TPS53513: MODE pin resistor value selection

K. Sasaki14

Guru 10200 points

Part Number: TPS53513
Other Parts Discussed in Thread: TPS548A20

TPS53513 has two MODE resistor value depend on R-C Time constant.

Skip mode: 0k ohm and 150k ohm

FCCM mode: 20k ohm and 150k ohm

How can we select these resistor value? Which case should we use lower or higher time constant value?

Best Regards,
Kohei Sasaki

over 6 years ago

0 Mathew Jacob1 over 6 years ago

TI__Expert 5910 points

Hello,
Please refer to Table 3 and 4. The goal is to set the time constant to mimic the internal values given in Table 3.

Regards,
Mathew

0 K. Sasaki14 over 6 years ago in reply to Mathew Jacob1

Guru 10200 points

Mathew-san,

How can we get internal RC setting of Table 3?
I think it is change when external components value are different from Table 3.

Best Regards,
Kohei Sasaki

0 JohnTucker over 6 years ago in reply to K. Sasaki14

TI__Guru**** 191445 points

Sasaki-san,

Table 3 fixes the switching frequency at 600 kHz. For 600 kHz operation there are two RC time constant options, 40 and 80 usec. Use the 40 usec option for lower output capacitance and the higher setting for increased output capacitance. You can use the same approach for the different switching frequencies.

0 K. Sasaki14 over 6 years ago in reply to JohnTucker

Guru 10200 points

John-san,

Thank you for your reply.
Is TPS53513 similar with TPS548A20? Should we also change RC time constant option by Vout setting higher or lower?

Best Regards,
Kohei Sasaki

0 JohnTucker over 6 years ago in reply to K. Sasaki14

TI__Guru**** 191445 points

Sasaki-san,

As you can see in TPS548A20 Table 2 (and TPS53513 Table 3), the RC value is mostly independent of output voltage. Use the longer time constant when more output capacitance is added.

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TPS53513: MODE pin resistor value selection