MAX194 Maxim, MAX194 Datasheet - Page 12

• Manufacturer Part Number: MAX194
• Description: 14-Bit / 85ksps ADC with 10A Shutdown
• Manufacturer: Maxim

be improved by trimming, but the drift is too great to
provide good stability over temperature. The MAX427
buffer provides the necessary drive current to stabilize
the REF input quickly after capacitance changes.
The reference inaccuracies contribute additional full-
scale error. A reference with less than
(61 parts per million) over the operating temperature
range is required to maintain full 14-bit accuracy. The
MAX6241 achieves a drift specification of 1ppm/°C
14-Bit, 85ksps ADC with 10µA Shutdown
Figure 11. High-Accuracy Reference
12
Figure 10. Typical Reference Circuit for AC Accuracy
0.1 F
______________________________________________________________________________________
MAX874
V
+15V
IN
V
GND
IN
4
2
8V
2.2 F
COMP
V
OUT
8
6
1 F
1000pF
4.096V
3
0.1 F
NR
1
MAX6241
⁄
2
2
3
GND
14
IN
MAX427
2
4
total error
-15V
TRIM
OUT
7
4
6
5
2k
6
0.1 F
0.1 F
(typ) and easily drives the REF input directly. This
allows large temperature changes with less than 1LSB
error. While the MAX6241’s initial-accuracy specifica-
tion (0.02%) results in a maximum error of about
±4LSB, the reference voltage can be trimmed or the
offset can be corrected in software if absolute DC
accuracy is essential. Figure 11’s circuit provides out-
standing temperature stability and also provides excel-
lent DC accuracy if the initial error is corrected.
10k
0.1 F
10
1k
LOW
ESR
47 F
2.2 F
0.1 F
0.1 F
1N914
12
1N914
10
REF
12
MAX194
AGND
REF
VSSA
-5V
14
15
MAX194
VDDA
AGND
+5V
16
14