Chapter 34 Voltage Regulators and Power Supplies
MPC5602P Microcontroller Reference Manual, Rev. 4
850
Freescale Semiconductor
The LVD_MAIN and LVD_MAIN5 detectors sense the V
DDIO
supply and provide
V
IOLVDMOK_H
/V
IOLVDM5OK_H
and V
IOLVDMOK_L
/V
IOLVDM5OK_L
as active high signals at 3.3 V and
1.2 V supply levels, respectively.
Two more LVD_MAIN detectors are also used for sensing VDDREG and VDDFLASH.
An LVD_DIG in the regulator senses the HPREG output. It provides V
MLVDDOK_H
and V
MLVDOK_L
as
active high signals.
The reference voltage used for all LVDs is trimmed for LVD_DIG using the bits LP[4:7]. Therefore,
during the pre-trimming period, LVD_DIG exhibits higher thresholds, whereas post trimming, the
thresholds come in the desired range. The trimming bits are provided by SSCM device option bits, which
are updated during the reset phase (RGM reset phase 2) only. Power-down pins are provided for LVDs.
When LVDs are powered down, their outputs are pulled high. LVDs are not controllable by the user. The
only option is the possibility to mask LVD_MAIN5 using the mask bit (5V_LVD_MASK)
in the
VREG_CTL register.
POR is required to initialize the device during supply rise. POR works only on the rising edge of main
supply. To ensure its functioning during the following rising edge of the supply, it is reset by the output of
the LVD_MAIN block when main supply reaches below the lower voltage threshold of the LVD_MAIN.
POR is asserted on power-up when V
DD
supply is above V
PORUP
minimum (refer to datasheet for details).
It is released only after V
DD
supply is above V
PORH
(refer to datasheet for details). V
DD
above V
PORH
ensures power management module including internal LVDs modules are fully functional.
34.1.3
VREG digital interface
The voltage regulator digital interface provides the temporization delay at initial power-up and at exit from
low-power modes. A signal, indicating that Low Power domain is powered, is used at power-up to release
reset to temporization counter. On completion of the delay counter, a end-of-count signal is released, it is
gated with an other signal indicating main domain voltage fine in order to release the VREGOK signal.
This is used by RGM to release the reset to the device.
The VREG digital interface also holds control register to mask 5 V LVD status coming from the voltage
regulator at the power-up.