MAX1400 Maxim, MAX1400 Datasheet - Page 20

• Manufacturer Part Number: MAX1400
• Description: %V / 18-Bit / Low-Power / Multichannel / Oversampling Sigma-Delta ADC
• Manufacturer: Maxim

+5V, 18-Bit, Low-Power, Multichannel,
Oversampling (Sigma-Delta) ADC
Table 11. Channel ID Tag Codes
A switching network provides selection between three
fully differential input channels or five pseudo-differen-
tial channels, using AIN6 as a shared common. The
switching network provides two additional fully differen-
tial input channels intended for system calibration,
which may be used as extra fully differential signal
channels. Table 12 shows the channel configurations
available for both operating modes.
Table 12. Input Channel Configuration in Fully and Pseudo-Differential Modes
(SCAN = 0)
X = Don’t care
* This combination is available only in pseudo-differential mode when using the internal scanning logic
** These combinations are only available in the calibration modes.
20
CID2
M1
______________________________________________________________________________________
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
1
1
1
CID1
M0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
1
1
0
0
1
1
DIFF
CID0
0
0
0
0
X
X
X
1
1
1
X
X
0
1
0
1
0
1
0
1
Switching Network
A1
CHANNEL
AIN1–AIN6
AIN2–AIN6
AIN3–AIN6
AIN4–AIN6
AIN1–AIN2
AIN3–AIN4
AIN5–AIN6
0
0
1
1
X
X
X
0
0
1
X
X
Calibration
A0
0
1
0
1
X
X
X
0
1
0
X
X
To sample and convert the available input channels
sequentially, set the SCAN control bit in the global
setup register. The sequence is determined by DIFF
(fully differential or pseudo-differential) and by the
mode control bits M1 and M0 (Tables 8, 9, 10). With
SCAN set, the part automatically sequences through
each available channel, transmitting a single conver-
sion result before proceeding to the next channel. The
MAX1400 automatically allows sufficient time for each
conversion to fully settle, to ensure optimum resolution
before asserting the data-ready signal and moving to
the next available channel. The scan rate is, therefore,
dependent on the clock bit (CLK), the filter control bits
(FS1, FS0), and the modulator frequency selection bits
(MF1, MF0).
The input circuitry also provides two “burnout” currents.
These small currents may be used to test the integrity
of the selected transducer. They can be selectively
enabled or disabled by the BOUT bit in the global
setup register.
Differential
Differential
Pseudo-
MODE
Fully
HIGH INPUT
CALGAIN+**
CALGAIN+**
CALOFF+**
CALOFF+**
AIN5*
AIN2
AIN3
AIN4
AIN3
AIN5
AIN1
AIN1
Scanning (SCAN-mode)
Burnout Currents
LOW INPUT
CALGAIN-**
CALGAIN-**
CALOFF-**
CALOFF-**
AIN6*
AIN6
AIN6
AIN6
AIN6
AIN2
AIN4
AIN6