Hello
I have a question about LM2651MTC.About the LM2651 .xlsx
I found the reverse current(min=-10.37A) to SW PIN when powering off LM2651MTC(Vin<4V)
(Please refer to the attached excel file)
It is over the Absolute Maximum Ratings ?
If your answer is <NG> please tell me the countermeasure for this.
I connected diode between Vout and GND,However it is no effect.
Regards
Hi Yuta,
It is normal behavior for Buck converter. When power off, the high-side and low-side MOSFET will turn off, because the inductor current cannot change instantaneously, at the very light load, the negative current must flow through the high-side MOSFET body diode, through the input capacitor and back through the output capacitor to complete its loop. The negative surge current may not damage the device. However, this reverse current creates a power dissipation and corresponding temperature rise. Because of the relatively high forward voltage drop of high-side MOSFET's body diode, the power may be quite high. Ensure that IC's junction temperature rating is not exceeded. The diode in series with the input also mitigates reverse current concerns. Please see application note in the link as below.
Hope this helps,
Thanks,
Nancy
