Freescale Semiconductor MPC5748G EVB, User Manual

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MPC5748G EVB User Guide, User Guide, Rev. 0, 08/2015
8 Freescale Semiconductor, Inc.
5.1.2. Power Switch (SW5)
Slide switch SW5 can be used to isolate the power supply input from the EVB voltage regulators if
required.

Moving the slide switch to the right (away from the fuse) will turn the EVB OFF.

Moving the slide switch to the left (towards the fuse) will turn the EVB ON.
5.1.3. Regulator Power Jumper (J23)
All of the regulators are permanently powered from the main 12 V supply line and active with the
exception of the 1.25 V linear regulator which has a 3-way jumper to allow selection of the input
voltage.
The table below details the jumper configurations for the linear 1.25 V regulator source voltage. By
default, the regulator is powered from the 12 V supply line.
Table 1. 1.25 V Linear Regulator Source Select (J23)
Jumper Position PCB Legend Description
J23
(INPUT SEL)
1-2 (D)
12V 1.25V Linear regulator is powered from main 12V
2-3
5V
1.25V Linear regulator is powered from 5V switching regulator output
Removed
1.25V Linear regulator is not powered (disabled)
5.1.4. Power Status LED’s and Fuse
When power is applied to the EVB, five green LED’s adjacent to the voltage regulators show the
presence of the supply voltages as follows:

LED DS4 – Indicates that the 1.25V linear regulator is enabled and working correctly

LED DS5 – Indicates that the 5.0V linear regulator is enabled and working correctly

LED DS6 – Indicates that the 3.3V linear regulator is enabled and working correctly

LED DS9 – Indicates that the 5.0V switching regulator is enabled and working correctly

LED DS10 – Indicates that the 3.3V switching regulator is enabled and working correctly
If no LED’s are illuminated when power is applied to the EVB and the regulators are correctly enabled
using the appropriate jumpers, it is possible that either power switch SW5 is in the “OFF” position or
that the fuse F1 has blown. The fuse is provided to protect the external power supply and for EVB
circuitry reverse-bias protection. If the fuse has blown, check the polarity of your power supply and
replace the fuse with a 20 mm 1.5 A fast blow fuse.
Note that the fuse will not protect against one of the EVB regulators being shorted. If this happens,
damage is likely to occur to the EVB and / or components.
CAUTION
In the event of a short in the regulator output, the regulator and/or the
shorted component may be hot