MAX174CM 查看數據表（PDF） - Maxim Integrated
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MAX174CM Datasheet PDF : 18 Pages
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MAX174/MX574A/MX674A
Industry-Standard, Complete 12-Bit ADCs
+15V
4.7µF
0.1µF
+VS
S/H
HA5320*
-15V
-VS
4.7µF
0.1µF
VOUT
-VIN
50I
+VIN
ANALOG
50I
INPUT
GND
STS
MAX174*
20VIN
VCC
10VIN
BIPOFF
VEE
REFOUT
CONTROL
INPUTS
D0 –11
0.1µF
+15V
4.7µF
0.1µF
-15V
4.7µF
REFIN
AGND
VL
DGND
0.1µF
+5V
4.7µF
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 11. MAX174 to HA5320 Sample-and-Hold Interface
Unipolar Input Operation
The unipolar transfer function and input connections are
shown in Figures 12 and 13.
Because all internal resistors of the MAX174/MX574A/
MX674A are trimmed for absolute calibration, additional
trimming is not necessary for most applications. The
absolute accuracy for each grade is given in the speci-
fication tables.
If the offset trim is not needed, BIPOFF can be tied direct-
ly to AGND. The two resistors and trimmer for BIPOFF
can then be discarded. A 50ω ±1% metal film resistor
should be attached between REFOUT and REFIN.
For a 0 to +10V input range, the analog input is con-
nected between AGND and 10VIN. For a 0 to +20V input
range, the analog input is connected between AGND
and 20VIN. These ADCs can easily handle an input signal
beyond the supplies. If full-scale trim is not needed, the
gain trimmer, R2, should be swapped with a 50ω resis-
tor. Should a 10.24V input range be selected, a 200ω
trimmer should be inserted in series with 10VIN. For a full-
scale input range of 20.48V, use a 500ω trimmer in series
with 20VIN. The nominal input impedance into 10VIN is
5kω and 10kω for 20VIN.
Offset and Full-Scale Adjustment
In applications where the offset and full-scale range
have to be adjusted, use the circuit shown in Figure 12.
The offset should be adjusted first. Apply 1/2 LSB at the
analog input and adjust R1 until the digital output code
flickers between 0000 0000 0000 and 0000 0000 0001.
To adjust the full-scale range, apply FS - 3/2 LSB at the
analog input and adjust R2 until the output code changes
between 1111 1111 1110 and 1111 1111 1111.
Bipolar Input Operation
The bipolar transfer function is shown in Figure 14, and
input connections are shown in Figure 15. One or both
of the trimmers can be exchanged with a 50ω ±1% fixed
resistor if the offset and gain specifications suffice.
Offset and Full-Scale Adjustment
To begin bipolar calibration, a signal 1/2 LSB above neg-
ative full-scale is applied. R1 is trimmed until the digital
output flickers between 0000 0000 0000 and 0000 0000
0001. Next, a signal 3/2 LSB below positive full scale
is applied. Then, R2 is trimmed until the output flickers
between 1111 1111 1110 and 1111 1111 1111.
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