Hola!
I am looking at Texas Instrument's CD74HC538 monostable multivibrator. Going thru the datasheet, I noticed that it does not have anything for Voh (high level output voltage for TTL loads) at VCC ranges lower than
4.5V.Does that mean that I won't be able to drive a TTL switch if my voltage supply range is around 3V?
I found an analog switch also on Texas Instruments that work at 3V, but it is labeled as having a TTL input. I wanted to interface this with multivibrator.
Any hints?
Gracias!
The standard TTL (SN54) is not specified with the Vcc below 4.5V - that's probably the reason why the CD74HC4538 is not specified neither with TTL loads with the Vcc below 4.5V.
It could work, but is not specified.
What is the part number ?
-- Andy
Hello Andy!
The switch part number is TS5A3159. It does not say that it has a TTL Control Input feature on the datasheet, but it states this in the TI Analog Switch Guide.
I'm new to this CMOS to TTL interfacing. After giving it much thought, the TI selection guide probably meant that TTL devices can also drive the switch (?). I figured since CMOS devices normally have voltage high outputs close to VCC and voltage low outputs close to VSS (GND), the voltage input high and voltage input low specifications for the TS5A3159 will be within the CD74HC538 voltage high and low output range, no?
Thanks!
Most certainly, I have not looked through the guide, but the input logic thresholds of the TS5A3159 at 5V suppy (4.5 to 5.5v) match the standard TTL output specifications.
Look at the input logic voltage specifications of the TS5A3159, for the
3.3V supply. For the Vcc range from 3.0 to 3.6V, the input logic high is >=2V, the input logic low is
-- CD4538B
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