LVDCI

UltraScale Architecture SelectIO Resources User Guide (UG571)

Document ID
UG571
Release Date
2022-08-31
Revision
1.14 English
Table 1-23:      Available I/O Bank Type 

HR

HP

N/A

Available

Using these I/O buffers configures the outputs as controlled impedance drivers. The receiver of low-voltage digitally controlled impedance (LVDCI) is identical to an LVCMOS receiver. Some I/O standards, such as LVCMOS, must have a drive impedance that matches the characteristic impedance of the driven line. The HP I/O banks provide a controlled impedance output driver to provide series termination without external-source termination resistors.

Source termination is controlled using the OUTPUT_IMPEDANCE attribute. The exact value of the impedance is determined by the OUTPUT_IMPEDANCE attribute and an external 240W resistor on the VRP pin. The only valid value of this attribute for LVDCI standards is RDRV_48_48, which corresponds to a 48W setting.

Sample circuits illustrating both unidirectional and bidirectional topologies for a controlled impedance driver are shown in This Figure and This Figure. The DCI I/O standards supporting a controlled impedance driver are: LVDCI_15 and LVDCI_18.

Figure 1-51:      Unidirectional Controlled Impedance Driver Topology

X-Ref Target - Figure 1-51

X16111-uni-controlled-impedance-driver-topology.jpg
Figure 1-52:      Bidirectional Controlled Impedance Driver Topology

X-Ref Target - Figure 1-52

X16112-bidi-controlled-impedance-driver-topology.jpg

Table: Allowed Attributes for the LVDCI I/O Standards  details the allowed attributes that can be applied to the LVDCI I/O standard. This standard is available in the HP I/O banks. Support is implied for primitives that are derivatives of the primitives listed in Table: Allowed Attributes for the LVDCI I/O Standards  (for example: *_DIFF_OUT, *_DCIEN, *_IBUFDISABLE, or *_INTERMDISABLE). Refer to the SelectIO Interface Primitives section for all supported derivatives.

Table 1-24:      Allowed Attributes for the LVDCI I/O Standards 

Attributes

Primitives

IBUF

OBUF/OBUFT/IOBUF

Allowed Values

Default

IOSTANDARD

LVDCI_15, LVDCI_18

LVDCI_15, LVDCI_18

SLEW

N/A

FAST, MEDIUM, SLOW

SLOW

OUTPUT_IMPEDANCE

N/A

RDRV_48_48