TDA9115 View Datasheet(PDF) - STMicroelectronics
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TDA9115 Datasheet PDF : 45 Pages
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TDA9115
9.8 MISCELLANEOUS
9.8.1 Safety functions
The safety functions comprise supply voltage
monitoring with appropriate actions, soft start and
soft stop features on H-drive and B-drive signals
on HOut and BOut outputs and X-ray protection.
For supply voltage supervision, refer to paragraph
Power supply and voltage references on page 23
and Figure 1. A schematic diagram putting togeth-
er all safety functions and composite PLL1 lock
and V-blanking indication is in Figure 15.
9.8.2 Soft start and soft stop functions
For soft start and soft stop features for H-drive and
B-drive signal, refer to paragraph Soft-start and
soft-stop on H-drive on page 27 and sub chapter-
DC/DC CONTROLLER SECTION on page 31, re-
spectively. See also the Figure 10. Regardless
why the H-drive or B-drive signal are switched on
or off (I2C bus command, power up or down, X-ray
protection), the signals always phase-in and
phase-out in the way drawn in the figure, the first
to phase-in and last to phase-out being the H-drive
signal, which is to better protect the power stages
at abrupt changes like switch-on and off. The tim-
ing of phase-in and phase-out only depends on
the capacitance connected to HPosF pin which is
virtually unlimited for this function. Yet it has a dual
function (see paragraph PLL1 on page 24), so a
compromise thereof is to be found.
9.8.3 X-ray protection
The X-ray protection is activated if the voltage lev-
el on XRay input exceeds VThrXRay threshold. As a
consequence, the H-drive and B-drive signals on
HOut and BOut outputs are inhibited (switched off)
after a 2-horizontal deflection line delay provided
to avoid erratic excessive X-ray condition detec-
tion at short parasitic spikes.
This protection is latched; it may be reset either by
tVeCr CId2CropBoUr Sby
I2C bus bit
CONTROL
XRayReset (see chap-
REGISTER MAP on
page 20).
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