MAX1192 Maxim, MAX1192 Datasheet - Page 23

• Manufacturer Part Number: MAX1192
• Description: Ultra-Low-Power / 22Msps / Dual 8-Bit ADC
• Manufacturer: Maxim

Figure 11 shows the MAX6066 precision bandgap ref-
erence used as a common reference for multiple con-
verters. The 2.500V output of the MAX6066 is followed
by a 10Hz lowpass filter and precision voltage-divider.
The MAX4254 buffers the taps of this divider to provide
the 1.75V, 1.5V, and 1.25V sources to drive REFP,
REFN, and COM. The MAX4254 provides a low offset
voltage and low noise level. The individual voltage fol-
lowers are connected to 10Hz lowpass filters, which fil-
ter both the reference-voltage and amplifier noise to a
level of 3nV/√Hz. The 1.75V and 1.25V reference volt-
Figure 11. External Unbuffered Reference Driving 160 ADCs with MAX4254 and MAX6066
3V
NOTE: ONE FRONT-END
REFERENCE CIRCUIT
SUPPORTS UP TO 160 MAX1192s
1MΩ
1MΩ
3V
0.1µF
12
13
MAX6066
Ultra-Low-Power, 22Msps, Dual 8-Bit ADC
MAX4254
______________________________________________________________________________________
1
3
1/4
2
4
11
UNCOMMITTED
0.1µF
14
2.500V
1µF
1%
30.1kΩ
1%
10.0kΩ
1%
10.0kΩ
1%
49.9kΩ
10
3
5
2
6
9
MAX4254
MAX4254
MAX4254
1/4
1/4
1/4
10µF
10µF
10µF
6V
6V
6V
1
7
8
1.47kΩ
1.47kΩ
1.47kΩ
47Ω
47Ω
47Ω
ages set the differential full-scale range of the associat-
ed ADCs at ±0.5V.
The common power supply for all active components
removes any concern regarding power-supply
sequencing when powering up or down.
With the outputs of the MAX4252 matching better than
0.1%, the buffers and subsequent lowpass filters sup-
port as many as 160 MAX1192s.
1.748V
1.498V
1.248V
330µF
6V
330µF
6V
330µF
6V
0.33µF
0.33µF
0.33µF
0.33µF
0.33µF
0.33µF
27
26
25
27
26
25
REFP
REFN
COM
REFP
REFN
COM
MAX1192
MAX1192
N = 160
N = 1
GND
GND
V
V
DD
DD
REFIN
REFIN
0.1µF
24
24
2.2µF
23