Brushed DC motor driver - Page 1
Forum section: electronics / projects

author: amintegia
author_rank: Contributor
timestamp: July 17, 2024, 09:33:12 am
content: Hello,I am looking for the best driver to control a 3V Brushed DC motor, maximum current in stall is about 300mA.- The motor should have current control on the motor, being able to cut the power supply when it exceeds a previously configured limit.- It must be able to control the motor in both directions. Selected using two switches.- System powered by 3.7V battery. Battery charging could be managed by an external module.I would appreciate any suggestion.Thanks in advance.

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 17, 2024, 11:34:46 am
content: There are many drivers to be found, but the low voltage and small current requirement might make it a bit harder to find one that does all that you want.Try searching on the TI website for brushed dc motor drivers. Toshiba also has good motor drivers.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 18, 2024, 08:58:43 am
content: Do you have a microcontroller in the system already / anyway? Almost all microcontrollers can easily provide a current-limited control for a brushed DC motor with a few dozen lines of code (utilizing PWM / analog comparator / ADC peripherals), and this is usually a better way than to add an extra "motor controller" IC, some of which are completely unusable, some difficult to control, and - finally - some probably fine but not much easier.For such low-voltage, low-current design you would just create H bridge out of two N and two P-channel MOSFETs, gates can be driven directly off the microcontroller. For current sensing, a separate shunt resistor + sense amplifier IC on both ground legs is probably easiest. When changing direction, you can at the same time change which of the current sense signals is routed to analog comparator peripheral. Then configure the analog comparator output to terminate PWM cycle, possible in many microcontrollers (e.g. the whole STM32 series including the lowest cost items), or if unavailable, let it generate interrupt and limit current in software.

author: Infraviolet
author_rank: Super Contributor
timestamp: July 18, 2024, 05:07:26 pm
content: TB6612 could be suitable, though I think it requires a low current 5V supply for its logic power inputs. Its motor voltage input should work down at your supply voltage. Current control could be done with a small shunt resistor between the h-brdge's ground and the circuits overall ground, with an op amp monitoring the current flow and a microncontroller with an ADC (attiny85 or something, you can prototype the code on an atmega328p based arduino beforehand) to change the PWM rate supplied to the TB6612 accordingly as the current being measured varies.You might need some sort of small boost converter circuit, there are modules for this sold by Pololu and other companies, to provide 5V for the TB6612's logic inputs. Your op-amp may need this 5V power too, and a stable 5V reference would be betetr for the attiny's ADC to compare against rather than comparing against a battery voltage which would change as the battery discharged during running time.

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 18, 2024, 06:52:42 pm
content: There is also the MX1508 that works from 2 to 10V, but it does not have the current limiting option. It is a dual full H bridge, so suited for two motors, but there are single siblings available like the MX612E or MX08E. English datasheets are harder to find, and on Aliexpress there are a lot of fakes or duds being sold. They are cheap though.LCSC also sells some of these parts and might be a better source for the real ones.https://www.lcsc.com/products/Brushed-DC-Motor-Drivers_13506.html?keyword=MX612

author: amintegia
author_rank: Contributor
timestamp: July 19, 2024, 07:45:49 am
content: Thanks for your suggestion. In principle, we do not want to use any microcontroller to carry out the control, with the aim of reducing development costs. However, we will analyze the option of integrating one if, as mentioned, avoiding using a microcontroller will generate more problems than solutions.

author: amintegia
author_rank: Contributor
timestamp: July 19, 2024, 09:50:08 am
content: Quote from: Infraviolet on July 18, 2024, 05:07:26 pmThanks for your extenden answer. We will analyze the option of usign the TB6612. However, we will prefer using one wich I could directly power without using a boost. In addition, our idea is to have a design which does not require to use a microncontroller.

author: amintegia
author_rank: Contributor
timestamp: July 19, 2024, 09:58:27 am
content: Quote from: pcprogrammer on July 18, 2024, 06:52:42 pmThank you! We will analyze this options.