18.3.3 Output Buffers

A500K output buffers have the following features:

  • Optional PCI compliance with PCI 2.1 Component Specification (3.3 Voltage pad only)
  • Selectable drive strengths
  • Selectable slew rates
  • Optional three-state functionality
  • ESD protection circuitry
  • Latch-up protection circuitry

Output Buffer Naming Conventions

The names for the output buffers are composed of up to five parts:

  • The name base indicating the type of output buffer (OB for output buffer, OTB for three-state output buffer)
  • An optional one character code (L) designating an active low enable input for the OTB output buffer. The code is omitted for the active high enable input
  • The number code 25 or 33 indicating a 2.5 or 3.3 voltage level
  • A code indicating the drive strength (2.5 Volt pad: L for 1 mA, H for 3.5 mA; 3.3 Volt pad: L for 5 mA and P for PCI compliant 10 mA).
  • A one character code indicating the slew rate (L for low 25 mA/ns, N for nominal 50 mA/ns, and H for high 100 mA/ns).
OB25HN
2.5 Volt output buffer, high drive strengths and nominal slew rate.
OTB33LH
Three-state output buffer, low drive strengths, high slew rate.
OB33PL
PCI compliant output buffer (= high drive strengths) and low slew rate.