INA232/INA260 just for voltage? - Page 1
Forum section: electronics / projects

author: ryanmills
author_rank: Unknown
timestamp: March 11, 2025, 08:31:03 pm
content: INA232 Datasheet:https://www.ti.com/lit/ds/symlink/ina232.pdf?ts=1741708708907&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FINA232I need to measure the voltage from a hand crank generator and at first I was thinking I could do a voltage divider with a zener to limit the peak (example attached) but I'm worried it would not protect the input enough. In the past I have used the INA219 but its lower voltage limit was problematic, the generator puts out 0-6V but spun fast enough can peak 25-40V or higher. in theory I'm looking at the updated INA232 that has a 48V max but feel like it might be overkill since I really only need to measure voltage not current and there is zero load. I assume my example is not ideal, not sure I could use an op amp to limit the peak to avoid damaging the input pin. Has anyone used something better than the INA219/INA232 when you just need to measure voltage with a relatively high peak of say 50V? Is there a better "old school" way to do this that would just give me an analog 0-3V I could measure safely?

author: ryanmills
author_rank: Unknown
timestamp: March 11, 2025, 08:48:46 pm
content: INA260 Datasheet:https://www.ti.com/lit/ds/symlink/ina260.pdf?ts=1741697998988&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FINA260I wonder if I could just use a voltage divider into an INA260, 36V limit but the block diagram looks as thou I could just use the VBUS without any of the current sense and limit my part count a little.

author: ryanmills
author_rank: Unknown
timestamp: March 11, 2025, 09:29:24 pm
content: Link:https://www.ti.com/lit/ug/tidu849/tidu849.pdf?ts=1741727671893&ref_url=https%253A%252F%252Fwww.google.com%252FTI has an example project that seems to do exactly what I was thinking, only thing I'm unsure of is if the current sense side is required to measure the bus voltage. Still seems overkill but cheaper fix than blowing the pin on an MCU. I can't find any examples of using anything in the INA family just for voltage, the block diagram looks like it would work thou. While I know I am an idiot, am I making an obvious mistake here?

author: thm_w
author_rank: Super Contributor
timestamp: March 11, 2025, 11:16:16 pm
content: Should work fine, Vbus is referenced to ground as shown on page 7.But I would not bother, voltage divider, decoupling cap, and have the zener/TVS either across the input resistor R2 shown in your schematic. Or have additional series resistor then zener after that. To limit power dissipation in zener.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 12, 2025, 12:19:13 am
content: Quote from: ryanmills on March 11, 2025, 09:29:24 pmNo, but I would short the IN+ and IN- pins instead of leaving them floating.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 12, 2025, 03:09:07 pm
content: Eh?

author: ryanmills
author_rank: Unknown
timestamp: March 13, 2025, 11:04:03 pm
content: Quote from: thm_w on March 11, 2025, 11:16:16 pmThank you, when you say across R2 is the example below what you mean, or should there still be another resistor in front of the zener?

author: thm_w
author_rank: Super Contributor
timestamp: March 13, 2025, 11:20:52 pm
content: Yes that is what I mean.40V input would be about 1.4W across that 1k1 resistor, if it was continuously applied. You can always raise the values of the divider if that is an issue. And verify the clamping voltage of the zener/TVS.