User Manual
687
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
Measurement Unit
22.6
Supplement Modules
The purpose of the supplement modules is to enable a certain infrastructure on the device to guarantee a fail
safe operation:
Module Features
• Bandgap Reference Voltage with accuracy ± 1.5%.
• Bandgap is monitored by an independent reference voltage.
• ADC1 Reference with accuracy ± 1%.
• ADC1 Reference has overload detection.
The next chapter lists the configuration possibilities of the on chip references.
22.6.1
Functional Safety Concept
8-bit ADC Module 2
• A known voltage, e.g. reference voltage of the main supply module, is periodically measured as part of the
measurement sequence in normal operation. (The local ADC’s reference voltage can, of course, not be
used for this purpose since a local reference voltage error would not be detectable.)
• The conversion result of the functional safety measurement is evaluated in the postprocessing unit. If the
results is not within the expected range an error is indicated.
Figure 186 Principle of PMU Bandgap Measurement
R
meas
= 50
k
I
bg
= V
bg
/ R
PMUBias
8b ADC
*
0.75
0
1
7
8
VBG
I
bg
= 20 uA
VDD1V5_PD_A
U
meas
= 1.000
V
8
DPP2
PMU