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Hello,
is it possible to get the VCM, (input voltage range, datasheet, 6.8 Electrical characteristics, page 6/27), voltage in more detail ? Especially the (V+)-2.0V, is that valid at -40deg C ? How is this voltage at 0 deg C ? And at other temperatures ? A diagram of V_CM = f( temp) would be helpful. Is it possible to get this ?
Thanks in advance, Martin
See sections 3.4 and 3.6 of the Application Design Guidelines for LM339, LM393, TL331 Family Comparators, which is linked to from the product page.
Hello Martin,
As Clemens showed, this is all explained in the Appnote:
Application Design Guidelines for LM339, LM393, TL331 Family Comparators
No, we do not have a graph of the VCM limit over temp. But it does creep away from V+ as you go colder at -4mV/ °C. So going cold needs more headroom, hence the Vcc-2V over temp to cover the cold range. Figure 3-4 gives a graphical representation of the common mode limits.
It sounds like you are trying to push the VCM limits. We really do not recommend that. We will only warrantee the Vcc-2V over temp.
If your supply voltage is 5V and under, you could use the TL331LV, which is rail-to-rail input and does not have the Vcc-2V limit.
If the supply is over 5V, take a look at the TLV1821 family, which also has R-R inputs and up to 40V operation.