Si5345-44-42-D-RM
Rev. 1.0
39
6.3.4. LVCMOS Output Terminations
LVCMOS outputs are dc-coupled as shown in Figure 19.
Figure 19. LVCMOS Output Terminations
6.3.5. LVCMOS Output Impedance and Drive Strength Selection
Each LVCMOS driver has a configurable output impedance to accommodate different trace impedances and drive
strengths. A source termination resistor is recommended to help match the selected output impedance to the trace
impedance. There are three programmable output impedance selections for each VDDO option as shown in
Table 22. The value for the OUTx_CMOS_DRIVE bits are given.
Table 22. Output Impedance and Drive Strength Selections
VDDO
OUTx_CMOS_DRV
Source Impedance (Rs)
Drive Strength (Iol/Ioh)
3.3 V
0x01
38
10 mA
0x02
30
12 mA
0x03*
22
17 mA
2.5 V
0x01
43
6 mA
0x02
35
8 mA
0x03*
24
11 mA
1.8 V
0x03*
31
5 mA
*Note:
Use of the lowest impedance setting is recommended for all supply voltages.
3.3V, 2.5V, 1.8V
LVCMOS
V
DDO
= 3.3V, 2.5V, 1.8V
50
Rs
50
Rs
DC Coupled LVCMOS
OUTx
OUTx