Freescale Semiconductor 56F8300 Series, Руководство пользователя

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Power Supply
Technical Summary, Rev. 1
Freescale Semiconductor 2-15
Preliminary
2.10 Power Supply
The main power input to the 56F8357EVM, +12V DC at 1.2A, is through a 2.1mm coax power
jack. This input power is rectified to provide a DC supply input. This allows a user the option to
use a +12V AC power supply. A 1.2Amp power supply is provided with the 56F8357EVM;
however, less than 500mA is required by the EVM. The remaining current is available for custom
control applications when connected to the Daughter Card connectors. The 56F8357EVM
pr5.0V DC regulation for the CAN interface and additional regulators. The
56F8357EVM pr3.3V DC voltage regulation for the processor, memory, D/A, ADC,
parallel JTAG interface and supporting logic; refer to
Figure 2-9 . Additional voltage regulation
logic provides a low-noise +3.3V DC voltage reference to the processor’s A/D V
REFH
. A jumper,
JG18, and resistor, R66, are provided to allow the analog and digital grounds to be isolated on the
56F8357EVM board. This allows the analog ground reference point to be provided on a custom
board attached to the 56F8357EVM Daughter Card connectors. By removing R66, the AGND
reference is disconnected from the 56F8357EVM’s digital ground. By placing a jumper in on
JG18, the AGND is reconnected to the 56F8357EVM’s digital ground. Power applied to the
56F8357EVM is indicated with a Power-ON LED, referenced as LED13. Optionally, the user
can provide the +2.5 DC voltage needed by the processor’s core on connector J24 and disable the
on-chip core voltage regulator by moving the resistor at R72 to R71. Additonally, four zero ohm
resistors or shorting wires must be added at R67, R68, R69, and R70 to allow the ex2.5V
DC to pass to the 56F8357.
Figure 2-9. Schematic Diagram of the Power Supply
+5.0V DC
+12V DC/AC
Power
Condition
CAN
56F8357
V
DD_IO
& PLL
+3.3V
Regulator
P3
56F8357EVM
Parts
56F8357
V
REFH
+3.3V DC
+3.3VA DC
+5.0V
Regulator
56F8357
ADC
+3.3V
Regulator
+3.3VA DC
56F8357
V
DD
Core
+2.5V DC
Ext In
1
2
J24
U15
R67-R70
Bridge
Rectifier
Input
+3.3V
Regulator
Power ON