TPS54360B: Calculation method of boot strap resistor

FRANK1

Part Number: TPS54360B

Hi sir,

I place 0.1 μf cap at the BOOT pin of TPS454360BDAR. 150kohm resistor is connected to the RTCLK pin and the switching frequency is set to about 700kHz.
In order to cope with EMC, the capacitor of BOOT pin is connected with resistor (boot strap resistor) in series.
Can you tell me how to calculate this boot strap resistor?
The output voltage is 5V.
Thanks.
Regards,

over 3 years ago

0 Sirui Zhu over 3 years ago

TI__Intellectual 2090 points

Hi Frank,

A 0.1uF Cboot is recommended, and the resistor in series is to control the slew rate of the high side switch.

Usually we will try resistance from 5-50ohm. Resistance too small will have limited effect, too big will trigger Vboot UVLO.

Regards

Sirui

0 Kiyotaka Kato over 3 years ago in reply to Sirui Zhu

Prodigy 10 points

Is there any particular formula for selecting 5 to 50Ω?
Is it a selection method such as selecting a value during this period and testing it? Thank you for your reply.

0 Sirui Zhu over 3 years ago in reply to Kiyotaka Kato

TI__Intellectual 2090 points

There is no particular formula for this resistance,

You can start from 5ohm and try increasing the value, until it matches your EMI criteria.

Sirui

+1 Sirui Zhu over 3 years ago

TI__Intellectual 2090 points

Hi Frank,

Since not hear from you for a while, I'll close this thread. Please raise another thread if you have further question.

Regards

Sirui

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TPS54360B: Calculation method of boot strap resistor