like "US" it is a acronym of United States. android talkback reads it as a word like "us" but it should read separate like U S.
Please help, is there any other speech voices that read it separately or any other settings in accessibility. please suggest.
The behavior your point out is necessary. Android uses all capital letters for some standard controls. For example, TabWidgets. All the letters in a TabWidget will be capitalized automatically. Would you want the tabs "TAB1", "TAB2"... to read out 'T A B 1'... of course not. There is however, a solution, for your circumstance.
You can provide a content description for items that have text. The content description will override the text when available. I would recommend the following.
Text: The USA is cool!
Content Description: The U S A is cool!
Recommended ContDesc: The United States of America is cool! (Do the acronym expansion for them, TalkBack actually reads this faster than U S A!)