LM5165: LM5165 schematic check

Lin_Charles

Part Number: LM5165

Hi team,

My customer wants to evaluate this device in the below application, Vin=15-51V, Vo=5V, Io=60mA; I use Webench to get below schematic, while my customer thinks the inductance value is too large for them, could you please help review below schematic and help me understand below two questions,

1. What will be worse if I use 47uH inductance here?

2. I saw in our datasheet figure 37, this device needs some ESR resistor in serial with the output capacitor. But not in the simulation, will it matter in this application?

Thanks.

over 4 years ago

0 Neal Zhang over 4 years ago

TI__Expert 4720 points

Hi,

1. If you use small inductance, the efficiency will be low. The inductor peak current is 120mA in your schematic. with small inductance, it will take less time for the inductor current to rise to 120mA from 0A. The switching frequency will be higher and efficiency will be lower.

2. No it doesn't matter. Figure 37 is for COT control mode. But now you choose PFM control mode. it doesn't need ESR.

0 Lin_Charles over 4 years ago in reply to Neal Zhang

TI__Expert 4260 points

Hi Neal,

Thank you for your response here. Do we have some test dat related to efficiency and switching frequency that can be shared with customer?

Customer want to use this device in TA=70C, I am afraid of the thermal performance and EMC test. Thanks.

0 Neal Zhang over 4 years ago in reply to Lin_Charles

TI__Expert 4720 points

Hi Charles,

Sorry we don't have that data. Please let customer to have a try.

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LM5165: LM5165 schematic check