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tokens: for stars hotter than 5500 K ( Ryabchikova et al. 2015 ). The Balmer lines in B to F stars are in general well matched by LTE computations, and they are practically identical to the non-LTE predictions ( Przybilla Butler 2004 ). The region around H was chosen because it harbours several iron lines with accurate atomic parameters. The Balmer lines provide an excellent diagnostic of for stars cooler than 8000 K ( Gray 1992 ; Heiter et al. 2002 ). For stars hotter than 8000 K, Balmer line profiles, in particular their wings, are sensitive to both temperature and gravity ( Gray 1992 ; Smalley 2005 ). Metal line diagnostics are also good indicators of , , and [Fe/H] as the best-fit synthetic spectrum corresponds to the spectrum that yields the same abundance for different ionization stages of the same element (ionization balance) and in the same abundance for all excitation potentials of the same element in a given ionization stage (excitation potential). On the other hand, lines such as the Mg ii triplet around 4481 Å and the Fe ii lines between 4500 and 4530 Å are excellent indicators of (see for example Royer et al. 2014 ). For all the above mentioned reasons, we applied the global spectral fitting technique to the whole spectral range from 4400 and 5000 Å. The derived parameters are obviously model dependent, but the models that we are using (Sect. 2.2 ) are well suited to describe the atmospheres and spectra of “normal” A and Am stars. The selection of the observed spectra and construction of the learning databases are detailed in Sect. 2 . The PCA and the derivation of the eigenvectors and coefficients are recalled in Sect. 3 . Radial velocity correction and re-normalization of the spectra are discussed in Sect. 4 . The results of the inversion are presented in Sect. 5 . A few outliers have been analysed in detail in Sect. 6 . Discussion and conclusion are gathered in Sect. 7 . 2. Observations and learning database 2.1. Target selection The PolarBase contains reduced stellar spectra collected with the NARVAL and ESPaDOnS high-resolution spectropolarimeters. These two spectropolarimeters are mounted on the 2 m aperture Télescope Bernard Lyot (TBL) in France and on the 3.6 m aperture CFHT telescope in Hawaii, respectively. Both instruments have a spectral resolving power of 65 000 in polarimetric mode and 76 000 when used for classical spectroscopy. As a first step, we have selected all high-resolution Echelle spectra of stars whose spectral type ranges from F0 up to B9 from the database at two different resolutions and in spectroscopy mode only. Fifty spectra were thus retrieved. We have also retrieved A-type stars spectra from the ELODIE and SOPHIE archives. These archives are on-line databases of high-resolution Echelle spectra and radial velocities. The ELODIE is a fiber-fed, cross-dispersed Echelle spectrograph that was attached to the 1.93-m telescope at Observatoire de Haute-Provence (OHP; Baranne et al. 1996 ). The ELODIE recorded