• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 3 answers
  • Subscribers 41 subscribers
  • Views 1632 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TIDA-00364: whats is 12v Power supply requirement for this design? Should it be regulated?

Vlad Blanshey
Intellectual 700 points
Part Number: TIDA-00364
Other Parts Discussed in Thread: UCC27211, UCC27212, UCC27212A-Q1, , CONTROLSUITE

what is the max amps from Vdd 12v in this design? Can it be directly connected to the 12v battery or should be regulated?

  • 0
    TI__Guru**** 189399 points
    Hi, Vlad,

    Thanks for your interest in this design. The UCC27211 is recommended for operation from 8 to 17V. I recommend you operate VDD at an appropriate value for the transistors you are using.

    As for the regulation, I would suggest +/-10% to keep the gate drive voltage relatively stable. If you have too much variation in VDD, your transistors will operate at different levels of voltage drop.

    If you have any other questions, let us know. If this answered your question, please mark this post as such! Thank you.
  • 0 in reply to Don Dapkus
    Intellectual 700 points
    Thank you for letting me know about 12v regulation. Please also reply regarding the max current requirement for 12v supply .
    Also if you could suggest does it make sense to replace UCC27211 with TI's latest upgrade UCC27212 driver without changes to the power inverters schematic? According to TI datasheet they are almost the same but wider Vg range.
    Thank you.
  • 0 in reply to Vlad Blanshey
    TI__Genius 12990 points
    Hi Vlad,

    Thanks for the followup question! Don is OOO so ill be answering all your questions for this thread.

    Take a look at "9.2.2.3 Peak Source and Sink Currents" of the datasheet. It explains current requirements for VDD which sources current for internal circuit blocks as well as outputs HO and LO.
    The peak current is associated to miller capactiance and is required to send Vds from rail to rail, for example, at a rate of 20V/ns and in the specified time limit of 20ns. With the typical Qgd of 33nC then the required peak current is 33nC/20ns or 1.65A. UCC2721x is capable of 4A peak source and sink current. However this peak current capability can be dI/dt limited by parasitic trace inductance. This can hinder the drivers ability to reach the peak current capibility and thus switching speeds and can be avoided by laying out a tight gate drive loop while minimizing parasitic inductance.

    From simply reading the datasheet of UCC27212 it seems like these parts are pin to pin replaceable. It looks like the rise/fall times are slightly better and a higher bus voltage is allowed. The most noteable is the wider VDD range like you noticed, also the UCC27212 is only offered in the WSON package.

    I will ask my team if these 2 parts are pin to pin replaceable or do a quick bench test and let you know the results.
    In the mean time, can you tell me anything about your application?

    Thanks,
  • 0 in reply to Jeffrey Mueller
    Intellectual 700 points
    Hi Jeff, thank you for reply.
    I am familiar with peak current requirements as per individual gate driver chip (got explanation on another TI forum) but it is quite long way to arrive from peak current to the power supply DC current requirement for the whole design board , which is my question in this post. I hoped that this key specification (12v DC supply current requirement) was practically verified during the tests.
    In terms of gate driver I am looking at UCC27212A-Q1 SOIC8(Powerpad package) - easy for prototyping.
    My application is a new electric propulsion for aircraft. Current stage is limited in power and the motor controller under development will run the usual 3-phase BLDC motors as the 1st step to get "building blocks" for a next generation controller (using LaunchPad). It will be installed in a currently built prototype and test flown. But the goal is development of a new kind of brushless motor which will need a new controller and I'll use blocks of TI's DMC library to experiment with it and tune up.
    Thanks again
    Vladimir
  • 0 in reply to Vlad Blanshey
    TI__Genius 12990 points

    Hi Vlad,

    Thanks for the clarification. DC power supply current can be found on page5 of the datasheet. Hopefully this answers your question. Please let me know if you have any more questions!

    Thanks

    Jeff

  • 0 in reply to Jeffrey Mueller
    Intellectual 700 points

    Hi Jeff, thank you for your input. I am sorry but my question was 12v current requirements for TIDA-00364 schematic  (not only UCC27211 chip in it).  Can you point me to the way to arrive to the actual answer to my question using the data you provided in datasheet?

    Calculating a total for 3 driver chips  from the driver datasheet would assume they all charge/discharge simultaneously (which is not so i know), another assumption would be that duty cycle for each driver is NO MORE than 50% (?) and switching frequency 100kHz . Yet assumption might not be right for this design as TI tested it switching PWM to 10 kHz  (what was 12v current in this test?) and also I am not sure if  it was assumed that 50% is the highest duty cycle for this design. Or is it easier just to make a rough estimate only based on the data for a single driver chip?

    "it is quite long way to arrive from peak current to the power supply DC current requirement for the whole design board , which is my question in this post"

  • 0 in reply to Vlad Blanshey
    TI__Guru**** 189399 points

    Hi Vlad,

    Sorry for the delay, as Jeff mentioned, I was out of the office.

    We discussed this internally, and here's what we calculated:

    Gate power = Qg*Vg*fsw = 144 nC *12 * 10k = 17.28mW
    There are five FETs in parallel, total low side switch gate power = 86.4 mW
    Total high side switch gate power = 86.4 mW (Simplified calculation - not included bootstrap diode and MOSFET Vdson drop while charging bootstrap cap)

    Peak gate current is supplied by bypass capacitors. Average VDD input current for driving gate load = 0.172 W/12 = 14.33 mA
    Leakage in R7, 19, 31, 43, 56, 68, 79, 89, 91, 102 gate to source resistors= 12/2k = 6 mA (Top and bottom switches are complementary, leakage will take place either across R7, 19, 31, 43, 56 or R68, 79, 89, 91, 102 independent of duty cycle)
    UCC27211 IDD operating current at 10kHZ @ 25C,(CL = 0pF) = 120uA (figure 4 datasheet)
    Boot voltage operating current at 10 kHz @ 25C,(CL = 0pF) = 140uA (figure 5 datasheet)
    Total current for one gate driver = 20.59 mA

    Average current from 12V input for three gate drivers ~ 65 mA
    It will also depend on the Qg of the FET selected by him and his PWM frequency

    We also have PSPICE models for the UCC27211 and UCC27212, so you could use those along with your exact operating conditions to get a value for the current drawn from the 12V supply.

    Let us know if you have any further questions about this TI Design.

  • 0 in reply to Don Dapkus
    Intellectual 700 points
    Thank you very much Don - this fully answers my question. I had hard time to simply accept the fact that so low power is enough to drive that high current switches (130A continuous) at the same time TI document for this design kind of evaded a direct spec for 12v - so I needed verification!!
    You helped me make a decision for our own motor controller - I'll use this design (for power stage) with UCC27212 , LaunchXL-F28069F for control and some parts of FTIDM-1003 for sensors and boosterPack interface connections. And finally switching our IDE to TI's ControlSUITE with CCS IDE. Many decisions have been made finalized.
    Thanks again.
    Sincerely
    Vladimir