AD215
FB 4
UNCOMMITTED
INPUT OP AMP
IN– 3
IN+ 1
IN COM 2
SIGNAL
MODULATOR
DEMODULATOR
T1
R
LOW-PASS
FILTER
150kHz
+VISO 6
–VISO 5
ISOLATED
DC
SUPPLY
POWER
T2
430kHz
POWER
OSCILLATOR
AD215
R
38 OUT HI
OUTPUT
BUFFER
36 TRIM
33kΩ 0.01µF
37 OUT LO
42 +15VIN
44 –15VIN
43 PWR RTN
Figure 1. Functional Block Diagram
PIN CONFIGURATIONS
1 35
246
BOTTOM VIEW OF
FOOTPRINT
37
36 38
43
42 44
AD215 PIN DESIGNATIONS
Pin Designation Function
1
IN+
Noninverting Input
2
IN COM
Input Common
3
IN–
Inverting Input
4
FB
Amplifier Feedback
5
–VISO OUT
Isolated –15 V dc Power Supply
6
+VISO OUT
Isolated +15 V dc Power Supply
36
TRIM
Output Offset Trim Adjust
37
OUT LO
Output Low
38
OUT HI
Output High
42
+15 VIN
43
PWR RTN
+15 V dc Power
± 15 V dc Power Supply Common
44
–15 VIN
–15 V dc Power
ORDERING GUIDE
Model
AD215AY
AD215BY
Temperature Range
–40°C to +85°C
–40°C to +85°C
VCMV
750
1500
*Typical @ +25°C, G = 1 V/V.
Nonlinearity*
0.01%
0.005%
INSIDE THE AD215
The AD215 is a fully self-contained analog signal and power
isolation solution. It employs a double-balanced amplitude
modulation technique to perform transformer coupling of sig-
nals ranging in frequency from true dc values to those having
frequencies of 120 kHz or less.
To generate the power supplies used for the isolated front-end
circuitry, an internal clock oscillator drives the primary winding
of the integral dc/dc power supply’s transformer, T2. The
resultant voltage developed across the secondary winding is
then rectified and filtered for use as the isolated power supply.
This built-in isolated dc/dc converter provides sufficient power
for both the internal isolated circuit elements of the AD215 as
well as any ancillary components supplied by the user. It saves
onboard space and component cost where additional amplifica-
tion or signal conditioning is required.
After an input signal is amplified by the uncommitted op amp,
it is modulated at a carrier frequency of approximately 430 kHz
and applied across the primary winding of the signal isolation
transformer T1.
The resultant signal induced on the secondary winding of the
transformer is then demodulated and filtered using a low-pass
Bessel response filter set at a frequency of 150 kHz. The func-
tion of the filter reconstructs the original signal as it appears on
the input.
The signal transformer design and construction allow non-
linearity to be independent of both the specified temperature
and gain ranges.
After complete reconstruction, the signal is subjected to an off-
set trim stage and final output buffer. The trim circuit allows
the designer flexibility to adjust for any offset as desired.
–4–
REV. 0