On-Die Termination (ODT)

ODT is used to terminate input signals, helping to maintain signal quality, saving board space, and reducing external component costs. ODT is available in receive mode and also in bidirectional mode when the I/O acts as an input. If ODT is not used or not available, the I/O standards may require an external termination for better signal integrity. For more information, see I/O External Termination.

ODT can be a pull-up, pull-down, differential, or Thévenin termination with both static and dynamic control available, and is set by using the I/O attribute editor in Libero SoC or by using a PDC command.

The following table lists ODT support in GPIO and HSIO.

Table 1. ODT Support in GPIO and HSIO
I/O Standards I/O Types 
(Input Only) ODT Control ODT Type ODT (Ω)
LVDS33, LVDS25

RSDS33, RSDS25,

MINILVDS33, MINILVDS25,

SUBLVDS33, SUBLVDS25,

LVPECL33,

GPIO, HSIO OFF

ON

Dynamic

OFF

Differential

100
SSTL18I, SSTL18II GPIO, HSIO OFF

ON

Dynamic

OFF

Thévenin

50, 75, 150
SSTL15I, SST15II GPIO, HSIO OFF

ON

Dynamic

OFF

Thévenin

20, 30, 40, 60, 120
SSTL135I, SSTL135II HSIO OFF

ON

Dynamic

OFF

Thévenin

20, 30, 40, 60, 120
POD12I, POD12II HSIO OFF ON Dynamic OFF Up 34, 40, 48, 60, 120, 240
HSUL12I, HSUL12II HSIO OFF ON Dynamic OFF

Up

120, 240
HSTL15I, HSTL15II GPIO OFF

ON

Dynamic

OFF

Differential

50
HSUL18I, HSUL18II GPIO, HSIO OFF

ON

Dynamic

OFF

Differential

50
LVCMOS25 GPIO, HSIO OFF

ON

OFF

Down

120, 240
LVCMOS18, LVCMOS15, LVCMOS12 GPIO, HSIO OFF

ON

OfFF

Up

Down

Thévenin

60, 120, 240
Note: GPIO banks can support 2.5 V and 3.3 V inputs with VDDI = 1.8 V or less.

Select ON in the ODT control to statically set to the ODT_VALUE. Select DYNAMIC to enable the ODT_VALUE when the ODT_EN pin is applied. The static ODT setting and values can be programmed by using the I/O attribute editor in Libero SoC or by using the following PDC command.

set_io –ODT <value> –ODT_VALUE <odt_value>

Value can be set as ON or OFF and ODT_VALUE can be set as listed in Table 1.