SNLS484J February 2015 – June 2026 DP83867CR , DP83867IR
PRODUCTION DATA
The DP83867 includes advanced link-drop capabilities that support various real-time applications. The link drop mechanism is configurable and includes enhanced modes that allow extremely fast reaction times to link drops.
Figure 7-12 Fast Link Drop MechanismAs described in Figure 7-12, the link loss mechanism is based on a time window search period in which the signal behavior is monitored. The T1 window is set by default to reduce typical link drops to less than 1ms in 100 = M and 0.5ms in 1000M mode.
The DP83867 supports enhanced modes that shorten the window called Fast Link Drop mode. In this mode, the T1 window is shortened significantly, in most cases less than 10μs. In this period of time, there are several criteria allowed to generate link loss event and drop the link:
The Fast Link Drop functionality allows the use of each of these options separately or in any combination. Note that because this mode enables extremely quick reaction time, the PHY is more exposed to temporary bad link quality scenarios.
When Fast Link Drop functionality is enabled on both the DUT and LP (link partner) and Link Drop is detected, the opportunity is essential to disable FLD using bit 14 of the FLD_CFG register (address 0x002D) for the link to re-establish. Once the link is up, enable FLD again using the same bit (FLD_CFG bit[14]).
As mentioned above there are five modes the PHY's FLD source can be configured to evaluate. These modes can be configured via FLD_CFG register (address 0x002D) bits[4:0]. In addition to register configuration, the 64-pin PAP package variant can also enable Fast Link Drop in Energy Loss mode via pin strapping. The pin strap sets register FLD_CFG (address 0x002D) bit[0] to high. When pin strapping is used register FLD_THR_CFG (address 0x002E) is set to 0x0222, this register must be re-configured to 0x0221.