MAX194 Maxim, MAX194 Datasheet - Page 14

• Manufacturer Part Number: MAX194
• Description: 14-Bit / 85ksps ADC with 10A Shutdown
• Manufacturer: Maxim

The REF and AIN signals should not exceed the
MAX194 supply rails. If this can occur, diode clamp the
signal to the supply rails. Use silicon diodes and a 10Ω
current-limiting resistor (Figures 10 and 12) or Schottky
diodes without the resistor.
When using the current-limiting resistor, place the resis-
tor between the appropriate input (AIN or REF) and any
bypass capacitor. While this results in AC transients at
the input due to dynamic input currents, the transients
settle quickly and do not affect conversion results.
Improperly placing the bypass capacitor directly at the
input forms an RC lowpass filter with the current-limiting
resistor, which averages the dynamic input current and
causes linearity errors.
14-Bit, 85ksps ADC with 10µA Shutdown
Figure 14. MAX400 Drives AIN for Low-Frequency Use
Figure 15. AIN Buffer for AC/DC Use
14
______________________________________________________________________________________
IN
2
3
MAX427
IN
+15V
-15V
REF and AIN Input Protection
7
4
2
3
6
MAX400
+15V
-15V
0.1 F
0.1 F
7
4
6
100pF
1k
1k
0.1 F
0.1 F
2
ELANTEC
EL2003
1000pF
-15V
+15V
100
1k
1
4
The MAX194 uses a capacitive DAC that provides an
inherent track/hold function. The input impedance is
typically 30Ω in series with 250pF in unipolar mode and
50Ω in series with 125pF in bipolar mode.
The analog input range can be either unipolar (0V to
V
state of the BP/UP/SHDN pin (see Digital Interface sec-
tion). The reference range is 0V to VDDA. When choos-
ing the reference voltage, the equivalent MAX194 input
noise (40µV
mode) should be considered.
REF
1.0 F
7
) or bipolar (-V
0.1 F
0.1 F
RMS
0.0033 F
-5V
in unipolar mode, 80µV
+5V
1N914
1N914
REF
to V
10
-5V
+5V
REF
1N914
1N914
), depending on the
10
AIN
Analog Input
RMS
Input Range
in bipolar
AIN