TPS92200: Request for LED Driver IC Without Sense Resistor for UV LED Application

Hi Mohamed,

I am wondering if we are talking about the same topic as this E2E thread - TPS92200: PCB Trace impedance affect on Sense Resistor of TPS92200D1DDCR and LM3414MRX/NOPB - Power management forum - Power management - TI E2E support forums

Do you still want to improve your TPS92200 design? Or do you now only want a driver without a sense resistor?

Best Regards,

Steven

Hi Steven ,
Thank you for your fast response , Yes I'm talking about that topic .
The problem is I can't follow the layout guideline and use the Kelvin connection because of layout limitations such as the board must be only one layer and the component placement of the UV LEDs is Fixed in a particular places for the UV Distribution ,and some MFR constrains . So , I  want a driver without a sense resistor to be free with components placement and not affected by the trace impedance -especially the ground zone passing through all circuit to the negative supply- the ground trace adds resistance to the sense resistor branch so the LED output power is reduced .

Best Regards,

Mohamed

Hi Mohamed, 

The keys of the PCB layout to improve current accuracy is to minimize the trace from the sensing point on the output power trace to the positive point of sense resister and the trace from the negative point of sense resister to LED driver's ground pin.

Other traces are not important to the current accuracy, such as the trace from LED cathod to the positive point of sense resister or the trace from sensing point on the output power trace to LED driver's FB pin. 

You could optimize the layout based on points above. 

Thanks! 

Best, 

John. 

Hi John ,
Thank you for the quick response  ,
So there is no LED Driver IC Without Sense Resistor for UV LED Application and I have to follow the IC layout guideline regardless the optical UV LED placement design and the PCB layers and MFR Limitations ?

Best Regards,

Mohamed

Hi Mohamed, 

Could you please share the voltage of power supply? We have a new device going to RTM next month, TPS92201(SOT version),1.6mmx1.6mm, which may help you save some area. Also, if you could choose a smaller inductor, it could also save some PCB area. 

For other kind of options, you could consider linear LED driver, such as TPS92622, which is a two channel (250mA/CH) current source or TPS92612, which is a single channel current source. These options do not need sense resistors to determine output current. But they need other external components, which might also limited by your PCB size. 

Thank you! 

Best, 

John, 

Hi John ,
Thank you for fast response , My application has 2 versions : 12V and 24V Power supply with UV LEDs of VF 6V , and IF max 500mA .

Best Regards,

Mohamed