Datasheet

CORE
-In
+In
Clamp
10kW
10kW
5kW
OPA330
10mAmax
+5V
V
IN
V
OUT
I
OVERLOAD
Current-limitingresistor
requiredifinputvoltage
exceedssupplyrailsby
³ 0.3V.
OPA330
OPA2330
OPA4330
SBOS432E –AUGUST 2008– REVISED FEBRUARY 2011 www.ti.com
APPLICATIONS INFORMATION
The OPA330, OPA2330, and OPA4330 are unity-gain
INPUT DIFFERENTIAL VOLTAGE
stable, precision operational amplifiers free from
The typical input bias current of the OPA330 during
unexpected output and phase reversal. The use of
normal operation is approximately 200pA. In
proprietary Zerø-Drift circuitry gives the benefit of low
over-driven conditions, the bias current can increase
input offset voltage over time and temperature, as
significantly (see Figure 17).The most common cause
well as lowering the 1/f noise component. As a result
of an over-driven condition occurs when the op amp
of the high PSRR, these devices work well in
is outside of the linear range of operation. When the
applications that run directly from battery power
output of the op amp is driven to one of the supply
without regulation. The OPA330 family is optimized
rails the feedback loop requirements cannot be
for low-voltage, single-supply operation. These
satisfied and a differential input voltage develops
miniature, high-precision, low quiescent current
across the input pins. This differential input voltage
amplifiers offer high-impedance inputs that have a
results in activation of parasitic diodes inside the front
common-mode range 100mV beyond the supplies
end input chopping switches that combine with 10kΩ
and a rail-to-rail output that swings within 100mV of
electromagnetic interference (EMI) filter resistors to
the supplies under normal test conditions. The
create the equivalent circuit shown in Figure 19.
OPA330 series are precision amplifiers for
Notice that the input bias current remains within
cost-sensitive applications.
specification within the linear region.
OPERATING VOLTAGE
The OPA330 series op amps can be used with single
or dual supplies from an operating range of V
S
=
+1.8V (±0.9V) up to +5.5V (±2.75V). Supply voltages
greater than +7V can permanently damage the
device. See the Absolute Maximum Ratings table.
Key parameters that vary over the supply voltage or
Figure 19. Equivalent Input Circuit
temperature range are shown in the Typical
Characteristics section of this data sheet.
INTERNAL OFFSET CORRECTION
INPUT VOLTAGE
The OPA330, OPA2330, and OPA4330 op amps use
The OPA330, OPA2330, and OPA4330 input
an auto-calibration technique with a time-continuous
common-mode voltage range extends 0.1V beyond
125kHz op amp in the signal path. This amplifier is
the supply rails. The OPA330 is designed to cover
zero-corrected every 8μs using a proprietary
the full range without the troublesome transition
technique. Upon power-up, the amplifier requires
region found in some other rail-to-rail amplifiers.
approximately 100μs to achieve specified V
OS
accuracy. This design has no aliasing or flicker noise.
Typically, input bias current is about 200pA; however,
input voltages exceeding the power supplies can
EMI SUSCEPTIBILITY AND INPUT FILTERING
cause excessive current to flow into or out of the
input pins. Momentary voltages greater than the
Operational amplifiers vary in their susceptibility to
power supply can be tolerated if the input current is
EMI. If conducted EMI enters the operational
limited to 10mA. This limitation is easily accomplished
amplifier, the dc offset observed at the amplifier
with an input resistor, as shown in Figure 18.
output may shift from its nominal value while the EMI
is present. This shift is a result of signal rectification
associated with the internal semiconductor junctions.
While all operational amplifier pin functions can be
affected by EMI, the input pins are likely to be the
most susceptible. The OPA330 operational amplifier
family incorporates an internal input low-pass filter
that reduces the amplifier response to EMI. Both
common-mode and differential mode filtering are
provided by the input filter. The filter is designed for a
cutoff frequency of approximately 8MHz (–3dB), with
a roll-off of 20dB per decade.
Figure 18. Input Current Protection
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Product Folder Link(s): OPA330 OPA2330 OPA4330