How would you define VOL and VOH of inverter?

Discussion in 'Homework Help' started by alphacat, Mar 10, 2010.

1. alphacat Thread Starter Active Member

Jun 6, 2009
186
0
I'm learning about inverters and I know that when:
Vin = VOL, Vout = VOH
&
Vin = VOH, Vout = VOL

However, what is the meaning of each of them?

Thanks.

2. vliang New Member

Mar 9, 2010
2
0
are you saying about TTL logic gates? inverter? symbol with a triangle and a small circle?

if it is, which from my knowledge, i'm using 74ls00 or 74ls04(forgot which is NOT/inverter and which is NAND)

when an input of 2.5~5v(i'm not sure the max input but too high will break the chip), the out put will be around 0.3v

When and input of 0~0.8v, the out put will give 5V.

This actually means there will be a grey region of 0.8V~2.5v.

In this grey region, the output will still be around 0.3v(i'm not very sure about this last statement)

Hope it helps

3. retched AAC Fanatic!

Dec 5, 2009
5,197
315
Voltage On Low and Voltage On High will be inverted.

4. Ghar Active Member

Mar 8, 2010
655
73
It's just the name of the output voltage level. The actual numbers depend on the circuit. Like vliang mentioned, a low output isn't necessarily 0 volts, just like a high output isn't necessarily your supply voltage.

VOH = output high
VOL = output low

5. Papabravo Expert

Feb 24, 2006
12,288
2,727
VOH is the minimum output high voltage of the inverter.
VOL is the maximum output low voltage of the inverter.

When you connect the output of the inverter to another logic circuit, you must insure that the following inequalities hold:

1. VOH > VIH
2. VOL < VIL
As you might suspect VIH is the minimum Input High voltage of a logic gate, and VIL is the maximum input low voltage. Here is the really important point: Any voltage between VIL and VIH is no mans land. A voltage in that range will result in an unpredictable output. This may happen with a disabled tri-state output when it is in the high impedance state.

6. kdillinger Active Member

Jul 26, 2009
141
3
If you now the thresholds, L's and W's you can calculate the output voltage.

It is also a point where Icc is high.

7. alphacat Thread Starter Active Member

Jun 6, 2009
186
0
wow, thank you very much for explaining it to me.

Are there terms for 'Minumum Output High Voltage' and 'Maximum Output Low Voltage'?

I assume that:
'Minumum Output High Voltage' = Vout(Vin=VIL)
'Maximum Output Low Voltage' = Vout(Vin=VIH)
Right?