I want to use EM2130L01QI to generate 1.0V. The schematic is as shown below. When I test, PVIN is powered by 5.0V,PVCC and VCC by 5V.
1. VOUT slowly increases from 0.17V to 0.333V, and then remains unchanged.
2. After powering on for a while, the voltage of VDD33 pin of EM2130 changes from 3.3V to 0V， but VOUT remains about 0.3V.
Please help me analyze the cause of the failure and give me some suggestions.
Thank you very much for your help.
Based on your schematic, first please help to increase the Cout capacitance and change Rtune to 0Ohm and test again if this fix the issue.
Please check the datasheet page#23 for the min output base capacitance needed to maintain the system stability.
Based on your description for the issue, it seems there is a fault protection triggered during the power on. so please help to provide a waveform during the issue, Please probe the PVIN, VDD33, Vout and VCC signals to confirm what exact fault happened.
If VDD33 drop from 3.3V to 0V that's mean the Vcc signal drop to 4.5V and the controller rest.
Please make sure that the 5V rail that supply the VCC bias voltage is stable and not noisy.
Thank you very much for your comments, but I cannot solve the current problem. After I changed it according to your suggestion, during the entire power-on process, the VCC and PIN voltages were 5.28V, but VDD33 still dropped from 3.3V to 0V. Vout slowly rises from 0V to 0.3V.
Thanks a lot for your feedback.
Could you please share the VDD33, Vout, PVCC and VIN waveforms during the startup?
Please note that when PVCC signal drop lower than 4.5V this will cause the controller to reset.
Also i will send you a personal email, to share any confidential information.