which action occurs. In either case, the system clock source is automatically switched to the PIOSC.
If a MOSC failure reset occurs, the NMI handler is used to address the main oscillator verification
failure because the necessary code can be removed from the general reset handler, speeding up
reset processing. The detection circuit is enabled by setting the
CVAL
bit in the
Main Oscillator
Control (MOSCCTL)
register. The main oscillator verification error is indicated in the main oscillator
fail status (
MOSCFAIL
) bit in the
Reset Cause (RESC)
register. The main oscillator verification circuit
action is described in more detail in the section called “Main Oscillator Verification Circuit” on page 236.
5.2.4
Power Control
The TM4C1294NCPDT microcontroller provides an integrated LDO regulator that is used to provide
power to the majority of the microcontroller's internal logic. Figure 5-4 shows the power architecture.
The voltage output has a maximum voltage of 1.2 V. Refer to “Dynamic Power
Management” on page 242 for more information on the LDO operation.
An external LDO may not be used.
Note:
VDDA
must be supplied with 3.3 V, or the microcontroller does not function properly.
VDDA
is the supply for all of the analog circuitry on the device, including the clock circuitry.
Figure 5-4. Power Architecture
Analog Circuits
I/O Buffers
LDO Voltage
Regulator
Internal
Logic and PLL
GND
GNDA
GNDA
VDDA
VDDA
VDDC
VDDC
+3.3V
GND
GND
GND
VDD
VDD
+3.3V
Note:
The V
DDA
voltage source is typically connected to a filtered voltage source or regulator.
229
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller