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DRV8305-Q1: PIN38 VCPH Functional application

ian wu
Intellectual 745 points
Part Number: DRV8305-Q1
Other Parts Discussed in Thread: DRV8305

Tool/software:

hi expert

Is there any relevant design data and introduction for PIN38 VCPH, which is used to drive mos? Are there any separate precautions？

  • 0
    TI__Expert 4395 points

    Hello,

    You can find a quick introduction/description of the VCPH Charge pump in section 7.3.3 of the datasheet (seen below)

    Regarding precautions for usage, here are some general tips:

    1. Make sure capacitors on each pin are the correct values AND correct voltage rating

    2. Be cautious of using too high of an IDRIVE setting. If you are unsure which one to use, we recommend testing with the lower drive settings first and slowly moving up if more drive current is needed.

    Thank you,

    Joseph

  • 0 in reply to Joseph Ferri
    Intellectual 745 points

    Regarding DRV8305-Q1, I have two questions to ask 1. As shown in our schematic diagram, WAKE is pulled up to 5V. Does this mean it won't enter the sleep mode unless there is a power outage at 5V? 2. If the MCU sets the EN_GATE pin high and the pre-drive operates normally, a fault occurs at this time. The pre-drive enters standby, but the EN_GATE pin is set high. Can it enter standby?

  • 0 in reply to ian wu
    TI__Expert 4395 points

    Hello,

    Here is a clearer description of the WAKE pin functionality:

    The sleep state can be entered by issuing a sleep command through the SLEEP bit in SPI register 0x9, bit D2 with the device in its standby state (EN_GATE = LOW). The device will not respond to a sleep command in its operating state.

    The device can then only be enabled through the WAKE pin which is a high-voltage tolerant input pin. For the DRV8305 to be brough out of sleep, the WAKE pin must be at a voltage greater than 3 V. This allows the wake pin to be driven, for example, directly by the battery through a switch, through the inhibit pin (INH) on a standard LIN interface, or through standard digital logic. The WAKE pin will only react to a wake up command if PVDD > VPVDD_UVLO2. After the DRV8305 is out of SLEEP mode, all activity on the WAKE pin is ignored.

    In regards to the sentence "pin cannot be used to disable LDO; Driver needs to be enabled and disabled separately", This means that EN_GATE is the driver enable and disable, and WAKE pin cannot be used like a regular sleep pin which can be found on our other devices. The WAKE pin will only remove the device from the sleep mode condition.

    If you are able to read the registers to determine which fault you see I can help with that. 

    If you encounter issue on start up maybe the inrush current to the motor is too high. 

    Thank you,

    Joseph