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OPA378_1 Datasheet, PDF (13/24 Pages) Texas Instruments – Low-Noise, 900kHz, RRIO, Precision OPERATIONAL AMPLIFIER Zerø-Drift Series
OPA378
OPA2378
www.ti.com ..................................................................................................................................................... SBOS417C – JANUARY 2008 – REVISED JUNE 2009
Load
V
ILOAD
RSHUNT
1W
R1
4.99kW
R3
4.99kW
3V
+5V
REF3330
R2
49.9kW
RS
100W
R6
71.5kW
RN
56W
OPA378
R4
48.7kW
C1
7nF
ADS8325
RN
I2C
56W
Stray Ground-Loop Resistance
R7
1.18kW
(PGA Gain = 4)
FS = 3.0V
NOTE: 1% resistors provide adequate common-mode rejection at small ground-loop errors.
Figure 31. Low-Side Current Monitor
RG
RSHUNT
zener(1)
R1(2)
10kW
V+
OPA378
CBYPASS
MOSFET rated to
stand-off supply voltage
such as BSS84 for
up to 50V.
+5V
V+
Two zener
biasing methods
are shown.(3)
Load
RBIAS
Output
RL
(1) Zener rated for op amp supply capability (that is, 5.1V for the OPA378).
(2) Current-limiting resistor.
(3) Choose zener biasing resistor or dual NMOSFETs (FDG6301N, NTJD4001N, or Si1034).
Figure 32. High-Side Current Monitor
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Product Folder Link(s): OPA378 OPA2378