I/O External Termination

If ODT is not used or not available, I/Os require an external termination for better signal integrity. Voltage-referenced standards generally have serial (driver) and parallel (receiver) termination schemes while differential standards only require parallel (receiver) termination.

The following table lists the external termination schemes for the supported I/O standards when the ODT/driver impedance calibration feature is not used.

Table 1. I/O External Termination with ODT Off
I/O Standards External Termination Schemes
SSTL15, SSTL18, SSTL2 single-ended Single-ended SSTL I/O standard termination
HSTL15 Single-ended HSTL I/O standard termination
SSTL15, SSTL18, SSTL2 differential Differential SSTL I/O standard termination
HSTL15 Differential HSTL I/O standard termination
LVCMOS12, LVCMOS15, LVCMOS18, LVCMOS25 No external termination required
LVDS 100 Ω, parallel termination (HSIO only)
MLVDS 100 Ω, parallel termination (HSIO only)
BLVDS 100 Ω, parallel termination (HSIO only)
RLVDS 100 Ω, parallel termination (HSIO only)
Mini-LVDS 100 Ω, parallel termination (HSIO only)
LVPECL 100 Ω, parallel termination (HSIO only)