Article ID: 000080542 Content Type: Troubleshooting Last Reviewed: 09/11/2012

Why does my ACEX or FLEX device either take 11 clock cycles to initialize or not initialize at all?

Environment

BUILT IN - ARTICLE INTRO SECOND COMPONENT
Description When configuration is complete on an ACEX® or FLEX® device, the device releases the CONF_DONE pin. From there, a pull-up resistor takes the DCLK signal to the logic-high level.

If the pull-up resistor is far away from the device, the rise time of the CONF_DONE pin may be too slow and the DCLK signal will be unable to latch the high state of the CONF_DONE pin.

This will cause the device to require more than 20 DCLK cycles to complete initialization.

There are two possible solutions to this problem:

  1. Use the smallest possible resistor as a pull-up for the CONF_DONE pin (around 500 ).
  2. Move the pull-up resistor closer to the device to decrease the rise time of the CONF_DONE pin.

Related Products

This article applies to 2 products

Acex® 1K
Flex® 10K

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