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DRV8870: Motor Driver Component as High Side or Low Side Driver

Peter Conklin
Prodigy 30 points
Part Number: DRV8870

Can the DRV8870 be used to operate as a high side driver or as a low side driver?

Example 1: Can the OUT1 pin be utilized as a high side driver output when connected to drive one side of a solenoid with the other side of the solenoid connected to circuit ground? The device H-bridge control pins would be configured such that only one control pin, IN1, would be used to drive current out the OUT1 pin. We would not have the option of using both the OUT1 and OUT2 pins directly as one side of the solenoid would already be referenced to circuit ground and it cannot be moved/connected to the OUT2 pin.

Example 2: Can the OUT2 pin be utilized as a low side driver output connected to drive a lamp with the other side of the lamp already connected to the same supply voltage as the VM pin? The device H-bridge control pins would be configured such that only one control pin, IN1, would be used to drive current into the OUT2 pin. We would not have the option of using both the OUT1 and OUT2 pins directly as one side of the lamp would already be connected to the supply voltage and it cannot be moved/connected to the OUT1 pin.

Given both examples, can the ISEN (current regulation) function still be utilized for either or both configurations? Maybe only the low side drive configuration?

The data sheet Functional Block Diagram indicates that Over Current Protection (OCP) is provided on both the high and low side outputs, OUT1 & OUT2. If the device can be utilized as a high side or low side driver will the OCP feature still work in both configurations?

Thank you for your help. 

  • 0
    TI__Guru 56650 points

    Peter,

    "When ITRIP is reached, the device enforces slow current decay by enabling both low-side FETs, and it does this for a time of tOFF (typically 25 μs)."

    According to the above datasheet description,

    a. the ISEN (current regulation) function cannot work if OUT1 and OUT2 are connected to two loads. If one half bridge current triggers Itrip, the other side half bridge's low FET will be turned on (call it slow decay).

    b. If the current regulation function is used, only one half bridge can be used because the other side half bridge's low FET will be turned on (call it slow decay) at Itrip triggering point.

    c, If the current regulation function is used,  OUTx pin cannot be utilized as a low side driver output connected to drive a lamp with the other side of the lamp already connected to the same supply voltage as the VM pin. ITRIP is triggered at high side FET on.

    OCP function works in both high side driver or low side driver.