Suggestions for a low side switch to drive inductive loads - HV contactors

Matthew Pole

Other Parts Discussed in Thread: ULQ2003A-Q1, TPS2400

Hi, I need to drive 4 inductive loads through switches and originally thought of switching the loads on with high-side switches. I ave come to the issue that all of the automotive grade HS switches that are capacle of driving coils at their needed current are not suitable for my supply voltage of 6V-36V. I need to support up to 36V supply voltage so I am wondering if I can use low side switches for my switching instead? What would that mean for what my low side would need to be rated to? The load I am driving is a Gigavac GV241MAB contactor. Would the pickup current still be seen on the positive side of the coil or what would I see on the low side if that is the one that is switching?

Any suggestions and help with this would be great! Also, any part recomendations to achieve this goal would be perfect.

Thank you!

over 2 years ago

0 Elizabeth Higgins over 2 years ago

TI__Genius 16145 points

Hi Matthew,

Our ULQ2003A-Q1 device is a 7-channel low side switch which supports voltages up to 50V.

More information on this device can be found here: https://www.ti.com/product/ULQ2003A-Q1?keyMatch=ULQ2003A-Q1&tisearch=search-everything&usecase=GPN.

An important consideration however, is the amount of current you plan for the contactor to draw.

This device can drive at max 500mA per channel and is derated depending on how many outputs are conducting simultaneously and the duty cycle as shown below:

Best Regards,

Elizabeth

0 Matthew Pole over 2 years ago in reply to Elizabeth Higgins

Intellectual 340 points

Hi Elizabeth,

My contactors have a pickup current of around 5A each. I also assume that the lowside switches don't need to be rated for a high voltage as they are just switching the negative/ground side of the coil?

Thanks!

0 Elizabeth Higgins over 2 years ago in reply to Matthew Pole

TI__Genius 16145 points

Hi Matthew,

For the OUT pins, they need to be rated for the voltage expected at the negative/ground side of the coil. However, for inductive loads, we require the COM pin to be tied to the supply voltage on the positive side of the load as shown below:

However, we do not the capability to drive 5A with our low side switch portfolio.

Have you considered our efuse portfolio, specifically our TPS2400?

https://www.ti.com/power-management/power-switches/efuse-hotswap-controllers/products.html#1715min=0.01%3B4.866&1715max=4.352%3B500&238max=36.8%3B100&238min=-90%3B4.3&sort=1715max;desc&

Unfortunately I cannot provide the best support on this TPS2400 device as it is not part of the Load switch/PMUX/Low-side switch portfolio, so please start a new thread with that part number to connect with a applications engineer with more accurate support on this part.

Best Regards,

Elizabeth

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Suggestions for a low side switch to drive inductive loads - HV contactors