15.4.3.7.2 Leading-Edge Blanking PCI Configuration

The LEB counter produces an “LEB active” signal that is supplied to the acceptance qualifier and/or termination qualifier selection multiplexers of the PCI blocks. This allows the LEB timer to be used as a gating signal for the selected PCI or PCI terminator signal. The polarity of the acceptance qualifier and termination qualifier signals can be inverted using the PCI control bits, so that the “LEB active” signal is changed to “LEB inactive”. It is recommended that the Latched PCI Acceptance mode be used when using LEB, so that the LEB active signal can only affect entry or exit to/from the PCI active state. Auto-termination can also be used to ‘reset’ the system after the Fault condition has cleared.

Example LEB initialization sequence:

  1. Select the type PCI to use for LEB (y = CL, FF, Fault).
  2. Select the PCI input using the PSS[31:0] (PGxyPCI2[31:0]) bits. This is typically connected to a comparator to sense overcurrent.
  3. Select LEB as the acceptance qualifier using the AQSS[2:0] (PGxyPCI1[10:8]) bits.
  4. Invert the acceptance qualifier using the AQPS (PGxyPCI1[11]) bit.
  5. Configure logic for Latched mode using the ACP[2:0] (PGxyPCI1[26:24]) bits.
  6. Select auto-terminate using the TREM[2:0] (PGxyPCI1[14:12]) bits.