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I'm thinking of buying a pair of L298Ns, to control a pair of 1.6A motors. I'd like to control each motor with a signal PWM wire and a direction wire. However, I've hit a couple of problems.

  1. It is unclear whether the chip includes internal diodes or not. Some sources say yes, some say no. There also seems to be general confusion between the 298 and the 293.
  2. Looks like I need to invert the direction line so that the two inputs are opposite. However, if that messed up, current could flow through the chip.
    • Would pulling the PWM "enable" line low while switching the direction signal solve this?
    • Would a MOSFET be suitable to negate the signal?

Or would I do better just to buy this complete motor driver?

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As far as a reference design, Solarbotics has a pretty solid little breakout board for the L298N. If you don't already have the chips, I would consider purchasing one: Solarbotics L298N.

If you already have the parts, then you could probably follow their design, L298N Schematic

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  • \$\begingroup\$ What does the 2937 chip refer to in their schematic? I can't seem to find it from the number alone... \$\endgroup\$ – Eric Mar 21 '11 at 9:29
  • \$\begingroup\$ It's a 5 Volt linear regulator. \$\endgroup\$ – mjcarroll Mar 21 '11 at 18:54
  • \$\begingroup\$ Never mind, found it. Needed to search for the LM2973. Looks like a voltage regulator, which I already have elsewhere. EDIT: whoops, late post \$\endgroup\$ – Eric Mar 21 '11 at 18:55
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Looked at this the other day for someone -the data sheet's example show the diodes are external

yes you invert the direction line - you can't damage it with having both inputs high or low - it ends up with both ends of the motor wired to gnd or VCC (active braking). Just hook up a TTL inverter, or a simple switching transistor (fet or bipolar) with say a 1k resistor between vcc and the collector and if it's a bipolar transistor something to limit base current

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