Impala ILC811 Microprocessor reset circuit Datasheet

Impala Linear Corporation
ILC811/812
Preliminary
Microprocessor Reset Circuits
General Description
Features
The ILC811/ILC812 is a low cost microprocessor supervisory circuit that asserts a reset if the power supply drops below
a designated threshold or the manual reset pin is forced low.
Several different reset thresholds are available to accommodate systems operating at 3V, 3.3V or 5V.
The ILC811 has an active low RESET output, while the
ILC812 offers an active high RESET output. The reset output
is guaranteed to remain asserted for a minimum of 140ms
after VCC has risen above the designated reset threshold.
The ILC811/ILC812 is available in a 4-pin SOT-143
Typical Circuit
MR
VCC
ILC811
ILC812
µP
RESET
(RESET)
Applications
! Critical Microprocessor Power Monitoring
! Portable Equipment
! Intelligent Instruments
! Computers & Printers
! Controllers
VCC
VCC
! Precision Voltage Monitor for 3V, 3.3V or 5V Power Supplies
! 6mA Supply Current
! 140ms Minimum Reset Pulse Width
! RESET Remains Valid with VCC as Low as 1.4V
! Active Low Manual Reset Input
! No External Components
! 4-Pin SOT-143 Package
RESET
INPUT
Ordering Information
Part
ILC811_U
ILC812_U
( ) = ILC812
Reset Threshold Voltage (V)
4.63
4.38
4.00
3.08
2.93
2.63
Top View
4
VCC
2
3
MR
GND 1
4
VCC
3
MR
ILC811
RESET
Temp. Range
-40°C to +85°C
-40°C to +85°C
Place the device suffix of desired reset threshold voltage from the
table [below] in the blank to complete the part number.
Pin Package Configuration
GND 1
Package
4-Lead SOT-143
4-Lead SOT-143
Device Suffix
L
M
J
T
S
R
ILC812
RESET
2
Impala Linear Corporation
ILC811/812 1.3
(408) 574-3939
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Sept 1999
1
Microprocessor Reset Circuits
Preliminary
Absolute Maximum Ratings
Parameter
Terminal Voltage
Input Current
Output Current
Rate of Rise
Operating Temperature Range
Storage Temperature Range
Lead Temperature (Soldering - 10 sec.)
Power Dissipation (TA = +70°C)
Symbol
VCC
MR
VCC, MR
RESET, RESET
VCC
TA
Ratings
-0.3 to 6.0
-0.3 to (VCC + 0.3)
20
20
100
-40 to +85
-65 to +150
300
320
Units
V
V
mA
mA
V/µs
°C
°C
°C
mW
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
VCC = 5V for ILC81_L/M/J, VCC = 3.3V for ILC81_S/T, VCC = 3V for ILC81_R, TA = Operating Temperature Range, unless
otherwise noted.
Parameter
Operating Voltage Range, VCC
Supply Current, ICC
Reset Voltage Threshold, VTH
Conditions
TA = 0°C to 70°C
TA = -40°C to 85°C
ILC811L/M/J, ILC812L/M/J
VCC < 3.6V, ILC811R/S/T, ILC812R/S/T
ILC811L, ILC812L
ILC811M, ILC812M
ILC811J, ILC812J
ILC811T, ILC812T
ILC811S, ILC812S
ILC811R, ILC812R
Reset Timeout Period, tR
RESET Output Voltage, VOH
RESET Output Voltage, VOL
RESET Output Voltage, VOH
RESET Output Voltage, VOL
Min
1.4
1.6
4.50
4.25
3.89
3.00
2.85
2.55
140
ISOURCE = 800µA, ILC811L/M/J
ISOURCE = 500µA, ILC811R/S/T
VCC = VTH Min., ISINK = 3.2mA, ILC811L/M/J
VCC = VTH Min., ISINK = 1.2mA, ILC811R/S/T
VCC > 1.4V, ISINK = 50µA, TA = 0°C to 70°C
VCC > 1.6V, ISINK = 50µA, TA = -40°C to 85°C
VCC – 1.5
0.8 x VCC
1.8V < VCC < VTH Min., ISOURCE= 150µA
ISINK = 3.2mA, ILC812L/M/J
ISINK = 1.2mA, ILC812R/S/T
0.8 x VCC
V
ms
V
V
V
0.4
0.3
VCC > VTH Max., ILC81_L/M/J
ILC81_R/S/T
VCC > VTH Max., ILC81_L/M/J
ILC81_R/S/T
V
µs
µs
2.3
0.7 x VCC
10
V
20
100
MR Glitch Immunity
Impala Linear Corporation
µA
0.5
MR Pull-Up Resistance
ILC811/812 1.3
Units
V
0.4
0.3
0.3
0.3
MR to Reset Delay
MR Input Threshold, VIL
9
6
4.63
4.38
4.00
3.08
2.93
2.63
240
Max
5.5
5.5
15
10
4.75
4.50
4.10
3.15
3.00
2.70
560
10
MR Minimum Pulse Width
MR Input Threshold, VIH
Typ
(408) 574-3939
www.impalalinear.com
0.8
0.25 x
VCC
30
V
kΩ
ns
Sept 1999
2
Microprocessor Reset Circuits
Preliminary
Pin Functions
Pin Name
Pin Number
ILC811
ILC812
Description
GND
1
1
Ground Pin.
RESET
2
N/A
RESET goes low if VCC falls below the reset threshold and
remains asserted for one reset timeout period (140ms min.)
after VCC exceeds the reset threshold.
RESET
N/A
2
RESET goes high if VCC falls below the reset threshold and
remains asserted for one reset timeout period (140ms min.)
after VCC exceeds the reset threshold.
MR
3
3
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 (140ms min.) after MR goes high.
This input can be shorted to ground via a switch or driven
from CMOS or TTL logic. Float if unused.
VCC
4
4
Power supply input, 3V, 3.3V or 5V.
Circuit Description
Microprocessor Reset
The RESET pin is asserted whenever VCC falls below the
reset threshold voltage or if MR (manual reset) is forced
low. The reset pin remains asserted for a period of 240ms
after VCC has risen above the reset threshold voltage or MR
has returned high. 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.
MR
tR
tR
RESET
VCC Transients
The ILC811/ILC812 are relatively immune to negative-going
VCC glitches below the reset threshold. Typically, a negative-going transient 125µV below the reset threshold with a
duration of 50ms (25µs for ILC81_R/S/T) or less will not
cause an unwanted reset.
Interfacing to Bidirectional Reset Pins
The ILC811/ILC812 can interface with µPs with bidirectional reset pins by connecting a 4.7kΩ resistor in series with
the ILC811/ILC812 output and the µP reset pin.
Impala Linear Corporation
ILC811/812 1.3
+
-
4
Reset
Threshold (V)
MR
RESET (ILC811)
Reset
Generator
2
RESET (ILC812)
3
1
GND
RESET Valid to 0V
A resistor can be added from the RESET pin to ground to
ensure the RESET output remains low with VCC down to
0V. A 100kW 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.
VTH
VCC
VCC
(408) 574-3939
VCC
VCC
VCC
ILC811
µP
RESET
RESET
100
K
Reset Valid to VCC =0V
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Sept 1999
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Microprocessor Reset Circuits
Preliminary
Alternate Source Cross Reference Guide
Industry P/N
MAX811JEUS-T
MAX811LEUS-T
MAX811MEUS-T
MAX811REUS-T
MAX811SEUS-T
MAX811TEUS-T
MAX812JEUS-T
MAX812LEUS-T
MAX812MEUS-T
MAX812REUS-T
MAX812SEUS-T
MAX812TEUS-T
ILC Direct
Replacement
ILC811JU
ILC811LU
ILC811MU
ILC811RU
ILC811SU
ILC811TU
ILC812JU
ILC812LU
ILC812MU
ILC812RU
ILC812SU
ILC812TU
Device Marking Information
SOT-143
ILC811J KJYY
ILC811L KLYY
ILC811M KMYY
ILC811R KRYY
ILC811S KSYY
ILC811T KTYY
ILC812J LJYY
ILC812L LLYY
ILC812M LMYY
ILC812R LRYY
ILC812S LSYY
ILC812T LTYY
YY = Lot Code
Impala Linear Corporation
ILC811/812 1.3
(408) 574-3939
www.impalalinear.com
Sept 1999
4
Microprocessor Reset Circuits
Preliminary
Packaging Information
4-Pin SOT-143
0.079
0.071
0.055
0.047
Dimensions are in inches
0.098
0.083
0.021
0.015
0.037
0.030
0.120
0.105
0.0059
0.0035
0.040
0.031
0.080
0.070
0-8°
0.010
0.005
0.004
0.001
Tape and Reel Information
4.0 ± 0.1
2.0 ± 0.05
O1.5 ± 0.1
1.75 ± 0.1
3.5 ± 0.05
8.0 ± 0.3
O1.1 ± 0.1
4.0 ± 0.1
2.7 ± 0.1
Dimensions are in millimeters
1.2 ± 0.1
3.1 ± 0.1
Devices sold by Impala Linear Corporation are covered by the warranty and patent indemnification provisions appearing
in its Terms of Sale only. Impala Linear Corporation makes no warranty, express, statutory, implied, or by description
regarding the information set forth herein or regarding the freedom of the described devices from patent infringement.
Impala Linear Corporation makes no warranty of merchantability or fitness for any purpose. Impala Linear Corporation
reserves the right to discontinue production and change specifications and prices at any time and without notice.
This product is intended for use in normal commercial applications. Applications requiring an extended temperature
range, unusual environmental requirements, or high reliability applications, such as military and aerospace, are specifically not recommended without additional processing by Impala Linear Corporation.
Life Support Policy
Impala Linear Corporation’s products are not authorized for use as critical components in life support devices or systems.
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
Impala Linear Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in an
Impala Linear Corporation product. No other circuits, patents, licenses are implied.
Impala Linear Corporation
ILC811/812 1.3
(408) 574-3939
www.impalalinear.com
Sept 1999
5
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