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Reset Circuit. MIC1815 Datasheet |
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MIC1815
MIC1815
Microprocessor Reset Circuit
Micrel
General Description
The MIC1815 is an inexpensive microprocessor supervisory
circuit that monitors power supplies in microprocessor 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
10% or 20% drop in 3.3V powered systems.
The MIC1815 has an active low /RESET output. The reset
output is guaranteed to remain asserted for a minimum of
100ms after VCChas risen above the designated reset thresh-
old level. The MIC1815 comes in a 3-pin SOT-23 package.
Features
• Precision voltage monitor for 10% or 20% drop in 3.3V
power supplies
• /RESET remains valid with VCC as low as 1V
• 5µA supply current
• 100ms minimum reset pulse width
• No external components required
• Available in 3-pin SOT-23 package
Applications
• Portable equipment
• Intelligent instruments
• Critical microprocessor power monitoring
• Printers/computers
• Embedded controllers
Ordering Information
Part Number
MIC1815-10U
MIC1815-20U
MIC1815-10UY
MIC1815-20UY
Marking
ND
NE
ND
NE
Threshold
Voltage
2.88V
2.55V
2.88V
2.55V
Operating Temp. Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Package
SOT-23
SOT-23
SOT-23
SOT-23
Pb-Free
No
No
Yes
Yes
Typical Application
VCC
VCC
MIC1815
RESET
VCC
µP
RESET
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 474-1000 • fax + 1 (408) 944-0970 • http://www.micrel.com
July 2005
1
MIC1815
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MIC1815
Pin Configuration
RESET 1
MIC1815
VCC 2
3 GND
3-Lead SOT23
Micrel
Pin Description
Pin Number
1
2
3
Pin Name
/RESET
VCC
GND
Pin Function
/RESET goes low if VCC falls below the reset threshold and remains as-
serted for one reset timeout period (100ms min) after VCC exceeds the reset
threshold.
Power supply input.
IC ground pin
MIC1815
2
July 2005
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MIC1815
Absolute Maximum Ratings(Note 1)
Terminal Voltage (VCC) ....................................–0.3V to +6V
Input Current (VCC)..................................................... 20mA
Output Current (/RESET) ........................................... 20mA
Rate of Rise (VCC).................................................. 100V/µs
Lead Temperature (soldering, 10 sec.)...................... 300°C
Storage Temperature (TS) .......................... –65°C to 150°C
ESD Rating, Note 3....................................................... 3kV
Micrel
Operating Ratings(Note 2)
Operating Temperature Range
MIC1815-10U ......................................... –40°C to +85°C
MIC1815-20U ......................................... –40°C to +85°C
Power Dissipation (TA = +70°C) .............................. 320mW
Electrical Characteristics
For typical values, VCC = 3.3V, TA = 25°C; bold values indicate –40°C ≤ TA ≤ +85°C; unless noted
Symbol
Parameter
Condition
Min
VCC
Operating Temperature Range
TA = –40°C to +85°C
ICC Supply Current
VTH Reset Voltage Threshold
MIC1815-10U
MIC1815-20U
1
2.80
2.47
tRST Reset Timeout Period
VOH /RESET Output Voltage
VOL /RESET Output Voltage
ISOURCE = 800µA
VCC = VTH min., ISINK = 10mA
VCC > 1V, ISINK = 50µA
100
1.5
Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Typ
5
2.88
2.55
150
Max Units
5.5 V
20 µA
2.97 V
2.64 V
250 ms
V
0.4 V
0.3 V
Timing Diagram
VCC
VTH
tRST
/RESET
VTH
Reset Timing Diagram
tRST
July 2005
3
MIC1815
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