problem to set Tdamp and Pdamp

hi all user,
     i am using npt system. how i will set Tdamp or Pdamp ? my timestep is
0.005, so Tdamp will be 100*0.005=0.5 or Pdamp will be
1000*0.005=5.0. is this correct?

In lammps manual one thing is written "A Nose-Hoover thermostat will not
work well for arbitrary values of Tdamp." we can't set arbitrary than hw i
will set?
   Thank you