Power Management Controller (PMC)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
1635
Chapter 35
Power Management Controller (PMC)
35.1
Introduction
Internally, MPC5644A devices have four supply voltages, nominally 5 V, 3.3 V, 1.2 V and 1.0 V V
STBY
.
Externally only a 5 V supply is required. The other voltages are supplied by internal regulators. All supply
voltages have voltage monitors and both the V
DD
regulator and all monitors are adjustable. The PMC
controls the internal voltage supplies, with the exception of V
STBY
, which has its own regulator.
Additionally the PMC controls the low voltage inhibit (LVI) circuits and power-on reset (POR) functions.
Note that although MPC5644Adevices have features intended for use in low-power applications, reduced
power modes are achieved by clock gating. It is not possible to switch off the power to any on-chip module.
Reduced power consumption is achieved by turning off the system clock to the modules. See
for details.
The power management controller contains circuitry to generate the internal 3.3 V supply and to control
the regulation of 1.2 V supply with external npn ballast transistor. It also contains low voltage inhibit (LVI)
and power-on reset (POR) circuits for the 1.2 V supply, the 3.3 V supply, the 3.3 V/5 V supply of the
closest I/O segment (VDDEH1) and the 5 V supply of the regulators (VDDREG). There is no requirement
for special power up or down sequencing. VDDREG can be tied to VSS to bypass the 3.3 V and 1.2 V
internal regulators.
NOTE
Although it is possible to bypass the internal regulators by tying the
VDDREG to ground (VSS), doing so also disables most PMC functions,
e.g., the user-programmable LVIs.
Regulators and power supply LVI/POR control blocks use a precision bandgap voltage reference.
A low impedance buffered version of the absolute and curvature corrected bandgap voltage reference is
available to be measured using an ADC dedicated channel. The PMC block has the following operating
modes:
•
Normal mode
•
Low power RAM test
•
VDDREG supply grounded (See
Section 35.4, Functional description
for details)
Summary of Contents for MPC5644A
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