OPERATING VOLTAGE
LOW VOLTAGE OPERATION
SINGLE-SUPPLY OPERATION
INA333
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INA333
10kW
Microphone,
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Thermocouple
INA333
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INPUT COMMON-MODE RANGE
INA333
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...................................................................................................................................................................................................... SBOS445 – JULY 2008
The INA333 operates over a power-supply range of
+1.8V to +5.5V ( ± 0.9V to ± 2.75V). Supply voltages
higher than +7V (absolute maximum) can
permanently damage the device. Parameters that
vary over supply voltage or temperature are shown in
the Typical Characteristics section of this data sheet.
The INA333 can be operated on power supplies as
low as ± 0.9V. Most parameters vary only slightly
throughout this supply voltage range — see the Typical
Characteristics section. Operation at very low supply
voltage requires careful attention to assure that the
input voltages remain within the linear range. Voltage
swing requirements of internal nodes limit the input
common-mode range with low power-supply voltage.
The Typical Characteristic curves Typical
Common-Mode Range vs Output Voltage (Figure 20
to Figure 23 ) show the range of linear operation for
various supply voltages and gains.
The INA333 can be used on single power supplies of
+1.8V to +5.5V. Figure 35 illustrates a basic
Figure 34. Providing an Input Common-Mode
single-supply circuit. The output REF terminal is
Current Path
connected to mid-supply. Zero differential input
voltage demands an output voltage of mid-supply.
Actual output voltage swing is limited to
approximately 50mV above ground, when the load is
referred to ground as shown. The typical
The linear input voltage range of the input circuitry of
characteristic curve Output Voltage Swing vs Output
the INA333 is from approximately 0.1V below the
Current (Figure 29 ) shows how the output voltage
positive supply voltage to 0.1V above the negative
swing varies with output current.
supply. As a differential input voltage causes the
output voltage to increase, however, the linear input
With single-supply operation, V
IN+
and V
IN –
must both
range is limited by the output voltage swing of
be 0.1V above ground for linear operation. For
amplifiers A
1
and A
2
. Thus, the linear common-mode
instance, the inverting input cannot be connected to
input range is related to the output voltage of the
ground to measure a voltage connected to the
complete amplifier. This behavior also depends on
noninverting input.
supply voltage — see Typical Characteristic curves
Typical Common-Mode Range vs Output Voltage To illustrate the issues affecting low voltage
(Figure 20 to Figure 23 ). operation, consider the circuit in Figure 35 . It shows
the INA333 operating from a single 3V supply. A
Input overload conditions can produce an output
resistor in series with the low side of the bridge
voltage that appears normal. For example, if an input
assures that the bridge output voltage is within the
overload condition drives both input amplifiers to the
common-mode range of the amplifier inputs.
respective positive output swing limit, the difference
voltage measured by the output amplifier is near
zero. The output of the INA333 is near 0V even
though both inputs are overloaded.
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