DRV8870: Using DRV8870 as a contactor driver

Mattia Zagatti

Part Number: DRV8870
Other Parts Discussed in Thread: DRV8871, DRV8872, DRV8872-Q1

Hi,

I have a question about the use of DRV8870 as a power contactor driver.

I connect the coil of the contactor between VM (24V) and OUT1.With IN2 and IN2, I drive the output of the contactor.

If IN1 and IN2 are both connected to GND (DRV8870 in High-Z), there is a current (25mA) that flow through che coil. Multimeter (with an internal resistance of 10Mohm) measures 20.5V between OUT1 and GND and 3.5V between VM and OUT1.

My question is: what is the path of that current? Is H-Bridge of DRV8870 in High-Z?

Best Regards,

Mattia

over 6 years ago

0 Rick Duncan over 6 years ago

TI__Guru** 114905 points

Hi Mattia,

We will investigate and should have a reply by Wednesday.

Is it possible to reconfigure the coil connections? By connecting the coil of the contactor between OUT1 and GND and setting OUT1 high when driving, the current should disappear.

0 Rick Duncan over 6 years ago in reply to Rick Duncan

TI__Guru** 114905 points

Hi Mattia,

Please refer to e2e.ti.com/.../2063645 for more details.

The DRV8870, DRV8871, DRV8872, and DRV8872-Q1 all have similar output structures. The outputs will act similarly to high voltage on the outputs when in sleep mode, trying to protect the high side gate against reverse VGS.

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DRV8870: Using DRV8870 as a contactor driver