Part Number:TPS61090
Hi,
I am testing the efficiency of TPS61090 converter set to 5.2V output voltage with
NR5040T6R8M (6.8uH inductor) and a 100uF low ESR ceramic capacitor on the output.
I have a bench power supply connected to the input and an electronic load to the output of the converter.
The electronic load is set to 500mA constant current and I am only varying the input voltage to simulate the battery discharge.
Here are the results of the Input voltage vs Input current:
4.2V - 665mA (best case scenario - Efficiency = 75%)
4.1V - 685mA
4.0V - 705mA
3.9V - 728mA
3.8V - 751mA
3.7V - 776mA
3.6V - 800mA
3.5V - 833mA
3.4V - 876mA
3.3V - 910mA
3.2V - 947mA
3.1V - 990mA
3.0V - 1039mA (Efficiency < 50%)
The TPS61090 converter suppose to operate down to 1.8V input voltage with 500mA output
current but with the efficiency bellow 50% at 3V input, there is not much point of testing any further.
According to the data, the efficiency at 3V input / 500mA output should be above 90% for this part.
Interestingly, the EVM for this part states:
To reduce the total PCB design area, the inductor used on the EVM is
smaller than the inductor used in characterization curves in the data sheet.
Generally, smaller size inductors decrease the efficiency in the design.
Can you please explain how and with what components were you able to achieve the claimed efficiency.
Best regards,
IT