1.7.2 On-chip Power-On Reset (POR) and Brown-Out Reset (BOR) Circuit
Two on-chip supervisory circuits, the power-on reset (POR) and the brown-out reset (BOR) remove the burden
of monitoring the V
DD
and V
DDIO
supply rails from the application board. The purpose of the POR is to create
a clean reset throughout the device during the entire power-up procedure. The trip point is a looser, lower trip
point than the BOR, which watches for dips in the V
DD
or V
DDIO
rail during device operation. The POR function
is present on both V
DD
and V
DDIO
rails at all times. After initial device power-up, the BOR function is present on
V
DDIO
at all times, and on V
DD
when the internal VREG is enabled (VREGENZ pin is pulled low). Both functions
pull the XRS pin low when one of the voltages is below their respective trip point. Additionally, when monitoring
the V
DD
rail, the BOR pulls XRS low when V
DD
is above its overvoltage trip point. See the device datasheet
for the various trip points as well as the delay time from the removal of the fault condition to enable the BOR
function, to the release of the XRS pin.
A bit is provided in the BORCFG register (address 0x985) to disable both the VDD and VDDIO BOR functions.
The default state of this bit is to enable the BOR function. When the BOR functions are disabled, the POR
functions will remain enabled. See
for a description of the BORCFG register. The BORCFG register
state can only be modified by software and the XRS pin signal. A CPU reset from the debugger will not modify
this register.
Figure 1-107. BOR Configuration (BORCFG) Register
15
3
2
1
0
Reserved
Reserved
Reserved
BORENZ
R-0
R-1
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-132. BOR Configuration (BORCFG) Field Descriptions
Bits
Field
Value
Description
15-1 Reserved
Reserved
0
BORENZ
BOR enable active low bit.
0
BOR functions are enabled.
1
BOR functions are disabled.
System Control and Interrupts
194
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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