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"Chapter 1 - The Op Amp's Place in the World" - HTL Wien 10

"Chapter 1 - The Op Amp's Place in the World" - HTL Wien 10

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<strong>Op</strong>erational Amplifier Parameter Glossary<br />

PARAMETER ABBV UNITS DEFINITION INFO<br />

Output current IO mA<br />

Output impedance Zo Ω<br />

Output resistance ro Ω<br />

Overshoot factor – –<br />

Phase marg<strong>in</strong> Φm °<br />

Power supply rejection ratio PSRR dB<br />

Rise time tr nS<br />

Settl<strong>in</strong>g time ts nS<br />

Short-circuit output current IOS mA<br />

Slew rate SR V/µs<br />

Storage temperature TS °C<br />

Supply current ICC/IDD mA<br />

Supply current (shutdown)<br />

ICC–/<br />

IDD–<br />

SHDN<br />

mA<br />

<strong>The</strong> amount of current that is drawn from <strong>the</strong> op amp output.<br />

Usually specified as an absolute maximum rat<strong>in</strong>g — not for<br />

long term operation at <strong>the</strong> specified level.<br />

<strong>The</strong> frequency dependent small-signal impedance that is<br />

placed <strong>in</strong> series with an ideal amplifier and <strong>the</strong> output term<strong>in</strong>al.<br />

<strong>The</strong> dc resistance that is placed <strong>in</strong> series with an ideal amplifier<br />

and <strong>the</strong> output term<strong>in</strong>al.<br />

<strong>The</strong> ratio of <strong>the</strong> largest deviation of <strong>the</strong> output voltage from its<br />

f<strong>in</strong>al steady-state value to <strong>the</strong> absolute value of <strong>the</strong> step after<br />

a step change at <strong>the</strong> output.<br />

<strong>The</strong> absolute value of <strong>the</strong> open-loop phase shift at <strong>the</strong> frequency<br />

where <strong>the</strong> open-loop amplification first equals one.<br />

<strong>The</strong> absolute value of <strong>the</strong> ratio of <strong>the</strong> change <strong>in</strong> supply voltages<br />

to <strong>the</strong> change <strong>in</strong> <strong>in</strong>put offset voltage. Typically both supply<br />

voltages are varied symmetrically. Unless o<strong>the</strong>rwise<br />

noted, both supply voltages are varied symmetrically.<br />

<strong>The</strong> time required for an output voltage step to change from<br />

<strong>10</strong>% to 90% of its f<strong>in</strong>al value.<br />

With a step change at <strong>the</strong> <strong>in</strong>put, <strong>the</strong> time required for <strong>the</strong> output<br />

voltage to settle with<strong>in</strong> <strong>the</strong> specified error band of <strong>the</strong> f<strong>in</strong>al<br />

value. Also known as total response time, ttot.<br />

<strong>The</strong> maximum cont<strong>in</strong>uous output current available from <strong>the</strong><br />

amplifier with <strong>the</strong> output shorted to ground, to ei<strong>the</strong>r supply, or<br />

to a specified po<strong>in</strong>t. Sometimes a low value series resistor is<br />

specified.<br />

<strong>The</strong> rate of change <strong>in</strong> <strong>the</strong> output voltage with respect to time<br />

for a step change at <strong>the</strong> <strong>in</strong>put.<br />

Temperature over which <strong>the</strong> op amp may be stored for long<br />

periods of time without damage.<br />

<strong>The</strong> current <strong>in</strong>to <strong>the</strong> VCC+/VDD+ or VCC–/VDD– term<strong>in</strong>al of <strong>the</strong><br />

op amp while it is operat<strong>in</strong>g.<br />

<strong>The</strong> current <strong>in</strong>to <strong>the</strong> VCC+/VDD+ or VCC–/VDD– term<strong>in</strong>al of <strong>the</strong><br />

amplifier while it is turned off.<br />

Understand<strong>in</strong>g <strong>Op</strong> Amp Parameters<br />

11.3.8<br />

11.3.15<br />

11.3.<strong>10</strong><br />

11.3.12<br />

Supply rejection ratio kSVR dB (see power supply rejection ratio) 11.3.<strong>10</strong><br />

Supply voltage sensitivity<br />

Supply voltage<br />

Temperature coefficient of<br />

<strong>in</strong>put offset current<br />

kSVS,<br />

∆VCC±,<br />

∆VDD±,<br />

or ∆VIO<br />

VCC/<br />

VDD<br />

αIIO<br />

dB<br />

V<br />

µA/°C<br />

<strong>The</strong> absolute value of <strong>the</strong> ratio of <strong>the</strong> change <strong>in</strong> <strong>in</strong>put offset<br />

voltage to <strong>the</strong> change <strong>in</strong> supply voltages.<br />

Bias voltage applied to <strong>the</strong> op amp power supply p<strong>in</strong>(s). Usually<br />

specified as a ± value, referenced to network ground.<br />

<strong>The</strong> ratio of <strong>the</strong> change <strong>in</strong> <strong>in</strong>put offset current to <strong>the</strong> change <strong>in</strong><br />

free-air temperature. This is an average value for <strong>the</strong> specified<br />

temperature range.<br />

11.3.<strong>10</strong><br />

11.3.2<br />

11-5

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