11.4. Hot-Socketing Feature
Arria® V devices support hot socketing—also known as hot plug-in or hot swap.
The hot-socketing circuitry monitors the following power supplies and banks:
- Arria V GX, GT, SX, and ST devices—VCCIO , VCCPD , VCC , and VCCP power supplies and all VCCIO and VCCPD banks.
- Arria V GZ devices—VCCIO , VCCPD , and VCC power supplies and all VCCIO and VCCPD banks.
When powering up or powering down these power supplies, refer to the Power-Up Sequence section of this handbook.
During the hot-socketing operation, the I/O pin capacitance is less than 15 pF and the clock pin capacitance is less than 20 pF.
The hot-socketing capability removes some of the difficulty that designers face when using the Arria® V devices on PCBs that contain a mixture of devices with different voltage requirements.
The hot-socketing capability in Arria® V devices provides the following advantages:
- You can drive signals into the I/O, dedicated input, and dedicated clock pins before or during power up or power down without damaging the device. External input signals to the I/O pins of the unpowered device will not power the power supplies through internal paths within the device.
- The output buffers are tri-stated during system power up or power down. Because the Arria® V device does not drive signals out before or during power up, the device does not affect the other operating buses.
- You can insert or remove an Arria V device from a powered-up system board without damaging or interfering with the system board's operation. This capability allows you to avoid sinking current through the device signal pins to the device power supply, which can create a direct connection to GND that causes power supply failures.
- During hot socketing, Arria® V devices are immune to latch up that can occur when a device is hot-socketed into an active system.
Altera uses GND as a reference for hot-socketing and I/O buffer circuitry designs. To ensure proper operation, connect GND between boards before connecting the power supplies. This prevents GND on your board from being pulled up inadvertently by a path to power through other components on your board. A pulled up GND could otherwise cause an out-of-specification I/O voltage or over current condition in the Altera® device.
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