LP5912: max allowed output capacitor

Olrik Maier

Expert 4760 points

Part Number: LP5912
Other Parts Discussed in Thread: TPS7A11, TPS735, TPS7A90

Hi LDO Team,

my customer is using the LP5912-33DRVx in his design.

Inputvoltage 3.6-3.7V,

Outputvoltage 3.3V, normally no load jumps. Constant load of the mainparts supplied.

In the DS is written that Cout max is 10uF. In their design they need 7.5uF as input for the MCU, plus some buffer capacitance for some additional electronics.

In addition they have fome furter HF filters (serial BLM) that in summary the LDO sees approx 20uF of capacitive load.

Does the LP5912 work stable with that load ?

Do we have some reccomendation on alternative LDO types which are able to drive 20uF ?

I have looked in TPS7A11 and TPS735 but haven't found a max specification for Cout.

Many Thanks

Best wishes,

Olrik

over 5 years ago

0 Ryan Eslinger over 5 years ago

TI__Guru 55940 points

Hi Olrik,

Due to design topology, LP5912 has a maximum capacitance of 10 uF.

LDOs with different design topologies such as TPS7A11 have different requirements for the output capacitor and therefore do not have the same restrictions. In fact you will note that TPS7A11 we did use a 22 uF output capacitor for some of the TPS7A11 characterization.

Very Respectfully,

Ryan

0 Olrik Maier over 5 years ago in reply to Ryan Eslinger

TI__Expert 4760 points

Hi Rayn,

thanks for feedback.

TPS7A11 isn't supporting the 3.6V input voltage.

From the DS it seem TPS7A90 might support the 20uF.

Can you pls crosscheck ?

Do we have some lower cost solution (like LP5912) which supports the 20uF ?

TPS735 Vdrop is too high.

Best wishes,

Olrik

0 Ryan Eslinger over 5 years ago in reply to Olrik Maier

TI__Guru 55940 points

Hi Olrik,

Yes TPS7A90 will support a 20 uF output capacitor.

Very Respectfully,
Ryan

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LP5912: max allowed output capacitor