EYE on NPI - STMicroelectronics TSC1641 Digital Power Monitor

Adafruit Industries

This week's EYE ON NPI is gonna give it to up high...then down low (https://en.wikipedia.org/wiki/High_five) ...ready to measure, never too slow! It's STMicroelectronics' TSC1641 Digital Power Monitor (https://www.digikey.com/en/product-highlight/s/stmicroelectronics/tsc1641-digital-power-monitor), a high-precision temperature, voltage, power, and temperature monitoring chip with I2C or I3C interfaces for integration with modern microcontrollers and microcomputers. This chip is great for tracking actual power usage into motors, LEDs, batteries etc. to detect anomalies or conserve power, with a tiny footprint and flexible usage. The TSC1641 is a modern take on the old-shunt-resistor-into-an-opamp method of power monitoring (https://learn.adafruit.com/portable-solar-charging-tracker/analog-stuff). For one, the TSC1641 can handle high or low-side measurements. That means you don't run the risk of having your grounds floating above earth, or managing multiple reference voltages. Also of course wiring is a snap, you just insert the board in between the power rail and load. Second, it can read up to 60VDC voltages - great for big battery packs, automotive or robotics. Third, it will calculate power and low-pass filter for you so you aren't affected by spiky power usage. Fourth, there's an onboard temperature sensor tossed in. Finally, this chip is not just I2C compatible, it has I3C support https://en.wikipedia.org/wiki/I3C_(bus) which makes it a great investment for long-term designs as I3C catches on and is supported in the next generations of microcontrollers. We covered I3C in a previous EYE ON NPI (https://blog.adafruit.com/2022/05/12/eye-on-npi-nxp-p3s0200gm-i3c-switch-with-hardware-select-and-enable-eyeonnpi-nxp-digikey/) so check it out for more details. To sum up fast: I3C is back-compatible with I2C but has push-pull logic support for up-to-12MHz speeds, in-channel interrupts so a separate IRQ line is not needed, and dynamic addressing so there's no address collision. A great update to all the things that make us batty about I2C. Support for I3C on the controller-side is still rolling out so you probably will use this chip in I2C mode for now, but your firmware can be adjusted-up to I3C on a future revision. This chip is a great response to the INA series from TI - and we love competition, it's great for all engineers when the chip companies clamor for our business by iterating and improving! Compared to the INA237, the ST TSC1641 (https://www.digikey.com/en/products/detail/stmicroelectronics/TSC1641IQT/21725159) has the same specs but is 10% less, plus you get that I3C support that none of the INA chips have yet. The high level of integration means you only need to spec a shunt resistor. The resistor selection will have to balance the dynamic current range measurable with the 16-bit precision. If you pick too small of a resistor, you'll max out the measurable current faster. If you pick too large of a resistor, you wont get good accuracy at low currents. Check the datasheet for how to select a good resistor and then how to tell the chip what value you've chosen: that will let the TSC1641 perform the power/current/voltage calculations on its own without you having to do any math. If you'd like to get started fast, there's also an eval board that is Arduino-shield-compatible (https://www.digikey.com/en/product-highlight/s/stmicroelectronics/steval-digafev1-evaluation-board-for-the-tsc1641), some firmware is provided for the Nucleo series of ST dev boards to evaluate without any soldering or coding. If you're interested in the STMicroelectronics TSC1641 Digital Power Monitor (https://www.digikey.com/en/products/detail/stmicroelectronics/TSC1641IQT/21725159) you are in luck because it's in stock right now at DigiKey! Order today and it will ship faster than you can give a high-five, and be at your doorstep tomorrow afternoon for your power-monitoring pleasure.