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PRELIMINARY DATA
June 2005
This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to change without notice.
STM1810, STM1811, STM1812, STM1813
STM1815, STM1816, STM1817, STM1818
Low Power Reset Circuit
Rev 5
FEATURES SUMMARY
PRECISION MONITORING OF 3V, 3.3V,
AND 5V SUPPLY VOLTAGES
FOUR OUTPUT CONFIGURATIONS
Push-Pull, Active-High (STM1812,1817)
Push-Pull, Active-Low (STM1810,1815)
Open Drain, Active-Low (STM1811,1816)
Open Drain, Active-Low with Push-Button
Detect (STM1813,1818)
RESET PULSE WIDTH - 100ms (min)
LOW SUPPLY CURRENT - 4uA (typ)
GUARANTEED ASSERTION DOWN TO
V
CC
= 1.0V (0C to 105C)
FACTORY-TRIMMED RESET
THRESHOLDS OF 2.55V, 2.88V, 3.06V,
4.37V, and 4.62V (typ)
POWER SUPPLY TRANSIENT IMMUNITY
PUSH-BUTTON/MANUAL RESET DETECT
(STM1813/1818)
OPERATING TEMPERATURE:
40C TO 105C
2.5% RESET THRESHOLD ACCURACY
(40C TO 105C)
AVAILABLE IN THE SOT23-3 PACKAGE
FULLY COMPATIBLE WITH DS181x AND
MXD181x PRODUCTS
Figure 1. Packages
Table 1. Device Options
Note: 1. Active-low RST with internal pull-up resistor
SOT23-3 (WX)
5V
3.3V/
3.0V
Active-Low
RESET
(Push-Pull)
Active-Low
RESET
(Open Drain)
Active-High
RESET
(Push-Pull)
Active-Low RESET
(Open Drain,
Bi-directional, with MR Detect)
STM1810L/M
STM1811L/M
(1)
STM1812L/M
STM1813L/M
STM1815T/S/R
STM1816T/S/R
(1)
STM1817T/S/R
STM1818T/S/R
STM1810/1811/1812/1813/1815/1816/1817/1818
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TABLE OF CONTENTS
FEATURES SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 1. Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 1. Device Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
SUMMARY DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Figure 2. Logic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Table 2. Signal Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Figure 3. SOT23-3 Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Figure 4. Hardware Hookup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
FUNCTIONAL BLOCK DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 5. Push-pull Active-Low Output (STM1810/1812/1815/1817) . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 6. Open Drain, Active-Low Output (STM1811/1816) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 7. Open Drain, Active-Low Output (Bi-directional, Manual Reset Detect, STM1813/1818). . 5
PIN DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 3. STM1810/STM1815. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 4. STM1811/STM1816. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 5. STM1812/STM1817. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 6. STM1813/STM1818. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Reset Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Push-Button Detect Reset (STM1813/1818) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Interfacing to Bidirectional Microcontrollers (MCU's) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Negative Going V
CC
Transients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Valid RST Output Down to V
CC
= 0V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 8. Reset Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 9. Push-Button Manual Reset with MR Detect (STM1813/1818) . . . . . . . . . . . . . . . . . . . . . 8
Figure 10.Manual Reset Timing Diagram, Switch Bounce/Debounce (STM1813/1818). . . . . . . . . . 8
Figure 11.Interfacing MCUs with Bi-Directional Reset Pins (RST, Open Drain, STM1811/1816) . . . 8
Figure 12.Valid Reset (RST) Output Down to V
CC
= 0V (Push-pull) . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 13.Valid Reset (RST) Output Down to V
CC
= 0V (Push-pull) . . . . . . . . . . . . . . . . . . . . . . . . . 9
TYPICAL OPERATING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 14.Supply Current vs. Temperature (no load) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 15.Normalized Reset Time-out Period (t
rec
) vs. Temperature - V
OD
= V
TH
V
CC
. . . . . . . 10
Figure 16.V
CC
-to-Reset Output Delay vs. Temperature - V
OD
= V
TH
V
CC
. . . . . . . . . . . . . . . . . 11
Figure 17.Voltage Output Low vs. I
SINK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 18.Voltage Output High vs. I
SOURCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 19.Normalized Reset Threshold vs. Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 20.Max Transient Duration NOT Causing Reset Pulse vs. Reset Threshold Overdrive . . . 13
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STM1810/1811/1812/1813/1815/1816/1817/1818
MAXIMUM RATING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 7. Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
DC AND AC PARAMETERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 8. Operating and AC Measurement Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 21.AC Testing Input/Output Waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 9. DC and AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
PACKAGE MECHANICAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 22.SOT23-3 3-lead Small Outline Transistor Package Outline . . . . . . . . . . . . . . . . . . . . . 16
Table 10. SOT23-3 3-lead Small Outline Transistor Package Mechanical Data . . . . . . . . . . . . . 16
PART NUMBERING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 11. Ordering Information Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 12. Marking Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
REVISION HISTORY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 13. Document Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
STM1810/1811/1812/1813/1815/1816/1817/1818
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SUMMARY DESCRIPTION
STM181x devices are low power reset devices
used to monitor power supplies for microcontrol-
lers. They perform a single function: asserting a
reset signal whenever V
CC
supply voltage drops
below a preset value and keeping it asserted until
V
CC
has risen above the preset threshold for a
minimum period of time (t
rec
). They provide excel-
lent circuit reliability without additional external
components when used with +3.0V/+3.3V
(STM1815STM1818), and +5V (STM1810
STM1813) power supply systems.
A precision voltage reference and comparator
monitors the V
CC
input for an out-of-tolerance con-
dition. When an invalid V
CC
condition occurs, the
reset output (RST) is forced low (or high in the
case of RST) and remains asserted for t
rec
after
V
CC
rises above the reset threshold. The
STM1813/1818 also keep reset asserted for t
rec
after the output is momentarily pulled to ground by
an external push-button switch.
The STM1812 and STM1817 have an active-high,
push-pull output. The STM1810 and STM1815
(push-pull) and STM1811, STM1813, STM1816,
and STM1818 (open drain) have an active-low
RST output. The open drain devices (STM1811/
STM1813/STM1816/STM1818) also have an in-
ternal pull-up resistor to V
CC
. The STM1813 and
STM1818 feature a debounced manual reset fea-
ture that asserts a reset if the RST pin is pulled low
for more than 1.5s. When used to initiate manual
reset, RST debounces signals from devices such
as mechanical switches. For devices with this fea-
ture, the release of the external switch triggers the
reset period.
The STM181x devices are guaranteed to output
the correct logic state for V
CC
down to 1.0V (0C
to +105C). They also provide a reset comparator
designed to ignore fast transients on V
CC
.
Reset thresholds are available between +2.55V
and +4.62V These small, low power devices are
ideal for use in portable equipment. All are avail-
able in the space-saving 3-pin SOT23 package,
and are specified from 40C to +105C.
Figure
4., page 5
shows a typical hardware hookup for
STM181x devices to a Microcontroller.
Figure 2. Logic Diagram
Note: 1. For STM1812, STM1817
Table 2. Signal Names
Note: 1. For STM1812, STM1817
Figure 3. SOT23-3 Connections
Note: RST for STM1812 and STM1817
AI09648
V
CC
STM181x
V
SS
RST (RST)
(1)
V
SS
Ground
RST
Active-low Reset Output
RST
(1)
Active-high Reset Output
V
CC
Supply Voltage and Input for Reset
Threshold Monitor
AI09649
2
3
1
RST (RST)
V
SS
V
CC
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STM1810/1811/1812/1813/1815/1816/1817/1818
Figure 4. Hardware Hookup
Note: 1. RST for STM1812 and STM1817 (see
Table 1., Device Options
)
2. Only valid for STM1813 and STM1818.
FUNCTIONAL BLOCK DIAGRAMS
Figure 5. Push-pull Active-Low Output (STM1810/1812/1815/1817)
Note: 1. RST for STM1812 and STM1817.
Figure 6. Open Drain, Active-Low Output (STM1811/1816)
Note: 1. 5.5k
internal pull-up resistor
Figure 7. Open Drain, Active-Low Output (Bi-directional, Manual Reset Detect, STM1813/1818)
Note: 1. 5.5k
internal pull-up resistor
AI09652a
V
CC
V
SS
V
CC
MCU
STM181x
RST
(1)
V
CC
V
SS
RESET
Input
Push-button
RESET
(2)
AI09651a
COMPARE
V
RST
V
CC
trec
Generator
RST
(1)
AI09672
COMPARE
V
RST
V
CC
trec
Generator
RST
5.5k
(1)
AI09673
COMPARE
Push-button
Detect
V
RST
V
CC
trec
Generator
RST
5.5k
(1)
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