
DV
CC
Voltage
V
CORE
SVS
H_IT+
SVS
L_IT+
Time
BOR
Reset from SVS
H
Reset from SVS
L
PMM Operation
2.2.3 Supply Voltage Supervisor - Power-Up
When the device is powering up, the SVS
H
and SVS
L
functions are enabled by default. Initially, DV
CC
is
low, and therefore the PMM holds the device in BOR reset. When both the SVS
H
and SVS
L
levels are met,
the reset is released.
shows this process.
Figure 2-3. PMM Action at Device Power-Up
After power-up is complete, both voltage domains are supervised while the respective modules are
enabled.
2.2.4 LPM3.5, LPM4.5
LPM3.5 and LPM4.5 are additional low-power modes in which the regulator of the PMM is completely
disabled, providing additional power savings. Because there is no power supplied to V
CORE
during LPMx.5,
the CPU and all digital modules including RAM are unpowered. This disables the entire device and, as a
result, the contents of the registers and RAM are lost. Any essential values should be stored to FRAM
prior to entering LPMx.5. See the SYS module for complete descriptions and uses of LPMx.5.
2.2.5 Brownout Reset (BOR)
The primary function of the brownout reset (BOR) circuit occurs when the device is powering up. It is
functional very early in the power-up ramp, generating a BOR that initializes the system. It also functions
when no SVS is enabled and a brownout condition occurs. It sustains this reset until the input power is
sufficient for the logic, to enable proper reset of the system.
In an application, it may be desired to cause a BOR via software. Setting PMMSWBOR causes a
software-driven BOR. PMMBORIFG is set accordingly. Note that a BOR also initiates a POR and PUC.
PMMBORIFG can be cleared by software or by reading SYSRSTIV. Similarly, it is possible to cause a
POR via software by setting PMMSWPOR. PMMPORIFG is set accordingly. A POR also initiates a PUC.
PMMPORIFG can be cleared by software or by reading SYSRSTIV. Both PMMSWBOR and PMMSWPOR
are self clearing. See the SYS module for complete descriptions of BOR, POR, and PUC resets.
2.2.6 RST/NMI
The external RST/NMI terminal is pulled low on a BOR reset condition. The RST/NMI can be used as
reset source for the rest of the application.
64
Power Management Module and Supply Voltage Supervisor
SLAU272C – May 2011 – Revised November 2013
Copyright © 2011–2013, Texas Instruments Incorporated