TPS23756: hy we need the external the slope compensation and when we need to add the external slope compensation.

Frank Xiao

Genius 12055 points

Part Number: TPS23756

Hi team,

My customer is using the TPS23756 now. They want to check why we need the external the slope compensation and when we need to add the external slope compensation. From the datasheet, we can get some ideas, could you please explain more about it? Thanks.

over 7 years ago

0 Darwin Fernandez over 7 years ago

TI__Mastermind 41760 points

Hi Frank,

Slope comp is needed in current mode controllers to prevent instability near and over 50% duty cycle. So slope comp is needed to have the same average current for different peak currents in different operating conditions. Most of our PoE desings will need this. I find the app note below is useful in understanding this concept.
www.ti.com/.../snva555.pdf

Regards,
Darwin

0 Frank Xiao over 7 years ago in reply to Darwin Fernandez

TI__Genius 12055 points

Hi Darwin,

Thank you for your help. We want to check when we need the external slope compensation for the device. Could you please help with it? Thanks.

0 Darwin Fernandez over 7 years ago in reply to Frank Xiao

TI__Mastermind 41760 points

Hi Frank,

Since the TPS23756 has a wide input PWM controller. The duty cycle can be larger than 50%. Therefore slope comp resistor will always be needed here. All our reference designs and EVMs that use the TPS23756 use the slope comp resistor. Thanks!

Power management

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TPS23756: hy we need the external the slope compensation and when we need to add the external slope compensation.