Low-Power Reset
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SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Power Control Manager (PCM)
Table 8-9. SVSMH Performance and Power Modes (continued)
Mode
PSS Bandgap
SVSMH
SVSMH Mode
When Enabled
AM_DCDC_VCORE1
Static
Optional
Full performance
(1)
AM_LF_VCORE0
Static
Optional
Full performance
(1)
AM_LF_VCORE1
Static
Optional
Full performance
(1)
LPM0_LDO_VCORE0
Static
Optional
Full performance
(1)
LPM0_LDO_VCORE1
Static
Optional
Full performance
(1)
LPM0_DCDC_VCORE0
Static
Optional
Full performance
(1)
LPM0_DCDC_VCORE1
Static
Optional
Full performance
(1)
LPM0_LF_VCORE0
Static
Optional
Full performance
(1)
LPM0_LF_VCORE1
Static
Optional
Full performance
(1)
LPM3
Sampled
Optional
Selectable
LPM4
Sampled
Optional
Selectable
LPM3.5
Sampled
Optional
Selectable
LPM4.5
Sampled
Optional
Selectable
LPM4.5 mode can be entered with SVSMH enabled or disabled. Disabling the SVSMH results in lower
power consumption, whereas enabling it provides the ability to detect supply drops and getting a "wake-
up" due to the supply drop below the SVSMH threshold. Note that the wake-up due to a supply failure
during LPM4.5 mode would be flagged as a SVSMH reset event. Enabling the SVSMH in LPM4.5 mode
results additionally in a faster start-up time than with disabled SVSMH.
NOTE:
Even if the SVSMH is configured as a monitor before entering LPM3.5 and LPM4.5 modes, it
behaves as a supervisor while in these modes, and if triggered, issues a POR reset and not
an interrupt.
NOTE:
SVSMH is supported only in full performance mode on devices that support extended
junction temperatures up to 125°C. See the device specific data sheet for details.
8.23 Low-Power Reset
In battery-operated applications, it might be desirable to limit the current drawn by the device to a
minimum after the supply drops below the SVSMH power-down level. In this case, the user should
configure the SVSMH in the monitor mode and in the interrupt service routine the application can
configure the I/Os into a defined state, disable any wake-up event (for example, from I/Os by clearing all
PxIE bits), disable any module that can be operational in LPM3.5 mode like RTC or WDT, disable SVSMH
by setting SVSMHOFF = 1, and then enter LPM4.5 mode.
In this low-power reset mode the SVSMH is disabled thus a complete power cycle (i.e. the supply needs
to drop below the VCCDET power-down level) is required to reset and restart the device. Pulling the
external reset pin (RSTn) low during the low-power reset state causes the device to enter its default reset
state (with higher current consumption) and the device starts up when the supply rises above the SVSMH
power-up level.
8.24 Power Requests During Debug
During a debug session, different requirements are necessary in order to support all the debug features of
the system. For example, in LPM0 modes the processor and interface clocks are normally disabled.
However, in a debug session, these clocks must remain active. This in turn leads to a different power
setting requirement to serve the additional current required. Power measurements during a debug session
may lead to different results compared to those during normal operation. The settings in the PCMCTL0
register reflect what the application code sees in normal operation.