Figure 5-2. External Circuitry to Extend Power-On Reset
R
PU
= 1 kΩ to 100 kΩ
C
1
= 1 nF to 10 µF
If the application requires the use of an external reset switch, Figure 5-3 on page 179 shows the
proper circuitry to use.
Figure 5-3. Reset Circuit Controlled by Switch
Typical R
PU
= 10 kΩ
Typical R
S
= 470 Ω
C
1
= 10 nF
The R
PU
and C
1
components define the power-on delay.
The external reset timing is shown in Figure 23-7 on page 985.
5.2.2.5 Brown-Out Reset (BOR)
The microcontroller provides a brown-out detection circuit that triggers if the power supply (V
DD
)
drops below a brown-out threshold voltage (V
BTH
). If a brown-out condition is detected, the system
may generate an interrupt or a system reset. The default condition is to reset the microcontroller.
Brown-out resets are controlled with the Power-On and Brown-Out Reset Control (PBORCTL)
register. The BORIOR bit in the PBORCTL register must be set for a brown-out condition to trigger
a reset; if BORIOR is clear, an interrupt is generated. When a Brown-out condition occurs during a
Flash PROGRAM or ERASE operation, a full system reset is always triggered without regard to the
setting in the PBORCTL register.
The brown-out reset sequence is as follows:
1. When V
DD
drops below V
BTH
, an internal BOR condition is set.
179July 24, 2012
Texas Instruments-Production Data
Stellaris
®
LM3S6G65 Microcontroller
OBSOLETE: TI has discontinued production of this device.