AD598 Analog Devices, AD598 Datasheet - Page 3

• Manufacturer Part Number: AD598
• Description: LVDT Signal Conditioner
• Manufacturer: Analog Devices

REV. A
NOTES
1
2
3
4
5
6
7
8
9
Specifications subject to change without notice.
Specifications shown in boldface are tested on all production units at final electrical test. Results from those tested are used to calculate outgoing quality levels. All
min and max specifications are guaranteed, although only those shown in boldface are tested on all production units.
THERMAL CHARACTERISTICS
SOIC Package
Side Brazed Package
ABSOLUTE MAXIMUM RATINGS
Total Supply Voltage +V
Storage Temperature Range
Operating Temperature Range
Lead Temperature Range (Soldering 60 sec) . . . . . . . . +300 C
Power Dissipation Up to +65 C . . . . . . . . . . . . . . . . . . . 1.2 W
Derates Above +65 C . . . . . . . . . . . . . . . . . . . . . . . 12 mW/ C
V
From T
Nonlinearity of the AD598 only, in units of ppm of full scale. Nonlinearity is defined as the maximum measured deviation of the AD598 output voltage from a
See Transfer Function.
This offset refers to the (V
For example, if the excitation to the primary changes by 1 dB, the gain of the system will change by typically 100 ppm.
Output ripple is a function of the AD598 bandwidth determined by C2, C3 and C4. See Figures 16 and 17.
R1 is shown in Figures 7 and 12.
Excitation voltage drift is not an important specification because of the ratiometric operation of the AD598.
the sum of V
error for the AD598AD from T
of FS
Full scale is defined as the voltage difference between the maximum positive and maximum negative output.
straight line. The straight line is determined by connecting the maximum produced full-scale negative voltage with the maximum produced full-scale positive voltage.
for (V
100 mV rms.] The 1 span is a convenient reference point to define offset referred to input. For example, with this input span a value of R2 = 20 k
V
produce the 10 V output span. In this case the offset is correspondingly magnified when referred to the output voltage. For example, a Schaevitz E100 LVDT
(V
multiplying the maximum value shown in the data sheet ( 1% of FS by 1/0.27 which equals 3.7% maximum. Similarly, to determine the maximum values of offset
drift, offset CMRR and offset PSRR when referred to the 10.69 V output, these data sheet values should also be multiplied by (1/0.27). For this example for the
AD598AD the maximum values of offset drift, PSRR offset and CMRR offset would be: 185 ppm/ C of FS; 741 ppm/V and 741 ppm/V respectively when referred
to the 10.69 V output.
requires 80.2 k for R2 to produce a 10.69 V output and (V
A
OUT
R Package . . . . . . . . . . . . . . . . . . . . . . . . . –65 C to +150 C
D Package . . . . . . . . . . . . . . . . . . . . . . . . . –65 C to +150 C
AD598JR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 C to +70 C
AD598AD . . . . . . . . . . . . . . . . . . . . . . . . . . –40 C to +85 C
A
and V
–V
span a value of 10 volts. Caution, most LVDTs will typically exercise less of the ((V
A
B
–V
)/(V
MIN
+65 C) + offset drift from –40 C to +25 C (50 ppm/ C of FS
B
B
represent the Mean Average Deviation (MAD) of the detected sine waves. Note that for this Transfer Function to linearly represent positive displacement,
)/(V
, to T
A
+V
A
A
and V
B
+V
) = (1.71 V rms – 0.99 V rms)/(1.71 V rms + 0.99 V rms). The maximum offset value referred to the 10.69 V output may be determined by
MAX
B
) to equal –1, V
, the overall error due to the AD598 alone is determined by combining gain error, gain drift and offset drift. For example the worst case overall
B
of the LVDT must remain constant with stroke length. See “Theory of Operation.” Also see Figures 7 and 12 for R2.
A
–V
22 C/W
25 C/W
B
S
MIN
JC
)/(V
to –V
to T
A
A
+V
must equal zero volts. Note that offset errors do not allow accurate use of zero magnitude inputs, practical inputs are limited to
MAX
S
B
) input spanning a full-scale range of 1. [For (V
is calculated as follows: overall error = gain error at +25 C ( 1% full scale) + gain drift from –40 C to +25 C (50 ppm/ C
. . . . . . . . . . . . . . . . . +36 V
80 C/W
85 C/W
JA
A
–V
B
)/(V
A
+65 C) = 1.65% of full scale. Note that 1000 ppm of full scale equals 0.1% of full scale.
+V
B
) equals 0.27. This ratio may be determined from the graph shown in Figure 18,
–3–
Model
AD598JR
AD598AD
A
–V
A
–V
B
)/(V
B
))/((V
B1 FILTER
B2 FILTER
A
LEVEL 2
LEVEL 1
FREQ 2
+V
FREQ 1
EXC 2
EXC 1
A
B
+V
) to equal +1, V
–V
V
B
B
S
Temperature
Range
0 C to +70 C
–40 C to +85C
)) input span and thus require a larger value of R2 to
10
2
3
4
5
6
7
8
9
1
ORDERING GUIDE
(Not to Scale)
TOP VIEW
AD598
B
must equal zero volts; and correspondingly
16
13
12
20
19
18
17
15
14
11
+V
OFFSET 1
OFFSET 2
SIGNAL REFERENCE
SIGNAL OUTPUT
FEEDBACK
OUTPUT FILTER
A2 FILTER
V
A1 FILTER
Package
Description
SOIC
Ceramic DIP
A
S
would give
AD598
Package
Option
R-20
D-20