FM803 Precision Reset Generator Circuit
PRELIMINARY
August 2001
FM803
Precision Reset Generator Circuit
General Description
The FM803 features comprehensive reset generation for
microcontroller/microprocessor based systems. If the system V
CC
voltage level is determined to be in an out-of-tolerance state, the
device automatically generates a low-going reset signal. The
reset signal is held in the active state (low) for a specified duration
(minimum 140 ms) after the V
CC
returns to an in-tolerance state.
This device is fabricated using CMOS technology. This device is
available in the SOT-23 package.
The FM803xx also can monitor a switch closure on its output,
enabling it to recognize an external reset from a pushbutton switch
or a microprocessor. In the case of a switch, the closure will be
debounced by circuitry internal to the FM803xx.
Features
I
Automatic reset generation on power-up
I
Minimum 140 ms reset pulse
I
Internal 5kΩ pull-up resistor
I
Other reset pulse choices available: 32 - 256 ms
I
Operating temperature -40°C to + 105°C
I
Choice of Reset Thresholds: 4.63V, 4.38V, 4.00V, 3.08V,
2.93V, 2.63V
I
SOT23-3 Package
Typical Operating Circuit
V
CC
3
FM803
Controller
1
2
/RESET
GND
Connection Diagram
GND 1
FM803 3 V
CC
/RESET 2
SOT23-3 Package
© 2001 Fairchild Semiconductor Corporation
FM803 Rev. A.3
1
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FM803 Precision Reset Generator Circuit
Absolute Maximum Ratings
Voltage on any terminal relative to GND
V
CC
/RESET
Input Current
Output Current: /RESET
-0.3V to +6.0V
-0.3V to +6.0V
20mA
20mA
Rate of Rise of V
CC
Continuous Power Dissipation (T
A
= +70°C)
SOT23-3 (derate 4mW/°C above +70°C)
Operating Temperature Range
Storage Temperature Range
Lead Temperature (soldering, 10s)
100V/µs
320mW
-40°C to +105°C
-65°C to +150°C
+300°C
These are stress ratings only, and functional operation is not implied for these levels or beyond. Exposure to Absolute Maximum Rating
conditions for extended periods may affect device reliability.
Electrical Characteristics
(T
A
= 25
°
C unless otherwise noted)
V
CC
= full range, as noted under conditions. See Note 1.
Parameter
Operating Voltage
Supply Current
Symbol
V
CC
I
CC
Conditions
T
A
= -40°C to +135°C
T
A
= -40°C to +135°C, V
CC
< 5.5V
FM803J/L/M
T
A
= -40°C to +135°C, V
CC
< 3.6V
FM803R/S/T
FM803L
FM803M
FM803J
FM803T
FM803S
FM803R
T
A
= -40°C to +105°C
T
A
= -40°C to +105°C
T
A
= -40°C to +105°C
T
A
= -40°C to +105°C
T
A
= -40°C to +105°C
T
A
= -40°C to +105°C
Min
1.1
Typ
(Note 2)
5
3
Max
5.5
10
6
4.86
4.52
4.18
3.19
3.00
2.70
Units
V
µA
Reset Threshold
V
TH
4.40
4.18
3.90
2.97
2.79
2.49
4.63
4.38
4.00
3.08
2.93
2.63
30
V
Reset Threshold Tempco
V
CC
to Reset Delay
Reset Active Timout Period
FM803 Output Low
V
OL
V
CC
= V
TH
to (V
TH
- 100mV)
T
A
= -40°C to +105°C
V
CC
= V
TH
(min), I
SINK
= 1.2mA,
FM803R/S/T
V
CC
= V
TH
(min), I
SINK
= 3.2mA,
FM803J/L/M
V
CC
= < 1.0V, I
SINK
= 50µA
V
CC
> V
TH
(max), I
RESET
= 1
PBV
DET
FM803L/M/J
FM803T/S/R
Pushbutton Release
PBV
REL
FM803L/M/J
FM803T/S/R (Note 3)
Note 1:
Testing in production is 25°C only. Limits over temperature are guaranteed by design.
Note 2:
Typical values are at 25°C.
Note 3:
It is recommended to connect a 100pF capacitor between the Reset pin and Ground pin if pushbutton reset is implemented.
ppm/°C
µs
560
0.3
0.4
0.3
ms
V
10
140
256
Open-Drain Output Leakage
Current
Pushbutton Detect
0.8V
CC
1.8
0.8
0.3
0.3
1
3.3
2.0
1.5
1.5
µA
V
V
2
FM803 Rev. A.3
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FM803 Precision Reset Generator Circuit
Pin Descriptions
Pin Number
1
2
Name
GND
/RESET
GROUND
Function
/RESET remains LOW while V
CC
is below
V
TH
, and for at least 140ms after V
CC
rises
above V
TH
.
3
V
CC
Circuit Timing (Ex: FM803)
V
CC
5V
V
TH
1V
GND
RESET
5V
V
TH
1V
GND
140ms
/Reset
PB
RD
PB
DV
t
RST
When operating properly with 5V V
CC
(for example), /RESET will
also be about 5V. When V
CC
starts to fall, /RESET will follow it
down as shown. When V
CC
drops below V
TH
, /RESET drops to
ground ("issues a RESET") and stays there unless V
CC
also falls
below its minimum operating voltage, approx. 1V. At this point, the
supervisor loses control, and its output may rise, only to again
follow V
CC
down to the ground.
When V
CC
begins to rise, /RESET follows it until 1.0V or so is
reached, whereupon the device regains control, /RESET is pulled
to ground, etc. When V
CC
rises above V
TH
, /RESET comes out of
RESET 140 ms later.
If it is required that a lower value than GND + 1.0V is needed on
RESET signal during V
CC
≤
1V, a 100K resistor may be used on
the device output to GND.
3
FM803 Rev. A.3
www.fairchildsemi.com
FM803 Precision Reset Generator Circuit
Typical Operating Characteristics
Supply Current Vs. Temperature
10
8
I
CC
(µA)
6
4
2
0
-55C
+25C
Temperature (C)
Power up Reset Timeout Vs. Temperature
10
V
CC
= 5V
8
6
4
2
+110C
0
V
CC
= 3.3V
Power up Reset timeout (ms)
600
500
400
300
200
100
-40C
+25C
Temperature (C)
+105C
600
500
400
300
200
100
Bi-Directional Reset
The FM803xx permits an external pushbutton to initiate a reset.
Such as connection to pin 2 will be debounced, RESET will go low
and recover in typically 250ms. For proper operation, the external
switch should be paralleled by an external capacitor of 100pF to
0.1F.
VCC
3
FM803
Controller
1
GND
100pF
2
/RESET
PUSH
BUTTON
4
FM803 Rev. A.3
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FM803 Precision Reset Generator Circuit
Ordering Information
Part
Number
FM803LS3
FM803MS3
FM803JS3
FM803TS3
FM803SS3
FM803RS3
FM803LES3 (Note 4)
FM803MES3 (Note 4)
FM803JES3 (Note 4)
FM803TES3 (Note 4)
FM803SES3 (Note 4)
FM803RES3 (Note 4)
FM803LFS3 (Note 4)
FM803MFS3 (Note 4)
FM803JFS3 (Note 4)
FM803TFS3 (Note 4)
FM803SFS3 (Note 4)
FM803RFS3 (Note 4)
FM803LHS3 (Note 4)
FM803MHS3 (Note 4)
FM803JHS3 (Note 4)
FM803THS3 (Note 4)
FM803SHS3 (Note 4)
FM803RHS3 (Note 4)
Top
Marking
03L
03M
03J
03T
03S
03R
03LE
03ME
03JE
03TE
03SE
03RE
03LF
03MF
03JF
03TF
03SF
03RF
03LH
03MH
03JH
03TH
03SH
03RH
RESET
Threshold (V)
4.63
4.38
4.00
3.08
2.93
2.63
4.63
4.38
4.00
3.08
2.93
2.63
4.63
4.38
4.00
3.08
2.93
2.63
4.63
4.38
4.00
3.08
2.93
2.63
RESET Pulse
Width (ms)
256
256
256
256
256
256
32
32
32
32
32
32
64
64
64
64
64
64
128
128
128
128
128
128
Output
Type
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Open-Drain, active LOW
Package
Type
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
3-Pin, SOT23
Note 4:
These devices are available upon special request only. Please contact Fairchild sales for availability and minimum ordering requirements.
5
FM803 Rev. A.3
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