CY8CMBR3116 resistors on GUARD and SHIELD

[heboc_4018381]

I'm implementing water and moisture resistant capsense buttons with the CY8CMBR3116 and looking in the design guide, AN90071, the recommendation is to put 560 ohm serial resistors on all sense pins, including GUARD and SHIELD. However, on the dev board it seems there are no resistors on these two pins. So why doesn't the dev board follow the recommendations in the design guide? Or am I misunderstanding something?

[BragadeeshV · Accepted solution]

Hi,

Yes, you're right. We recommend to use 560 ohms resistors in the Guard and shield lines as mentioned in our MBR3 design guide.

In the MBR3 kit, you can find that the guard sensor pin (CS2/ GUARD) has a 560 ohm resistor. In the kit we use jumpers (A,B,C) to select the different features (any two from liquid tolerance, Buzzer and HI).  Since the HI and shield pin are multiplexed in the pin#9 (CS15/SH/HI),  we didn't use the 560 ohms resistor there.

Regards,

Bragadeesh

[heboc_4018381]

Great, thanks!