Rainbow Electronics MAX12553 - Manual (Page 23)

MAX12553
14-Bit, 65Msps, 3.3V ADC
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Buffered External Reference
Drives Multiple ADCs
The buffered external reference mode allows for more
control over the MAX12553 reference voltage and
allows multiple converters to use a common reference.
The REFIN input impedance is >50MΩ.
Figure 13 uses the MAX6029EUK21 precision 2.048V
reference as a common reference for multiple convert-
ers. The 2.048V output of the MAX6029 passes through
a one-pole 10Hz lowpass filter to the MAX4230. The
MAX4230 buffers the 2.048V reference and provides
additional 10Hz lowpass filtering before its output is
applied to the REFIN input of the MAX12553.
MAX12553
NOTE: ONE FRONT-END REFERENCE
CIRCUIT IS CAPABLE OF SOURCING 15mA
AND SINKING 30mA OF OUTPUT CURRENT.
*PLACE THE 1µF REFP-to-REFN BYPASS CAPACITOR AS CLOSE TO THE DEVICE AS POSSIBLE.
16.2kΩ
0.1µF
0.1µF
1µF
2
5
2.048V
2.048V
+3.3V
1
2
4
1
3
5
47Ω
1.47kΩ
+3.3V
10µF
6V 330µF
6V
+3.3V
2.2µF
2.2µF
0.1µF
1µF* 10µF
0.1µF
0.1µF
0.1µF
REFP
REFN
COM
3
2
1 V DD
GND
REFIN
39
REFOUT
38
MAX12553
+3.3V
2.2µF
2.2µF
0.1µF
1µF* 10µF
0.1µF
0.1µF
0.1µF
REFP
REFN
COM
3
2
1 V DD
GND
REFIN
39
REFOUT
38
MAX6029EUK21
MAX4230
Figure 13. External Buffered Reference Driving Multiple ADCs