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| A question about motor driver ICs |
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| Prithul0218:
A typical h-bridge DC motor driver IC has two voltage pins. One is the logic voltage and the other is the voltage used to power the motors. Like - L293, L298, TB6612. Why do they need the voltage for motor to always be slightly (2-3V) higher than the logic voltage? I've attached datasheet for the L298 below.http://cloud.tapatalk.com/s/5c34267fca44c/L298_H_Bridge.pdf |
| spec:
Hi Prithul0218 --- Quote from: Prithul0218 on January 08, 2019, 04:26:42 am ---A typical h-bridge DC motor driver IC has two voltage pins. One is the logic voltage and the other is the voltage used to power the motors. Like - L293, L298, TB6612. Why do they need the voltage for motor to always be slightly (2-3V) higher than the logic voltage? I've attached datasheet for the L298 below.http://cloud.tapatalk.com/s/5c34267fca44c/L298_H_Bridge.pdf --- End quote --- There is no absolute reason why the two voltages cannot be independent. It is just that the designers probably found the chip design easier with the +2V3 stipulation. |
| Ian.M:
Back in the old days before LiPOs there wasn't much demand for motor drivers with Vmotor <= Vlogic. If you needed one, then it was easy enough to build with discrete transistors or MOSFETs directly driven from the logic signals. Also the high On state saturation voltage of bipolar motor driver ICs made low motor supply voltage operation very inefficient. In recent years, this has changed considerably due to cellphones and other gadgets that operate of a single LiPO cell. However the new MOSFET motor driver IC for this market usually don't support high motor voltages. For many, 5V is more than their maximum! |
| Prithul0218:
--- Quote from: spec on January 08, 2019, 09:50:19 am ---Hi Prithul0218 --- Quote from: Prithul0218 on January 08, 2019, 04:26:42 am ---A typical h-bridge DC motor driver IC has two voltage pins. One is the logic voltage and the other is the voltage used to power the motors. Like - L293, L298, TB6612. Why do they need the voltage for motor to always be slightly (2-3V) higher than the logic voltage? I've attached datasheet for the L298 below.http://cloud.tapatalk.com/s/5c34267fca44c/L298_H_Bridge.pdf --- End quote --- There is no absolute reason why the two voltages cannot be independent. It is just that the designers probably found the chip design easier with the +2V3 stipulation. --- End quote --- So are there any motor driver ICs that can easily drive motors at lower voltage than logic voltage? I'm learning robotics and plan on using tiny 3V toy motors. My microcontroller runs on 5V logic. |
| Ian.M:
Google: low voltage H-bridge this one looks interesting: http://www.ti.com/lit/ds/symlink/drv8837.pdf |
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