About concern to LM2840's light load operation

Pokkun

Genius 4695 points

Other Parts Discussed in Thread: LM2842, LM2840

Hello.

My customers are considering the use of the LM2842.

There is no description of Light Load Operation (Discontinuous Mode) to LM2842's datasheet.

So, I think that is a problem for use in always Discontinuous Mode's Operation.

Is it possible to use the LM2840 in such cases?

＜Customer's Power Supply Specifications＞

VIN：30V

VOUT：3.3V

IOUT_MAX：420mA

But it becomes Degree less than 5mA, when the microcomputer of latter stage is in the RESET state.

(The intent of the question is concerned about the time of this state.)

Could you tell me in this things?

Best Regards, Masumi Sekiguchi

over 9 years ago

0 Akshay Mehta over 9 years ago

TI__Genius 15810 points

Hello,
The LM2842 is a non synchronous device and at light loads it works simply in discontinuous conduction mode. There is no pulse skipping mode integrated.

Regards,
Akshay

0 Pokkun over 9 years ago in reply to Akshay Mehta

Genius 4695 points

Thank you very much to Akshay-san.

Please let check…

Is there a risk in using discontinuous mode?
(For example：Decrease in efficiency, Noise increase, Unstable output (shaking of more than ripple))

Regards,
Pokkun（Masumi Sekiguchi）

0 Akshay Mehta over 9 years ago in reply to Pokkun

TI__Genius 15810 points

There is no risk in using DCM. There will be a decrease in efficiency because of lack of pulse skipping. But the output shouldn't be unstable.

0 Pokkun over 9 years ago in reply to Akshay Mehta

Genius 4695 points

Thank you for the answer.

Are there any precautions such as not to cause a decrease in efficiency and unstable output ?
Could you tell me advice if present?

Best regards,
Pokkun（Masumi Sekiguchi）

0 Akshay Mehta over 9 years ago in reply to Pokkun

TI__Genius 15810 points

Unfortunately there is no way to improve DCM efficiency with the LM2840. This device doesn't employ the pulse skipping mode. The output will not be unstable in this mode of operation.

Regards,
Akshay

Power management

Power management forum

About concern to LM2840's light load operation