User Manual
698
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
Measurement Core Module (incl. ADC2)
(23.2)
The timing of the analog MUX and the digital DEMUX is controlled by the channel controller accordingly. The
analog MUX with sample and hold stage needs one clock cycle for channel switching and the ADC consumes,
as default setting, 12 clock cycles for the sampling of the input voltage. The conversion time for a single
channel measurement value is 10 clock cycles.
As already mentioned above, the channel controller has a fixed sequence register setting which cannot be
changed by the user. The fixed register setting is needed, to fulfill the sampling frequency requirements of the
internal circuits, e.g. shutdown in case of overtemperature for the low sides and protection overtemperature
protection of the system.
The minimum measurement periodicity, which can be achieved, by enabling only channel 1 in the sequence
registers, depends on the MI_CLK frequency and is given by:
This following calculations include already the sampling time of ADC2. If all programmable channels are
enabled, the maximum periodicity is calculated:
(23.3)
(23.4)
For a MI_CLK frequency of 24 MHz, the channel 1 is measured with min. 4 µs. The maximum update time of
channel 1 with 24 MHz clock frequency is 10 µs. As mentioned before, this is calculated with the assumption,
that all channels are enabled and channel1 is enabled in every sequence register. As a prerequisite for this
calculation we take
= 4 (sample period = 14 MI_CLK clock cycles).
[ ]
meas
m
m
T
n
SQ
⎟
⎠
⎞
⎜
⎝
⎛
∑
=
7
1
N
meas, n
=
T
meas_CH1_min
=
f
MI_CLK
32
T
meas_CH1_max
=
f
MI_CLK
320