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Original question:

TPS61197: Can I use TPS61197 for my system?

TPS61197: Is the TPS61197 the correct IC for my design ?

Georgios Kefis
Intellectual 450 points
Part Number: TPS61197
Other Parts Discussed in Thread: TPS61199

Dear TI team,

i would like to use the TPS61197 in my design, in order to control  the  Backlight LEDs of a specific Display. The backlight voltage or simply said the output voltage of the IC must be up to 46,1V and the TPS61197 should be able to provide ,according to the datasheet of the display, (typically) 545 mA. Could this IC be a solution for my design?? The input voltage of my system is 24 Volts. Are there any equations , in order to be  able to calculate if the device can deliver this power (in this case approxímately 23Watts)

Regards,
George

  • 0
    Intellectual 450 points
    The input voltage is 24Volts
  • 0 in reply to Georgios Kefis
    TI__Mastermind 22745 points
    Hi Georgios,
    Let me clarify your application: Vin=24V, Vout=46.1V, Iout=545mA? You only have one LED string? And do you have any special demand for dimming? If my understand is right, TPS61197 is a good choice for your application. Can you tell me your detail application? Thanks.
    Best Regards
    Sean
  • 0 in reply to Sean Zhou
    Intellectual 450 points

    Hello Sean,

    thank you for your answer. For the dimming of the backlight we use a PWM signal 0-5V at 110 Hz, that comes out from a controller. Regarding the application, there are 2 connectors used to power the backlight of the Display. Every connector has 2 pins (V_backlight +&-). At these 2 Pins are connected 8 Rows-strings of LEDs , of 8 LEDs per Row which means totally 64 LEDs. I believe that the TP61197 would be ok for my application, using 1 of them for every stripe of LEDs, which means totally 2 ICs.
    Could you please give me some detailed information regarding the power, that the TPS61197 can deliver? I am asking you because it seems, that it could be used in other projects too, but i need to know what can this IC deliver.

    Regards,
    George 

  • 0 in reply to Georgios Kefis
    TI__Mastermind 22745 points
    Hi George,
    Yes, TPS61197 is active now, we can deliver that, for your application, you have 8 strings of LEDs, have you considered the 8 channels devices, like TPS61199? For eight channels, you can get better current match performance.
    Best Regards
    Sean
  • 0 in reply to Sean Zhou
    Intellectual 450 points
    Hi Sean,
    as i wrote before, the connections of the LEDs are in the Display and the only thing i see is 2 connectors for 2 Voltages V+&V- and there i have to connect my board which must be able to deliver the needed voltage and current. If i had the ability to change the design of the display , i would do it but i cannot and i have to live with that. Where can i find the needed equations, in order to calculate if the TPS61197 can deliver the needed voltages and currents for other applications?

    Regards,
    George
  • 0 in reply to Sean Zhou
    Intellectual 450 points
    Hello Sean ,

    thank you for your answer. As i wrote before the Display is as it is and the LED connections are inside. The only thing that i see is the 2 connectors . If i could change that i would have done it, but unfortunately i cannot and i have to live with it. Are there any equations or a matrix, in order to be able to calculate what this device can deliver for future projects??

    Regards,
    George
  • 0 in reply to Georgios Kefis
    TI__Mastermind 22745 points
    Hi George,
    Understand that. I'm sorry that I don't have the equation or matrix, it depends on the real application. We can offer help to choose best device for your application if you have any demand. So please contact us when you have nay demand and question in future.
    Best Regards
    Sean
  • 0 in reply to Sean Zhou
    Intellectual 450 points

    Hello Sean,

    i would like to know what would be the behaviour of the IC if the output voltage would be equal with the the input voltage, which means now that :
    Vin=24V
    Vout=24V
    Iout=0,6A.

    My only consideration in this case is, that the device does not "boost" the voltage anymore. Could this device work properly with these parameters?

    Regards,
    George

  • 0 in reply to Georgios Kefis
    TI__Mastermind 22745 points
    Hi George,
    Yes, TPS61197 can suport this case. The TPS61197 consistently adjusts the boost output voltage to account for any changes in LED forward
    voltages. In the event that the boost controller is not able to regulate the output voltage due to the minimum pulse width (ton(min), in the Electrical Characteristics table), the TPS61197 enters pulse skip mode. In this mode, the device keeps the power switch off for several switching cycles to prevent the output voltage from rising above the regulated voltage. This operation typically occurs in light load condition or when the input voltage is higher than the output voltage.
    Best Regrads
    Sean
  • 0 in reply to Sean Zhou
    Intellectual 450 points
    Hello again Sean,

    i am trying to program the output voltage of the device but i miss something here. Is there any equation that connects the Vout and the Vin?? Could you please give me an example?

    Regards,
    George
  • 0 in reply to Georgios Kefis
    TI__Mastermind 22745 points
    Hi George,
    I'm sorry there is no equation between Vin and Vout, because it works on pulse skipe when the vout is near vin, it's complicate to give an equation.
    Regards
    Sean
  • 0 in reply to Sean Zhou
    Intellectual 450 points

    Hello Sean,

    Thank you very much for your answer but in order to use this device in my design I have to know exactly how to regulate the output voltage using the two resistors of the voltage divider,shown in the datasheet. I have not found any examples of how the output voltage is set. Could I have an example please?

    Regards,

    George

  • 0 in reply to Georgios Kefis
    TI__Mastermind 22745 points
    Hi George,
    TPS61197 is integrated adaptive boost conver, it will output adaptive voltage depennds on the LED current, so what you need to do is to check the LED spec, and know whta's the maximum volatge forward on LEDs and add some margin to set the OVP point, please refer to 7.4.1.6 for OVP setting. Thanks. You can also refer to 8.2 for application information.
    regrads
    Sean