Hi Anil,
When the "truncate log on checkpoint" option is on for a database, the checkpoint process ignores the "recovery interval in minutes" setting. Instead the checkpoint process will check once a minute and if there have been more than a handful of new log records generated since it last ran, it will issue the checkpoint and attempt to truncate the log. Since you have "trunc log" on, I don't think adjusting the recovery interval will have any effect on your process.
Having "truncate log on checkpoint" for this kind of process is normal. The convenience of having the logs automatically truncated very likely outweighs any performance benefit you might get from trying to reduce these Unpins.
My guess is that for this process, a larger ULC would reduce both the flushes by full ULC and Unpin values.
-bret