SH7619_09 Datasheet, PDF (717/860 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7619 Series

Section 22 Ethernet Physical Layer Transceiver (PHY)
1. Common Amplitude Adjustment Method in Tx10 and Tx100
 Advantage:
As a common amplitude adjustment method in Tx10 and Tx100, there is a method of
modifying the resistances of the resistors R1 and R2 in figure 22.10. The amplitudes in
Tx10 and Tx100 have correlations with the resistances of both the resistors R1 and R2.
Increasing the resistances increases the amplitudes in both Tx10 and Tx100, while
decreasing the resistances decreases the amplitudes.
 Disadvantage:
Unfavorable outcomes may often appear in harmonic content testings.
2. Amplitude Adjustment Method in Tx10
 Advantage:
The amplitudes in Tx10 depend on VccnA (meaning PVCC in the example of connection
above; n = 1 to 3). Increasing VccnA increases the amplitudes, while decreasing VccnA
decreases the amplitudes.
The amplitudes in Tx100 also depend on VccnA, though, less than in Tx100. Therefore, the
amplitudes in Tx10 can be adjusted with modifying VccnA, with no influence on the
results in Tx100.
 Disadvantage:
However, since VccQ and VccnA are connected with diode inside this LSI, the permanent
potential difference in them may damage the LSI’s reliability. Therefore, the method has
the disadvantage that VccQ must be adjusted simultaneously.
Rev. 6.00 Jul. 15, 2009 Page 677 of 816
REJ09B0237-0600