Hot-Socketing Feature; Hot-Socketing Implementation - Altera Cyclone V Device Handbook

10-2

Hot-Socketing Feature

The equation shows that power is design-dependent and is determined by the operating frequency of your
design. Cyclone V devices minimize static and dynamic power using advanced process optimizations. This
technology allows Cyclone V designs to meet specific performance requirements with the lowest possible
power.
Hot-Socketing Feature
Cyclone V devices support hot socketing—also known as hot plug-in or hot swap.
The hot-socketing circuitry monitors the V
banks.
You can power up or power down these power supplies in any sequence.
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 Cyclone V
devices on PCBs that contain a mixture of devices with different voltage requirements.
The hot-socketing capability in Cyclone 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 Cyclone 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 a Cyclone 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, Cyclone 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.
Related Information
Cyclone V Device Datasheet
Provides details about the Cyclone V hot-socketing specifications.

Hot-Socketing Implementation

The hot-socketing feature tri-state the output buffer during power up and power down of the power supplies.
When these power supplies are below the threshold voltage, the hot-socketing circuitry generates an internal
signal.
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