LM7481-Q1: Higher Power and Common Source Configuration

Hi Yoonseo Kang,

Can you please share the following details,

• Vin (max):
• Iload(max):
• Lad current during startup : 

Hi Praveen,

Certainly, my answer below.

Vin (max): 58VDC (48VDC nominal)

Iload (max): 20A (continuous)

Load current during start-up: 30A (soft startable down to 20A-25A)

Hi Yoonseo Kang,

Thanks for sharing the details. While I check on the possibility of using LM74810-Q1 for 1000W solution, can you share the total capacitance on the output rail ?

This will help us understand the the current flowing through the FET during startup. 

At what voltage will your load start drawing current during startup ?

Hi Praveen,

Direct output rail capacitance is ~100uF because of isolation from our 1000uF+ capacitor banks. If the banks were directly connected, would 10K uF to 100K uF with appropriate ESR be incompatible with the IC?

Current-drawing start-up voltage is 14V low-use, 36V MIN high-use.

Hi Yoonseo Kang,

Just to summarize your requirement,

• Vin (max): 58VDC (48VDC nominal)
• Iload(max): 20A (continuous)
• Lad current during startup : soft startable and load current is drawn after Vout reaches 14V
• Cout = 100uF (startup into 10mF or 100mF would be challenging)
• Application: common source configuration for unsuppressed load dump protection. Use multiple LM74810 for redundant power inputs with reverse voltage protection

Please let me know if this is correct. 

There shouldn't be any issue in using LM74810 for the above requirement. LM74810 has stronger Gate and is generally used for applications where AC super imposed test needs to be passed. LM74800 can work here as well.