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I was looking over LTC2990, which is a voltage, current and temperature monitor.

enter image description here

It is perfect for my project as I'm newbie. I want to build a power supply which will show on a display the voltage, current and the temperature using the arduino Atmega328. But the input voltage of the IC is maximum +0.3V over the VCC voltage. Is there a way of raising that value up to 15V?

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Unfortunately, you can't "raise" the operating voltage of an IC above the maximum that is given in the datasheet, in this case 5v. It appears that the input voltages to be measured are constrained to also be in this range, i.e. no more than 5v, which is what is causing your problem.

You have a couple of options: if you want to measure just the voltages, but no currents, you can use voltage divider(s) as shown on the right side of page 18 of the datasheet. If you need to measure current also, they show a circuit on the left side of the same page, using a separate current sense monitor chip (LTC6102HV) which adds lot of complexity and cost.

Instead, I suggest using a voltage/current monitor IC designed for higher voltages, such as the ISL28022. It can measure voltage and current over a range of 0-60v. It doesn't include a temperature measurement function, but I2C temperature sensors are a dime a dozen (well, maybe not quite that cheap, but this one -- LM75B goes for 60 cents).

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  • \$\begingroup\$ Atmega328p-pu already have an internal temperature sensor. \$\endgroup\$ – Pedro Quadros Mar 26 '15 at 11:17
  • \$\begingroup\$ @PedroQuadros If the OP is trying to measure the interior temperature of the power supply, it may be in a separate enclosure than the Arduino. \$\endgroup\$ – tcrosley Mar 26 '15 at 12:09
  • \$\begingroup\$ @Pedro Quadros: the measured temperature is that of the linear IC heatsink. \$\endgroup\$ – machineaddict Mar 26 '15 at 12:14
  • \$\begingroup\$ @tcrosley: Thank you very much for pointing that out! I don't know how I missed that one. I'm gonna grab a couple of those IC and have a test. \$\endgroup\$ – machineaddict Mar 26 '15 at 12:16
  • \$\begingroup\$ Now that I looked over ISL28022, it's cheaper and it measures the voltage from zero compared to LTC2990 which has the lowest point of 5V. I see a lot of testing ahead :) \$\endgroup\$ – machineaddict Mar 26 '15 at 13:09

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