SPRADO8 March 2025 AM62L
PORz is the external WKUP domain cold reset input to the processor. The recommendation is to hold the PORz pulled low during the supply ramp and oscillator start-up. Follow the recommended PORz timing in the Power-Up Sequencing diagram of the processor-specific data sheet.
For the PORz (3.3V tolerant, fail-safe input), applying a 3.3V input is an acceptable use case. The input thresholds are a function of the 1.8V IO supply voltage (VDDS_OSC0).
Slow rising reset input causes internal processor reset circuit to glitch. Recommend using a fast rise time discrete push-pull output buffer as PORz input and add a capacitor (22pF) filter provision.
When PMIC output is used, connect the output through push-pull output type logic gate or discrete buffer (with fast rise time) as an PORz input, rather than connecting a slow rising open-drain PMIC output (can glitch the internal reset circuit).
Provision to connect a filter capacitor at the PORz input is recommended. The capacitor value and mounting is use-case dependent. Verify the capacitor value does not cause the LVCMOS input to violate the slew rate requirements or glitch internally due to slow ramp.
Not connecting a valid input to PORz is not a allowed use case and can cause unpredictable and random behavior. Due to the device not going through a valid reset, internal circuits can be random (undefined) states.
Connect external warm reset input RESETz as per the Pin Connectivity Requirements section of the processor-specific data sheet. Warm reset inputs (LVCMOS inputs) have input slew rate requirements specified. Connecting a capacitor directly at the input is not recommended due to the slow ramp input. A schmitt trigger-based debouncing circuit is recommended. For implementing the debouncing logic, see the processor-specific EVM schematic.