HC4GX15 Datasheet, PDF (143/668 Pages) Altera Corporation – HardCopy IV Device Handbook

Chapter 9: Hot Socketing and Power-On Reset in HardCopy IV Devices
9–5
Conclusion
The POR signal pulse width is selectable using the PORSEL input pin. When PORSEL is
set to low, the POR signal pulse width is set within the range of 100 ms to 300 ms. A
POR pulse width of 100 ms to 300 ms allows serial flash devices with a 65 ms to 100 ms
internal POR delay to be powered-up and ready to receive the nSTATUS signal from a
HardCopy IV device. When the PORSEL is set to high, the POR signal pulse width is
set within the range of 4 ms to 12 ms. A POR pulse width of 4 ms to 12 ms allows time
for power supplies to ramp-up to full rail.
Because not all power supplies are monitored by POR, ensure that the power supplies
are fully ramped up before the device starts to communicate with other devices on the
system. Regardless of the voltage level of these power supplies, a HardCopy IV
device continues to enter user-mode. One difference between Stratix IV and
HardCopy IV devices is that Stratix IV devices allow more time for power supplies to
ramp up during the configuration phase, before the device enters user mode.
HardCopy IV devices, however, can enter user mode and release CONF_DONE within
12 ms or 100 ms. Therefore, you should always verify the voltage level of the power
supply system before the HardCopy IV device starts to run.
Conclusion
HardCopy IV devices are hot-socketing compliant and allow successful device
power-up without the need for any power sequencing. The POR circuitry keeps the
devices in the reset state until the power supply voltage levels are within operating
range.
Document Revision History
Table 9–3 shows the revision history for this chapter.
Table 9–3. Document Revision History
Date
December 2008
Version
1.0 Initial release.
Changes Made
© December 2008 Altera Corporation
HardCopy IV Device Handbook, Volume 1