Other Parts Discussed in Thread: TPS54560
Hi Team,
In our customer's application, the TPS54560BDDA drops out/locks out when the input voltage is greater than 4.5V for an output of 5V. Please see the details of his inquiry below.
We are observing converter dropping out/Locking out Vout at Vin>4.5V. Converter is designed to operate at 6.5Vin and generate Vout = 5V. We are observing occurrences where some units are dropping out/locking out or going unstable at 5-6Vin. We believe devices behaved normally above 4.5Vin initially, but don't have initial dropout/lockout voltage characterized, something we will do moving forward. Does TI have any history of this situation? We can provide further info a necessary.
I told the customer that the TPS54560BDDA cannot operate from an input voltage of 5V-6V and output 5V since the input voltage of a buck converter should always be higher than the output voltage to operate properly. I suggested to use buck-boost converter instead and here is his response.
I agree that the converter will not maintain 5V out with <6Vin, but we see Vout drop to 0V where we would think we would see 4V or so. When we observe the behavior described, so far it has always been fixed by replacing the component. Then we see pretty stable operation down to between 4.2-4.5V. We did not “prescreen” for low voltage when we initially built, so do not know if a part was compromised during assembly and testing, or had this issue initially.
We are now looking at low voltage operation on any new part when replacing, and then time-to-time during test. One other thing is that some devices had the EN line lifted off the PCB trace and were touched with a soldering iron. Could that potentially result in damage to the EN ckt within the chip?
Here is a sample of 7 devices that we lowered Vin until Vout dropped out (went to 0V).
Regards,
Danilo
