Figure 6-2 . extended acquisition time -4, Table 6-1, Figure 6-2 – Maxim Integrated MAX31782 User Manual
Page 47
MaximIntegrated 6-4
MAX31782 User’s Guide
Revision 0; 8/11
The time required for the ADC to make a temperature measurement is greater than the time required for a voltage
measurement . When a temperature conversion is performed, the ADC’s internal current source forces current into the
diode connected to the channel . As the current is being sourced, the ADC integrates the voltage across the diode .
This is known as the integration time (t
INT
) . The integration time lasts approximately 2 .91ms . This integration time is a
constant and does not scale when the ADC clock speed is changed . When the integration time is complete, the ADC
performs a voltage conversion of the integration . The voltage conversion is a normal voltage conversion and takes 34
ADC clock cycles . A temperature conversion requires that this integration and conversion process be performed twice .
The extended acquisition time function does not apply when in temperature sensing mode . The time required for a
complete temperature conversion can be calculated to be:
2 x (t
INT
+ 34 ADC clocks)
Table6-1.ExtendedAcquisitionTimeinTermsofADCClocks
Figure 6-2. Extended Acquisition Time
ADACQ[3:0]
ADCCLOCKDIVIDER
=16
ADCCLOCKDIVIDER
=32
ADCCLOCKDIVIDER
=64
ADCCLOCKDIVIDER
=128
0
16
16
16
16
1
32
32
32
32
2
48
48
48
16
3
64
64
64
32
4
80
80
16
16
5
96
96
32
32
6
112
112
48
16
7
128
128
64
32
8
144
16
16
16
9
160
32
32
32
10
176
48
48
16
11
192
64
64
32
12
208
80
16
16
13
224
96
32
32
14
240
112
48
16
15
256
128
64
32
10 11
1 2 3 4 5 6 7 8 9
18
16
15
14
13
12
28 29
19 20 21 22 23 24 25 26 27
17
34
33
32
31
30
1
19 20
ADACQ
HOLD AND CONVERT SAMPLE 1
HOLD AND CONVERT SAMPLE 2
ADC
STARTUP
SAMPLE 1
SAMPLE 2
ADC DATA
VALID
ADCCLK
ADCONV
ADDATA