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MPC5668EVB Users Manual Rev 0.1 May 2009
MPC5668EVBUM/D Page 5 of 29
3.1.3 Regulator Power Jumpers (J42, J44, J45 and J46)
The Power supply control jumpers are located adjacent to the respective regulators.
As mentioned above, the EVB has four voltage regulators on board:
- 2.5V switching regulator (U17) to supply the MCU MLB Pads voltage and the SMSC INIC (U6).
- 3.3V switching regulator (U18) for EVB peripherals and MCU regulator, logic and I/O.
-
5.0V switching regulator (U19) for the MCU regulator and I/O and EVB peripherals.
-
5.0V linear regulator (U14) for the MCU ADC power supply.
All of the regulators have the option of being disabled if they are not required. The table below details the
jumper configurations for enabling and disabling the regulators. By default, all of the regulators are enabled.
Table 3-1 Regulator Power Jumpers
Jumper Position PCB
Legend Description
J81 (2.5V)
FITTED
DISABLE
2.5V switching regulator output is
Disabled
REMOVED (D) 2.5V switching regulator output is
Enabled
J82 (3.3V)
FITTED
DISABLE
3.3V switching regulator output is
Disabled
REMOVED (D) 3.3V switching regulator output is
Enabled
J83 (5.0V)
FITTED
DISABLE
5.0V switching regulator output is
Disabled
REMOVED (D)
5.0V switching regulator output is
Enabled
J84 (5.0V-LINEAR)
FITTED (D) ENABLE 5.0V linear regulator output is Enabled
REMOVED 5.0V linear regulator output is Disabled
3.1.4 Power Status LED’s and Fuse
When power is applied to the EVB, four green power LED’s adjacent to the voltage regulators show the
presence of the supply voltages as follows:
LED DS8 – Indicates that the 5.0V linear regulator is enabled and working correctly
LED DS9 – Indicates that the 1.5V switching regulator is enabled and working correctly
LED DS10 – Indicates that the 3.3V switching regulator is enabled and working correctly
LED DS11 – Indicates that the 5.0V 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 SW6 is in the “OFF” position or that the fuse F1
has blown. The fuse will blow if power is applied to the EVB in reverse-bias, where a protection diode ensures
that the main fuse blows rather than causing damage to the EVB circuitry. If the fuse has blown, check the
bias of your power supply connection then replace fuse F1 with a 20mm 500mA fast blow fuse.