Hi,
I have the following 1.8V power supply using the TPS720 (see schematics below):
- It provides the MGTVCCAUX power domain for an Xilinx FPGA.
- There is nothing on the output power domain except an additional 4.7uF decoupling cap.
- Input voltage R3V3 is 3.3V
- Bias R5 is 5V.
I am observing the following behaviour:
- Under No-Load condition (FPGA is not yet mounted) the output slowly rises to 3.3V instead of staying at the target 1.8V.
- If a <10kOhm resistor is connected as a load to ground, the LDO is able to regulate the output to the target 1.8V.
What is wrong with the way we are using the TPS720 such that it is not working as described in the datasheet under NO-LOAD condition?
Thanks!
Pascal