TYPICAL CHARACTERISTICS (Cont.)
At TA = +25°C, VS = +5V, RL = 10kΩ connected to VS /2, and VOUT = VS /2, unless otherwise noted.
SETTLING TIME vs CLOSED-LOOP GAIN
COMMON-MODE RANGE vs SUPPLY VOLTAGE
Maximum Common-Mode
100
10
1
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
Unity-gain
requires one
complete Auto-Zero
Cycle—see text.
0.01%
0.1%
Minimum Common-Mode
–0.5
1
10
Gain (V/V)
100
2.7
3.2
3.7
4.2
4.7
5.2 5.5
Supply Voltage (V)
OPA334 ENABLE FUNCTION
APPLICATIONS INFORMATION
The enable/shutdown digital input is referenced to the V–
supply voltage of the amp. A logic high enables the op amp. A
valid logic high is defined as > 75% of the total supply voltage.
Thevalidlogichighsignalcanbeupto5.5Vabovethenegative
supply, independent of the positive supply voltage. A valid
logic low is defined as < 0.8V above the V– supply pin. If dual
orsplitpowersuppliesareused,besurethatlogicinputsignals
are properly referred to the negative supply voltage. The
Enable pin must be connected to a valid high or low voltage, or
driven, not left open circuit.
The OPA334 and OPA335 series op amps are unity-gain
stable and free from unexpected output phase reversal. They
use auto-zeroing techniques to provide low offset voltage
and very low drift over time and temperature.
Good layout practice mandates use of a 0.1µF capacitor
placed closely across the supply pins.
For lowest offset voltage and precision performance, circuit
layout and mechanical conditions should be optimized. Avoid
temperature gradients that create thermoelectric (Seebeck)
effects in thermocouple junctions formed from connecting
dissimilar conductors. These thermally-generated potentials
can be made to cancel by assuring that they are equal on
both input terminals.
The logic input is a high-impedance CMOS input, with sepa-
rate logic inputs provided on the dual version. For battery-
operated applications, this feature can be used to greatly
reduce the average current and extend battery life.
• Use low thermoelectric-coefficient connections (avoid dis-
similar metals).
The enable time is 150µs, which includes one full auto-zero
cycle required by the amplifier to return to VOS accuracy.
Prior to this time, the amplifier functions properly, but with
unspecified offset voltage.
• Thermally isolate components from power supplies or
other heat-sources.
Disable time is 1µs. When disabled, the output assumes a
high-impedance state. This allows the OPA334 to be oper-
ated as a gated amplifier, or to have the output multiplexed
onto a common analog output bus.
• Shield op amp and input circuitry from air currents, such as
cooling fans.
Following these guidelines will reduce the likelihood of junc-
tions being at different temperatures, which can cause ther-
moelectric voltages of 0.1µV/°C or higher, depending on
materials used.
INPUT VOLTAGE
The input common-mode range extends from (V–) – 0.1V to
(V+) – 1.5V. For normal operation, the inputs must be limited
to this range. The common-mode rejection ratio is only valid
within the valid input common-mode range. A lower supply
voltage results in lower input common-mode range; there-
fore, attention to these values must be given when selecting
the input bias voltage. For example, when operating on a
single 3V power supply, common-mode range is from 0.1V
below ground to half the power-supply voltage.
OPERATING VOLTAGE
The OPA334 and OPA335 series op amps operate over a
power-supply range of +2.7V to +5.5V (±1.35V to ±2.75V).
Supply voltages higher than 7V (absolute maximum) can
permanently damage the amplifier. Parameters that vary
over supply voltage or temperature are shown in the Typical
Characteristics section of this data sheet.
OPA334, OPA2334, OPA335, OPA2335
7
SBOS245D
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