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DRV8816: disabled DRV8816 is not 'Z' at output!

ralf klut
Prodigy 40 points
Part Number: DRV8816

Hello Ti-forum,

my application has pullup (47kOhm) connected to output

when disabled I measure:

V-supply =35V -> V-output = 14V

V-supply= 15V -> V-output = 12V

measure DC-current with multimeter:

V-out <-> Gnd - 700µA (That's the pullup@35V)

V-out <-> V-supply - 45mA ??? why??

!! it gets 150mA in sleep-mode

please explain this

can I be sure, that V-out in disabled mode never is below 12V ??

please help..]

  • 0
    TI__Guru** 114905 points
    Hi Ralf,

    Can you clarify:

    V-out <-> V-supply - 45mA ??? why??

    !! it gets 150mA in sleep-mode

    Did you connect a DC ammeter from V-supply directly to the output in both conditions above?

    Please confirm sleep mode is VM = 35V, nSLEEP = logic low
  • 0 in reply to Rick Duncan
    Prodigy 40 points
    Hi Rick,
    a.) yes, I connected the DC-multimeter directly between V-supply and output in both conditions
    b.) sleep-mode means nSleep = logic low
  • 0 in reply to ralf klut
    TI__Guru** 114905 points
    Hi Ralf,

    The device outputs are in High-Z, but some paths inside the device can conduct current in sleep mode. These paths are intended to protect the high side FET.

    Can you provide a few more details regarding your application?
    How are the outputs connected? Which of the three connections in Figure 4 is used?
    If you are using the load connected to VBB, can you switch to the load connected to GND?
    Are you using the VPROPI feature?
  • 0 in reply to Rick Duncan
    Prodigy 40 points
    Hi Rick,
    forget sleep-mode. Because I found Problems in activ-mode I just checked what happens in sleep-mode!
    My application has:
    a.) 16 DRV8816 devices,32 outputs with pullup(47kOhm) that typically will switch to VBB when nessecary (one at time)
    b.) 16 DRV8816 devices,32 outputs that continuously switch to GND
    in work extern is a Matrix of (diode, coil, switch) in serial.
    If switch is open I hope to get a 'high'-Signal under a.) , when 'Z'-state and pullup works
    c.) What I get is something between 12...15V when VBB is 15...35V WHY??
    I get that result even without any external stuff only with pullup-47kOhm
    d.) MOST IMPORTANT QUESTION: ???? CAN I BE SURE THAT THE VOLTAGE AT OUTn WILL NEVER!! DROP BELOW 12V ????
    Figure4: Pullup is connected like the most right picture
    Yes, I can switch the load to GND
    Pin 15 VPROPI is open in my app.

    P.S.
    My app works fine at all.
    I have to answered my questions under c.) and d.) !!
  • 0 in reply to ralf klut
    TI__Guru** 114905 points
    Hi Ralf,

    c.) What I get is something between 12...15V when VBB is 15...35V WHY??
    I get that result even without any external stuff only with pullup-47kOhm

    The internal path activates at approximately 12V to protect the high side FET.

    d.) MOST IMPORTANT QUESTION: ???? CAN I BE SURE THAT THE VOLTAGE AT OUTn WILL NEVER!! DROP BELOW 12V ????
    Figure4: Pullup is connected like the most right picture
    Yes, I can switch the load to GND
    Pin 15 VPROPI is open in my app.

    When the output is disabled, consider it a 12V zener to ground. With variations, it is possible to be slightly lower or higher across temperature. With a 47kOhm pullup to VM (and VM is >15V), the voltage at OUTn should be above 11V when the outputs are Hi-Z.
  • 0 in reply to Rick Duncan
    Prodigy 40 points
    Hi Rick,
    that was very helpful.
    My internal Reference is 5V, so also 11V is high enough.
    I can use those devices for my app
    Thank you