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TPS1HB08-Q1: Request H/W Design Guide

MyungJae LEE
Prodigy 10 points
Part Number: TPS1HB08-Q1

I'm trying to use TPS1HB08AQPWPRQ1.

The MAX Current load is 6.8A and the Nominal Current is 4.5A.

The operating range of my controller

is -40℃~+75℃.

I want to cut off the current when the load consumes more than MAX 6.8A current in an environment of -40℃~+75℃.

I checked the range of KCL values.

※ KCL(Current Limit Ratio Version A) = 160 (min:120~max:208 [A*kΩ]

- 1st inquiry: Does this high side switch block the current by cutting it off?
                     Or, I wonder if the maximum current is maintained by limiting the maximum current.

- 2nd inquiry: Because of the range of KCL, I would like to know how much the error value of the blocking current varies depending on temperature.

  • 0
    TI__Prodigy 335 points

    Hi, PS Team

    This is additional explanation on top of customr's comment.

    Requirements of High Side Switch are

    • Input voltage: 12V
    • Max current: 6.8A
    • Nominal current: 4.5A
    • Should shut down when current touch up to max current, 6.8A, that is switch off.
    • Not just limiting max current.

    In the datasheet, KCL range is 120~208(A version) which makes the wide tolerance of current limit, for example, nominal(6.4A) with range 4.7A~8.1A(RILIM=25k).

    Customer wants to shut down around 6.5A, but the tolerance is too wide, customer thought.

    So, customer wants to know what the tolerance range in case of -40℃~+75℃ temperature and how to make the range narrow so that HS would shut down around 6.5A.

    thanks.

  • 0 in reply to Luke Park
    TI__Genius 15465 points

    Hi Luke, 

    With regard to your inquiries: 

    1. 

    The HSS will disable the switch after a current limit is exceeded. 

    2. Unfortunately, the current limit variance is pretty consistent across temperature for this device. With a RILIM=25k, we would expect the device to shutdown around 6.4A, but it is possible it could shutdown as low as 4.7A or as high as 8.1A. Since 4.7A is outside of the nominal current of the application, would this be acceptable? 

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    TI__Prodigy 335 points

    Hi, Elizabeth

    Can you guess the KCL range in case of -40℃~+75℃ temp?

    4.7A is so much out of spec. 

  • 0 in reply to Luke Park
    Prodigy 10 points

     

    Please review the circuit.

    Input voltage: 12V
    Max current: 6.8A
    Nominal current: 4.5A
    Should shut down when current touch up to max current, 6.8A, that is switch off.
    Not just limiting max current.

  • 0 in reply to MyungJae LEE
    TI__Genius 15465 points

    Hello, 

    We do not have KCL rated for a specific temperature range. Please refer to the ICL calculator linked here to calculate variation in current limit: https://www.ti.com/tool/download/SLVRBG2

    Please also add a bypass capacitor on VBB

    Additionally for the best EMC performance we recommend the following capacitors:

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    Prodigy 10 points

    I have two questions for you.

    - What is the output waveform of pin 2 (SNS)?
    - Is the circuit diagram above designed to fit Typical: 4.5A, MAX: 6.8A specifications?

  • 0 in reply to MyungJae LEE
    TI__Genius 15465 points

    Hello, 

    • The output waveform of SNS will be a result of the current reference from the load current. 
    • The circuit above is not designed for a typical 4.5A, max 6.8A specification as shown below and in the datasheet: 

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    TI__Prodigy 335 points

    Elizabeth

    Sorry for pushing, but can you look over the schematic that customer has posted over two weeks ago? Looking forward to seeing your feedback. Thanks.

  • 0 in reply to Luke Park
    TI__Genius 15465 points

    Hi Luke, 

    Appologies for the confusion; I have reviewed the schematic in an earlier response over 2 weeks ago. 

    To repeat my comments are: 

    • We do not have KCL rated for a specific temperature range. Please refer to the ICL calculator linked here to calculate variation in current limit: www.ti.com/.../SLVRBG2
    • Please also add a bypass capacitor on VBB
    • Additionally for the best EMC performance we recommend the following capacitors:
    • Do note, the circuit above is not designed for a typical 4.5A, max 6.8A specification as shown below and in the datasheet: 

    Best Regards, 

    Elizabeth