LM5145: [LM5145]Why LM5145 would have slow response time when it operates on Diode emulation mode ?

HAN LEE

Part Number: LM5145

Hi everyone,

As datasheet described, I'm confused about why LM5145 would have slow response time when it operates on Diode emulation mode ?

Thanks.

over 7 years ago

0 David Baba over 7 years ago

TI__Mastermind 40120 points

Hello Han,

With Voltage mode control operating in DCM, the bandwidth of the loop drops to a lower frequency because the modulator gain reduces..

please follow the link below of a paper that discusses this in detail.

www.ti.com/.../slva301.pdf

Hope this helps?

David.

0 HAN LEE over 7 years ago in reply to David Baba

Expert 1515 points

hI David ,

Thanks for your reply.

Could you please help to tell me how to improve the response speed at light-load when Diode Emulation Mode ?

Seem only the COMP pin (Pin 4 of LM5145) and RC2 / CC3 can adjust… Right ?

0 David Baba over 7 years ago in reply to HAN LEE

TI__Mastermind 40120 points

Hello Han,

Suggest using the online calculator and increasing the bandwidth (BW) of the loop in CCM to as high a frequency as possible while still being stable. This is typically done by increasing Rc1 and adjusting other compensation components to suite. A higher CCM BW will ensure a higher DCM BW by default.

Hope this helps?

David.

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LM5145: [LM5145]Why LM5145 would have slow response time when it operates on Diode emulation mode ?