LTC6804-1/LTC6804-2
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Measuring Cell Voltages (ADCV Command)
The ADCV command initiates the measurement of the
battery cell inputs, pins C0 through C12. This command
has options to select the number of channels to measure
and the ADC mode. See the section on Commands for the
ADCV command format.
Figure 3 illustrates the timing of ADCV command which
measures all twelve cells. After the receipt of the ADCV
command to measure all 12 cells, ADC1 sequentially
measures the bottom 6 cells. ADC2 sequentially measures
the top 6 cells. After the cell measurements are complete,
each channel is calibrated to remove any offset errors.
Table 5 shows the conversion times for the ADCV com
-
mand measuring all 12 cells. The total conversion time is
given by t
6C
which indicates the end of the calibration step.
Figure 4 illustrates the timing of the ADCV command that
measures only two cells.
Table 6 shows the conversion time for ADCV command
measuring only 2 cells. t
1C
indicates the total conversion
time for this command.
operaTion
Figure 3. Timing for ADCV Command Measuring All 12 Cells
Table 6. Conversion Times for ADCV Command Measuring Only 2
Cells in Different Modes
CONVERSION TIMES (in µs)
MODE t
0
t
1M
t
1C
27kHz 0 57 201
14kHz 0 86 230
7kHz 0 144 405
3kHz 0 260 521
2kHz 0 493 754
26Hz 0 29,817 33,568
Table 5. Conversion Times for ADCV Command Measuring All 12 Cells in Different Modes
CONVERSION TIMES (in µs)
MODE t
0
t
1M
t
2M
t
5M
t
6M
t
1C
t
2C
t
5C
t
6C
27kHz 0 57 103 243 290 432 568 975 1,113
14kHz 0 86 162 389 465 606 742 1,149 1,288
7kHz 0 144 278 680 814 1,072 1,324 2,080 2,335
3kHz 0 260 511 1,262 1,512 1,770 2,022 2,778 3,033
2kHz 0 493 976 2,425 2,908 3,166 3,418 4,175 4,430
26Hz 0 29,817 59,623 149,043 178,850 182,599 186,342 197,571 201,317
CALIBRATE
C8 TO C7
CALIBRATE
C7 TO C6
MEASURE
C12 TO C11
MEASURE
C8 TO C7
MEASURE
C7 TO C6
ADC2
SERIAL
INTERFACE
t
CYCLE
t
SKEW2
ADCV + PEC
CALIBRATE
C2 TO C1
CALIBRATE
C12 TO C11
CALIBRATE
C6 TO C5
CALIBRATE
C1 TO C0
MEASURE
C6 TO C5
MEASURE
C2 TO C1
MEASURE
C1 TO C0
ADC1
t
0
t
1M
t
2M
t
6M
t
5M
t
1C
t
2C
t
5C
t
6C
t
REFUP
Figure 4. Timing for ADCV Command Measuring 2 Cells
CALIBRATE
C10 TO C9
MEASURE
C10 TO C9
ADC2
SERIAL
ADCV + PEC
CALIBRATE
C4 TO C3
MEASURE
C4 TO C3
ADC1
t
0
t
1M
t
1C
REFUP
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