Hi Team,
My customer design LM5010A for 13.5V to 11.2V in his system, the function work well in his board. Recently, he has to do a test that drop Vin from 13.5V to 11.5V to see Vout's performance. If the Vin drop slew rate is fast then LM5010A will shut down suddenly then restart to switching again.
CH1:Vin , CH2:Vout , CH3:FB , CH:SW
You can find once Vin dropped to 11.5V, PWM switching stop then Vout, Vfb drop as well. About 8mS later, socket start switching to establish Vout. Due to the Vin voltage is very close to target Vout voltage that cause to a bit drop on Vout voltage, but the Vout is still stable.
(During switching off period, SW pin in not at low level but follow Vout's dropping curve, it seems like LM5010A is disabled)
CH1:Vin , CH2:Vout
Turn the power supply's voltage knob to let Vin drops slowly, LM5010A work as normal except a bit drop on Vout.
Here is customer's SCH. Does team any have idea for this issue? Or, any experiment is need to clarify this problem?
Backup :
Change Vin voltage from 16V to 14V quickly, Vout maintains stable w/o any abnormal.
Thanks a lot.
Vincent Chen
