  (abridged) We analyse the spectral and pulse properties of the 11 Hz
transient accreting pulsar, IGR J17480-2446, in the globular cluster Terzan 5,
considering all the available RXTE, Swift and INTEGRAL observations performed
between October and November, 2010.
  By measuring the pulse phase evolution we conclude that the NS spun up at an
average rate of <nu_dot>=1.48(2)E-12 Hz/s, compatible with the accretion of the
Keplerian angular momentum of matter at the inner disc boundary. Similar to
other accreting pulsars, the stability of the pulse phases determined by using
the second harmonic component is higher than that of the phases based on the
fundamental frequency. Under the assumption that the second harmonic is a good
tracer of the neutron star spin frequency, we successfully model its evolution
in terms of a luminosity dependent accretion torque. If the NS accretes the
specific Keplerian angular momentum of the in-flowing matter, we estimate the
inner disc radius to lie between 47 and 93 km when the luminosity attains its
peak value. Smaller values are obtained if the interaction between the magnetic
field lines and the plasma in the disc is considered.
  The phase-averaged spectrum is described by thermal Comptonization of photons
with energy of ~1 keV. A hard to soft state transition is observed during the
outburst rise. The Comptonized spectrum evolves from a Comptonizing cloud at an
electron temperature of ~20 keV towards an optically denser cloud at kT_e~3
keV. At the same time, the pulse amplitude decreases from 27% to few per cent
and becomes strongly energy dependent. We discuss various possibilities to
explain such a behaviour, proposing that at large accretion luminosities a
significant fraction of the in-falling matter is not channelled towards the
magnetic poles, but rather accretes more evenly onto the NS surface.
