Re: [CAD_CAM_EDM_DRO] Re: L297/L298 And a "correction"

Wayne C. Gramlich wrote:

> To the best of my knowledge the LMD18245 is just a
> single H-bridge. For a bi-polar driver, you would need
> two of these. Thus,
>
> 2 x L298 (Jameco: 245403; $2.95 for 1) = ~$6

Wrong - you only need one L298 + the output diodes and large current
sense resistors, against 2 LMD's - parts cost comes to about 5GBP

> versus:
>
> 2 x LMD18245 (Digikey: LMD18245-ND $13.02 for 1) = ~$26

The GBP price each is approaching 12GBP so we are looking at 24GBP but
you do not need any of the output circuitry that you would include with
the L298. I've just kitted for a batch of the EMS driver kits and even
bulk buying the chips, nearly all the cost is the 2 chips :( The only
slight plus is that the pic is cheaper than the L297 ;)

The main difference is however in the fact that the L298 is only 2A and
needs to be kept below 46V and 36V seems a safer limit when using a raw
DC supply, while the LMD18245 will handle 3A at 55V and is quite happy
on a simple 50V supply. And of cause the LMD18245 microsteps!

The 160Ncm motors, which are a nice size to work with and a good price,
run at 2.5A, so while the L298 will drive them, the LMD18245 will give
them a lot more poke. Next step is to see exactly what the performance
difference is :)

--
Lester Caine - G8HFL
-----------------------------
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