MIC1815 [MICREL]
Microprocessor Reset Circuit; 微处理器复位电路
| 型号： | MIC1815 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Microprocessor Reset Circuit |
| 文件： | 总8页 (文件大小：161K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC1815 Microprocessor Reset Circuit
MIC1815
Microprocessor Reset Circuit
Description
Pin Configuration
The MIC1815 is an inexpensive microprocessor
supervisory circuit that monitor power supplies in
microprocessor based systems.
Top View
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.
Features
Typical Applications
RESET Remains Valid with V
as 1.4V
as Low
CC
·
·
Portable Equipment
·
Intelligent Instruments
·
Precision Voltage Monitor for 10% or
20% drop in 3.3V Power Supplies
Available in 3-Pin SOT23 Package
9µA Supply Current
Critical Microprocessor Power Monitoring
·
Printers/Computers
·
Controllers
·
·
·
·
·
Reset Threshold
Device
Suffix
100ms Minimum Reset Pulse Width
No External Components Required
Voltage (V)
2.88
2.55
-10
-20
Typical Operating Circuit
Ordering Information
Package
Part
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.
1
MIC1815 Microprocessor Reset Circuit
Absolute Maximum Ratings
Terminal Voltage
. . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.0V
Operating Temperature Range
V
MIC1815 U . . . . . . . . . . . . . . . . . . . . . . . . -40°C to 85°C
CC
-
Storage Temperature Range . . . . . . . . . . . . .-65°C to 150°C
Lead Temperature (Soldering - 10 sec.) . . . . . . . . . . . 300°C
Input Current, V , . . . . . . . . . . . . . . . . . . . . . . . 20mA
CC
Output Current, RESET . . . . . . . . . . . . . .
Rate of Rise, V . . . . . . . . . . . . . . . . . . . . . . 100V/µs
20mA
Power Dissipation (T = +70°C) . . . . . . . . . . . . . . . . 320mW
A
CC
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.
Electrical Characteristics
V
= 3.3V, T = Operating Temperature Range, unless otherwise noted.
A
CC
Parameter
Conditions
Min
Typ
Max
Units
Operating Voltage Range, V
T
T
A
= 0°C to 70°C
= -40°C to 85°C
1.4
1.6
5.5
5.5
V
A
CC
TH
Supply Current, I
9
20
µA
CC
Reset Voltage Threshold, V
MIC1815-10
MIC1815-20
2.80
2.47
2.88
2.55
2.97
2.64
V
Reset Timeout Period
100
150
250
ms
V
RESET Output Voltage, V
RESET Output Voltage, V
I
= 800µA
V
- 1.5V
CC
OH
OL
Source
V
V
=V
Min., I
=1.2mA
Sink
=50µA
0.4
0.3
V
TH
>1.4V, I
CC
CC
Sink
2
MIC1815 Microprocessor Reset Circuit
Pin Functions
Pin Name
Pin No.
1
RESET
RESET goes low if V
falls below the reset threshold and remains asserted for one
CC
reset timeout period (100ms min.) after V
Power supply input, 3.3V.
IC Ground Pin.
exceeds the reset threshold.
CC
V
2
3
CC
GND
3
MIC1815 Microprocessor Reset Circuit
Block Diagram
Figure 1. MIC1815 Block Diagram
4
MIC1815 Microprocessor Reset Circuit
Circuit Description
Microprocessor Reset
The RESET pin is asserted whenever V
falls below
CC
the reset threshold voltage. The reset pin remains
asserted for a period of 150ms after V has risen
CC
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 V
as low as 1.4V.
CC
Figure 2. Reset Timing Diagram
V
Transients
CC
The MIC1815 is relatively immune to negative-going
glitches below the reset threshold. Typically, a
V
CC
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.
Figure 3. RESET Valid to V
CC
= OV
5
MIC1815 Microprocessor Reset Circuit
Alternate Source Cross Reference Guide
MIC Direct
Industry P/N
DS1815-10
Replacement
MIC1815-10U
MIC1815-20U
DS1815-20
6
MIC1815 Microprocessor Reset Circuit
Packaging Information
U Package, 3-Pin SOT-23 Small-Outline Transistor Package
Dimensions are in inches.
Device Marking Information
Lot Code
NDXX = MIC1815-10U
NEXX = MIC1815-20U
7
MIC1815 Microprocessor Reset Circuit
Packaging Information
Tape and Reel Information
Dimensions are in millimeters.
8
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