SGM824 [SGMICRO]
Microprocessor Supervisory Circuit with Watchdog Timer;
| 型号： | SGM824 |
| 厂家： | 
Shengbang Microelectronics Co, Ltd |
| 描述： | Microprocessor Supervisory Circuit with Watchdog Timer |
| 文件： | 总12页 (文件大小：676K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SGM824
Microprocessor Supervisory
Circuit with Watchdog Timer
GENERAL DESCRIPTION
FEATURES
The SGM824 is
a
complete microprocessor
● Ultra-Low Supply Current: < 1μA (TYP)
● Precision Supply-Voltage Monitor
4.63V for SGM824-L
supervisory device which combines reset and
watchdog functions in a SOT-23-5 package. System
reliability is significantly improved by such integration
compared to the designs with individual ICs or
discrete components. The SGM824 also features an
excellent transient immunity to ignore fast VCC
transients.
3.08V for SGM824-T
2.93V for SGM824-S
2.63V for SGM824-R
● Guaranteed Reset Valid at VCC = 1V
● Two Reset Output Options
Push-Pull nRESET
This device has an active-low push-pull reset output
(nRESET) that is activated by a watchdog expiry
event or due to a low VCC voltage. The nRESET output
can still be in the correct logic state even if VCC is
lower than 1V. The SGM824 is offered in four fixed
Push-Pull RESET
● Reset Pulse Width: 200ms (TYP)
● Debounced TTL/CMOS-Compatible
● Watchdog Timer with 1.6s (TYP) Timeout
● Fully Specified over Temperature
● Power-Supply Transient Immunity
● Without External Components
● -40℃ to +125℃ Operating Temperature Range
● Available in a Green SOT-23-5 Package
V
CC reset threshold voltages.
The SGM824 is available in a Green SOT-23-5
package. It operates over an ambient temperature
range of -40℃ to +125℃.
TYPICAL APPLICATION
APPLICATIONS
VCC
Computers
Portable Equipment
Automotive Equipment
Intelligent Instruments
Critical μP Power Monitoring
VCC
VCC
SGM824
Microprocessor
nRESET
nRESET
RESET
I/O
RESET
WDI
GND
GND
SG Micro Corp
JULY 2022–REV. A.3
www.sg-micro.com
Microprocessor Supervisory
Circuit with Watchdog Timer
SGM824
PACKAGE/ORDERING INFORMATION
RESET
THRESHOLD (V)
PACKAGE
DESCRIPTION
ORDERING
NUMBER
PACKAGE
MARKING
PACKING
OPTION
MODEL
4.63
3.08
2.93
2.63
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SGM824-LXN5G/TR
SGM824-TXN5G/TR
MZ1XX
MG9XX
MGAXX
MGBXX
Tape and Reel, 3000
Tape and Reel, 3000
Tape and Reel, 3000
Tape and Reel, 3000
SGM824
SGM824-SXN5G/TR
SGM824-RXN5G/TR
MARKING INFORMATION
NOTE: XX = Date Code.
YYY X X
Date Code - Week
Date Code - Year
Serial Number
Green (RoHS & HSF): SG Micro Corp defines "Green" to mean Pb-Free (RoHS compatible) and free of halogen substances. If
you have additional comments or questions, please contact your SGMICRO representative directly.
ABSOLUTE MAXIMUM RATINGS
OVERSTRESS CAUTION
Terminal Voltage (with Respect to GND)
Stresses beyond those listed in Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to
absolute maximum rating conditions for extended periods
may affect reliability. Functional operation of the device at any
conditions beyond those indicated in the Recommended
Operating Conditions section is not implied.
VCC ................................................................ -0.3V to 6.0V
All Other Inputs ................................. -0.3V to (VCC + 0.3V)
Input Current
VCC ............................................................................20mA
GND ..........................................................................20mA
Output Current
All Outputs.................................................................20mA
Package Thermal Resistance
ESD SENSITIVITY CAUTION
This integrated circuit can be damaged if ESD protections are
not considered carefully. SGMICRO recommends that all
integrated circuits be handled with appropriate precautions.
Failureto observe proper handlingand installation procedures
can cause damage. ESD damage can range from subtle
performance degradation tocomplete device failure. Precision
integrated circuits may be more susceptible to damage
because even small parametric changes could cause the
device not to meet the published specifications.
SOT-23-5, θJA .......................................................... 234℃/W
Junction Temperature .................................................+150℃
Storage Temperature Range.........................-65℃ to +150℃
Lead Temperature (Soldering, 10s) ............................+260℃
ESD Susceptibility
HBM.............................................................................4000V
MM.................................................................................400V
CDM ............................................................................1000V
RECOMMENDED OPERATING CONDITIONS
Ambient Temperature Range........................-40℃ to +125℃
DISCLAIMER
SG Micro Corp reserves the right to make any change in
circuit design, or specifications without prior notice.
SG Micro Corp
www.sg-micro.com
JULY 2022
2
Microprocessor Supervisory
Circuit with Watchdog Timer
SGM824
PIN CONFIGURATION
(TOP VIEW)
nRESET
GND
1
2
5
4
VCC
RESET
WDI
3
SOT-23-5
PIN DESCRIPTION
PIN
NAME
FUNCTION
Active-Low Reset Output Pin. It delivers a 200ms (TYP) low pulse when activated. nRESET remains low if
VCC is below the reset threshold. It goes (or remains) low for 200ms after either of the following events:
VCC rises above the reset threshold or a watchdog expiry triggers a reset.
1
nRESET
2
3
GND
Ground.
RESET
Active-High Reset Output Pin. It is the inverse of nRESET.
Watchdog Input Pin. If the high or low state of WDI exceeds the watchdog timeout period, the internal
watchdog timer is expired and a reset is triggered. The internal watchdog timer is clear while a reset is
asserted. The timer is also cleared if the WDI input is changed (on rising or falling edges). The watchdog
feature is disabled if the WDI is left open or if it is connected to a three-stated buffer output.
4
5
WDI
VCC
Supply Voltage Pin.
SG Micro Corp
JULY 2022
www.sg-micro.com
3
Microprocessor Supervisory
Circuit with Watchdog Timer
SGM824
ELECTRICAL CHARACTERISTICS
(TA = +25℃, VCC = 4.73V to 5.5V for SGM824-L, VCC = 3.14V to 5.5V for SGM824-T, VCC = 2.99V to 5.5V for SGM824-S, VCC
=
2.68V to 5.5V for SGM824-R, Full = -40℃ to +125℃, unless otherwise noted.)
PARAMETER
CONDITIONS
TEMP
Full
MIN
TYP
MAX
5.5
UNITS
Operating Voltage Range (VCC
)
1
V
VCC = 3.6V
VCC = 5.5V
Full
0.5
0.7
1.2
Supply Current (ISUPPLY
)
μA
Full
1.4
+25℃
Full
4.55
4.54
3.03
3.02
2.88
2.87
2.59
2.58
4.63
4.63
3.08
3.08
2.93
2.93
2.63
2.63
20
4.70
4.73
3.13
3.14
2.98
2.99
2.67
2.68
SGM824-L
SGM824-T
SGM824-S
SGM824-R
+25℃
Full
Reset Threshold (VRST
)
V
+25℃
Full
+25℃
Full
SGM824-L
SGM824-T
SGM824-S
SGM824-R
+25℃
+25℃
+25℃
+25℃
Full
14
Reset Threshold Hysteresis (VHYS
)
mV
13
12
Reset Threshold Temperature Coefficient
Reset Pulse Width (tRP
20
ppm/℃
)
Full
140
200
290
0.4
ms
SGM824-L, VCC = VRST(MAX)
ISOURCE = 120μA
SGM824-T/S/R, VCC = VRST(MAX)
ISOURCE = 30μA
,
Full
Full
Full
VCC - 1.5
VOH
,
0.8 × VCC
SGM824-L, VCC = VRST(MIN)
,
nRESET Output Voltage
V
ISINK = 3.2mA
SGM824-T/S/R, VCC = VRST(MIN)
ISINK = 1.2mA
,
VOL
Full
Full
Full
0.3
0.3
460
VCC = 1V, VCC falling, ISINK = 50μA
SGM824-L, nRESET = 0V,
VCC = 5.5V
nRESET Output Short-Circuit Current
(ISOURCE
μA
)
SGM824-T/S/R, nRESET = 0V,
VCC = 3.6V
Full
Full
Full
430
VOH
VOL
VCC > 1.8V, ISOURCE = 150μA
0.8 × VCC
SGM824-L, VCC = VRST(MAX)
,
0.4
0.3
RESET Output Voltage
V
ISINK = 3.2mA
SGM824-T/S/R, VCC = VRST(MAX)
,
Full
ISINK = 1.2mA
VCC to Reset Delay (tRD
)
VRST - VCC = 100mV
+25℃
Full
Full
Full
Full
Full
Full
Full
Full
84
μs
sec
ns
Watchdog Timeout Period (tWD
)
1.1
90
1.6
2.4
0.8
0.8
0.5
WDI Pulse Width (tWP
)
VIL = 0V, VIH = VCC
VCC = 5V
Low
High
Low
High
VCC = 5V
3.5
0.7 × VCC
-0.5
WDI Input Threshold
V
VRST(MAX) < VCC < 3.6V
VRST(MAX) < VCC < 3.6V
WDI = VCC, time average
WDI = 0V, time average
0.02
WDI Input Current
μA
-0.01
SG Micro Corp
www.sg-micro.com
JULY 2022
4
Microprocessor Supervisory
Circuit with Watchdog Timer
SGM824
TYPICAL PERFORMANCE CHARACTERISTICS
Reset Timeout Period vs. Temperature
Reset Comparator Propagation Delay vs. Temperature
240
230
220
210
200
190
180
140
120
100
80
VCC Falling
60
40
20
-50 -25
0
25
50
75 100 125 150
-50 -25
0
25
50
75 100 125 150
Temperature (℃)
Temperature (℃)
Watchdog Timeout Period vs. Temperature
Normalized Reset Threshold Voltage vs. Temperature
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.06
1.04
1.02
1.00
0.98
0.96
0.94
-50 -25
0
25
50
75 100 125 150
-50 -25
0
25
50
75 100 125 150
Temperature (℃)
Temperature (℃)
SG Micro Corp
www.sg-micro.com
JULY 2022
5
Microprocessor Supervisory
Circuit with Watchdog Timer
SGM824
FUNCTIONAL BLOCK DIAGRAM
VCC
+
nRESET
Reset
Generator
RESET
_
+
1.25V
_
Watchdog
Transition
Detector
Watchdog
Timer
WDI
SGM824
GND
SG Micro Corp
www.sg-micro.com
JULY 2022
6
Microprocessor Supervisory
Circuit with Watchdog Timer
SGM824
DETAILED DESCRIPTION
Reset Output
Watchdog Input
The internal watchdog circuit monitors the μP’s activity
by checking the WDI input. If the μP does not toggle the
WDI within the watchdog tWD (1.6s, TYP) period, the
reset output will send a low pulse to reset the μP. So,
the code should be written such that successive
toggles on WDI occur in periods not longer than the
lowest tWD time to reset the internal watchdog timer and
prevent μP reset when the code is running normally.
The watchdog timer is cleared by either toggling WDI or
by a pulse with a duration as short as 90ns. While the
reset is asserted, the watchdog timer is cleared and
timer does not count. It starts counting when the reset
is released (Figure 2).
The reset input of a microprocessor (μP) initiates it to a
known state. The SGM824 supervisory circuit asserts a
reset to the supervised μP to prevent the
code-execution errors that may occur due to power-up,
power-down, brownout conditions or other transients.
The nRESET output is still in the correct logic state
even if VCC is lower than 1V. During power-up, when
VCC exceeds the rising threshold voltage (VRST + VHYS),
an internal timer keeps nRESET in low state for the
reset timeout period (tRP) before nRESET returns to the
high state (Figure 1).
If VCC drops below the falling threshold voltage (VRST) (a
brownout condition occurs), a reset is asserted and
nRESET goes low. In general, nRESET remains low for
the tRP (200ms, TYP) period every time after the last
event. So, if during the low period of nRESET, VCC goes
up and dips below VRST again, the internal timer will
restart for a new tRP period. The nRESET output can
source and sink current. The RESET function is the
inverse of nRESET.
To disable the watchdog function, leave the WDI pin
open. If WDI is driven by a 3-state buffer, set it to the
Hi-Z state. In this case the buffer leakage current
should not exceed 10μA. The maximum capacitance
seen on the WDI pin should be less than 200pF to
assure that watchdog remains disabled. The watchdog
input is internally oscillating when it is left open to clear
the watchdog timer and prevent it from generating a
reset. It is driven low during the first 7/8 of the watchdog
timeout period and driven high in the last 1/8 of that.
For example if WDI input is open and the watchdog
timeout is 1.6s, the watchdog timer will automatically
clear every 1.4s and reset will not occur.
VCC
VRST
VRST + VHYS
1V
1V
tRP
tRD
nRESET
VCC
VRST + VHYS
RESET
GND
tRP
tRD
tRP
nRESET
tWD
tRP
Figure 1. Reset Timing Diagram
tWD
tRP
RESET
WDI
tRP
Figure 2. Watchdog Timing Relationship
SG Micro Corp
www.sg-micro.com
JULY 2022
7
Microprocessor Supervisory
Circuit with Watchdog Timer
SGM824
APPLICATION INFORMATION
Using SGM824 with Microprocessors with
Bidirectional Reset Pins
Watchdog Software Considerations
To have a more effective watchdog in software
monitoring, rather than generating pulses by a code
segment, set and reset the WDI input at different points
of the program code. For example, set it in the main
program and reset it in a periodic timing interrupt. For
example if WDI is toggled within an unwanted infinite
loop, it will continuously reset watchdog as a normal
condition and the processor is not reset.
Some microprocessors can internally force their reset
pins low to assert a reset (bidirectional reset pins). The
low pull-up current of the SGM824 allows using of them
along with the microprocessors with bidirectional resets
like the 68HC11. The microprocessor can force
nRESET low when nRESET is pulled high by the
SGM824 with no issues (Figure 3).
An example of a watchdog flow is shown in Figure 4.
The WDI is set high at the start of the program, and is
set low at the start of every subroutine or loop, then is
set high again when the program returns to the start. If
the processor hangs in any subroutine, the WDI
toggling will not occur and the watchdog will reset the
processor and correct the situation.
VCC
VCC
SGM824
VCC
VCC
μP
ISOURCE = 460μA
(SGM824-L)
Reset
Generator
nRESET
The reset output may also be connected to an interrupt
input of the μP for a corrective action if preferred.
GND
GND
Note that such watchdog control schemes may not be
optimal if the total power consumption is critical as
discussed in the watchdog input current section.
Figure 3．Interfacing to μP with Bidirectional Resets
Start
Negative-Going VCC Transient Immunity
The SGM824 has the ability to immune short time and
negative VCC transients or even glitches. It does not
need to shut down the entire system. Resets are
applied to the microprocessor during power-up,
power-down and brownout conditions and not when an
insignificant VCC transient occurs.
Set WDI High
Program Code
A 0.1μF ceramic capacitor is recommended between
the VCC and GND pin to reduce the input supply noise.
Subroutine or
Program Loop Set
WDI Low
Watchdog Input Current
The WDI input is internally driven by a buffer and series
resistor from an internal counter chain stage of the
watchdog. Therefore, when WDI is open, the watchdog
timer is automatically cleared before timeout (by an
internal low-high-low pulse).
Return
Figure 4. Watchdog Flow Diagram
To get the minimum WDI input current (minimum power
loss), keep WDI low for the majority of the timeout
period and send a high pulse at the first 7/8 of the
timeout period for clearing the watchdog timer.
SG Micro Corp
www.sg-micro.com
JULY 2022
8
Microprocessor Supervisory
Circuit with Watchdog Timer
SGM824
REVISION HISTORY
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
JULY 2022 ‒ REV.A.2 to REV.A.3
Page
Updated General Description section...................................................................................................................................................................1
Updated Detailed Description section ..................................................................................................................................................................7
Updated Application Information section..............................................................................................................................................................8
JULY 2020 ‒ REV.A.1 to REV.A.2
Page
Updated Features section....................................................................................................................................................................................1
Changed Detailed Description section .................................................................................................................................................................7
JANUARY 2020 ‒ REV.A to REV.A.1
Page
Changed Electrical Characteristics section..........................................................................................................................................................4
Changed Typical Performance Characteristics section ........................................................................................................................................5
Changed Figure 1................................................................................................................................................................................................7
Changes from Original (DECEMBER 2018) to REV.A
Page
Changed from product preview to production data.............................................................................................................................................All
SG Micro Corp
www.sg-micro.com
JULY 2022
9
PACKAGE INFORMATION
PACKAGE OUTLINE DIMENSIONS
SOT-23-5
1.90
D
e1
2.59
E1
E
0.99
b
e
0.95
0.69
RECOMMENDED LAND PATTERN (Unit: mm)
L
A
A1
c
θ
0.2
A2
Dimensions
In Millimeters
Dimensions
In Inches
Symbol
MIN
MAX
1.250
0.100
1.150
0.500
0.200
3.020
1.700
2.950
MIN
MAX
0.049
0.004
0.045
0.020
0.008
0.119
0.067
0.116
A
A1
A2
b
1.050
0.000
1.050
0.300
0.100
2.820
1.500
2.650
0.041
0.000
0.041
0.012
0.004
0.111
0.059
0.104
c
D
E
E1
e
0.950 BSC
1.900 BSC
0.037 BSC
0.075 BSC
e1
L
0.300
0°
0.600
8°
0.012
0°
0.024
8°
θ
SG Micro Corp
www.sg-micro.com
TX00033.000
PACKAGE INFORMATION
TAPE AND REEL INFORMATION
REEL DIMENSIONS
TAPE DIMENSIONS
P2
P0
W
Q2
Q4
Q2
Q4
Q2
Q4
Q1
Q3
Q1
Q3
Q1
Q3
B0
Reel Diameter
P1
A0
K0
Reel Width (W1)
DIRECTION OF FEED
NOTE: The picture is only for reference. Please make the object as the standard.
KEY PARAMETER LIST OF TAPE AND REEL
Reel Width
Reel
Diameter
A0
B0
K0
P0
P1
P2
W
Pin1
Package Type
W1
(mm)
(mm) (mm) (mm) (mm) (mm) (mm) (mm) Quadrant
SOT-23-5
7″
9.5
3.20
3.20
1.40
4.0
4.0
2.0
8.0
Q3
SG Micro Corp
TX10000.000
www.sg-micro.com
PACKAGE INFORMATION
CARTON BOX DIMENSIONS
NOTE: The picture is only for reference. Please make the object as the standard.
KEY PARAMETER LIST OF CARTON BOX
Length
(mm)
Width
(mm)
Height
(mm)
Reel Type
Pizza/Carton
7″ (Option)
7″
368
442
227
410
224
224
8
18
SG Micro Corp
www.sg-micro.com
TX20000.000
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