SP809EK-L-2-9/TR Exar Corporation, SP809EK-L-2-9/TR Datasheet - Page 6

• Manufacturer Part Number: SP809EK-L-2-9/TR
• Description: IC MPU RESET CIRC 2.9V SOT23-3
• Manufacturer: Exar Corporation
• Type: Simple Reset/Power-On Resetr
• Series: -r

Specifications of SP809EK-L-2-9/TR

• Package / Case: TO-236-3, SC-59, SOT-23-3
• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active Low
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 2.9V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Internal Hysteresis: No
• Operating Temperature Range: - 40 C to + 85 C
• Output Type: Push-Pull
• Manual Reset: No
• Watchdog: No
• Battery Backup Switching: No
• Power-up Reset Delay (typ): 20 us
• Supply Voltage (max): 6 V
• Supply Voltage (min): 0.9 V
• Supply Current (typ): 1 uA
• Maximum Power Dissipation: 320 mW
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

THEORY OF OPERATION
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
APPLICATION INFORMATION
N
In addition to issuing a reset to the µP during
power-up,
conditions,
resistant to short-duration negative-going V
transient.
E
TO
When V
output no longer sinks current; it becomes an
open circuit. In this case, high-impedance
CMOS logic inputs connecting to RESET can
drift to undetermined voltages. Therefore,
SP809/810 with CMOS is perfect for most
applications of V
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.
© 2011 Exar Corporation
TH
NSURING A
EGATIVE
>V
V
CC
CC
=0
>0.9V. Once V
CC
G
CC
falls below 0.9V, SP809 RESET
OING
V
SP809
power-down,
goes below the reset threshold,
ALID
CC
down to 0.9V.
V
CC
R
ESET
series
T
CC
RANSIENTS
exceeded the reset
O
UTPUT
and
are
D
brownout
relatively
CC
OWN
drops
CC
3
3
6/8
P
P
i
i
n
n
V
RESET remains low for the reset timeout
period.
B
T
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 pre-
trimmed thresholds are reducing the range
over which an undesirable reset may occur.
I
R
The RESET output on the SP809N is open
drain, this device interfaces easily with μPs
that have bidirectional reset pins. Connecting
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.
T
NTERFACING TO µ
CC
HRESHOLD
EST
ENEFIT OF
ESET
M
M
i
i
returns above the reset threshold, and
c
c
C
r
r
P
IRCUIT
o
o
INS
p
p
r
r
o
o
H
c
c
IGHLY
e
e
Fig. 10: Test Circuit
s
s
s
s
o
P
o
r
r
A
WITH
S
S
CCURATE
S
S
u
u
P
P
p
p
8
8
B
e
e
0
0
r
IDIRECTIONAL
r
v
v
9
9
i
i
R
s
s
/
/
o
o
ESET
r
r
S
S
Rev. 2.0.0
C
C
P
P
i
i
r
r
8
8
c
c
1
1
u
u
0
i
0
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t
t