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CC3220MOD: Reset circuitry options

prachi p
Intellectual 300 points
Part Number: CC3220MOD
Other Parts Discussed in Thread: CC3220SF

Hi,

In the datasheet of the CC3220MOD module, there are two connections recommended for the reset pins-

1. "Connect nRESET to a switch, external controller, or host, only if nRESET will be in a defined state under all operating conditions. Leave VBAT_RESET unconnected to save power." -> Is it required to leave the VBAT_RESET input unconnected or it is fine to connect it to the 3.3V supply voltage? (as is done in the LAUNCH-CC3220MODSF development board)

2. "If nRESET cannot be in a defined state under all operating conditions, connect VBAT_RESET to the main module power supply (VBAT1 and VBAT2). Due to the internal pullup resistor a leakage current of 3.3 V / 100 kΩ is expected." -> Is it required to keep the nRESET pin open, or it can be driven from a reset switch? 

Can you please show me an example of the schematic where the two options are shown? It will help with understanding clearly.

Regards,

Prachi

  • 0
    TI__Mastermind 40965 points

    Hi Prachi,

    To answer your questions:
    1. Regarding the nRESET and VBAT_RESET, you should connect VBAT_RESET to 3V3 if nRESET is not always driven from another device to a known state. By doing so, nRESET is pulled high through an internal 100k pullup. If you look at sheet 2 of the CC3220SF (not the module) launchpad schematic, J9 pin1 would be what VBAT_RESET is on the CC3220mod - a method of pulling up reset when it is not asserted.

    2. You can use some active driving solution for nRESET, or use the VBAT_RESET pullup and have a normally-open switch that connects to ground to assert reset, which is what the launchpad uses.

    You can use the LAUNCHCC3220MODASF design files as a guide: www.ti.com/.../swrc342

    Regards,
    Michael