FAIRCHILD FM812TUX

www.fairchildsemi.com
FM811/812
Microprocessor Reset Circuits
Description
• Feature
• Precision Voltage Monitor for 3V, 3.3V or 5V Power
Supplies
• 6µA 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
The FM811/FM812 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 FM811 has an active low RESET output, while the
FM812 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 FM811/FM812 is available in a 4-pin SOT-143.
Applications
•
•
•
•
•
Critical Microprocessor Power Monitoring
Portable Equipment
Intelligent Instruments
Computers & Printers
Controllers
Typical Applications
VCC
MR
VCC
VCC
FM811
FM812
µP
RESET
(RESET)
RESET
INPUT
( ) = FM812
PRELIMINARY INFORMATION describes products that are in the design stage. Specifications may change
in any manner whatever without notice. Contact Fairchild Semiconductor for current information.
REV. 1.5.1 7/15/02
Preliminary Information
Features
FM811/812
Pin Assignments
Top View
4
1
GND
VCC
GND
1
FM811
Preliminary Information
VCC
3
MR
FM812
3
2
RESET
4
MR
RESET
2
Pin Definitions
Pin Number
Pin Name
FM811
FM812
Description
GND
1
1
RESET
2
N/A
RESET goes low if VCC falls below the reset threshold and remains
asserted for one reset time-out 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 time-out period (140ms min.) after VCC exceeds the
reset threshold.
MR
3
3
Manual reset input. Shorting this pin to GND forces a reset. The reset will
remain asserted as long as MR is held low and for one reset time-out
period (140ms min.) after MR goes high. This input cannot be driven by a
CMOS or TTL logic. Push-button switch is recommended to be used with
this pin. Float if unused.
VCC
4
4
Power supply input, 3V, 3.3V, or 5V
Ground Pin
Internal Block Diagram
VCC
4
Reset
Threshold (V)
MR
+
–
Reset
Generator
2
RESET (FM811)
RESET (FM812)
3
1
GND
2
REV. 1.5.1 7/15/02
FM811/812
Absolute Maximum Ratings
Parameter
Terminal Voltage
Input Current
Output Current
Rate of Rise
Operating Temperature Range
Symbol
Ratings
Units
VCC
-0.3 to 6.0
V
MR
-0.3 to (VCC + 0.3)
V
VCC, MR
20
mA
RESET, RESET
20
mA
VCC
100
V/µs
TA
˚C
˚C
Lead Temperature Range
300
˚C
Power Dissipation (TA = +70˚C)
320
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 FM81_L/M/J, VCC = 3.3V for FM81_S/T, VCC = 3V for FM81_R, TA = Operating Temperature Range,
unless otherwise noted.
Parameter
Operating Voltage Range
Supply Current, ICC
Reset Voltage Threshold,
VTH
Conditions
TA = 0˚C to 70˚C
TA = -40˚C to 85˚C
FM811L/M/J, FM812L/M/J
VCC < 3.6V, FM811R/S/T, FM812R/S/T
FM811L, FM812L
FM811M, FM812M
FM811J, FM812J
FM811T, FM812T
FM811S, FM812S
FM811R, FM812R
Min.
1.4
1.6
4.40
4.18
3.90
2.97
2.79
2.49
140
VCC - 1.5
0.8 x VCC
Reset Time-out Period, tR
RESET Output Voltage, VOH ISOURCE = 800µA, FM811L/M/J
ISOURCE = 500µA, FM811R/S/T
RESET Output Voltage, VOL VCC= VTH Min., ISINK = 3.2mA, FM811L/M/J
VCC= VTH Min., ISINK = 1.2mA, FM811R/S/T
VCC > 1.4V, ISINK = 50µA, TA= 0˚C to 70˚C
VCC > 1.6V, ISINK = 50µA, TA= -40˚C to
85˚C
0.8 x VCC
RESET Output Voltage, VOH 1.8V < VCC < VTH Min., ISOURCE = 150µA
RESET Output Voltage, VOL ISINK = 3.2mA, FM810L/M/J
ISINK = 1.2mA, FM810R/S/T
10
MR Minimum Pulse Width
MR to Reset Delay
MR Input Threshold, VIH
VCC > VTH Max., FM81_L/M/J
2.3
FM81_R/S/T
0.7 x VCC
MR Input Threshold, VIL
VCC > VTH Max., FM81_L/M/J
FM81_R/S/T
MR Pull-Up Resistance
10
MR Glitch Immunity
REV. 1.5.1 7/15/02
Typ.
9
6
4.63
4.38
4.00
3.08
2.93
2.63
240
Max.
5.5
5.5
15
10
4.86
4.52
4.18
3.19
3.00
2.70
560
Units
V
0.4
0.3
0.3
0.3
V
0.4
0.35
V
ms
V
V
V
µs
µs
V
0.5
20
100
µA
0.8
0.25xVCC
30
kΩ
ns
3
Preliminary Information
-40 to +85
-65 to +150
Storage Temperature Range
FM811/812
Circuit Description
Microprocessor Reset
Interfacing to Bidirectional Reset Pins
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 40ms 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.
The FM811/ FM812 can interface with µPs with
bidirectional reset pins by connecting a 4.7kΩ resistor in
series with the FM811/ FM812 output and the µP reset pin.
Preliminary Information
VCC
VTH
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 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.
MR
VCC
tR
tR
RESET
VCC Transients
The FM811/ FM812 are relatively immune to negative-going
VCC glitches below the reset threshold. Typically, a negativegoing transient 125mV below the reset threshold with a
duration of 50ms (25ms for FM81_R/S/T) or less will not
cause an unwanted reset.
VCC
VCC
FM811
µP
RESET
RESET
100k
Manual Reset Function
Momentarily connecting the Manual Reset input pin (MR) to
GND forces a reset. Typically a Push-button switch is used
in most of the applications to force a manual reset. See
Typical Applications diagram. The reset will remain asserted
as long as MR is held low and for one reset time-out period
(140ms min.) after MR goes high. Note that this input cannot
be driven by a CMOS or TTL logic. This pin should be left
floating if manual reset feature is unused.
4
REV. 1.5.1 7/15/02
FM811/812
Packaging Information
4-Pin SOT-143
0.079
0.071
0.098
0.083
0.055
0.047
Dimensions are in inches
0.021
0.015
0.037
0.030
0.040
0.031
0.080
0.070
Preliminary Information
0.120
0.105
0.0059
0.0035
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
4.0 ± 0.1
O1.1 ± 0.1
2.7 ± 0.1
1.2 ± 0.1
Dimensions are in millimeters
3.1 ± 0.1
REV. 1.5.1 7/15/02
5
FM811/812
Preliminary Information
Ordering Information
Part
Number
Top
Marking*
RESET
Threshold (V)
Output Type
Package
Packing
Method
FM811LUX
KLYY
4.63
Push-Pull, active LOW
4-Pin, SOT143
3000 units in T&R
FM811MUX
KMYY
4.38
Push-Pull, active LOW
4-Pin, SOT143
3000 units in T&R
FM811JUX
KJYY
4.00
Push-Pull, active LOW
4-Pin, SOT143
3000 units in T&R
FM811TUX
KTYY
3.08
Push-Pull, active LOW
4-Pin, SOT143
3000 units in T&R
FM811SUX
KSYY
2.93
Push-Pull, active LOW
4-Pin, SOT143
3000 units in T&R
FM811RUX
KRYY
2.63
Push-Pull, active LOW
4-Pin, SOT143
3000 units in T&R
FM812LUX
LLYY
4.63
Push-Pull, active HIGH
4-Pin, SOT143
3000 units in T&R
FM812MUX
LMYY
4.38
Push-Pull, active HIGH
4-Pin, SOT143
3000 units in T&R
FM812JUX
LJYY
4.00
Push-Pull, active HIGH
4-Pin, SOT143
3000 units in T&R
FM812TUX
LTYY
3.08
Push-Pull, active HIGH
4-Pin, SOT143
3000 units in T&R
FM812SUX
LSYY
2.93
Push-Pull, active HIGH
4-Pin, SOT143
3000 units in T&R
FM812RUX
LRYY
2.63
Push-Pull, active HIGH
4-Pin, SOT143
3000 units in T&R
* YY = Lot Code
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO
ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME
ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN;
NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
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 (c) 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 of the user.
2. A critical component in 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.
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7/15/02 0.0m 004
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