LM5009A load transient

Shinichi Inoue

Other Parts Discussed in Thread: LM5009

Dear specialists,

My customer is measuring the LM5009 that is using for the LED driver.

When he was setting RT=1.4Mohm, output response time became very long.
It is good response when RT is 1M ohm.
Please see the attached files.

The difference is only Rt's value.

Basically RT is for determine switching frequency.

Could you please explain the reason why the phenomenon caused ?

Best regards,

0 Vijay86929 over 11 years ago

Hi Shinichi1,

I don't see any output capacitor. Is this the whole circuit?

regards,

Vijay

0 Shinichi Inoue over 11 years ago in reply to Vijay86929

Guru 21696 points

Dear Vijay

Thank you for your reply.

Output cap is C31(22uF).

The output is constant voltage.

Best regards,

0 Vijay86929 over 11 years ago in reply to Shinichi Inoue

What is the time scale on the waveforms? Is it showing the output current? Is there a waveform for SW node, Inductor current, and output voltage?

Thanks and regards,

Vijay

0 Shinichi Inoue over 11 years ago in reply to Vijay86929

Guru 21696 points

Dear Vijay

Thank you for your reply.

The timescale of all waveforms is 500ms/div.

The waveforms(output current, SW node, inductance current and output voltage) are required to the customer.

Could you please wait for a while?

Best regards,

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