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I use a L293D to drive a 7.4V (280mA/phase) stepper motor. I rotate the small motor 1 rev per DAY. The L293D is hot all the time even though the motor turns only once per day. I saw there are “Enable” pins, and I keep them high all the time.

If I set the Enable pins LOW most of the day, will this reduce the heat I feel on the chip?

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The enable pin can disable the output driver. Turning off the output drivers will reduce the current consumption of the unit.

However, it will also remove all torque from the motor and put in free-running as described in Table 3 of TI's datasheet.

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  • \$\begingroup\$ Hmm, then to keep the chip completely cool most of the day, maybe I could apply 7V to the chip’s Vcc2 pin with a relay? Basically, having 0V to Vcc2 most of the day and using the relay to apply 7V to Vcc2 when I need to turn the motor. For now, I just use a heat sink. \$\endgroup\$ – Donn Lee Nov 19 '18 at 20:51
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    \$\begingroup\$ "However, it will also remove all torque from the motor..." All of the stepper motors I've used or touched have had quite healthy cogging torque, even when they're unpowered. I'd check to see if the stepper has sufficient holding torque when it isn't powered, and maybe go shopping for one with more if it doesn't. \$\endgroup\$ – TimWescott Nov 19 '18 at 21:12
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    \$\begingroup\$ @DonnLee About powering-down Vcc2 with a relay ...data sheet says that Vcc2 should always be equal to, or greater than Vcc1 (+5v). I take it that "bad things" could happen if you try to shut Vcc2 down completely. \$\endgroup\$ – glen_geek Nov 19 '18 at 22:31

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