4.1.3. Power Status LED
When power is applied to the LCEVB, two green LED’s adjacent to the regulator and power connector
show the presence of the supply voltages as follows:
LED DS5 – Indicates that the 5.0 V supply voltage is present
LED DS6 – Indicates that the 3.3 V switching regulator is functioning
If no LED’s are illuminated when power is supplied to the LCEVB and the power switch is in the
“ON” position, the power adapter may be faulty or there may be a fault with the LCEVB. If only one
LED is illuminated there may be a short in that power supply rail – check there is nothing shorting on
the EVB. If you continue to have problems, contact NXP for support.
CAUTION
In the event of a short on the regulator output (in which case one of the
LED’s would be off or dimly illuminated), the regulator and/or the shorted
component will likely be hot.
4.1.4. MCU and Peripheral Voltage Configuration
The following MCU supply rails are connected to the 3.3 V switching regulator:
VDD_HV_ADC0
VDD_HV_ADC1
VDD_HV_ADC1_REF
VDD_HV_A
VDD_HV_B
VDD_HV_FLA
External Ballast Transistor Supply
Similarly all of the peripheral interfaces (or the I/O power in the peripheral interface) are supplied
from 3.3 V as is the reset circuitry and the voltage sense wire on the JTAG connector.
4.2. Reset Control (SW3)
The
reset circuitry is
located in the bottom left
quarter of the LCEVB
next to the power switch
The MCU has a single bi-directional open drain Reset pin. Rather than connect multiple devices to the
reset pin directly, a reset-in and reset-out buffering scheme has been implemented on the LCEVB as
shown in
Figure 4
. The reset “in” from the reset switch (SW3) and the debug connectors are logically
OR’d together using an AND gate and then connected to the buffer to provide an open-drain output.
The “reset-out” circuitry provides a buffered reset signal that can be used to drive any circuitry
requiring a reset control from the MCU.
MPC5748G Low Cost EVB User Guide, Rev. 1, 08/2016
8
NXP Semiconductors
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