Datasheet

V
OUT
R =20kW
P
OpAmpV =GND-
OPA330
V
IN
V+=+5V
-5V
Additional
Negative
Supply
R
1
V
EX
V
OUT
V
REF
R
1
OPA330
R
R
R R
+5V
OPA330
ADS1100
Load
V
I C
2
R
1
4.99kW
R
3
4.99kW
R
4
48.7kW
R
2
49.9kW
+5V
3V
REF3130
R
7
1.18kW
R
SHUNT
1W
R
6
71.5kW
R
N
56W
R
N
56W
(PGAGain=4)
FS=3.0V
StrayGround-LoopResistance
I
LOAD
OPA330
OPA2330
OPA4330
www.ti.com SBOS432E –AUGUST 2008–REVISED FEBRUARY 2011
ACHIEVING OUTPUT SWING TO THE OP The OPA330, OPA2330, and OPA4330 have an
AMP NEGATIVE RAIL output stage that allows the output voltage to be
pulled to its negative supply rail, or slightly below,
Some applications require output voltage swings from
using the technique previously described. This
0V to a positive full-scale voltage (such as +2.5V)
technique only works with some types of output
with excellent accuracy. With most single-supply op
stages. The OPA330, OPA2330, and OPA4330 have
amps, problems arise when the output signal
been characterized to perform with this technique; the
approaches 0V, near the lower output swing limit of a
recommended resistor value is approximately 20kΩ.
single-supply op amp. A good single-supply op amp
Note that this configuration will increase the current
may swing close to single-supply ground, but will not
consumption by several hundreds of microamps.
reach ground. The output of the OPA330, OPA2330,
Accuracy is excellent down to 0V and as low
and OPA4330 can be made to swing to ground, or
as –2mV. Limiting and nonlinearity occurs
slightly below, on a single-supply power source. To
below –2mV, but excellent accuracy returns as the
do so requires the use of another resistor and an
output is again driven above –2mV. Lowering the
additional, more negative, power supply than the op
resistance of the pull-down resistor will allow the op
amp negative supply. A pull-down resistor may be
amp to swing even further below the negative rail.
connected between the output and the additional
Resistances as low as 10kΩ can be used to achieve
negative supply to pull the output down below the
excellent accuracy down to –10mV.
value that the output would otherwise achieve, as
shown in Figure 20.
APPLICATION CIRCUITS
Figure 21 shows the basic configuration for a bridge
amplifier.
A low-side current shunt monitor is shown in
Figure 22.
Figure 20. For V
OUT
Range to Ground
Figure 21. Single Op Amp Bridge Amplifier
NOTE: 1% resistors provide adequate common-mode rejection at small ground-loop errors.
Figure 22. Low-Side Current Monitor
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