Part Number: INA181
for a bidirectional current sensing application I'm using an INA181.I'm sensing the current in- and outflow of a leadacid-battery, so approx. 12V. As a µC I use a CC2640R2F.I applied 3.3V to VS, ~12V to IN+ and IN- and gave it as a reference the VDDR pin of the CC2640, which is ~1.7V, the output goes directly to an analog pin of the µC.There are two problems occuring:
1. When my board is completely switched off, but the 12V on IN+ and IN- still applied, there is a Voltage on VDDS present, which I don't want. If switched off, the board is required to carry no voltage at all (but the 12V) .
2. After a while the INA181 heats up (you can't touch it with the finger), and eventually it broke due to overheating.
So my question is, is there anything I'm missing out on? I sticked to the datasheet as close as possible, but the INA181 shows the stated behaviour. Maybe using the VDDR pin of the CC2640 as a reference was a mistake, would that explain it? Any suggestions on how to make it work on the prototype?
Any help is highly appreciated, thank you. Alex
Thanks for choosing TI. We will look into this, but could you answer a couple questions. What are you using to power the INA181/VDDS? Also, what supply voltage configuration are you putting the CC2640R2F in? Basically what configuration are you choosing below?
Current Sensing Applications
Mitch M, TI Sensing Products Applications Support
Getting Started with Current Sensing Video Training Series
TI makes no warranties and assumes no liability for applications assistance or customer product design. You are fully responsible for all design decisions and engineering with regard to your products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning your designs.
In reply to Peter Iliya:
In reply to Mitch M:
In reply to Alexander Gemmer:
my board is hooked on a laboratory DC power supply with 12V. There's not yet a batterie involved (That would be P5/BB on the schematic). As a load there's only the µC + peripherals on the board.As for question 3.):
When I power the µC with the CC2640 LaunchPad via the JTAG-plug and common-mode is turned off (DC-power supply off), it didn't heat up.
It went like this:As I was programming, my board powered by the LaunchPad, everything was fine. Then I switched on the DC power supply ~12V and unplugged the LaunchPad and realized a voltage on VDDS, even though the µC was switched off (SW4). I followed this and it was coming from the common mode voltage. I then desoldered the INA181 to make sure it was the reason for the voltage and it was. I stopped then looking into this matter and didn't solder the INA181 back on.
Later I was programming a second board of the same kind which had the INA181 still soldered on. I switched on the DC power supply and everything seemed to be okay until after (I have to lie) ~5-10min my board shut off. That was when the thermal protection of the 3.3V LDO (U1) was triggered. From then on, if I switched on the board with SW4 after 2-3seconds it would shut down again. I then realized how hot the INA181 and the LDO were, desoldered the INA181 and everything was functioning fine again and the INA181 most likely gone.
Maybe this is of help to you. Thank you for looking into this, find the schematic attached. Regards Alex
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.