Datasheet

MAX11190 4-Channel, Dual, Simultaneous Sampling,
2.2V to 3.6V, 12-Bit, 3Msps SAR ADC in Tiny
3mm x 3mm TQFN Package
www.maximintegrated.com
Maxim Integrated │ 16
between the application of an input voltage step and the
point at which the output signal reaches and stays within
a given error band centered on the resulting steady-state
amplifier output level. The ADC input sampling capaci-
tor charges during the sampling cycle, referred to as the
acquisition period. During this acquisition period, the set-
tling time is affected by the input resistance and the input
sampling capacitance. This error can be estimated by
looking at the settling of an RC time constant using the
input capacitance and the source impedance over the
acquisition time period.
Figure 14 shows a typical application circuit. The
MAX4430, offering a settling time of 37ns at 16 bits, is
an excellent choice for this application. See the THD
vs. Input Resistance graph in the Typical Operating
Characteristics.
Choosing a Reference
For devices using an external reference, the choice of
the reference determines the output accuracy of the
ADC. An ideal voltage reference provides a perfect initial
accuracy and maintains the reference voltage indepen-
dent of changes in load current, temperature, and time.
Considerations in selecting a reference include initial
voltage accuracy, temperature drift, current source, sink
capability, quiescent current, and noise. Figure 14 shows
a typical application circuit using the MAX6126 to provide
the reference voltage. The MAX6033 and MAX6043 are
also excellent choices.
Figure 14. Typical Application Circuit
MAX11190
MAX6126
OVDD
V
OVDD
+3V
SCLK
DIGITAL
INTERFACE
DOUTA/
DOUTB
CHSEL
SCK
MISO
CS SS
0.1µF
1µF
10µF
0.1µF
AGND
AIN1A/
AIN1B
IN1A/IN1B
V
DC
4
1
5
2
2
3
AIN2A/
AIN2B
V
DD
72
1
6
4
3
10µF
0.1µF
0.1µF
0.1µF
+5V
-5V
470pF
COG CAPACITOR
10Ω
500Ω
470pF
COG CAPACITOR
10µF
+5V
10µF
0.1µF
0.1µF 10µF
REFA
OUTF IN
NR
OUTS
GNDS
GND
EP
MAX4430
IN2A/IN2B
V
DC
4
1
5
3
0.1µF
+5V
-5V
10Ω
10µF
0.1µF 10µF
MAX4430
500Ω
500Ω
500Ω
100pF COG
100pF COG
REFB