LM3S6952 Datasheet, PDF (71/626 Pages) Texas Instruments – Stellaris LM3S6952 Microcontroller

Stellaris® LM3S6952 Microcontroller
Figure 6-2. External Circuitry to Extend Power-On Reset
VDD
Stellaris®
R_PU
RST
C₁
R_PU = 1 kΩ to 100 kΩ
C₁ = 1 nF to 10 µF
If the application requires the use of an external reset switch, Figure 6-3 on page 71 shows the
proper circuitry to use.
Figure 6-3. Reset Circuit Controlled by Switch
VDD
Stellaris®
R_PU
RST
R_S
C₁
6.1.2.5
Typical R_PU = 10 kΩ
Typical R_S = 470 Ω
C₁ = 10 nF
The R_PU and C₁ components define the power-on delay.
The external reset timing is shown in Figure 23-5 on page 586.
Brown-Out Reset (BOR)
A drop in the input voltage resulting in the assertion of the internal brown-out detector can be used
to reset the controller. This is initially disabled and may be enabled by software.
The system 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 a controller interrupt or a system reset.
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.
The brown-out reset is equivalent to an assertion of the external RST input and the reset is held
active until the proper V_DD level is restored. The RESC register can be examined in the reset interrupt
April 05, 2010
71
Texas Instruments-Production Data