Datasheet

Internal Reference
The MAX1169 contains an internal 4.096V bandgap ref-
erence. This bandgap reference is connected to
REFADJ through a 5kΩ resistor. Bypass REFADJ with a
0.1μF capacitor to AGND. The MAX1169 reference
buffer has a unity gain to provide +4.096V at REF.
Bypass REF with a 10μF capacitor to AGND when the
internal reference is used (Figure 12).
The internal reference is adjustable to ±1.5% using the
circuit of Figure 13.
External Reference
For external reference operation, disable the internal
reference by connecting REFADJ to AVDD. During con-
version, an external reference at REF must deliver up to
100μA of DC load current and have an output imped-
ance of less than 10Ω.
For optimal performance, buffer the reference through
an op amp and bypass REF with a 10μF capacitor.
Consider the MAX1169’s equivalent input noise
(38μV
RMS
) when choosing a reference.
Transfer Function
The MAX1169 has a standard unipolar transfer function
with a valid analog input voltage range from V
AGNDS
to
V
REF
. Output data coding is binary with 1LSB =
(V
REF
/2
N
) where N is the number of bits (16). Code
transitions occur halfway between successive-integer
LSB values. Figure 14 shows the MAX1169 input/output
(I/O) transfer function.
Input Buffer
Most applications require an input buffer amplifier to
achieve 16-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
MAX1169
58.6ksps, 16-Bit, 2-Wire Serial ADC
in a 14-Pin TSSOP
______________________________________________________________________________________ 17
Figure 12. Internal Reference
4.096V
BANDGAP
REFERENCE
5kΩ
SAR
ADC
REF
0.1μF
10μF
REF
REFADJ
4.096V
AGNDDGND
A
V
= 1.0
12
13
9
1
MAX1169
Figure 13. Adjusting the Internal Reference
4.096V
BANDGAP
REFERENCE
5kΩ
SAR
ADC
REF
0.1μF
10μF
REF
REFADJ
4.096V
AGNDDGND
A
V
= 1.0
12
13
9
1
MAX1169
0.1μF
150kΩ
100kΩ
POTENTIOMETER
68kΩ
AVDD
5.0V
8