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Old 22nd Nov 2018, 12:25 am   #11
Argus25
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Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: Quick query: IC with 2 ENA pins and at least 2 input / outputs

Al,

I'm not sure exactly what you are trying to do but I assume you are looking for a simpler way to replace the UCC37321/2 driver IC's ?

74 or 74S, 74LS etc has an unsuitable output stage as they only sink current well and cannot source it well and the output voltage when high is only around 3.6V on a 5V supply rail. If you were driving an actual fet gate your driver has to be able to sink & source current well to be able to charge and discharge the power Mosfet's gate capacitance, if used as a gate driver. If you went to 74HC series IC's you get the rail to rail output swing and it would help, and if you are driving that from TTL you should have a pullup resistor on the inputs, or use the 74HCT series IC's.

Looking at those UCC37322 IC's they have a transistor assisted mosfet output stage so clearly they were designed for a very low Z output and handle high peak currents and a high capacitive load on their outputs. The circuit you have shows them driving a coil/transformer, but I see from diagrams they often feed heavy capacitive loads in power supplies and they could drive mosfet gates well directly. Perhaps this was a circuit where some high voltage isolation of the drive was required.

To make a circuit you can enable you can use the Nand as suggested, perhaps 74HC00 then it might or might not be better to invert that with a 74HC14 schmitt trigger inverting buffer to be sure there are sharp rises and falls on the outputs. But whether the output stage of a 74HC series IC is up to your task, I cannot be sure.

Hugo

Last edited by Argus25; 22nd Nov 2018 at 12:33 am.
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