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AD215 View Datasheet(PDF) - Analog Devices

Part Name
Description
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AD215 Datasheet PDF : 12 Pages
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AD215
Input Gain Adjustments for the Inverting Mode
Figure 17 shows a suggested inverting gain adjustment circuit.
In this circuit, gain adjustment is made using a potentiometer
(RP) in the feedback loop. The adjustments are effective for all
gains in the 1 to 10 V/V range.
RIN RC
RF
1k
RF
CF
47pF
VSIGNAL
FB
4
3 IN–
IN+
1
IN COM
2
AD215
OUTPUT
FILTER,
BUFFER
AND
TRIM
CIRCUITRY
OUT HI
38
OUT LO
37
TRIM
36
COM
43
PWR
RTN
Figure 17. Gain Adjustment for Inverting Configuration
For an approximate ± 1% gain trim range,
RX
=
RIN
RIN
× RF
+ RF
and select
RC = 0.02 × RIN
while
RF < 10 k
CF = 47 pF
Note: RF and RIN should have matched temperature coefficient
drift characteristics.
Output Offset Adjustments
Figure 18 illustrates one method of adjusting the output offset
voltage. Since the AD215 exhibits a nominal output offset of
–35 mV, the circuit shown was chosen to yield an offset correc-
tion of 0 mV to +73 mV. This results in a total output offset
range of approximately –35 mV to +38 mV.
IN–
3
IN+
1
FB
4
IN COM
2
LOW-PASS OUTPUT
FILTER, BUFFER
(150k)
33k
AD215
OUT HI
38
RT
TRIM 1M
36
0.01µF
OUT LO
37
RP2
10k
RS
100k
+15VIN 42
PWR RTN 43
–15VIN 44
2.2µF
2.2µF
+15V dc
COM
–15V dc
Figure 18. Output Offset Adjustment Circuit
Output Gain Adjustments
Since the output amplifier stage of the AD215 is fixed at unity
gain, any adjustments can be made only in a subsequent stage.
USING ISOLATED POWER
Each AD215 provides an unregulated, isolated bipolar power
source of ± 15 V dc @ ± 10 mA, referred to the input common.
This source may be used to power various ancillary components
such as signal conditioning and/or adjustment circuitry, refer-
ences, op amps or remote transducers. Figure 19 shows typical
connections.
LOAD
1.5k
1.5k
C1
6.8µF
C2
6.8µF
3 IN–
IN+
1
FB
4
IN COM
2
OUTPUT
FILTER,
BUFFER
AND
TRIM
CIRCUITRY
AD215
OUT HI
38
OUT LO
37
TRIM
36
+VISO
6
–VISO
5
ISOLATED
DC
SUPPLY
430kHz
POWER
OSCIL-
LATOR
+VS
42
PWR
RTN
43
–VS
44
+15V dc
2.2µF
COM
2.2µF
–15V dc
Figure 19. Using the Isolated Power Supplies
PCB LAYOUT FOR MULTICHANNEL APPLICATIONS
The pin out of the AD215 has been designed to easily facilitate
multichannel applications. Figure 20a shows a recommended
circuit board layout for a unity gain configuration.
+15V dc
PWR
RTN
–15V dc
2.2µF
36
38
37
42
43
36
38
37
42
43
36
38
37
36
38
37
42
43
42
43
2.2µF
2.2µF
44
44
44
44
2.2µF
SUPPLY BYPASS
CAPACITORS FOR
EVERY FOUR
AD215s
OUT HI0
TRIM 0
OUT HI1
TRIM 1
OUT HI2
TRIM 2
OUT HI3
TRIM 3
ANALOG
STAR
GROUND
Figure 20a. PCB Layout for Unity Gain
CAUTION
The AD215 design does not provide short-circuit protection of
its isolated power supply. A current limiting resistor should be
placed in series with the supply terminals and the load in order
to protect against inadvertent shorts.
REV. 0
–9–
 

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