How would you define VOL and VOH of inverter?

[alphacat]

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.

[vliang]

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

[retched]

Voltage On Low and Voltage On High will be inverted.

[Ghar]

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

[Papabravo]

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.

[kdillinger]

Originally Posted by Papabravo

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.

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.

[alphacat]

Originally Posted by Papabravo

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.

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?