Impala Linear Corporation
ILC811/812
Preliminary
Microprocessor Reset Circuits
General Description
The ILC811/ILC812 is a low cost microprocessor superviso-
ry 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 accom-
modate 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 V
CC
has risen above the designated reset threshold.
The ILC811/ILC812 is available in a 4-pin SOT-143
Features
!
Precision Voltage Monitor for 3V, 3.3V or 5V Power Supplies
!
6mA Supply Current
!
140ms Minimum Reset Pulse Width
!
RESET Remains Valid with V
CC
as Low as 1.4V
!
Active Low Manual Reset Input
!
No External Components
!
4-Pin SOT-143 Package
Applications
Typical Circuit
V
CC
V
CC
ILC811
ILC812
MR
RESET
(RESET)
V
CC
!
Critical Microprocessor Power Monitoring
!
Portable Equipment
!
Intelligent Instruments
!
Computers & Printers
!
Controllers
µ
P
RESET
INPUT
Ordering Information
Part
ILC811_U
ILC812_U
Package
4-Lead SOT-143
4-Lead SOT-143
Temp. Range
-40°C to +85°C
-40°C to +85°C
( ) = ILC812
Place the device suffix of desired reset threshold voltage from the
table [below] in the blank to complete the part number.
Pin Package Configuration
Top View
GND
1
ILC811
RESET
2
3
MR
4
V
CC
Reset Threshold Voltage (V)
4.63
4.38
4.00
3.08
2.93
2.63
Device Suffix
L
M
J
T
S
R
GND
1
ILC812
RESET
2
4
V
CC
3
MR
Impala Linear Corporation
ILC811/812 1.3
(408) 574-3939
www.impalalinear.com
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 (T
A
= +70°C)
Symbol
V
CC
MR
V
CC
, MR
RESET, RESET
V
CC
T
A
Ratings
-0.3 to 6.0
-0.3 to (V
CC
+ 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 reliabil-
ity. Operating ranges define those limits between which the functionality of the device is guaranteed.
Electrical Characteristics
V
CC
= 5V for ILC81_L/M/J, V
CC
= 3.3V for ILC81_S/T, V
CC
= 3V for ILC81_R, T
A
=
Operating Temperature Range, unless
otherwise noted.
Parameter
Operating Voltage Range, V
CC
Supply Current, I
CC
Reset Voltage Threshold, V
TH
Conditions
T
A
= 0°C to 70°C
T
A
= -40°C to 85°C
ILC811L/M/J, ILC812L/M/J
V
CC
< 3.6V, ILC811R/S/T, ILC812R/S/T
ILC811L, ILC812L
ILC811M, ILC812M
ILC811J, ILC812J
ILC811T, ILC812T
ILC811S, ILC812S
ILC811R, ILC812R
I
SOURCE
= 800µA, ILC811L/M/J
I
SOURCE
= 500µA, ILC811R/S/T
V
CC
= V
TH
Min., I
SINK
= 3.2mA, ILC811L/M/J
V
CC
= V
TH
Min., I
SINK
= 1.2mA, ILC811R/S/T
V
CC
> 1.4V, I
SINK
= 50µA, T
A
= 0°C to 70°C
V
CC
> 1.6V, I
SINK
= 50µA, T
A
= -40°C to 85°C
Min
1.4
1.6
Typ
Max
5.5
5.5
15
10
4.75
4.50
4.10
3.15
3.00
2.70
560
Units
V
µA
V
Reset Timeout Period, t
R
RESET Output Voltage, V
OH
RESET Output Voltage, V
OL
4.50
4.25
3.89
3.00
2.85
2.55
140
V
CC
– 1.5
0.8 x V
CC
9
6
4.63
4.38
4.00
3.08
2.93
2.63
240
ms
V
0.4
0.3
0.3
0.3
V
RESET Output Voltage, V
OH
RESET Output Voltage, V
OL
MR Minimum Pulse Width
MR to Reset Delay
MR Input Threshold, V
IH
MR Input Threshold, V
IL
MR Pull-Up Resistance
MR Glitch Immunity
1.8V < V
CC
< V
TH
Min., I
SOURCE
= 150µA
I
SINK
= 3.2mA, ILC812L/M/J
I
SINK
= 1.2mA, ILC812R/S/T
0.8 x V
CC
0.4
0.3
10
0.5
V
V
µs
µs
V
0.8
0.25 x
V
CC
30
V
V
CC
> V
TH
Max., ILC81_L/M/J
ILC81_R/S/T
V
CC
> V
TH
Max., ILC81_L/M/J
ILC81_R/S/T
2.3
0.7 x V
CC
10
20
100
kΩ
ns
Impala Linear Corporation
ILC811/812 1.3
(408) 574-3939
www.impalalinear.com
Sept 1999
2
Microprocessor Reset Circuits
Preliminary
Pin Functions
Pin Name
GND
RESET
Pin Number
ILC811
ILC812
1
2
1
N/A
Description
Ground Pin.
RESET goes low if V
CC
falls below the reset threshold and
remains asserted for one reset timeout period (140ms min.)
after V
CC
exceeds the reset threshold.
RESET goes high if V
CC
falls below the reset threshold and
remains asserted for one reset timeout period (140ms min.)
after V
CC
exceeds the reset threshold.
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.
Power supply input, 3V, 3.3V or 5V.
RESET
N/A
2
MR
3
3
V
CC
4
4
Circuit Description
Microprocessor Reset
The RESET pin is asserted whenever V
CC
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 V
CC
has risen above the reset threshold voltage or MR
has returned high. The reset function ensures the micro-
processor is properly reset and powers up into a known
condition after a power failure. RESET will remain valid with
V
CC
as low as 1.4V.
V
CC
V
TH
V
CC
4
Reset
Threshold (V)
+
-
Reset
Generator
2
RESET (ILC811)
RESET (ILC812)
MR
3
1
GND
MR
t
R
RESET
t
R
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.
V
CC
V
CC
V
CC
VCC Transients
The ILC811/ILC812 are relatively immune to negative-going
V
CC
glitches below the reset threshold. Typically, a nega-
tive-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 bidirection-
al reset pins by connecting a 4.7kΩ resistor in series with
the ILC811/ILC812 output and the
µP
reset pin.
ILC811
RESET
100
K
RESET
µP
Reset Valid to V
CC
=0V
Impala Linear Corporation
ILC811/812 1.3
(408) 574-3939
www.impalalinear.com
Sept 1999
3
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
0.098
0.083
Dimensions are in inches
0.037
0.030
0.021
0.015
0.120
0.105
0.040
0.031
0.080
0.070
0.0059
0.0035
0-8°
0.004
0.001
0.010
0.005
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
1.2 ± 0.1
Dimensions are in millimeters
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 specif-
ically not recommended without additional processing by Impala Linear Corporation.
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.
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 pro-
vided 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 reason-
ably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
Impala Linear Corporation
ILC811/812 1.3
(408) 574-3939
www.impalalinear.com
Sept 1999
5
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