October 2006
rev 1.6
ASM1832
.
the
microprocessor
or
Tolerance
Select
Tolerance
TRIP Point Voltage
(V)
Min
TOL = V
CC
20%
10%
2.47
2.80
Nom
2.55
2.88
Max
2.64
2.97
monitors
Detailed Description
The
ASM1832
microcontroller power supply and issues reset signals, both
active HIGH and active LOW, that halt processor operation
whenever the power supply voltage levels are outside a
predetermined tolerance.
RESET and RESET outputs
RESET and RESET signals are active for a minimum of
250ms after the supply has returned to in-tolerance level.
This allows the power supply and monitored processor to
stabilize before instruction execution is allowed to begin.
Trip Point Tolerance Selection
The TOL input is used to determine the level V
CC
can vary
below 3.3V without asserting a reset. With TOL conected to
V
CC
, RESET and RESET become active whenever V
CC
falls
below 2.64V. RESET and RESET become active when the
V
CC
falls below 2.98V if TOL is connected to ground.
After V
CC
has risen above the trip point set by TOL, RESET
and RESET remain active for a minimum time period of
250ms. On power-down, once V
CC
falls below the reset
threshold RESET stays LOW and is guaranteed to be 0.4V or
less until V
CC
drops below 1.2V. The reset output on the
ASM1832 uses a push-pull drive stage that can maintain a
valid output below 1.2V. To sink current with V
CC
below 1.2V,
a resistor can be connected from the reset pin (RESET) to
Ground. This configuration will give a valid value on the reset
output with V
CC
approaching 0V. During both power up and
down, the configuration will draw current when the RESET is
in the high state. The value of 100KΩ should be adequate to
maintain a valid condition. The active HIGH reset signal is
valid down to a V
CC
level of 1.2V also.
TOL = GND
t
R
V
CCTP
(MAX)
V
CCTP
(MIN)
~
~
V
CCTP
t
RPU
V
CC
V
OH
RESET
~
~
Figure 1: Timing Diagram : Power Up
V
OL
RESET
~
~
V
CC
V
CCTP
(MAX)
V
CCTP
V
CCTP
(MIN)
t
F
RESET
t
RPD
V
OH
V
OL
~~
~~
RESET
Figure 2: Timing Diagram : Power Down
ASM1832
RESET
100kΩ
Microprocessor
RESET
Application Information
Manual Reset Operation
Push-button switch input, PBRST, allows the user to override
the internal trip point detection circuits and issue reset
3.3V µP Power Supply Monitor and Reset Circuit
Notice: The information in this document is subject to change without notice
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3 of 9
PULSECORE [ PulseCore Semiconductor ]
