L298 Flyback Diodes

Hi,

Am building a Dcc model train controller using a L298 as the output stage which feeds its output onto the rails. The pulses are received by decoders in the locos, the input to which is typically a bridge recitifer.

Because there is no direct motor connection to the L298 is it still necessary to fit the Flyback diodes ?

Have seen several working designs, some fitted with these diodes, some without ...?

Thanks

Your train motor is inductive. I would use the diodes.

why won't that piece of crap die???? the L29x family of motor chips are GARBAGE!!!

ST L297 $10 +L289 $5 for 4A TOTAL current + flyback diodes and a heatsink, half stepping

Allegro A3982 $6 1.5A per coil, synchronous flyback (no diodes required) and microstepping included!

Diodes are a good idea, but since there is a lot of electronics between the DCC powered track and any motor, I see no harm in leaving them out. It would be good to have them if there are any other loads powered by the track.

Ubergeek63 said:

why won't that piece of crap die???? the L29x family of motor chips are GARBAGE!!!

ST L297 $10 +L289 $5 for 4A TOTAL current + flyback diodes and a heatsink, half stepping

Allegro A3982 $6 1.5A per coil, synchronous flyback (no diodes required) and microstepping included!

Click to expand...

The DCC model train system is not a stepper motor. Microstepping would certainly screw it up.

mneary said:

Diodes are a good idea, but since there is a lot of electronics between the DCC powered track and any motor, I see no harm in leaving them out. It would be good to have them if there are any other loads powered by the track.The DCC model train system is not a stepper motor. Microstepping would certainly screw it up.

Click to expand...

so use a DC PWM version of the chip, the fact remains that the L298 chip is an archaic piece of junk. ... sorry I just equated the two since they are normally used together