Hi,
I have an inverting amplifier based on TLE2061AM having gain of G=8. the input is 1 volt AC of 3Khz.Power supply is +/- 15V.
As per datasheet Figure 18, the Aol ~ 58dB @3Khz, 25degC &RL=10k.
In my application my circuit has a resistive load of 600ohm. Can you please give an estimate about the Worst Case Open loop gain variation at 3KHz when the operating temperature is -55degC to +100degC.
Thanks,
Shihab.
Hi Shibab,
The TLE2061 datasheet lists the full over- temperature range minimum Aol values for a 600 Ohm load in the Electrical Characteristics table. That is the extent of the information we have regarding that specific load. Therefore, all we can provide is an estimate of the lowest level that Aol might attain at 3 kHz with the 600 ohm load. The lowest level is the worst-case condition.
The basic Aol curve shown in Fig. 18 will persist even if Aol moves up and down. The dominant pole frequency and -20 dB/ dec roll-off will be consistent with Aol levels that differ from this 10 k-Ohm case.
According to the Electrical Characteristics table the full range minimum Aol for a Vo of 0 to +8 V output and RL= 600 Ohms, is 7 V/mV, or 77 dB. Similarly, for a Vo of 0 to -8 V, the minimum Aol is 1 mV/V, or 60 dB. Graphing curves based on 77 dB and 60 dB Aol levels on top of Fig. 18 shows that the minimum positive swing Aol at 3 kHz can be as low as 20 dB. Using a similar curve for the negative swing condition indicates the Aol may be only a few dB above 0 dB, at 3 kHz. These results would indicate if the Aol really reached that low level the TLE2061 would not be a good choice for the application.
Although not specified in its datasheet with a 600 ohm load, the OPA2171 is a newer design, high performance op amp with good output current drive capability. Its specified temperature range is -40 C to +125 C, but has an operating temperature range from -55 C to +150 C. Here's the datasheet:
Regards, Thomas
PA - Linear Applications Engineering
