OPA1652_16 Datasheet, PDF (17/42 Pages) Texas Instruments – Audio Operational Amplifiers

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OPA1652, OPA1654
SBOS477A – DECEMBER 2011 – REVISED AUGUST 2016
Feature Description (continued)
Another common question involves what happens to the amplifier if an input signal is applied to the input when
the power supplies (V+ or V–) are at 0 V. Again, this question depends on the supply characteristic when at 0 V,
or at a level below the input signal amplitude. If the supplies appear as high impedance, then the input source
supplies the operational amplifier current through the current-steering diodes. This state is not a normal bias
condition; most likely, the amplifier does not operate normally. If the supplies are low impedance, then the current
through the steering diodes can become quite high. The current level depends on the ability of the input source
to deliver current, and any resistance in the input path.
If there is any uncertainty about the ability of the supply to absorb this current, add external Zener diodes to the
supply pins; see Figure 37. Select the Zener voltage so that the diode does not turn on during normal operation.
However, the Zener voltage must be low enough so that the Zener diode conducts if the supply pin begins to rise
above the safe-operating, supply-voltage level.
7.4 Device Functional Modes
7.4.1 Operating Voltage
The OPA165x series op amps operate from ±2.25 V to ±18 V supplies while maintaining excellent performance.
The OPA165x series can operate with as little as +4.5V between the supplies and with up to +36 V between the
supplies. However, some applications do not require equal positive and negative output voltage swing. With the
OPA165x series, power-supply voltages do not need to be equal. For example, the positive supply could be set
to +25 V with the negative supply at –5 V.
In all cases, the common-mode voltage must be maintained within the specified range. In addition, key
parameters are assured over the specified temperature range of T_A = –40°C to +85°C. Parameters that vary
significantly with operating voltage or temperature are shown in the Typical Characteristics.
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