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LDK320M-R Linear Voltage Regulator: Adjustable pin configuration unclear on datasheet

Mariku
Associate

Hello,

 

I am using the LDK320M-R, Linear Voltage Regulator IC with Positive Adjustable Output, in one of my current projects. The data sheet states that the ADJ pin voltage range is from - 0.3 to 2V, but does not show how this voltage range configures the regulated output voltage. 

 

I have search on the LDK320 product line page on STM website and was not able to find any useful information regarding how to configure the ADJ for the desired output. 

 

My input voltage is 8V, the desired output voltage is 7V

My guess is to take the ADJ voltage range and divide it by the input voltage to get the steps I need for incremental steps of input voltage. Please help! 

 

Thanks,

Marco Jacome

 

1 ACCEPTED SOLUTION

Accepted Solutions
Peter BENSCH
ST Employee

Welcome @Mariku, to the community!

The value you gave for VADJ only refers to the abs Max and is of little relevance for normal operation.

The example circuit from the data sheet, fig 4, shows how it works: the output voltage is applied to VADJ via a voltage divider, as is usual with adjustable LDOs, and compared with the reference voltage of 1.185V. If there is a deviation from this, the LDO adjusts accordingly. I recommend reading up on the function of an LDO on Wikipedia, for example.

Hope that helps?

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

View solution in original post

3 REPLIES 3
Peter BENSCH
ST Employee

Welcome @Mariku, to the community!

The value you gave for VADJ only refers to the abs Max and is of little relevance for normal operation.

The example circuit from the data sheet, fig 4, shows how it works: the output voltage is applied to VADJ via a voltage divider, as is usual with adjustable LDOs, and compared with the reference voltage of 1.185V. If there is a deviation from this, the LDO adjusts accordingly. I recommend reading up on the function of an LDO on Wikipedia, for example.

Hope that helps?

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
AScha.3
Chief III

from ds :

AScha3_0-1697886049606.png

the Vadj is in ds. so some basic math is too much ?

If you feel a post has answered your question, please click "Accept as Solution".

Thank you for taking the time to explain it to me. 

 

Much Appreciated.