AD1380KD Analog Devices Inc, AD1380KD Datasheet - Page 9

• Manufacturer Part Number: AD1380KD
• Description: A/D Converter (A-D) IC
• Manufacturer: Analog Devices Inc

Specifications of AD1380KD

• No. Of Bits: 16 Bit
• Mounting Type: Through Hole
• Features: Low Cost, 16?Bit Sampling ADC
• No. Of Channels: 1
• Interface Type: Serial, Parallel
• Package / Case: 32-CDIP
• Rohs Status: RoHS non-compliant
• Number Of Bits: 16
• Sampling Rate (per Second): 50k
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 900mW
• Voltage Supply Source: Dual ±
• Operating Temperature: 0°C ~ 70°C

CALIBRATION (14-BIT RESOLUTION EXAMPLES)
External zero adjustment and gain adjustment potentiometers,
connected as shown in Figure 3 and Figure 4, are used for
device calibration. To prevent interaction of these two
adjustments, zero is always adjusted first and then gain. Zero is
adjusted with the analog input near the most negative end of the
analog range (0 for unipolar and minus full scale for bipolar
input ranges). Gain is adjusted with the analog input near the
most positive end of the analog range.
0 V to +10 V Range
Set analog input to +1 LSB
output = 11111111111110. Zero is now calibrated. Set analog
input to +FSR − 2 LSB = +9.99878 V; adjust gain for
00000000000001 digital output code; full scale (gain) is now
calibrated. Half-scale calibration check: set analog input to
5.00000 V; digital output code should be 01111111111111.
−10 V to +10 V Range
Set analog input to −9.99878 V; adjust zero for 1111111111110
digital output (complementary offset binary) code. Set analog
input to 9.99756 V; adjust gain for 00000000000001 digital
output (complementary offset binary) code. Half-scale
calibration check: set analog input to 0.00000 V; digital output
(complementary offset binary) code should be 01111111111111.
Other Ranges
Representative digital coding for 0 V to +10 V and −10 V to
+10 V ranges is given in the 0 V to +10 V Range section and
−10 V to +10 V Range section. Coding relationships and
calibration points for 0 V to +5 V, −2.5 V to +2.5 V and −5 V to
+5 V ranges can be found by halving proportionally the
corresponding code equivalents listed for the 0 V to +10 V and
−10 V to +10 V ranges, respectively, as indicated in Table 4.
Zero and full-scale calibration can be accomplished to a
precision of approximately ±1/2 LSB using the static adjustment
procedure described above. By summing a small sine or
triangular wave voltage with the signal applied to the analog
14
B
= 0.00061 V; adjust zero for digital
Rev. D | Page 9 of 12
input, the output can be cycled through each of the calibration
codes of interest to more accurately determine the center (or
end points) of each discrete quantization level. A detailed
description of this dynamic calibration technique is presented
in Analog-Digital Conversion Handbook , edited by D. H.
Sheingold, Prentice-Hall, Inc., 1986.
GROUNDING, DECOUPLING AND LAYOUT
CONSIDERATIONS
Many data acquisition components have two or more ground
pins that are not connected together within the device. These
grounds are usually referred to as the DIGITAL COMMON
(logic power return), ANALOG COMMON (analog power
return), or analog signal ground. These grounds (Pin 8 and
Pin 30) must be tied together at one point as close as possible to
the converter. Ideally, a single solid analog ground plane under
the converter would be desirable. Current flows through the
wires and etch stripes on the circuit cards and, since these paths
have resistance and inductance, hundreds of millivolts can be
generated between the system analog ground point and the
ground pins of the AD1380. Separate wide conductor stripe
ground returns should be provided for high resolution
converters to minimize noise and IR losses from the current
flow in the path from the converter to the system ground point.
In this way, AD1380 supply currents and other digital logic-gate
return currents are not summed into the same return path as
analog signals where they would cause measurement errors.
Each of the AD1380 supply terminals should be capacitively
decoupled as close to the AD1380 as possible. A large value
(such as 1 μF) capacitor in parallel with a 0.1 μF capacitor is
usually sufficient. Analog supplies are to be bypassed to the
ANALOG COMMON (analog power return) Pin 30 and the
logic supply is bypassed to DIGITAL COMMON (logic power
return) Pin 8.
The metal cover is internally grounded with respect to the
power supplies, grounds and electrical signals. Do not
externally ground the cover.
AD1380