TLE8242-2 Datasheet, PDF (33/78 Pages) Infineon Technologies AG – 8 Channel Fixed Frequency Constant Current Control With Current Profile Detection

TLE8242-2
Functional Description and Electrical Characteristics
5.8.1 Zone 1
When the OUTx pin transitions from low-to-high, zone 1 of the logic is entered. The TLE8242 compares the
difference between successive A/D samples and calculates the ADDIFF value. This value is compared with
Threshold1 as follows:
– ADDIFF = A/D_m+1 - A/D_m
– IF (ADDIFF > Threshold1) THEN count = count +1
When ADDIFF is greater than Threshold 1 for Count1 out of Count1 + 1 successive comparisons, zone 1 is passed
and zone 2 is entered. Note that if one of the tests fails, the actual test performed on the next sample after the
single failure is
– ADDIFF = A/D_m+1 - A/D_m-1
– IF (ADDIFF > 2 * Threshold1) THEN count = count +1
This has the effect of filtering out a single noise spike in the A/D measurement.
5.8.2 Zone 2
In zone 2, the TLE8242 compares the difference between successive A/D samples and calculates the ADDIFF
value. This value is compared with Threshold2 as follows:
– ADDIFF = A/D_m+1 - A/D_m
– IF (ADDIFF <Threshold2) THEN count = count +1
When ADDIFF is less than Threshold2 for Count2 out of Count2 + 1 successive comparisons, zone 2 is passed
and zone 3 is entered. When the thresold2 is set to 0, a negative difference in the A/D samples (negative slope)
must be detected. Note that if one of the tests fails, the actual test performed on the next sample after the single
failure is
– ADDIFF = A/D_m+1 - A/D_m-1
– IF (ADDIFF <2 * Threshold2) THEN count = count +1
This has the effect of filtering out a single noise spike in the A/D measurement.
5.8.3 Zone 3
In zone 3, the TLE8242 sample rate for the CPD function can be altered from the sample rate used for zone 1 and
zone 2. As in zone 1 and zone 2, the TLE8242 compares the difference between two A/D samples and calculates
ADDIFF. The sample rate can be altered in zone 3 such that ADDIFF is calculated as shown in Table 5.This allows
for more noise immunity and also allows the programming of a lower effective slope to be detected. When ADDIFF
is greater than Threshold3 for Count3 output of Count3 + 1 successive comparisons, the test passes and zone 3
is completed. When zone 3 passes, the current profile is passed.
Table 6 Zone 3 Sample Rate Selection
SPI Bit Values
Samples Used
00
successive A/D samples
01
every 2nd A/D sample
10
every 3rd A/D sample
11
every 4th A/D sample
ADDIFF
A/D_m - A/D_m-1
A/D_m - A/D_m-2
A/D_m - A/D_m-3
A/D_m - A/D_m-4
Note that if one of the tests fails, the actual test performed on the next sample after the single failure is
– ADDIFF = A/D_m - A/D_m-2*a (a=1, 2, 3, 4 depending on the settings in Table 6)
– IF (ADDIFF > 2 * Threshold3) THEN count = count +1
This has the effect of filtering out a single noise spike in the A/D measurement.
Data Sheet
33
Rev. 1.0, 2010-02-09