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EP3C5E144C8N Datasheet, PDF (250/348 Pages) Altera Corporation – Ability to disable external JTAG port | |||
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10â4
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 VCCINT, VCCIO (banks 1, 6, 7,
and 8), and VCCA pins during power-on. The enhanced POR circuit of the Cyclone III
LS device includes monitoring VCCBAT to ensure that VCCBAT is always at the minimum
requirement voltage level.
1 The VCCBAT power supply is the new design security feature power supply introduced
for Cyclone III LS devices only. Cyclone III devices do not have VCCBAT power supply.
After Cyclone III device family enters user mode, the POR circuit continues to
monitor the VCCINT or VCCA pins so that a brown-out condition during user mode is
detected. If the VCCINT or VCCA voltage sags below the POR trip point during user
mode, the POR circuit resets the device. If the VCCIO 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 (tPOR) 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 VCC 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 Configuration,
Design Security, and Remote System Upgrades in the Cyclone III Device Family chapter.
f For more information about the VCCBAT pin connection, refer to the Cyclone III Device
Family Pin Connection Guidelines.
Document Revision History
Table 10â1 lists the revision history for this document.
Table 10â1. Document Revision History (Part 1 of 2)
Date
December 2011
December 2009
July 2009
June 2009
October 2008
Version
Changes
â Updated âPOR Circuitryâ on page 10â3.
3.3 â Updated hyperlinks.
â Minor text edits.
3.2 Minor changes to the text.
3.1 Made minor correction to the part number.
â Updated chapter part number.
â Updated âI/O Pins Remain Tristated During Power-Upâ on page 10â2.
3.0
â Updated âHot-Socketing Feature Implementationâ on page 10â3.
â Updated âPOR Circuitryâ on page 10â4.
â Updated chapter to new template.
1.2
â Added handnote to the âCyclone III Hot-Socketing Specificationsâ section.
Cyclone III Device Handbook
Volume 1
December 2011 Altera Corporation
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