Internal Reference

The MAX1069 contains an internal 4.096V bandgap ref-

erence. This bandgap reference is connected to

REFADJ through a 5k

Ω resistor. Bypass REFADJ with a

0.1µF capacitor to AGND. The MAX1069 reference

buffer has a unity gain to provide +4.096V at REF.

Bypass REF with a 10µF capacitor to AGND when the

The internal reference is adjustable to ±1.5% using the

External Reference

For external reference operation, disable the internal

version, an external reference at REF must deliver up to

100µA of DC load current and have an output imped-

ance of less than 10

Ω.

For optimal performance, buffer the reference through

an op amp and bypass REF with a 10µF capacitor.

Consider the MAX1069’s equivalent input noise

Transfer Function

The MAX1069 has a standard unipolar transfer function

transitions occur halfway between successive-integer

(I/O) transfer function.

Input Buffer

Most applications require an input buffer amplifier to

achieve 14-bit accuracy. If the input signal is multi-

plexed, the input channel should be switched immedi-

ately after acquisition, rather than near the end of or

58.6ksps, 14-Bit, 2-Wire Serial ADC

in a 14-Pin TSSOP

______________________________________________________________________________________

17

Figure 12. Internal Reference

4.096V

BANDGAP

REFERENCE

5k

Ω

SAR

ADC

REF

0.1

µF

10

µF

REF

REFADJ

4.096V

AGND

DGND

12

13

9

1

MAX1069

Figure 13. Adjusting the Internal Reference

4.096V

BANDGAP

REFERENCE

5k

Ω

SAR

ADC

REF

0.1

µF

10

µF

REF

REFADJ

4.096V

AGND

DGND

12

13

9

1

MAX1069

0.1

µF

150k

Ω

100k

Ω

POTENTIOMETER

68k

Ω

5.0V

8