Datasheet

4
3
2
1
0
1
2
3
4
-
-
-
-
-500
1000
Time( s)m
Voltage(V)
-250 0 750250 500
V
OUT
V
IN
V = 2.5V±
S
R
S
OPA320
V+
V
IN
V
OUT
I
10mA,Max
OVERLOAD
OPA320, OPA2320
OPA320S, OPA2320S
www.ti.com SBOS513E –AUGUST 2010–REVISED JUNE 2013
APPLICATION INFORMATION
RAIL-TO-RAIL INPUT
OPERATING VOLTAGE
The OPA320 product family features true rail-to-rail
input operation, with supply voltages as low as ±0.9V
The OPA320 series op amps are unity-gain stable
(1.8V). The design of the OPA320 amplifiers include
and can operate on a single-supply voltage (1.8V to
an internal charge-pump that powers the amplifier
5.5V), or a split supply voltage (±0.9V to ±2.75V),
input stage with an internal supply rail at
making them highly versatile and easy to use. The
approximately 1.6V above the external supply (V
S+
).
power-supply pins should have local bypass ceramic
This internal supply rail allows the single differential
capacitors (typically 0.001μF to 0.1μF). The OPA320
input pair to operate and remain very linear over a
amplifiers are fully specified from +1.8V to +5.5V and
very wide input common-mode range. A unique zero-
over the extended temperature range of –40°C to
crossover input topology eliminates the input offset
+125°C. Parameters that can exhibit variance with
transition region typical of many rail-to-rail,
regard to operating voltage or temperature are
complementary input stage operational amplifiers.
presented in the Typical Characteristics.
This topology allows the OPA320 to provide superior
common-mode performance (CMRR > 110dB,
INPUT AND ESD PROTECTION
typical) over the entire common-mode input range,
The OPA320 incorporates internal electrostatic
which extends 100mV beyond both power-supply
discharge (ESD) protection circuits on all pins. In the
rails. When driving analog-to-digital converters
case of input and output pins, this protection primarily
(ADCs), the highly linear V
CM
range of the OPA320
consists of current-steering diodes connected
assures maximum linearity and lowest distortion.
between the input and power-supply pins. These ESD
protection diodes also provide in-circuit input
PHASE REVERSAL
overdrive protection, provided that the current is
The OPA320 op amps are designed to be immune to
limited to 10mA as stated in the Absolute Maximum
phase reversal when the input pins exceed the supply
Ratings. Many input signals are inherently current-
voltages, therefore providing further in-system
limited to less than 10mA; therefore, a limiting resistor
stability and predictability. Figure 34 shows the input
is not required. Figure 33 shows how a series input
voltage exceeding the supply voltage without any
resistor (R
S
) may be added to the driven input to limit
phase reversal.
the input current. The added resistor contributes
thermal noise at the amplifier input and the value
should be kept to the minimum in noise-sensitive
applications.
Figure 33. Input Current Protection
Figure 34. No Phase Reversal
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Product Folder Links: OPA320 OPA2320 OPA320S OPA2320S