Datasheet

I/OPin
In
Out
DIR(0=Input,1=Output)
(ForceHi-ZWhenHigh)
SYSRS
C28
Core
Sync
RS
XRS
PLL
+
Clocking
Logic
MCLKRS
VREGHALT
Deglitch
Filter
On-Chip
Voltage
Regulator
(VREG)
VREGENZ
POR/BOR
Generating
Module
XRS
Pin
SYSCLKOUT
WDRST
(A)
JTAG
TCK
Detect
Logic
PBRS
(B)
Internal
WeakPU
TMS320F28030, TMS320F28031, TMS320F28032
TMS320F28033, TMS320F28034, TMS320F28035
SPRS584J –APRIL 2009–REVISED OCTOBER 2013 www.ti.com
3.6.2 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 tied low). Both functions tie the XRS pin low when one of the voltages is below their
respective trip point. Additionally, when the internal voltage regulator is enabled, an over-voltage
protection circuit will tie XRS low if the V
DD
rail rises above its trip point. See Section 6 for the various trip
points as well as the delay time for the device to release the XRS pin after the under/over-voltage
condition is removed. Figure 3-7 shows the VREG, POR, and BOR. To disable both the V
DD
and V
DDIO
BOR functions, a bit is provided in the BORCFG register. Refer to the TMS320x2803x Piccolo System
Control and Interrupts Reference Guide (literature number SPRUGL8) for details.
A. WDRST is the reset signal from the CPU-watchdog.
B. PBRS is the reset signal from the POR/BOR module.
Figure 3-7. VREG + POR + BOR + Reset Signal Connectivity
46 Functional Overview Copyright © 2009–2013, Texas Instruments Incorporated
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