MP8768 AAM terminal processing

DC-DC Power Converters
1

If the AAM pin of the MP8768 is floated as shown in the circuit diagram in the datasheet, witch operate in CCM or DCM?

2

Hi Tatsuro,

The AAM pin does not directly affect whether or not it is in CCM or DCM mode. What load current are you working with?

If left floating, the converter will transition between non-synchronous and synchronous mode depending on the load condition. It is worth noting, that there is a critical range in which the converter will operate between synch and non-synch mode. Therefore, depending on your operating conditions we would recommend tying it to a GND or a voltage divider.

If working with light loads, tie AAM to GND for higher efficiency. If working with higher loads, tie AAM to a voltage divider. The MP8768 will enter DCM at light loads (e.g < 0.8A) and CCM at higher loads.

3

Hi Stephen
Now that’s cleared up thanks to you.

Just want to confirm one thing: If AAM is connected to GND,the data sheet states the following:
“Tie to ground forces the MP8768 in synchronous Mode”
When synchronous mode = CCM mode, I thought the terminal processing was reversed, but am I misunderstanding this?

4

Can you clarify, what do you mean when you say the terminal processing is reversed?

5

Hi Stepahen
Thank you for reply.

From your answer,If the AAM is floating and changes between DCM and CCM depending on the load, the relationship between the terminal treatment and the operating mode is as follows based on the contents of the data sheet.
To GND: CCM
Froating: DCM⇔CCM
To Voltage divider: DCM⇔CCM

But your answer is:
"If working with light loads, tie AAM to GND for higher efficiency. If working with higher loads, tie AAM to a voltage divider. "

I think that what is written in the data sheet and what you are answer about for the terminal treatment are opposite, so which is correct?

6

Hi Tatsuro,

Apologies, for the confusion. Disregard my comment as it is reversed when compared to the datasheet, that is my mistake. The datasheet content is correct.

7

Hi Stephan
Thanks for checking. Your answer made it clear.

Best Regard
kishimoto