EPM240_10 Datasheet, PDF (51/88 Pages) Altera Corporation – MAX II Device Family Data

4. Hot Socketing and Power-On Reset in
MAX II Devices
MII51004-2.1
Introduction
MAX^® II devices offer hot socketing, also known as hot plug-in or hot swap, and
power sequencing support. Designers can insert or remove a MAX II board in a
system during operation without undesirable effects to the system bus. The hot
socketing feature removes some of the difficulties designers face when using
components on printed circuit boards (PCBs) that contain a mixture of 3.3-, 2.5-, 1.8-,
and 1.5-V devices.
The MAX II device hot socketing feature provides:
■ Board or device insertion and removal
■ Support for any power-up sequence
■ Non-intrusive I/O buffers to system buses during hot insertion
This chapter contains the following sections:
■ “MAX II Hot-Socketing Specifications” on page 4–1
■ “Power-On Reset Circuitry” on page 4–5
MAX II Hot-Socketing Specifications
MAX II devices offer all three of the features required for the hot-socketing capability
listed above without any external components or special design requirements. The
following are hot-socketing specifications:
■ The device can be driven before and during power-up or power-down 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.
■ Signal pins do not drive the V_CCIO or V_CCINT power supplies. External input signals
to device I/O pins do not power the device V_CCIO or V_CCINT power supplies via
internal paths. This is true if the V_CCINT and the V_CCIO supplies are held at GND.
1
Altera uses GND as reference for the hot-socketing and I/O buffers circuitry designs.
You must connect the GND between boards before connecting the V_CCINT and the V_CCIO
power supplies to ensure device reliability and compliance to the hot-socketing
specifications.
Devices Can Be Driven before Power-Up
Signals can be driven into the MAX II device I/O pins and GCLK[3..0] pins before
or during power-up or power-down without damaging the device. MAX II devices
support any power-up or power-down sequence (V_CCIO1, V_CCIO2, V_CCIO3, V_CCIO4, V_CCINT),
simplifying the system-level design.
© October 2008 Altera Corporation
MAX II Device Handbook