SP810EK-2-3 SIPEX [Sipex Corporation], SP810EK-2-3 Datasheet - Page 5

• Manufacturer Part Number: SP810EK-2-3
• Description: 3 Pin Microprocessor Supervisor Circuit
• Manufacturer: SIPEX [Sipex Corporation]

Negative-Going V
In addition to issuing a reset to the µP during
power-up, power-down, and brownout condi-
tions, SP809 series are relatively resistant to
short-duration negative-going V
Ensuring a Valid Reset Output Down to
VCC= 0
When V
output no longer sinks current; it becomes
an open circuit. In this case, high-imped-
ance CMOS logic inputs connecting to
RESET can drift to undetermined voltages.
Therefore, SP809/810 with CMOS is
perfect for most applications of V
0.9V.
µP will be activated at a valid reset state.
These µP supervisory circuits assert reset to
prevent code execution errors during power-
up, power-down, or brownout conditions.
Reset is guaranteed to be a logic low for
V
threshold, an internal timer keeps RESET low
for the reset timeout period; after this interval,
RESET goes high.
If a brownout condition occurs (V
below the reset threshold), RESET goes low.
Any time V
the internal timer resets to zero, and RESET
goes low. The internal timer is activated after
V
RESET remains low for the reset timeout
period.
Date: 5/02/06 Rev B
TH
CC
>V
R
R
returns above the reset threshold, and
E
E
CC
P
S
S
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E
E
CC
>0.9V. Once V
G
T
T
V
N
N
falls below 0.9V, SP809 RESET
C
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S (
CC
a
C
D
m
P
P
goes below the reset threshold,
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0
1
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CC
Transients
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exceeded the reset
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SP809/810, 3 Pin Microprocessor Supervisor Circuit
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Benefits of Highly Accurate Reset
Threshold
SP809/810 with specified voltage as 5V±10%
or 3V±10% are ideal for systems using a
5V±5% or 3V±5% power supply. The reset is
guaranteed to assert after the power supply
falls below the minimum specified operating
voltage range of the system ICs. The
pretrimmed thresholds are reducing the range
over which an undesirable reset may occur.
However in applications where RESET
must be valid down to 0V, adding a pull-
down resistor to RESET causes any
leakage currents to flow to ground, holding
RESET low.
Interfacing to
Reset Pins
The RESET output on the SP809N is open
drain, this device interfaces easily with µPs
that have bidirectional reset pins. Connect-
ing the µP supervisor's RESET output
directly to the microcontroller's RESET pin
with a single pull-up resistor allows either
device to assert reset.
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APPLICATION INFORMATION
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µ
DETAILED DESCRIPTION
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© Copyright 2006 Sipex Corporation
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