MIC1815 DATA SHEET (11/05/2015) DOWNLOAD

MIC1815
Micrel
MIC1815
Microprocessor Reset Circuit
General Description
Features
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 threshold level. The MIC1815 comes in a 3-pin SOT-23 package.
• 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
Ordering Information
Applications
•
•
•
•
•
Portable equipment
Intelligent instruments
Critical microprocessor power monitoring
Printers/computers
Embedded controllers
Part Number
Marking
Threshold
Voltage
Operating Temp. Range
Package
Pb-Free
MIC1815-10U
ND
2.88V
–40°C to +85°C
SOT-23
No
MIC1815-20U
NE
2.55V
–40°C to +85°C
SOT-23
No
MIC1815-10UY
ND
2.88V
–40°C to +85°C
SOT-23
Yes
MIC1815-20UY
NE
2.55V
–40°C to +85°C
SOT-23
Yes
Typical Application
VCC
VCC
VCC
MIC1815
µP
RESET
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
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MIC1815
MIC1815
Micrel
Pin Configuration
RESET 1
MIC1815
3 GND
VCC 2
3-Lead SOT23
Pin Description
Pin Number
Pin Name
1
/RESET
MIC1815
Pin Function
/RESET goes low if VCC falls below the reset threshold and remains asserted for one reset timeout period (100ms min) after VCC exceeds the reset
threshold.
2
VCC
Power supply input.
3
GND
IC ground pin
2
July 2005
MIC1815
Micrel
Absolute Maximum Ratings(Note 1)
Operating Ratings(Note 2)
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
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
VCC
Operating Temperature Range
TA = –40°C to +85°C
ICC
Supply Current
VTH
Reset Voltage Threshold
tRST
Reset Timeout Period
VOH
/RESET Output Voltage
VOL
Typ
1
Max
Units
5.5
V
5
20
µA
MIC1815-10U
2.80
2.88
2.97
V
MIC1815-20U
2.47
2.55
2.64
V
100
150
250
ms
0.4
V
0.3
V
1.5
ISOURCE = 800µA
/RESET Output Voltage
Min
VCC = VTH min., ISINK = 10mA
VCC > 1V, ISINK = 50µA
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.
V
Timing Diagram
VCC
VTH
VTH
tRST
tRST
/RESET
Reset Timing Diagram
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MIC1815
MIC1815
Micrel
Functional Diagram
VCC(2)
RESET
GENERATOR
Reset
Threshold (VTH)
RESET (1)
GND (3)
MIC1815
4
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MIC1815
Micrel
Applications Information
/RESET Valid at Low Voltage
A resistor can be added from the /RESET pin-to-ground to
ensure the /RESET output remains low with VCC down to
0V. A 100kΩ resistor connected from /RESET-to-ground is
recommended. The resistor should be large enough not to
load the /RESET output and small enough to pull-down any
stray leakage currents. See Figure below.
Microprocessor Reset
The /RESET pin is asserted whenever VCC falls below the
reset threshold voltage. The reset pin remains asserted for a
period of tRST after VCC has risen above the reset threshold
voltage. The reset function ensures the microprocessor is
properly reset and powers up into a known condition after
a power failure. /RESET will remain valid with VCC as low
as 1V.
VCC Transients
The MIC1815 is relatively immune to negative-going VCC
glitches below the reset threshold. Typically, a negative-going
transient 125mV below the reset threshold with a duration of
20µs or less will not cause an unwanted reset.
VCC
VCC
VCC
MIC1815
µP
RESET
RESET
100K
/RESET Valid to VCC = 0V
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MIC1815
MIC1815
Micrel
Package Information
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3-Pin SOT-23 Small Outline Transistor
MICREL, INC.
2180 FORTUNE DRIVE
SAN JOSE, CA 95131
USA
TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use.
Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not�
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into
the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s
use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser’s own risk and Purchaser agrees to fully indemnify
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© 2005 Micrel, Incorporated.
MIC1815
6
July 2005