TLD1125EL_15 Datasheet, PDF (24/36 Pages) Marl International Limited – Basic LED Driver

TLD1125EL
Load Diagnosis
10
Load Diagnosis
10.1
Open Load
An open load diagnosis feature is integrated in the TLD1125EL driver IC. If there is an open load on the output,
the output is turned off. The potential on the IN_SET pin rises up to V_{IN_SET(OL/SC)}. This high voltage can be used
as input signal for an µC as shown in Figure 13. The open load status is not latched, as soon as the open load
condition is no longer present, the output stage will be turned on again. An open load condition is detected, if the
voltage drop over the output stage V_PS is below the threshold according Pos. 10.3.11. The output is deactivated
after a filter time t_D, which is defined by the charging current I_D Pos. 10.3.10. The time is adjustable by the
capacitor connected to the D pin according the following equation:
t_{D, typ}
=
C_-----D----⋅_---V_{----D----(-t--h--)}
I_D
(10)
V_{IN_ SET}
V_{IN_ SET(OL )}
V_{IN_ SET(ref )}
V_D
t
VD( th)
t_D
t_{IN_ SET (re se t)}
t
V_OUT
V_S
VS – VPS( OL)
V_F
open load
occurs
open load
disappears
t
Figure 20 IN_SET behavior during open load condition with ST pin connected to GND
Data Sheet
24
Rev. 1.0, 2013-08-08