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# OPA2140: OPA2140 quiescent current

Part Number: OPA2140

Hello,

We have a design where the minimum consumption on both amplifier power supplies (+/-12V) is a key design driver.

-          What is the minimum quiescent current per amplifier to be considered  ? At room temperature and in the whole temperature range ?

-          How is split the quiescent current in both operational amplifier power supplies ?

Best regard,

• Hello Frederic,

A minimum operating current limit is not specified for the OPA2140 as is the case for most op amps and TI makes no datasheet assurances about what it will be for the OPA2140.

Figure 13 in the datasheet, Quiescent Current vs Temperature, shows the "typical" per op amp section quiescent current over temperature. Using the graph you can see that at the minimum temperature of -40 C, the quiescent current is minimum at about 1.4 mA per op amp. When you include the normal variations that occur across manufacturing lots the graph line in Figure 13 can shift up or down. Since you are concerned about minimum current that would be a shift downward for the entire line. Since TI doesn't make any datasheet assurances about minimum current all we can provide is an estimate of that minimum current. A practical estimate is that it might be about 25 % lower than that depicted in the Figure 13 graph.

The current normally splits about 50-50 between the two OPA2140 op amps, and most other dual op amps. That is because the layout of one op amp is almost always the flip of the other so all the active circuits have the same dimensions resulting a close match.

Regards, Thomas

Precision Amplifiers Applications Engineering

1.4mA x 0.75 = 1.05mA minimum is a good estimation per amplifier

Regarding my second question ("How is split the quiescent current in both operational amplifier power supplies"), my question was rather regarding the split of the quiescent current of one given operational amplifier between its two +12V and -12V power supplies ?

best regards

• Hi Frederic,

Actually, if the op amp is not delivering current to a load as in the quiescent state 100% (ideally) of the current sourced from the positive supply (V+) flows through the op amp internal circuits, and then is sunk to the negative supply (V-). Therefore, if you measure 3.0 mA being sourced from the OPA2140 V+ supply, you should measure something very close to 3.0 mA flowing into the (V-) supply.

Once you start sinking and sourcing current load current from an OPA2140 output the V+ and V- operating currents will no longer be equal. That is normal.

Regards, Thomas

Precision Amplifiers Applications Engineering

• Thank you for your valuable information

Best regards