LM1085: LDO Stability with high capacitve loading

Eli Hait54

Part Number: LM1085

In the "7.4.2 Stability Consideration" chapter of LM1085ISX-ADJ datasheet is written:

"Output capacitance can be increased indefinitely to improve transient response and stability"

Does it really means that it can be loaded with huge capacitors, 20 milli-Farads and even more without losing stability? Can it charge SuperCap?

Thanx,

Eli.

over 8 years ago

0 David Hopkins over 8 years ago

TI__Expert 8905 points

Hi Eli,

It won't handle supercaps - just electrolytics. Just ESR in the range of 500 ohm to 20 ohm for a general range. As this is an older device (1999, possibly older) I don't quite know exactly the ESR range

-David

0 Eli Hait54 over 8 years ago in reply to David Hopkins

Prodigy 240 points

Thanx, David.

Can you recommend for similar LDO Vin>12V that can feed super capacitor to 4.2V?

If the short current is issue i can pre-charge the capacitor to 4.2V via resistor and only then connect the LDO to it...

0 David Hopkins over 8 years ago in reply to Eli Hait54

TI__Expert 8905 points

Hi Eli,

None that I can think of - and you to supply much more information then just supercap - what exact capacitor are you looking at?

Reference design for super cap charging:

http://www.ti.com/tool/pmp7327

-David

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LM1085: LDO Stability with high capacitve loading