INA241A: NC pin connection

Hello Go, 

Thank you for your post. 

My Recommendation: Connect Pin 4 to Ground

The datasheet recommendation is the one to follow. Connect pin 4 (NC) to ground for your production design.

The datasheet is clear: pin 4 is classified as a "Ground" type pin with the description "Reserved. Connect to ground." [1]. This is reinforced by the recommended PCB layout (Figure 8-3), which shows pin 4 connected via a via to the ground plane [2], and by TI's reference design schematic, which also ties it to GND [3].

Why the EVM Differs (and Why It Still Works)

A TI engineer directly addressed this discrepancy and confirmed that leaving pin 4 floating poses no operational risk — in fact, the EVM designer intentionally left it unconnected [4]. The reason it works either way is that pin 4 has a weak internal pull-down resistor, so it self-biases to ground even when floating [5].

That said, externally grounding it is best practice because it provides improved noise immunity by fixing the potential externally rather than relying on the weak internal pull-down.

Bottom Line

For a standard design with GND at 0V, ground pin 4 per the datasheet. The EVM's floating pin is acceptable but not the recommended practice for production designs.

1. INA241A Datasheet - Pin Functions (Page 2)
2. INA241A Datasheet - Recommended Layout (Page 25)
3. INA241A Reference Design Schematic (TIDUF82B, Page 6)
4. TI E2E: INA241A Pin 4 NC
5. TI E2E: INA241A NC Pin Internal Pull-Down

I hope this helps, 

Joe