How to protect my motor driver from stall current


I am using baby orangutan 328p to drive a DC motor (70 mA) the problem here that the stall current for this DC motor is 1.6 A and the maximum current this driver can supply is 1 anything more than that will blow up the driver, and I already did it (motor driver hear up each time I am just conennection power source to baby orangutan ). I can’t change any of them now (limited pudget)

I want to protect now my second baby orangutan from the stall current. The solutions I had either to use a current limiter (which I did not found any one below 1 A, I want it to be less than 1 A to protect the baby orangutan not to be on the limit ), or to use PTC. I have not use PTC at all but during research I found one which has a maximum current of 250 mA. What I understood from reading about PTC that it will cut the circut if the current is more that the maximum current, but when the DC motor start to work it will draw a current = 1.6 A (short period) so is not that will be a problem at least for the start ?? Any one used it before ? or used the current limiter IC.

Any one has another idea how to protect my motor driver ?



The PTC should be an okay way to go since it is triggered by temperature and therefore won’t instantly trip from quick startup spikes. However, the ones I have seen can have a big difference between the hold current and trip current, so you might need to be careful about the rating. For instance, if you want one that will trip for sure at 1A, it might only guarantee you staying “closed” at 0.5A.

Alternatively, you could monitor the current electronically and reduce power to the motor when it’s too high or monitor the driver temperature and similarly limit the power when that gets too high.

In my experience, though, the TB6612 is fairly robust, so if you’re breaking them, you might be doing something else bad. For instance, switching directions can draw double your stall current, and if you’re doing a lot of that, the current might be spiking faster than the thermal protection on the chip can kick in. Gradually ramping up your speed and braking for a while before switching directions might be enough to protect your driver.

- Jan


Like Jan, I’m concerned that you’re doing something else wrong with the driver to break it. What are you using to power your Baby Orangutan and how long are your power supply leads?

- Ben

well , I was just trying to test it and the power was around 6 V or maby 7 . it was just on the bread board and I didnot chatch the dc motor it rotoat several time , wire twisted then motor driver get heated and didnot work again.

I was asking to know a way to prevent this issue when my robot will stuck in way. Currently I am desinging a PCB so I want to include over current protection in my desgin so in suggestion.


The TB6612 has thermal protection that should generally kick in and protect the driver in such situations. In my experience, more dangerous situations arise when using voltages closer to the driver’s absolute maximum of 15 V (we recommend keeping the input voltage under 13.5 V), since voltage spikes from motor noise or even just application of power can exceed this absolute maximum and damage the H-bridge MOSFETs. Note also that a motor’s stall current scales linearly with the motor voltage, so a motor with a 1.6 A stall current at 6 V will have a 3.2 A stall current at 12 V. The driver can only tolerate current peaks up to 3 A, so it’s important to make sure you won’t be trying to draw more than this.

- Ben