4. Hot Socketing & Power-On
Reset
CII51004-3.1
Cyclone® II devices offer hot socketing (also known as hot plug-in, hot
insertion, or hot swap) and power sequencing support without the use of
any external devices. You can insert or remove a Cyclone II board in a
system during system operation without causing undesirable effects to
the board or to the running system bus.
Introduction
The hot-socketing feature lessens the board design difficulty when using
Cyclone II devices on printed circuit boards (PCBs) that also contain a
mixture of 3.3-, 2.5-, 1.8-, and 1.5-V devices. With the Cyclone II
hot-socketing feature, you no longer need to ensure a proper power-up
sequence for each device on the board.
The Cyclone II hot-socketing feature provides:
■
Board or device insertion and removal without external components
or board manipulation
■
■
Support for any power-up sequence
Non-intrusive I/O buffers to system buses during hot insertion
This chapter also discusses the power-on reset (POR) circuitry in
Cyclone II devices. The POR circuitry keeps the devices in the reset state
until the VCC is within operating range.
Cyclone II devices offer hot-socketing capability with all three features
listed above without any external components or special design
requirements. The hot-socketing feature in Cyclone II devices offers the
following:
Cyclone II
Hot-Socketing
Specifications
■
■
The device can be driven before power-up without any damage to
the device itself.
I/O pins remain tri-stated during power-up. The device does not
drive out before or during power-up, thereby affecting other buses
in operation.
Altera Corporation
February 2007
4–1
ALTERA [ ALTERA CORPORATION ]
