PXS20RM Datasheet, PDF (1172/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Power Management Unit (PMU)
Power-on
circuitry
LVD_MAIN_1
LVD_MAIN_2
LVD_MAIN_3
HPREG1
HPREG2
LVD_DIG_MAIN
LVD_DIG_BKUP
Current
comparator
HVD_DIG_MAIN
HVD_DIG_BKUP
VDDIO and flash memory
Core
Core
Figure 39-1. PMU block diagram
Table 39-1. PMU blocks
Abbreviation
HPREG1
HPREG2
LVD_MAIN_1
LVD_MAIN_2
LVD_MAIN_3
LVD_DIG_MAIN
LVD_DIG_BKUP
HVD_DIG_MAIN
HVD_DIG_BKUP
Block name
Block function
High-power regulator 1
Provides internal ballast to support core current
High-power regulator 2
Provides external NPN to support core current
Low-voltage detector 1
Monitors the 3.3 V supply of VDDIO
Low-voltage detector 2
Monitors the 3.3 V supply of VDDREG
Low-voltage detector 3
Monitors the 3.3 V supply of VDDFLASH
Main digital low-voltage detector
Monitors the 1.2 V digital core supply (HPVDD)
Backup digital low-voltage detector Assists in the self-test of LVD_DIG_MAIN
Main digital high-voltage detector Monitors the 1.2 V digital core supply (HPVDD)
Backup digital high-voltage detector Assists in the self-test of LVD_DIG_MAIN
39.3 High-power regulators
The PMU includes two high-power regulators, HPREG1 and HPREG2.
HPREG1 uses internal ballast to support the core current, whereas HPREG2 gets ON only when external
NPN is present on board to supply core current. The device always powers up using HPREG1. If an
external NPN is present, the device then makes a transition from HPREG1 to HPREG2. This transition is
dynamic. Once HPREG2 is fully operational, controller part of HPREG1 is switched OFF.
If an external NPN is connected to the device, HPREG2 takes control. The output voltage of HPREG2 is
higher than HPREG1. This guarantees that internal Ballast (HPREG1) gets OFF as soon as external NPN
takes control. The base of the Bipolar is driven by a control signal generated by the CONTROL part and
available on a dedicated pin (BCTRL).
39-2
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor