SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
POK modules are responsible for accurately detecting the voltage levels. Each module is trimmed to account for process and temperature variations. The trim values are provided by eFuse chains enabled by a POR module.
During POR, coarse monitors on supplies VDDA18, VDD12, 1.8V LDO, BGAP are enabled. The status of this can be monitored through TOP_CTRL.PMU_COARSE_STAT register during runtime.
The table below shows different voltage monitors available. Enabling/Disabling of this monitors can be controlled by TOP_CTRL.VMON_CTRL, TOP_CTRL.ADC_REF_COMP_CTRL register. There are corresponding status bits available in TOP_CTRL.VMON_STAT, TOP_CTRL:ADC_REF_GOOD_STATUS. The output of voltage monitors comparators are filtered using a configurable digital glitch filter module. The configuration of filter can be done using TOP_CTRL.VMON_FILTER_CTRL.SELECT_VALUE to select from no filtering option to max of 14.4us filtering of voltage monitor signals. The output of the voltage monitors are aggregated and the aggregated output is forward to ESM. Individual mask bits in TOP_CTRL.MASK_VMON_ERROR_ESM_L and TOP_CTRL.MASK_VMON_ERROR_ESM_H can be used to MASK the corresponding monitor to trigger ESM event.
POK is set to 1 when the voltage supply is within the range and goes to 0 when out of range. See device datasheet for POK tolerance.
The ESM event is generated only when POK signals out of range.
Voltage Comparator subsystem compares the sensed voltage level (VSENSE) to a reference voltage supply (VREF) against a reference voltage to generate a POWER good/OK (POK) signal. For all comparators, VSENSE is derived from the supply being monitored (VMON) through a resistor divider (Vsense=Vmon R2/(R1+R2)) ). Therefore, threshold value can be calculated as (Vth=Vref (R1+R2)/R2). For an under voltage comparator, if VMON>Vth then POK=1. Comparators have a decision range where this transition may occur. This decision range is influenced by the variation in reference voltage, resistor ratio and comparator offset due to the process variation and mismatch. Threshold should be set to a voltage level such that decision range of the comparator would be outside of the operating range of the supply.
Voltage Monitored | Comparator block | UV/OV(1) | Description |
---|---|---|---|
VDDA18 | C0 | UV | Voltage monitor for 1.8V LDO output using 3.3V as reference |
VDDA18 | C2 | UV/OV | Voltage monitor for 1.8V LDO output using BGAP as reference |
VBGAP09 | C1 | UV/OV | Voltage monitor for 0.9V bandgap. |
VDD12 | C3 | UV/OV | Voltage monitor for 1.2V I/O supply |
VDDSBIO | C5 | UV/OV | Voltage monitor for 1.8V IO bias supply |
VSYS_MON | C7 | UV | Voltage monitor for external VSYS_MON |
VDDA33 | C8 | UV | Voltage monitor for 3.3V I/O supply |
ADC0_REF | C4 | UV/OV | Voltage monitor for ADC0_REF |
ADC12_REF | C9 | UV/OV | Voltage monitor for ADC12_REF |
ADC34_REF | C6 | UV/OV | Voltage monitor for ADC34_REF |
See below table for a list of the supplies and where they are monitored:
Supply | External Reset | Internal Reset | Safety System |
---|---|---|---|
VDDA33 | Y | N | Y |
VDDA18 | N | Y | Y |
VBGAP09 | N | Y | Y |
VDD12 | Y | Y | Y |
VDDSBIO | N | N | Y |
VOUT_LDO* | N | Y* | N |
VSYS_MON | Y | N | Y |
ADC0_REF, ADC12_REF | N | N | Y |
ADC34_REF | N | N | Y |
*:LDO output has monitoring in addition to the monitoring on VDDA18.