10–4
Chapter 10: Hot-Socketing and Power-On Reset in the Cyclone III Device Family
Document Revision History
The POR circuit of the Cyclone III device monitors the V
CCINT
, V
CCIO
(banks 1, 6, 7,
and 8), and V
CCA
pins during power-on. The enhanced POR circuit of the Cyclone III
LS device includes monitoring V
CCBAT
to ensure that V
CCBAT
is always at the minimum
requirement voltage level.
1
The V
CCBAT
power supply is the new design security feature power supply introduced
for Cyclone III LS devices only. Cyclone III devices do not have V
CCBAT
power supply.
After Cyclone III device family enters user mode, the POR circuit continues to
monitor the V
CCINT
or V
CCA
pins so that a brown-out condition during user mode is
detected. If the V
CCINT
or V
CCA
voltage sags below the POR trip point during user
mode, the POR circuit resets the device. If the V
CCIO
voltage sags during user mode,
the POR circuit does not reset the device.
In some applications, it is necessary for a device to wake up very quickly to begin
operation. Cyclone III device family offers the Fast-On feature to support fast
wake-up time applications. For Cyclone III device family, the
MSEL[3..0]
pin settings
determine the POR time (t
POR
) of the device. Fast POR ranges from 3 ms to 9 ms, while
standard POR ranges from 50 ms to 200 ms.
If you cannot meet the maximum V
CC
ramp time requirement, use an external
component to hold
nCONFIG
low until the power supplies have reached their
minimum recommend operating levels. Otherwise, the device may not properly
configure and enter user mode.
f
For more information about the
MSEL[3..0]
pin settings, refer to the
chapter.
f
For more information about the V
CCBAT
pin connection, refer to the
Document Revision History
lists the revision history for this document.
Table 10–1. Document Revision History (Part 1 of 2)
Date
July 2012
Version
3.4
Changes
Updated tolerance control circuit voltage level in the
section.
■
Updated “POR Circuitry” on page 10–3.
Updated hyperlinks.
Minor text edits.
December 2011
December 2009
July 2009
3.3
3.2
3.1
■
■
Minor changes to the text.
Made minor correction to the part number.
■
Updated chapter part number.
Updated “I/O Pins Remain Tristated During Power-Up” on page 10–2.
Updated “Hot-Socketing Feature Implementation” on page 10–3.
Updated “POR Circuitry” on page 10–4.
June 2009
3.0
■
■
■
Cyclone III Device Handbook
Volume 1
July 2012 Altera Corporation
ALTERA [ ALTERA CORPORATION ]
