MIC809/810
Microprocessor Reset Circuits
General Description
The MIC809 and MIC810 are inexpensive microprocessor
supervisory circuits that monitor power supplies in micro-
processor based systems.
The function of these devices is to assert a reset if the power
supply drops below a designated reset threshold level. Several
different reset threshold levels are available to accommodate
3V, 3.3V or 5V powered systems.
The MIC809 has an active-low /RESET output, while the
MIC810 offers an active-high RESET output. The reset output
is guaranteed to remain asserted for a minimum of 140ms
after V
CC
has risen above the designated reset threshold
level. Having a push-pull output stage, the MIC809/810 does
not require a pull-up resistor at the output. The MIC809/810
comes in a 3-pin SOT-23 and SC-70 package.
The MIC809 is also available with a shorter reset timeout
(30ms min.). See the MIC809-5.
All support documentation can be found on Micrel’s web site
at www.micrel.com.
Features
• Precision voltage monitor for 3V, 3.3V or 5V power sup-
plies
• /RESET remains valid with V
CC
as low as 1.4V for SOT-
23 packaged part
• /RESET remains valid with VCC as low as 1V for SC70
packaged part
• Typically less than15µA supply current for SOT-23 pack-
aged part
• 5µ typical supply current for SC70 packaged part
• 140ms minimum reset pulse widths available
• Available in 3-pin SOT-23 and SC-70 package
Applications
•
•
•
•
•
Portable equipment
Intelligent instruments
Critical microprocessor power monitoring
Printers/computers
Controllers
Typical Application
VCC
VCC
VCC
µP
RESET
MIC809
RESET
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 2005
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M0450-041405
MIC809/810
Micrel
Part Number
MIC809LBC3
MIC809MBC3
MIC809JBC3
MIC809TBC3
MIC809SBC3
MIC809RBC3
MIC810LBC3
MIC810MBC3
MIC810JBC3
MIC810TBC3
MIC810SBC3
MIC810RBC3
MIC809LYC3
MIC809MYC3
MIC809JYC3
MIC809TYC3
MIC809SYC3
MIC809RYC3
MIC810LYC3
MIC810MYC3
MIC810JYC3
MIC810TYC3
MIC810SYC3
MIC810RYC3
Threshold
Voltage
4.63
4.38
4.00
3.08
2.93
2.63
4.63
4.38
4.00
3.08
2.93
2.63
4.63
4.38
4.00
3.08
2.93
2.63
4.63
4.38
4.00
3.08
2.93
2.63
Operating
Temp. Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Lead Finish
Standard
Standard
Standard
Standard
Standard
Standard
Standard
Standard
Standard
Standard
Standard
Standard
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Ordering Information
MIC809LU
MIC809MU
MIC809JU
MIC809TU
MIC809SU
MIC809RU
MIC810LU
MIC810MU
MIC810JU
MIC810TU
MIC810SU
MIC810RU
MIC809LUY
MIC809MUY
MIC809JUY
MIC809TUY
MIC809SUY
MIC809RUY
MIC810LUY
MIC810MUY
MIC810JUY
MIC810TUY
MIC810SUY
MIC810RUY
3-lead SOT-23 Package3-lead SC-70 Package
Marking
IL
IM
IJ
IT
IS
IR
JL
JM
JJ
JT
JS
JR
IL
IM
IJ
IT
IS
IR
JL
JM
JJ
JT
JS
JR
Note: Contact factory for SC70 packaged Pb-free options..
Pin Configuration
GND 1
GND 1
MIC809
RESET 2
3 V
CC
RESET 2
MIC810
3 V
CC
MIC809 3-Lead SOT23
MIC809 3-Lead SC70
MIC810 3-Lead SOT23
MIC810 3-Lead SC70
Pin Description
Pin Number
MIC809
1
2
Pin Number
MIC810
1
N/A
Pin Name
GND
/RESET
Pin Function
IC Ground Pin.
/RESET goes low if V
CC
falls below the reset threshold and remains as-
serted for one reset timeout period (140ms min.) after V
CC
exceeds the reset
threshold.
RESET goes high if V
CC
falls below the reset threshold and remains as-
serted for one reset timeout period (140ms min.) after V
CC
exceeds the reset
threshold.
Power Supply Input.
N/A
2
RESET
3
3
VCC
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April 2005
MIC809/810
Micrel
Absolute Maximum Ratings
(1)
Terminal Voltage (V
CC
) ...................................–0.3V to 6.0V
Input Current (V
CC
)..................................................... 20mA
Output Current (RESET, /RESET) .............................. 20mA
Lead Temperature (soldering, 10 sec.) ...................... 300°C
Storage Temperature (T
S
) .......................... –65°C to 150°C
Rate of Rise (V
CC
) .................................................. 100V/µs
ESD Rating
(3) ............................................ 3kV (SC70 Package)
Operating Ratings
(2)
Operating Temperature Range
MIC809 ..................................................... –40°C to 85°C
MIC810 ..................................................... –40°C to 85°C
Power Dissipation (T
A
= +70°C) .............................. 320mW
Electrical Characteristics
(4)
For typical values, V
CC
= 5V for MIC8_L/M/J, V
CC
= 3.3V for MIC8_S/T, V
CC
= 3V for MIC8_R; T
A
= 25°C,
bold
values indicate –40°C
≤ T
A
≤ +85°C; unless noted.
Symbol
V
CC
Parameter
Condition
Min
1.4
1.6
1
9
5
6
Typ
Max
5.5
5.5
5.5
15
15
10
Operating Voltage Range
T
A
= 0°C to 70°C
SOT-23 package
SOT-23 package
SC70 package
V
V
V
µA
µA
µA
Units
T
A
= –40°C to 85°C
T
A
= –40°C to 85°C
I
CC
Supply Current
MIC809L/M/J, MIC810L/M/J SOT-23 Package
For SC-70 Package: MIC809L/M/J,
MIC810L/M/J
V
CC
< 3.6V, MIC809R/S/T, MIC810R/S/T
SOT-23 package
For SC-70 Package: V
CC
< 3.6V,
MIC809R/S/T, MIC810R/S/T
V
TH
Reset Voltage Threshold
MIC809L, MIC810L
MIC809M, MIC810M
MIC809J, MIC810J
MIC809T, MIC810T
MIC809S, MIC810S
MIC809R, MIC810R
t
RST
V
OH
V
OL
Reset Timeout Period
/RESET Output Voltage
MIC809
/RESET Output Voltage
MIC809
I
SOURCE
= 500µA, MIC809R/S/T
I
SOURCE
= 800µA, MIC809L/M/J
4.50
4.25
3.89
3.00
2.85
2.55
140
V
CC
–1.5V
0.8×V
CC
5
4.63
4.38
4.00
3.08
2.93
2.63
240
10
4.75
4.50
4.10
3.15
3.00
2.70
560
µA
V
V
V
V
V
V
ms
V
V
V
CC
= V
TH
min., I
SINK
= 3.2mA, MIC809L/M/J
V
CC
> 1.4V, I
SINK
= 50µA, T
A
= 0°C to +70°C
For SC-70 Package: V
CC
= 1V, I
SINK
= 50µA
A
T
A
= –40°C to 85°C
0.4
0.3
0.3
0.3
0.3
V
V
V
V
V
V
V
V
V
CC
= V
TH
min., I
SINK
= 1.2mA, MIC809R/S/T
`
V
OH
V
OL
RESET Output Voltage
RESET Output Voltage
MIC810
MIC810
V
CC
> 1.6V, I
SINK
= 50µA, T
A
= –40° to +85°C
I
SINK
= 3.2mA, MIC810L/M/J
1.8V < V
CC
< V
TH
min., I
SOURCE
= 150µA
I
SINK
= 1.2mA, MIC810R/S/T
0.8×V
CC
0.4
0.3
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
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M0450-041405
MIC809/810
Micrel
Timing Diagram
V
CC
V
TH
t
RST
/RESET
V
TH
t
RST
Reset Timing Diagram
Functional Diagram
VCC (3)
Reset
Threshold (V)
+
-
RESET
GENERATOR
RESET (2)
RESET (MIC810)
GND (1)
M0450-041405
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April 2005
MIC809/810
Micrel
Interfacing to Bidirectional Reset Pins
The MIC809/810 can interface with µPs with bidirectional
reset pins by connecting a 4.7kΩ resistor in series with the
MIC809/810 output and the µP reset pin.
/RESET Valid at Low Voltage
A resistor can be added from the /RESET pin to ground to
ensure the /RESET output remains low with V
CC
down to
0V. A 100kΩ resistor connected from the /RESET to ground
is recommended. The resistor should be small enough to
pull-down any stray leakage currents and large enough not
to load the reset output. See Figure below.
VCC
VCC
VCC
µP
RESET
100K
Applications Information
Microprocessor Reset
The /RESET (or RESET) pin is asserted whenever V
CC
falls
below the reset threshold voltage. The /RESET pin remains
asserted for a period of 140ms after V
CC
has risen above
the reset threshold voltage. The reset function ensures the
microprocessor is properly reset and powers up in a known
condition after a power failure. /RESET will remain valid with
V
CC
as low as 1.4V (1V for SC-70 package).
V
CC
Transients
The MIC809/810 are relatively immune to negative-going V
CC
glitches below the reset threshold. Typically, a negative-going
transient 125mV below the reset threshold with a duration of
20µs or less (SC70 package) will not cause a reset.
MIC809
RESET
Reset Valid to V
CC
= 0V
April 2005
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M0450-041405
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