LM1117 - Phase Compensation

Hirotaka Matsumoto

Other Parts Discussed in Thread: LM1117

Hello,

We'd like to ask about LM1117.

Please teach us method of phase compensation of LM1117.
Then, In order to improve phase compensation, should we use high ESR capacitance for Co(Out capacitance)?

Then, we could not find out followings from the data sheet.
1. ESR - phase compensation
2. Bode Plot of Erro Amplifier Gain and Phase

Kind regards,

Hirotaka Matsumoto

over 11 years ago

0 Shashank Reddi over 11 years ago

TI__Intellectual 1695 points

Hi Hirotaka-San,

As stated in the datasheet, a capacitor with good ESR is needed for output stability.

The plots you asked for aren't on the datasheet. I will have to check if we have them somewhere else, but I doubt it.

Thanks,

Shashank

0 Hirotaka Matsumoto over 11 years ago in reply to Shashank Reddi

Guru 27585 points

Hi Shashank san,

Thank you for your help and your suggestion.
At fisrt, we will confirm that the ESR value of the output capacitanse range between 0.3-22Ω.
Then, if we have some questions, we will not hesitate to ask you again.

Kind regards,

Hirotaka Matsumoto

0 Shashank Reddi over 11 years ago in reply to Hirotaka Matsumoto

TI__Intellectual 1695 points

Hi Hirotaka-San,

No Problem! Hope everything works well!

Best Regards,
Shashank

0 Hirotaka Matsumoto over 11 years ago in reply to Shashank Reddi

Guru 27585 points

Hi Shashank-San,

We asked our customer to confirm the ESR value of the output capacitanse.
The value was so small as like 100mΩ.

In order to increasse(to range between 0.3-22Ω) the ESR value of the output capacitanse,
we asked our customer to insert resistance XΩ.

Kind reagrds,

Hirotaka Matsumoto

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LM1117 - Phase Compensation