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SN74LV123A-Q1: VOH (min) at the condition of Vcc=3.3V, IOH=-70uA

Ryuji
Guru 20090 points
Part Number: SN74LV123A-Q1

Hello,

I have some questions about VOH specification of SN74LV123A-Q1

(1) VOH at IOH=-50uA
In the datasheet P.5, VOH(min) at IOH=-50uA is 0.1V.
I think that the specification is typo. 
Could you please let me know the correct value ? Is it Vcc-0.1V?

(2)VOH(min) at IOH=-70uA, Vcc=3.3V
Could you please let me know the VOH(min) at the condition of IOH=-70uA, Vcc=3.3V?
Our customer connected the device which have 2.1V(min) of VIH.
Could you please let me know the maximum IOH for ensure 2.1V VOH at Vcc=3.3V?

Best Regards,
Ryuji 

  • 0
    TI__Guru* 97046 points

    Hello Ryuji-san,

    For (1), you are correct that there is an error in the datasheet.  It definitely should say "Vcc - 0.1" and not just "0.1"

    Thank you for identifying this  --  we will correct this error as soon as possible.

    For (2), we would not expect a significant difference between a 70 uA load versus a 50 uA load. Typically, in either case, the output high voltage (VOH) will be approximately Vcc.  Note that this device has a rated VOH (3V @ 6mA) of 2.48 V, which means the output FET's resistance is approximately R = (Vcc - VOH)/IOH = (3-2.48)/0.006 = 86.67 ohms.

    As Vcc increases, this value will decrease, however we will use the same value to estimate the output voltage.

    VOH at 70uA will be expected to be VOH = Vcc - (R*IOH) = 3.3 - (86.67 * 0.000070) ~= 3.294 V.

    The value of "Vcc - 0.1 V " is very exaggerated and is given on basically every datasheet for logic devices as the limit for low current.  This is partially due to variation across devices and change in behavior of the output as it approaches zero current (there is some small drop across components in the device), however -- as I mentioned above, the output at low current will typically be ~Vcc.

    We also have an FAQ page that talks about how VOH is derived here: