• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 187 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS62170: Low Efficiency for Low Output Currents

Dekel Meyuhas
Prodigy 30 points
Part Number: TPS62170

Hi,

I'm using the DC-DC regulator tps62170 and having trouble with its efficiency. I'm using 5.8V as input and steady 3V as output.

When measuring an output current of 9mA, the input current is 6.2mA and the resulting efficiency is around 75%, which is somehow acceptable according to the datasheet (expected to get ~85%).

Nonetheless, when measuring output currents of 0.22mA and 0.53mA, the input currents are 0.75mA and 2.8mA (accordingly) and resulting efficiencies are 15% and 10% (accordingly), which does not meet the expectations based on the data sheet (expected to get ~70%).

Attached is the regulator's diagram:

Any ideas why lower output currents result in such low efficiencies?

Would appreciate your help!

Thanks,

Dekel

  • 0
    TI__Mastermind 47020 points

    Hi Dekel,

    Did you measure the efficiency on TI EVM or your board? I think this is your measurement issue. Please follow below steps to double check again.

    1. Vin measurement: use DC meter to measure input voltage on Cin which is close to IC Vin and GND pin.

    2. Vout measurement: use DC meter to measure output voltage on Cout which is close to IC VOS and GND pin. VOS is Vout sense pin.

    3. Input current measurement: use 100mA max range DC current meter(most DC meter has this feature) or use accurate shunt resistor series with IC input pin to power supply. Make sure no other current going through this path. This will get accurate input current. 

    4. Output current measurement: For such a lower load current, you could not use electrical load. I recommend use at least 1% resistance substitution box to select different output current. See the picture as below. For example, 0.22mA/3V, select resistance 13.63k.

    Please let me know if you still have a problem.

    Thanks,

    Nancy

  • 0 in reply to Nancy Zhang
    Prodigy 30 points

    Thank you for your quick reply.

    Measurements are more acceptable now.

  • 0 in reply to Dekel Meyuhas
    TI__Mastermind 47020 points

    Hi Dekel,

    Thanks for your update. I will close this post.

    Thanks,

    Nancy