On my FPGA Board I'm using three of the PTH04070WAZ and three of the PTH05050WAZ. I adjusted the output voltage with the required resistors as defined in the data sheet. With the PTH05050WAZ-Module it worked perfect but with the PTH04070WAZ I cant get the desired output value with the resistors from the datasheet: with 2k3 Ohms -> 1.8V (instead of 2.5V) for 2.5V output I have to lower the Resistor down to 470 Ohms. Any suggestion what is wrong (since the marking of the device is on the bottom side I cant crosscheck this after the modules have been soldered onto the PCB).
The PTH04070 when there is no connection to t e Vadjustment pin, the Vout should be 0.9V . When the 2.5V, 2k3 resistor is in circuit, what is the voltage ured on the Rset resistor pin 4 as referenced to ground. Can you open the Rset resistor and measure Vout.
I steh 2.5V regulator PTH04070W the only voltage which is in correct.
The PTH04070W is not prebias capable. It is possible there is a feedback occurring across t he FPGA to the circuitry.
Can you send me the complete schematic for thsi system. I am interested in the inhibit control function. .
Can you send me your schematic after evaluating teh requested responses.
My e-mail is firstname.lastname@example.org
When I'm opening the Rset I get 0.7V and this is the case on all of the three PTH04070W on the Board. As well as I get 1.9V instead of 2.5V on the other two Converters.
I do not think that the prebais is a problem, since I've more or less copied the schematic from an Avnet Eval. Board for the Xilinx Virtex5 LX50. I send you the schematics by email.
Thanks for your help.
Thank you very much for your help. The inhibit pullup was really to weak, with the 1k Resistor it works fine now. Wish you not too much snow..
Thank you for the response .
COMPLETE JANUARY 2010
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