Hello,
We are using LM2577SX-ADJ/NOPB (U19) converter to boost the voltage from 23.7 V to 27.3 V. Attached schematic circuit is working and tested circuit and we have been using this circuit for long time and we get expected boost voltage i.e. 27.3 V.
The board has this exact connected circuit but at an instant of 27.3 V we get a boost voltage of 23.9 V.
We are facing an issue with one board. The board has this exact attached circuit but at an instant of 27.3 V we get 23.9 V boost voltage. We compared the voltages on the working board (boost output voltage = 27.3 V) and the issue board (boost output voltage = 23.9 V). We get the following observations.
| Issue Board | Working Board | |
| TP198 | 23.7 V | 23.7 V |
| TP194 | 36.2 V | 36.2 V |
| TP199 | 23.9 V | 27.3 V |
| TP200 | 23.9 V | 27.3 V |
| TP196 | 6.6 V | 0.54 V |
| TP201 | 6.7 V | 0.53 V |
| TP203 | 1 V | 1.23 V |
| TP202 | 2.3 V | 2.71 V |
On the above observation, we understood there is an issue with the feedback pin (TP203) and comp pin (TP196) of LM2533 on the issue board.
Can you please look into this issue and let us know your comments on what could be the cause of this issue?
Thanks,
Sonali
