ADS-937MC-C Murata, ADS-937MC-C Datasheet - Page 4

• Manufacturer Part Number: ADS-937MC-C
• Description: or 0 to -10v input range, no pipeline delays, 0 c to +70 c temperature range, rohs compliant....
• Manufacturer: Murata

DATEL
CALIBRATION PROCEDURE
Connect the converter per Table 1 for the appropriate input
voltage range. Any offset/gain calibration procedures should
not be implemented until the device is fully warmed up. To
avoid interaction, adjust offset before gain. The ranges of
adjustment for the circuits in Figure 2 are guaranteed to
compensate for the ADS-937's initial accuracy errors and may
not be able to compensate for additional system errors.
A/D converters are calibrated by positioning their digital
outputs exactly on the transition point between two adjacent
digital output codes. This is accomplished by connecting LED's
to the digital outputs and performing adjustments until certain
LED's "fl icker" equally between on and off. Other approaches
employ digital comparators or microcontrollers to detect when
the outputs change from one code to the next.
For the ADS-937, offset adjusting is normally accomplished
when the analog input is 0 minus ½LSB (–76.3μV). See Table
2 for the proper bipolar and unipolar output coding.
Gain adjusting is accomplished when the analog input is at
nominal full scale minus 1½LSB's (–9.999771V for unipolar
and –4.999771V for bipolar).
Zero/Offset Adjust Procedure
1. Apply a train of pulses to the START CONVERT input
(pin 16) so that the converter is continuously converting.
2. For unipolar or bipolar zero/offset adjust, apply –76.3μV to
®
the ANALOG INPUT (pin 1).
–FS +1 LSB
UNIPOLAR
–7/8 FS
–3/4 FS
–1/2 FS
–1/4 FS
–1/8 FS
–1 LSB
SCALE
0
INPUT VOLTAGE
COMPLEMENTARY BINARY
-9.999847
-8.750000
-7.500000
-5.000000
-2.500000
-1.250000
-0.000153
0.000000
0 to -10V
®
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1111 1111 1111 1111
1110 0000 0000 0000
1100 0000 0000 0000
1000 0000 0000 0000
0100 0000 0000 0000
0010 0000 0000 0000
0000 0000 0000 0001
0000 0000 0000 0000
MSB
Table 2. Output Coding
LSB
OUTPUT CODING
3. For a bipolar input - Adjust the offset potentiometer until the
GAIN ADJUST PROCEDURE
1. Apply –4.999771V to the ANALOG INPUT (pin 1) for bipolar
2. For a unipolar input - Adjust the gain potentiometer until all
3. To confi rm proper operation of the device, vary the applied
0000 0000 0000 0000
0001 1111 1111 1111
0011 1111 1111 1111
0111 1111 1111 1111
1011 1111 1111 1111
1101 1111 1111 1111
1111 1111 1111 1110
1111 1111 1111 1111
MSB
output code fl ickers equally between 1000 0000 0000 0000
and 0111 1111 1111 1111.
For a unipolar input - Adjust the offset potentiometer until all
output bits are 0's and the LSB fl ickers between 0 and 1.
gain adjust or apply –9.999771V to pin 1 for unipolar gain
adjust.
output bits are 1's and the LSB fl ickers between 1 and 0.
For a bipolar input - Adjust the gain potentiometer until all
output bits are 1's and the LSB fl ickers between 1 and 0.
input voltage to obtain the output coding listed in Table 2.
INPUT VOLTAGE RANGE
Table 1. Setting Output Coding Selection (Pin 35)
0 to -10V
±5V
COMPLEMENTARY OFFSET BINARY
LSB
16-Bit, 1MHz Sampling A/D Converters
INPUT RANGE
+4.999847
+3.750000
+2.500000
+0.000000
-2.500000
-3.750000
-4.999847
-5.000000
01 Apr 2011 MDA_ADS-937.A03 Page 4 of 8
INPUT PIN
±5V
Pin 1
Pin 1
–FS +1 LSB
+FS -1 LSB
BIPOLAR
+3/4 FS
+1/2 FS
–1/2 FS
–3/4 FS
SCALE
ADS-937
–FS
TIE TOGETHER
0
Pins 2 and 3
Pins 3 and 5