I am currently working on an SDR board with a LTC2208 16 bit 125 MHz ADC
and a 14 bit 125 MHz DAC and everything is working well except for the
USB interface. I am using the Cypress FX2LP CY7C68013A-56PVXC chip. It
is driving the SLOE/PA2 pin at all times (even in reset). It is supposed
to default to input according to Cypress, so that means something is
either wrong with my board or the chips. 3 chips act the same. On one, I
connected nothing but power and ground and the same symptoms exist.
Oddly enough, it drives SLOE high when not in reset and drives it low
when in reset. The USB interface and 8051 parts work fine. Any ideas? I
have been trying to get this working for nearly a month and may have to
do a board revision to get rid of the FX2. I would appreciate any ideas.
If anyone has one of the original CY7C68013-56 parts, I may be
interested in buying it to test on my board.
I put the schematic on the web if anyone wants to take a look:
I have since changed the RC reset circuit to the values recommended by
Cypress and added a few jumpers.
The power supply ramp up rate is within the spec given by Cypress.