We have a board with another accelerometer. I want to replace it with MMA8452QR1.
All powers are +3.3V
All looks fine, but in this case pin 15 of MMA8452QR1 will be tied to +3.3V and all other NC pins tied to ground.
Pin 3 (DNC) remains unconnected.
Can it cause any problem?
I would not expect any problems as both pins 8 and 15 are internally not connected and also according to Table 1 of the AN4077 can be connected either to Vdd or GND.
Yes, pin 3 should remain unconnected.