How can I Skip calendar_system functions in calling format_date

Hello

In my drupal site, I have installed calendar_systems and it works well in persian language.

but my problem is :

I have created my own custom module that in it's php codes I have this command :
format_date(REQUEST_TIME,'custom','Y-m-d H:i:00')

I need to get date in Georgian format in all languages EN or FA (Not Jalali/Shamsi) but it returns date as jalali format

Please tell me how can I skip calendar_system functions when I want to call format_date function.