Other Parts Discussed in Thread: TL074, LM358,
Hello,
Why does the pspice model of the TL074 not work in single supply?
The same simulation with the LM358 model works
Thanks for your helpSimu.docx
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See the attached modeltl07xh_tl08xh_a.lib
Hi Kai,
Section8.4 Device Functional Modes
These devices are powered on when the supply is connected. These devices can be operated as a single-supply.
I don't understand, why it does not work in single supply?
I have trouble understanding this notion: the TL074H is not an input rail-to-rail OPAmp. Section 6.5 of datasheet recommends an input voltage range of (VCC–) + 2V to (VCC+) + 0.1V. Can you explain me
Thank you
Hello Druilhe,
TL074H has a single pair of NMOS transistors on the inputs. Transistors need some headroom to operate. When input voltage gets too close to VCC- pin (ground in single supply), the transistor will cut off (become like open circuit). At this time output is abraitary; it may want to go low or high. Very unlikely would be alternating both low and high in a noise pattern.
In summary TL074H does work in single supply, if common voltage is correct.
Hello Ron,
If I understand correctly, if the power supply voltage Vcc- = 0V, the voltage on the +and- pins of the AOP must be at least 2V for the input stage to be correctly polarized
Yes, that is true. Below 2V the offset voltage becomes worse, below 1V the output could phase reverse. So design application for 2V or greater.