This document introduces the hot socketing and power-on reset features of Altera Cyclone III devices.
Cyclone III family devices support hot socketing (hot plug-in or hot swap) without external components. This feature allows users to insert or remove the device or board during system operation without affecting the running bus or causing undesirable effects, simplifying designs with mixed voltage levels.
The document also covers the Power-On Reset (POR) circuitry which keeps devices in a reset state until power supplies stabilize. It includes specifications for I/O pin behavior during power transitions, latch-up immunity, and implementation details such as ground connection recommendations.
| Maximum power ramp rate (fast POR) | 3 ms |
|---|---|
| Minimum power ramp rate | 50 us |
| I/O pin capacitance during hot socketing | < 15 pF |
Yes, you can drive signals into I/O pins, dedicated input pins, and dedicated clock pins of Cyclone III family devices before or during power up without damaging the device.
The POR circuitry keeps the devices in a reset state until the power supplies are in operating range and ensures Veco levels reach acceptable levels before configuration.