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# SN74AHC1G04: SN74AHC1G04DCKR - The variability of output resistance

Part Number: SN74AHC1G04

Hello,
I have a request about SN74AHC1G04.

Is there the following data?
・The variability of output resistance.
For example, 70Ω(High) 45Ω(Low) @25℃
or
・Vo (output voltage) vs Io (output current)  High and Low

[supplementary explanation]
In brief, for a 1mA load, I want to know how output voltage variability turns out.
I OK even it if I understand output resistance (I calculate in I*R).
Or by the specification of Vo vs Io, I can estimate output Z equally.

Regards,
Dice-K

• Hi Dice-K,

I'm afraid I don't have data on that in particular, however at a 1mA load, you would expect to see a very small voltage drop at the output of the SN74AHC1G04 -- typically less than 0.1V.

If you are attempting to impedance match this device, I would recommend testing various values on a prototype board. I have seen good matching with ~33 ohms in series for a 50 ohm transmission line.

Also, just to mention, it is _extremely_ uncommon to find a logic circuit that truly requires impedance matching. It is true that feeding a logic signal into a 50 ohm transmission line will result in some ringing on the distant end, however the noise margins are sufficient in typical logic inputs to eliminate any problems from that.
• Hello Emrys,

I want the structure of Output Stage.

"Simplified Output Stage of an AHC Circuit" is described in SCAA034C.

www.ti.com/.../scaa034c.pdf

Is there a detailed Output Stage structure?

Best regards,
Dice-K

• The AHC(T) Designer's Guide (SCLA013) is a little bit more detailed:

• I'm afraid that the internal structure of our devices isn't something I can share publicly.

Can you share the application you are working on that requires such intricate detail for a simple logic inverter?
• See these application reports:
Input and Output Characteristics of Digital Integrated Circuits at 5-V Supply Voltage (SZZA008)
Input and Output Characteristics of Digital Integrated Circuits at 3.3-V Supply Voltage (SZZA010)
Input and Output Characteristics of Digital Integrated Circuits at 2.5-V Supply Voltage (SZZA012)