  The efficiency of dynamical decoupling pulse sequences in removing noise due
to a charge fluctuator is studied for a singlet-triplet spin qubit. We develop
a numerical method to solve the dynamical equations for all three components of
the Bloch vector under a general pulse protocol, and with an arbitrary rotation
axis. The qubit is shown to undergo both dephasing and dissipative dynamics,
pending on its working point. Analytical solutions are found for the limits of
weakly and strongly coupled fluctuators, shedding light on the distinct
dynamics in the different parameter regimes. Scaling of the qubit decay time
with the number of control pulses is found to follow a power law over a wide
range of TLF parameters and qubit bias points.
