Datasheet

LNBH23L Application information
Doc ID 15335 Rev 4 7/25
down for a time T
OFF
, typically 900 ms. Simultaneously the diagnostic OLF I²C bit of the
system register is set to "1". After this time has elapsed, the output is resumed for a time
T
ON
= 1/10 T
OFF
= 90 ms (typ.). At the end of T
ON
, if the overload is still detected, the
protection circuit will cycle again through T
OFF
and T
ON
. At the end of a full T
ON
in which no
overload is detected, normal operation is resumed and the OLF diagnostic bit is reset to
LOW. Typical T
ON
+ T
OFF
time is 990ms and an internal timer determines it. This dynamic
operation can greatly reduce the power dissipation in short circuit condition, still ensuring
excellent power-on start-up in most conditions. However, there could be some cases in
which a highly capacitive load on the output may cause a difficult start-up when the dynamic
protection is chosen. This can be solved by initiating any power start-up in static mode (PCL
= 1) and, then, switching to the dynamic mode (PCL = 0) after a chosen amount of time
depending on the output capacitance. When in static mode, the diagnostic OLF bit goes to
"1" when the current clamp limit is reached and returns LOW when the overload condition is
cleared.
2.9 Thermal protection and diagnostic
The LNBH23L is also protected against overheating: when the junction temperature
exceeds 150 °C (typ.), the step-up converter and the liner regulator are shut-off, and the
diagnostic OTF SR bit is set to "1". Normal operation is resumed and the OTF bit is reset to
LOW when the junction is cooled down to 135 °C (typ.)
2.10 Output current limit selection
The linear regulator current limit threshold can be set by an external resistor connected to
ISEL pin. The resistor value defines the output current limit by the equation:
I
MAX
(A) = 10000 / R
SEL
where R
SEL
is the resistor connected between I
SEL
and GND. The highest selectable current
limit threshold shall be 0.65 A typ with R
SEL
= 15 kΩ. The above equation defines the typical
threshold value.
Note: External components are needed to comply DiSEqC™ bus hardware requirements. Full
compliance of the whole application with DiSEqC™ specifications is not implied by the bare
use of this IC. NOTICE: DiSEqC™ is a trademark of EUTELSAT.