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TPS61169: Can control pin be driven with 1.8Volt level?

Aliasgar lightwala
Prodigy 50 points
Part Number: TPS61169

HI team,

I need confirmation on the Control Pin of the driver IC.

I have a processor whose output levels are 1.8V, which is connected to control pin of the driver.

Will this 1.8V levels will be sufficient for the proper operation (i.e complete high brightness)?

As the datasheet states,VH(high voltage) is 1.2Volts minimum.

Vin= 3.3V for the driver ic.

Data sheet also states: Over operating free-air temperature range, VIN = 3.6 V, CTRL = VIN (unless otherwise specified).

So is it necessary to connect CTRL pin to 3.3Volts if VCC=3.3Volts? 

I dont wish to use level translator in between.

Please let me know your views.

TIA,

ALi

  • 0
    TI__Genius 15776 points

    Hardy, could you help in this case.

  • 0
    TI__Genius 12915 points

    Hi Ali,

    The VIN for CTRL pin is 1.2V, you could use 1.8V IO to control it.

    The statement 'over operating free-air temperature range, VIN = 3.6 V, CTRL = VIN (unless otherwise specified)' is only test condition for electrical characteristic table, but not a limitation.

  • 0 in reply to Hardy Wu
    Prodigy 50 points

    Hello Hardy Wu,

    Thank you,i understood.

    I have 2 more queries.

    1.What will be the input current of the CTRL pin,?( i believe it should be in few micro amps just to be confirm)

    2.How to set the output voltage(Vout,SW)? In design implementation and design requirements Vout is not shown/given.

       So do i need to use Inductor selection formula and just put the value of Vout in the inductor equation,and calculate for inductor.

    Kindly help.

    TIA,

    Ali

  • 0 in reply to Aliasgar lightwala
    TI__Genius 12915 points

    Hi Ali,

    1. Here is a pull down resistor around 300kohm inside the IC. For the input current of CTRL pin, it could be calculated as 1.8V / 300kohm = 6uA

    2. For the output voltage, it is depended on the forward voltage of the LED you used. You could find I-V curve in LED datasheet and find Vf value in the current you want to set. Plus feedback voltage 200mV, you could get the Vout.

  • 0 in reply to Hardy Wu
    Prodigy 50 points

    Hello Hardy,

    Thank you much!!

    I appreciate the efforts.

    I have Led string with VF=24Volt and 60mA.

    Am just keen to know how this IC is able to understated that it has to boost the output voltage to 24 Volts?(just trying to understand how it works internally.)

    As we have seen in most of the boost converter IC's,Vout can be programmed with 2 voltage divider resistors on the FB pin.(in general)

    Regards,

    Ali

  • 0 in reply to Aliasgar lightwala
    TI__Genius 15776 points

    Hi Hardy, please help to keep following this case.