RE: [CAD_CAM_EDM_DRO] Re: stepper driver help

The L298 can do 2-3 A (depending on duty cycle) *or* 46 V, but not at the
same time. It's limited to 25 Watts, ie 3 A @ 8.3 V or 0.5 A at 46 V.
And that's *total* power dissipation, the L298 has two internal H-bridges,
so if you use both you're limited to 12.5 Watts per H-bridge.

[Paul Kelly] Ahhh,, no. Those equations only come into play when it's
switching.
The dissipation is Volts (across the device) * Amps. As each leg of the
bridges turns on and off (which they do a lot for current control) there is
a time when the voltage and current are both high, heat is generated then.
When the 298 is conducting, you might see 1 or 2 volts across it.
With a small heatsink I run 298's at 2A and 38V in my lathe all day.
I highly recommend implementing idle current reduction. It slashes the heat
dissipation requirements of any stepper driver.

PK

Source: the ST Microelectronics L298 Data Sheet
<http://www.st.com/stonline/products/literature/ds/1773/l298.pdf>

If anyone knows how to push the L298 design to 138 Watt (3 A @ 46 V),
I'd love to hear it.


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Sebastian Kuzminsky


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