data/text/DLP3/898512

LM5069: Reverse current during motor Regen

Part Number: LM5069 Hi, I am going to use this device as the application note suggested, but the information is not clear about the reverse current. During the reverse current the source voltage go higher than the gate (or enough to turn off the MOSFET). So the reverse current will flow through the MOSFET body diode for a shorter period, until the drain voltage (Vin) equal (one diode drop less) to the source to turn on the MOSFET again. Does it going to cause any issues. Hot swap circuit in my application is situated between the motor and the load dump, the current flows in reverse direction when the motor in Regen mode. Thank you Siva

Hi Siva, If the LM5069 stays in enabled state, the external MOSFET remains in fully enhanced state and allows reverse current to flow from Source to the Drain. You have to make sure that the input is capable to absorb the energy (i.e., enough capacitance or supply having sinking capability). Let me know if it is not clear. Best Regards, Rakesh

Hi Rakesh, Thanks for the info. Yes we dump this energy using the load dump. How the MOSFET remains in conduction even the source voltage goes above the gate voltage. Do you mean as I have mentioned the body diode makes the Vin to go high, so keep the Vgs in biasing region. Regards Siva

Hi Siva, Under this condition, the drain voltage follows the source voltage (through body diode or though the MOSFET channel if the MOSFET is already in ON condition). The controller biases the GATE potential at Vin+12V always unless the controller sees OV, UV fault. You can use simulation tools to verify <secret URL>/product/LM5069/toolssoftware Best Regards, Rakesh

Hi Rakesh, Thanks for the info. Does these TINA models work in LTSpice. Regards Siva

Hi Siva, You can use unencrypted PSpice model in LTSpice. I have sent you private message. Please reach me for the same. Best Regards, Rakesh