AD8215YRZ(Rev0) View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
AD8215YRZ Datasheet PDF : 16 Pages
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AD8215
THEORY OF OPERATION
In typical applications, the AD8215 amplifies a small differential
input voltage generated by the load current flowing through a
shunt resistor. The AD8215 rejects high common-mode
voltages (up to 65 V) and provides a ground-referenced,
buffered output that interfaces with an analog-to-digital converter
(ADC). Figure 26 shows a simplified schematic of the AD8215.
ISHUNT
RSHUNT
IIN
R1
R
A1
V+
PROPRIETARY
OFFSET
CIRCUITRY
ROUT
G = +20
OUT =
(ISHUNT × RSHUNT) × 20
AD8215
GND
Figure 26. Simplified Schematic
A load current flowing through the external shunt resistor
produces a voltage at the input terminals of the AD8215. The
input terminals are connected to A1 by R and R1. The inverting
terminal, which has very high input impedance, is held to
(VCM) − (ISHUNT × RSHUNT)
because negligible current flows through R. A1 forces the
noninverting input to the same potential. Therefore, the current
that flows through R1 is equal to
IIN = (ISHUNT × RSHUNT)/R1
This current (IIN) is converted back to a voltage via ROUT. The
output buffer amplifier has a gain of 20 V/V and offers excellent
accuracy as the internal gain setting resistors are precision trimmed
to within 0.01% matching. The resulting output voltage is equal to
OUT = (ISHUNT × RSHUNT) × 20
Rev. 0 | Page 10 of 16
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