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Altera_Forum's avatar
Altera_Forum
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16 years ago

Cyclone3 Power Up level doesn't work

A design with an EP3C40F324I7 has the pin U18 as an registered output. This pin is used to control another dcdc's nSHDN (Shutdown negativ logic) The fpga is configured via epcs. this dcdc is ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

The PCB is already produced :-(

The designs works fine execpt for the power up when this dcdc is started during configuration. currently all i can do is change something on quartus side or change the values of the divider and the cap.

there is a 100k from that pin to the 560k in parallel to the 47n and the nSHDN is connected between 100k and 560k.

so your 2k pull down could be done if i change the softstart due to the RC to a non softstart with just the 2k pull down and a 0 ohm instead of the 100k