Tougher INA3221 Power Monitor

Description

Power monitor with three channels, each capable of continuous 10A and 24V. It is compatible with both Arduino and Feather, and is based on a popular INA3221. The power monitor is more robust compared to other modules based on this IC. Each channel has proper RC filtering with TVS diodes to prevent INA3221 from being destroyed by transients, and to eliminate glitches. Pluggable screw terminals are rated for 15A, and can handle 12 to 30 AWG wires.

The third channel has a TPS1HB08A power switch, to be able to disconnect the load.
The board can also provide power to the Feather or Arduino from the first channel via a built-in buck converter.

The KiCAD project is available on Github.

Files

TougherPowerMonitor-schematics.pdf

Adobe Portable Document Format - 155.09 kB - 09/05/2020 at 13:04

Preview

Components

1 × TPS1HB08A 40-V, 8-mΩ Single-Channel Smart High-Side Switch

1 × INA3221 26V, triple channel, 13-bit, i2c output current/voltage monitor w/alerts

1 × AP63205 3.8V TO 32V INPUT, 2A LOW IQ SYNCHRONOUS BUCK WITH ENHANCED EMI REDUCTION

Project Logs

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Assembled the board
Beast Devices • 11/05/2020 at 19:21 • 0 comments

I have assembled the first board and have done some test. Everything works fine, except that I have swapped the I2C lanes, but it is easy to fix for the next PCB spin. :)
PCBs received
Beast Devices • 09/22/2020 at 08:27 • 0 comments

Got the PCBs, of course with the matte black solder mask.
Designing the PCB
Beast Devices • 09/10/2020 at 07:48 • 0 comments

I wanted to keep the design 2-layer, and with some insignificant shortcuts, I kept it at two layers. I have tried to avoid large currents to pass around INA3221 to prevent ground bouncing, so I added some cutouts in the ground. Cutouts are made so that differential traces from current resistor don’t experience ground plane breaks. I didn’t add any ground pours on the bottom layer, because it wouldn’t add any significant benefit that I can see. It would just introduce more headache with controlling where the ground current are going. The ground path in the power area is solid and uninterrupted, and the ground path in signal areas is good enough.

The size of PCB is 130 mm by 53 mm, and could probably be made a bit smaller with a 4-layer design, by having Feather/Arduino sitting on top of everything. But this approach would also make it harder to do any changes later on. In the current design, if I want to change from Feather/Arduino to something else, I don’t have to modify anything in the power area.
The schematics
Beast Devices • 09/05/2020 at 13:15 • 0 comments

My first ever schematics in KiCAD is finished. It was a bit difficult to get used to it after working mostly in Altium and CircuitStudio.