Page 1
1
The MIC1815 is an inexpensive microprocessor
supervisory circuit that monitor 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 accomodate 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 VCC has risen above the
designated reset threshold level. The MIC1815 comes
in a 3-pin SOT-23 package.
Top View
Part Package Temp. Range
MIC1815_U 3-Lead SOT23 -40°C to +85°C
Place the device suffix of desired reset threshold voltage from table above in
blank to complete the part number.
·
Portable Equipment
·
Intelligent Instruments
·
Critical Microprocessor Power Monitoring
·
Printers/Computers
·
Controllers
·
RESET Remains Valid with VCCas Low
as 1.4V
·
Precision Voltage Monitor for 10% or
20% drop in 3.3V Power Supplies
·
Available in 3-Pin SOT23 Package
·
9µA Supply Current
·
100ms Minimum Reset Pulse Width
·
No External Components Required
Typical Operating Circuit
Features
Description Pin Configuration
Ordering Information
Typical Applications
Reset Threshold Device
Voltage (V) Suffix
2.88 -10
2.55 -20
MIC1815 Microprocessor Reset Circuit
MIC1815
Microprocessor Reset Circuit
查询MIC1815供应商
V
CC
1
MIC1815
2
RESET
GND
3
V
CC
V
CC
MIC1815
V
CC
µP
RESET
RESET
Page 2
2
Electrical Characteristics
VCC= 3.3V, TA= Operating Temperature Range, unless otherwise noted.
Parameter Conditions Min Typ Max Units
Operating Voltage Range, V
CC
TA= 0°C to 70°C 1.4 5.5 V
TA= -40°C to 85°C 1.6 5.5
Supply Current, I
CC
920µA
Reset Voltage Threshold, V
TH
MIC1815-10 2.80 2.88 2.97 V
MIC1815-20 2.47 2.55 2.64
Reset Timeout Period 100 150 250 ms
RESET Output Voltage, V
OH
I
Source
= 800µA
VCC- 1.5V
V
RESET Output Voltage, V
OL
VCC=VTHMin., I
Sink
=1.2mA
0.4 V
VCC>1.4V, I
Sink
=50µA
0.3
Stresses above those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent device failure. Functionality at or above these limits is not implied. Exposure to absolute
maximum ratings for extended periods may affect device reliability. Operating ranges define those limits between which the functionality of the device is guaranteed.
Absolute Maximum Ratings
Terminal Voltage
VCC. . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.0V
Input Current, VCC, . . . . . . . . . . . . . . . . . . . . . . . 20mA
Output Current, RESET . . . . . . . . . . . . . . 20mA
Rate of Rise, V
CC
. . . . . . . . . . . . . . . . . . . . . . 100V/µs
Operating Temperature Range
MIC1815
-
U . . . . . . . . . . . . . . . . . . . . . . . . -40°C to 85°C
Storage Temperature Range . . . . . . . . . . . . .-65°C to 150°C
Lead Temperature (Soldering - 10 sec.) . . . . . . . . . . . 300°C
Power Dissipation (TA= +70°C) . . . . . . . . . . . . . . . . 320mW
MIC1815 Microprocessor Reset Circuit
Page 3
Pin Functions
3
RESET goes low if VCCfalls below the reset threshold and remains asserted for one
reset timeout period (100ms min.) after VCCexceeds the reset threshold.
Power supply input, 3.3V.
IC Ground Pin.
Pin Name Pin No.
RESET 1
V
CC
2
GND 3
MIC1815 Microprocessor Reset Circuit
Page 4
4
+
-
Reset
Threshold (VTH)
VCC(2)
RESET (1)
GND (3)
RESET
GENERATOR
Figure 1. MIC1815 Block Diagram
Block Diagram
MIC1815 Microprocessor Reset Circuit
Page 5
5
Microprocessor Reset
The RESET pin is asserted whenever V
CC
falls below
the reset threshold voltage. The reset pin remains
asserted for a period of 150ms after VCChas 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 VCCas low as 1.4V.
VCCTransients
The MIC1815 is relatively immune to negative-going
VCCglitches below the reset threshold. Typically, a
negative-going transient 125mV below the reset
threshold with a duration of 50µs or less will not cause
an unwanted reset.
RESET Valid to 0V
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 RESET
to ground is recommended. The size of the resistor
should be large enough to not load the RESET output
and small enough to pull-down any stray leakage
currents.
Circuit Description
Figure 2. Reset Timing Diagram
Figure 3. RESET Valid to VCC= OV
MIC1815 Microprocessor Reset Circuit
V
CC
RESET
V
thr
V
thr
t1t1
V
CC
V
CC
MIC1815
RESET
100K
V
RESET
CC
µP
Page 6
6
MIC Direct
Industry P/N Replacement
DS1815-10 MIC1815-10U
DS1815-20 MIC1815-20U
Alternate Source Cross Reference Guide
MIC1815 Microprocessor Reset Circuit
Page 7
7
Packaging Information
U Package, 3-Pin SOT-23 Small-Outline Transistor Package
Device Marking Information
Lot Code
NDXX = MIC1815-10U
NEXX = MIC1815-20U
Dimensions are in inches.
MIC1815 Microprocessor Reset Circuit
0.021
0.015
0.120
0.105
0.079
0.071
0.055
0.047
0.004
0.001
0.098
0.083
0.0059
0.040
0.031
0.0035
0.010
0.005
0-8¼
Page 8
8
Packaging Information
Tape and Reel Information
Dimensions are in millimeters.
MIC1815 Microprocessor Reset Circuit
2.7±0.1
3.1±0.1
4.0±0.1
2.0±0.05
4.0±0.1
1.2±0.1
¯1.5±0.1
¯1.1±0.1
1.75±0.1
3.5±0.05
8.0±0.3
Loading...