MIC8115 - Micrel

MIC8115
Microprocessor Reset Circuit
General Description
Features
The MIC8115 is an inexpensive microprocessor
supervisory circuit that monitors power supplies in
microprocessor-based systems.
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The function of the MIC8115 is to assert a reset if the
power supply drops below a designated reset threshold
level or /MR is forced low.
The MIC8115 has an active low /RESET
output is guaranteed to remain asserted
1100ms after VCC has risen above the
threshold level. The MIC8115 comes in
package.
output. The reset
for a minimum of
designated reset
a 4-pin SOT-143
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Precision voltage monitor for 3.3V power supplies
Specifically-tailored to the AMD Elan SC500 Series
/RESET remains valid with VCC as low as 1.4V
<15µA supply current
1100ms minimum reset pulse width
Manual reset input
Available in 4-Pin SOT-143 Package
Applications
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Portable equipment
Intelligent instruments
Critical microprocessor power monitoring
Printers/computers
Embedded controllers
Typical Application
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
August 3, 2015
Revision 2.0
Micrel, Inc.
MIC8115
Ordering Information
(1)
Part Number
Marking
Junction Temperature Range
Package
Lead Finish
MIC8115-TUY
NT
–40°C to +85°C
4-Pin SOT-143
Pb-Free
Note:
1. Underbar (__) may not be to scale.
Pin Configuration
4-Pin SOT-143
(Top View)
Pin Description
Pin Number
Pin Name
Pin Function
1
GND
IC Ground Pin.
2
/RESET
3
/MR
Manual Reset Input. A logic low on /MR forces a reset. The reset will remain asserted as long as /MR
is held low and for one reset timeout period (1100ms, minimum) after /MR goes high. This input can
be shorted to ground via a switch or driven from CMOS or TTL logic. Pulled high internally through a
20kΩ resistor. Float if unused.
4
VCC
Power Supply Input.
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/RESET goes low if either VCC falls below the supply reset threshold voltage or if /MR is asserted.
/RESET remains asserted for one reset timeout period 1100ms (minimum) after both VCC exceeds
the supply reset threshold voltage and /MR is deasserted.
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Revision 2.0
Micrel, Inc.
MIC8115
Absolute Maximum Ratings(2)
Operating Ratings(3)
Terminal Voltage
(VCC) ......................................................... –0.3V to 6.0V
(/MR) ............................................... –0.3V (VCC + 0.3V)
Input Current (VCC, /MR) ............................................ 20mA
Output Current (/RESET) ............................................ 20mA
Rate of Rise (VCC) ................................................... 100V/µs
Lead Temperature (soldering, 10s) ............................ 300°C
Storage Temperature (TS) ......................... –65°C to +150°C
(4)
ESD Rating .................................................................. 3kV
Operating Temperature Range .................. –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 Voltage Range
TA = –40°C to +85°C
ICC
Supply Current
Min.
Reset Voltage Threshold
IRST
Reset Timeout Period
1100
VOH
/RESET Output Voltage
VOL
/Reset Output Voltage
VIL
/MR Input Threshold
5.5
V
5
15
µA
3.08
3.15
V
1700
2500
ms
V
VCC = VTH(MIN), ISINK = 1.2mA
0.3
VCC = 1V, ISINK = 50µA,
TA = –40°C to +85°C
0.3
V
10
/MR to Reset Delay
/MR Input Threshold
Units
0.8 × VCC
ISOURCE = 500µA
/MR Minimum Pulse Width
VIH
Max.
1
3.00
VTH
Typ.
µs
0.5
µs
0.7 × VCC
V
0.25 × VCC
10
/MR Pull-Up Resistance
/MR Glitch Immunity
20
100
30
kΩ
ns
Notes:
2. Exceeding the absolute maximum ratings may damage the device.
3. The device is not guaranteed to function outside its operating ratings.
4. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.
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Micrel, Inc.
MIC8115
Timing Diagram
Functional Diagram
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Micrel, Inc.
MIC8115
Application Information
Microprocessor Reset
The /RESET pin is asserted whenever VCC falls below the
reset threshold voltage. The reset pin remains asserted
for a period of 1100ms 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 1.4V.
VCC Transients
The MIC1815 is relatively immune to the negative-going
VCC glitches below the reset threshold. Typically, a
negative- going transient 125mV belt the reset threshold
with duration of 20µs or less will not cause a reset.
/RESET Valid at Low Voltage
A resistor can be added from the /RESET pin to the
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.
Figure 1. /RESET Valid to VCC = 0V
August 3, 2015
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Revision 2.0
Micrel, Inc.
MIC8115
Package Information and Recommended Landing Pattern(5)
4-Pin SOT-143 (TU)
Note:
5. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.
August 3, 2015
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Micrel, Inc.
MIC8115
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
Micrel, Inc. is a leading global manufacturer of IC solutions for the worldwide high performance linear and power, LAN, and timing & communications
markets. The Company’s products include advanced mixed-signal, analog & power semiconductors; high-performance communication, clock
management, MEMs-based clock oscillators & crystal-less clock generators, Ethernet switches, and physical layer transceiver ICs. Company
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