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CCS/TIDA-00121: MSP430

Part Number: TIDA-00121

Tool/software: Code Composer Studio

Dear sir,

I want to increase the output current for led driver boost (1.1Amp) is their any changes in code,I am facing problem to setting the ADC value of led full brightness once i set the adc count more then 900 driver goes to protection mode once i comment protection part it works is any changes needed in SFR OR Comparator.

Or it can be done only by changing the shunt resistance for led current setting without changing in ADC value

Best regard"s

Prem sagar

kREATE LIGHTS PVT LTD

Mob:+91 8586018427 

  • Hi Prem,

    You can just change the sense resistor R2 to 0.43 ohm to get 1.1A output current without altering the code. Alternatively, you can keep the power loss in the resistor to be same at 0.3W by changing sense resistor to 0.25 ohms and re-adjust the output current by changing the code.

    However, it is better to re-design the boost power stage consisting of C7, L2, Q5, D1 and C8 to get better efficiency and thermal performance. Q5 is sufficiently rated for this current and you need not have to change it. However, all other components should be recalculated using boost power stage design equations as described in http://www.ti.com/lit/an/slva372c/slva372c.pdf

    Regards,

    Salil

  • Dear sir,

    Still facing problem in led boost section like if we put inductance of inductor 33uH light glow but in flickering mode,once we decrease inductance and put 10uH flicker removed but more heating found on inductor and mosfet kindly provide solution.

    We want to take output 45V;1.2Amp kindly suggest component rating,Their no any change in schematic we are using same schematic which i found in TIDA-00121 design file.

    Best regard's

    Prem sagar 

  • Hi Prem,

    At 45V, 1.2A, the output power is 54W, and there will be significant power dissipation in the power stage. Even if we assume 90% efficiency, there will be 6W power dissipation in the power components. So the power components should be big enough to handle this power dissipation.

    From your description, it is not clear that you have done calculation of the power stage correctly. Please follow the procedure discussed in the appnote.

    Regards,

    Salil