TLE 6244X
1.8 Unused Power Stages
To avoid an „open load“ fault indication an unused power switch has to be connected to an exter-
nal pull up resistor connected to UUB or has to be switched on by the input pin or via SPI or the
µsec-bus-interface.
UUBatt
Voltage
regulator
Udrop
RPull-up
U
Batt
UUB
UBR
TLE6244X
Idiag
OUTi
UthresOL
RPull-up,max = (UBRmin - Udrop,max - UthresOL,max) / Idiag,max
UBRmin is the required minimum battery voltage for diagnostic function of the ECU. The drop volt-
age is composed of the drop voltage of the regulator and the drop voltage of the reverse protec-
tion circuit of the regulator resp. the forward voltage of a reverse protection diode.
Attention:
This equation also applies to power switches that are used as signal drivers (pull up resistor
inside ECU or outside ECU): the permissible pull up resistance without a wrong diagnostic infor-
mation is calculated by the same equation. On dimensioning the pull up resistance in combination
with the diagnostic current, in applications as signal drivers attention must be paid especially to
the required high level (also for low battery voltage).
Final Data Sheet
32
V4.2, 2003-08-29
INFINEON [ Infineon ]
