[sdiy] 4069 vs 4049

[Magnus Danielson]

From: Scott Gravenhorst <music.maker at gte.net>
Subject: [sdiy] 4069 vs 4049
Date: Sat, 29 Sep 2001 14:10:06

Scott,

> Both are hex inverters, On the 4069, ESD double diodes
> are mentioned in text, but not shown.  The 4049 shows
> the diodes with a resistor from the input pin to the
> gates.  Diode cathodes are on either side of the resistor,
> anodes to Vss.
> 
> It looks like the 69 has lower input capacitance and
> lower supply current than the 49.

The 4049UB has an input protection consisting of a resistor with a
distributed diode to ground and directly on the input a diode pair
(back to back in opposite direction) to the Vcc. After the
resistor/distributed diode setup the signal reached the gates of a P/N
FET pair which are the output transistors. There is a separate
protection diode between Vcc and ground in order to protect for
incorrect voltages.

The 4069UB has an input protection consisting of a resistor with a
distributed diode to Vdd and a diode directly from the input to the
ground. The actual inverter stage is similar to that of the 4049UB.

The main difference between them lies in the transistors of the
inverter stage where the 4069UB is symmetrical where as the 4049UB is
not symmetrical. The reason for the 4049UB to be non-symmetrical is
that it is intended for CMOS-to-TTL conversions.

It is also time to note that the 4009UB is also not symmetrical in
output and is also intended for CMOS-to-TTL conversions. However, the
internal topology of a 4009UB is quite different to that of the 4049
and 4069 since it uses no less than 5 FETs per inverter as compared to
the classical 2 which the 4049 and 4069 uses.

> I have 49s, is there a reason why a 49 wouldn't work
> in place of the 69 in the René's 4069?

I would stick to the 4069s.

Cheers,
Magnus