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UCC21520: Input signal and PIN7

Lillian Liu(SH)
Expert 4620 points
Part Number: UCC21520
Other Parts Discussed in Thread: UCC21550

Hi team,

I have two question need your support:

1. Is the input signal 25Khz 0-3.3V square wave acceptable?

2. Pin 7 is an NC pin, can it be grounded?

Thanks

Lillian

  • 0
    TI__Mastermind 23226 points

    Hi Lillian,

    Yes, UCC21520 can support 25kHz. With no load, it can switch up to 25MHz. 

    NC pins are sometimes used for testing, and in those cases cannot be grounded. However, in the UCC21520, the NC pins are floating, with no electrical connection to the die. They can be connected to ground.

    However, an update to this part has just been released, and you should strongly consider using the improved design. It is called the UCC21550.

    Best regards,

    Sean

  • 0 in reply to Sean Cashin
    TI__Expert 4620 points

    Hi Sean,  

    Thanks for your reply.

    Could you help provide the comparison table for me to show the advantage of new device? Do we have price advantage of new deivce?

    Thanks

    Lillian

  • 0 in reply to Lillian Liu(SH)
    TI__Mastermind 23226 points

    Hi Lillian,

    Yes, it is a 300mm wafer part and can support a lower cost. Here is the comparison table:

    Parameter

    UCC21520

    UCC21550

    UCC21550 System Impact

    Isolation

    CMTI Min

    100 V/ns

    125 V/ns

    Driver voltage clamping to increase IC robustness

    VIOWM: (DC) Working

    2121 V

    2121 V

    VIOTM: (Vpk, 60s):Transient

    8000 V

    8000 V

    VIOSM (Vpk, 1.2/50us): Surge

    8000 V

    8000 V

    Input stage

    VCCI rec. operating range

    3–18 V

    3–5.5 V

    Optimized for use with digital controllers as understood market trend, reduces die area

    ICC (non-switching TYP)

    1.5 mA

    1.5 mA

    ICC (switching TYP)

    2 mA

    3.2 mA

    Lower VCCI results in slightly higher current

    O/P driver

    Vdd Abs Max

    30 V

    30 V

    VDDx rec. operating range

    6.5–25V

    6.5–25V

    Max Drive Current TYP (IO+/IO-)

    4A/6A

    4A/6A

    Pull up/Pull down

    5/0.55 Ω

    5/0.55 Ω

    Active pull down

    1.6 V

    1.6 V

    VDDx Power-up Delay MAX

    100 μs

    10 μs

    Have the device turn ON and start switching FET/IGBT sooner

    IDDx Quiescent Current MAX

    2.5 mA

    3.7 mA

    Increase IC’s robustness to electrical noise without impacting end application battery cycle time

    Timing

    Prop Delay TYP,MAX

    19 ns,30ns

    28ns,40ns

    Tradeoff made by adding pulse rejection onto INx pins, CMTI and cross-channel glitch rejection

    PWD

    <6 ns

    < 5 ns

    CHA-CHB Dly Matching MAX

    <5 ns

    <5 ns

    Features

    Deadtime Formulae

    10*RDT

    8.6 RDT+13

    New DT circuit to improve noise immunity, caused change in equation

    DT pin open

    Min deadtime

    Deadtime not enforced. Open > 340K

    Circuit copied from other design with better noise tolerance across range

    DT pin shorted

    Not defined

    Min deadtime

    Circuit copied from other design with better noise tolerance across range

    Dead time range

    5–5000 ns

    27-873 ns

    DT range of previous dual-channel gate drivers were wider than necessary for most applications

    Robustness

    Min Pulse (Typ)

    10 ns

    10 ns

    Min off pulse extension at high CLOAD

    No extension

    Output fully discharges before going high

    Prevents overvoltage from high output current interruption

    VDDx Max Slew rate

    < 5 V/μs

    < 0.5 V/ns

    Prevents overvoltage on internal components with fast power-up

    VDDx Deglitch (Typ)

     

    200 ns

    Increase IC robustness to electrical noise

    VCCIx Deglitch

     

    300 ns

    Increase IC robustness to electrical noise

    INx Deglitch

     

    5 ns

    Increase IC robustness to electrical noise

    DIS floating state

    Internal pull down (Driver enabled)

    Internal pull up (Driver disabled)

    IC is off if EN pin left open/floating for safety

    DIS Deglitch

     

    20 ns

    Increase IC robustness to electrical noise

    ESD

    HBM

    ± 4000 V

    ± 2000 V

    Industry and TI standard, but is capable of more

    CDM

    ± 1500 V

    ± 500 V/± 750 V Coner pins

    Different metric specified; still meets industry standards. Same ESD ruggedness

    Temperature

    Tj Recommended Max

    -40–125 C

    -40–150 C

    Improve thermal performance
  • 0 in reply to Sean Cashin
    TI__Expert 4620 points

    Hi Sean,

    Thank you for your feedback. But still have a question that whether the two input ports can support 3.3V square signal or not?  the highest input voltage was 2V,(UCC21520) and 2.3V(UCC21550) but we would input 3.3V , would that  be acceptable?

  • 0 in reply to Lillian Liu(SH)
    TI__Mastermind 23226 points

    Hi Lillian,

    Yes, 3.3V is above the 2V input threshold for "high". The input high voltage should be the same as the input supply voltage.

    Best regards,

    Sean