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Altera_Forum
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17 years ago

Alternative to weak pull-up for I/O during configuration?

Hello, I've got the following problem: I use a Cyclone II FPGA in a complex design. Some User I/Os are connected to npn transistors. The problem is, that during configuration thru an epc...
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Altera_Forum
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17 years ago

In unconfigured state, the device didn't yet receive any configuration data. How should Quartus be able to change the device behaviour then? the weak pull-up mechanism is hardwired in fpga silicon only.

An external pull-down resistor is a simple and reliable method to achieve the required behaviour. The weak pull-up resistor range is given in device manual (10 k minimum for most devices), it's easy to calculate a suitable pull-down resistor dimensioning.