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Power Management Controller (PMC)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
1649
Figure 35-6. Vreg 3.3 V power connection
The regulator output voltage is adjustable via software by writing to field PCM_TRIMR[VDD33TRIM],
which selects one of the 16 voltages available. The reset value of the 4-bit register is “0000”,
corresponding to nominal voltage of 3.39 V. This is the typical default value, the real default value may
vary from sample to sample according to process, temperature and voltage supply conditions, as detailed
in the “PMC Electrical Characteristics” table in the device data sheet.
The 3.3 V supply is internally connected to a 5 V ADC channel such that the actual voltage may be read.
Moreover, if an external 3.3 V voltage source will be used, the user can disable this regulator by clearing
the shutdown bit NVUSRO[V33DIS]. The user might have both internal 3.3 V regulator and external
3.3 V voltage sources at the same time at the cost of additional power consumption on the external voltage
source. It is recommended to disable the internal 3.3 V regulator in this case.
Additional features of this regulator include a current limiter that protects a PMOS pass device from
overload condition and soft start-up to avoid overshoot during power-on.
If an external 3.3 V supply will be used, this regulator can be disabled by setting vdd33shutdown bit to
logical 1. The bit resides in the NVUSRO register in the flash memory shadow row. See
and
for details.
Osc
Vreg 3.3
Vref_3p3
Vreg 1.2
Internal 3.3V
Supply
VRC33
Flash
VDDREG
VDDREG
VDD33
VRC
Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...