev. 6.00 Jul. 15, 2009 Page 679 of 816
REJ09B0237-0600