Ultra-Low-Power, 22Msps, Dual 8-Bit ADC

22

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Figure 10 shows the MAX6061 precision bandgap ref-

erence used as a common reference for multiple con-

verters. The 1.248V output of the MAX6061 is divided

down to 1.023V as it passes through a one-pole, 10Hz,

lowpass filter to the MAX4250. The MAX4250 buffers

the 1.023V reference before its output is applied to the

MAX1192. The MAX4250 provides a low offset voltage

(for high gain accuracy) and a low noise level.

Unbuffered External Reference Drives

Multiple ADCs

The unbuffered external reference mode allows for pre-

cise control over the MAX1192 reference and allows

multiple converters to use a common reference.

Connecting REFIN to GND disables the internal refer-

ence, allowing REFP, REFN, and COM to be driven

directly by a set of external reference sources.

MAX4250

3V

2

4

2

1.248V

3

5

10Hz

LOWPASS

FILTER

1

15

Ω

1

REFIN

MAX1192

N = 1

24

GND

1.023V

NOTE: ONE FRONT-END REFERENCE

CIRCUIT PROVIDES

±15mA OF OUTPUT

DRIVE AND SUPPORTS OVER

1000 MAX1192s.

3

0.1

µF

0.1

µF

3V

1

µF

1%

20k

Ω

1%

90.9k

Ω

0.1

µF

2.2

µF

0.1

µF

REFP

27

0.33

µF

REFN

26

0.33

µF

COM

25

0.33

µF

REFIN

MAX1192

N = 1000

24

GND

0.1

µF

REFP

27

0.33

µF

REFN

26

0.33

µF

COM

25

0.33

µF

MAX6061

Figure 10. External Buffered (MAX4250) Reference Drive Using a MAX6062 Bandgap Reference