MAX6825RUK [MAXIM]
Power Management Circuit, BICMOS, PDSO5;型号: | MAX6825RUK |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | Power Management Circuit, BICMOS, PDSO5 信息通信管理 光电二极管 |
文件: | 总9页 (文件大小:355K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
19-1868; Rev 2; 12/05
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
General Description
Features
The MAX6821–MAX6825 are low-voltage microprocessor
(µP) supervisory circuits that combine voltage monitor-
ing, watchdog timer, and manual reset input functions in
a 5-pin SOT23 package. Microprocessor supervisory cir-
cuits significantly improve system reliability and accura-
cy compared to separate ICs or discrete components.
These devices assert a reset signal whenever the moni-
tored voltage drops below its preset threshold, keeping it
o Monitors +1.8V, +2.5V, +3.0V, +3.3V, +5.0V
Supplies
o 140ms (min) Reset Timeout Delay
o 1.6s Watchdog Timeout Period
(MAX6821/MAX6822/MAX6823/MAX6824)
o Manual Reset Input
(MAX6821/MAX6822/MAX6823/MAX6825)
o Three Reset Output Options
asserted for a minimum timeout period after V
rises
CC
above the threshold. In addition, a watchdog timer moni-
tors against code execution errors. A debounced manual
reset is also available. The MAX6821–MAX6825 monitor
voltages from +1.8V to +5.0V. These outputs are guaran-
Push-Pull RESET
Push-Pull RESET
Open-Drain RESET
o Guaranteed Reset Valid to V
o Immune to Short Negative V
o No External Components
= +1.0V
Transients
CC
teed to be in the correct state for V
down to +1.0V.
CC
CC
Nine preprogrammed reset threshold voltages are
available (see the Threshold Suffix Guide). The
MAX6821, MAX6822, and MAX6823 all have a manual
reset input and a watchdog timer. The MAX6821 has
push-pull RESET, the MAX6822 has open-drain RESET,
and the MAX6823 has push-pull RESET. The MAX6824
has a watchdog timer and both push-pull RESET and
push-pull RESET. The MAX6825 has a manual reset
input and both push-pull RESET and push-pull RESET.
The Selector Guide explains the functions offered in
this series of parts.
o Small 5-Pin SOT23 Packages
Ordering Information
PART*
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
MAX6821_UK-T
MAX6822_UK-T
MAX6823_UK-T
MAX6824_UK-T
MAX6825_UK-T
________________________Applications
*Insert the desired suffix letter (from the table below) into the blank
to complete the part number
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
Set-Top Boxes
Automotive Systems
Critical µP Monitoring
Computers and
Controllers
Portable/Battery-
Embedded Controllers
Intelligent Instruments
Powered Equipment
Threshold Suffix Guide
RESET
THRESHOLD (V)
SUFFIX
Pin Configurations
L
M
T
4.63
4.38
3.08
2.93
2.63
2.32
2.19
1.67
1.58
TOP VIEW
RESET(RESET)
1
2
3
5
V
CC
S
R
Z
MAX6821
MAX6822
MAX6823
GND
MR
Y
4
WDI
W
V
SOT23-5
Note: Bold indicates standard versions. Samples are typically
available for standard versions only. All parts require a 2.5k
minimum order increment. Contact factory for availability.
(RESET) MAX6821 ONLY
Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
Selector Guide appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
ABSOLUTE MAXIMUM RATINGS
CC
Open-Drain RESET................................................-0.3V to +6.0V
Push-Pull RESET, RESET, MR, WDI ...........-0.3V to (V + 0.3V)
V
to GND...........................................................-0.3V to +6.0V
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
CC
Input Current (V ).............................................................20mA
CC
Output Current (RESET, RESET).........................................20mA
Continuous Power Dissipation (T = +70°C)
A
5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
= +4.5V to +5.5V for MAX682_L/M, V
= +2.7V to +3.6V for MAX682_T/S/R, V
= +2.1V to +2.75V for MAX682_Z/Y, V
=
CC
CC
CC
CC
+1.53V to +2.0V for MAX682_W/V, T = -40°C to +125°C, unless otherwise specified. Typical values are at T = +25°C.) (Note 1)
A
A
PARAMETER
SYMBOL
CONDITIONS
= 0°C to +85°C
MIN
1.0
TYP
MAX
5.5
UNITS
T
T
A
Operating Voltage Range
V
V
CC
= -40°C to +125°C
1.2
5.5
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
10
7
20
V
= +5.5V, no load
CC
30
16
V
Supply Current
CC
I
V
V
= +3.6V, no load
= +3.6V, no load
µA
CC
CC
CC
(MR and WDI Unconnected)
25
5
12
(MAX6825 only)
20
4.50
4.63
4.63
4.38
4.38
3.08
3.08
2.93
2.93
2.63
2.63
2.32
2.32
2.19
2.19
1.67
1.67
1.58
4.75
4.78
4.50
4.53
3.15
3.17
3.00
3.02
2.70
2.72
2.38
2.40
2.25
2.27
1.71
1.72
1.62
MAX682_L
= -40°C to +125°C 4.47
= -40°C to +85°C 4.25
= -40°C to +125°C 4.22
= -40°C to +85°C 3.00
= -40°C to +125°C 2.97
= -40°C to +85°C 2.85
= -40°C to +125°C 2.83
= -40°C to +85°C 2.55
= -40°C to +125°C 2.53
= -40°C to +85°C 2.25
= -40°C to +125°C 2.24
= -40°C to +85°C 2.12
= -40°C to +125°C 2.11
= -40°C to +85°C 1.62
= -40°C to +125°C 1.61
= -40°C to +85°C 1.52
MAX682_M
MAX682_T
MAX682_S
MAX682_R
MAX682_Z
MAX682_Y
V
(V
Reset Threshold
Falling)
CC
V
V
TH
CC
MAX682_W
MAX682_V
Reset Threshold Temperature
Coefficient
60
ppm/°C
Reset Threshold Hysteresis
2 ✕ V
mV
µs
TH
V
to Reset Output Delay
t
V
= V to (V - 100mV)
20
CC
RD
CC
TH
TH
2
_______________________________________________________________________________________
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
ELECTRICAL CHARACTERISTICS (continued)
(V
= +4.5V to +5.5V for MAX682_L/M, V
= +2.7V to +3.6V for MAX682_T/S/R, V
= +2.1V to +2.75V for MAX682_Z/Y, V
=
CC
CC
CC
CC
+1.53V to +2.0V for MAX682_W/V, T = -40°C to +125°C, unless otherwise specified. Typical values are at T = +25°C.) (Note 1)
A
A
PARAMETER
SYMBOL
CONDITIONS
= -40°C to +85°C
MIN
140
100
TYP
MAX
280
UNITS
T
T
200
A
Reset Timeout Period
t
ms
V
RP
= -40°C to +125°C
320
A
V
≥ 1.0V, I
= 0°C to +85°C
= 50µA, reset asserted,
= 100µA, reset asserted
SINK
CC
SINK
0.3
T
A
RESET Output LOW
(Push-Pull or Open-Drain)
V
V
V
≥ 1.2V, I
0.3
0.3
0.4
V
CC
OL
≥ 2.55V, I
= 1.2mA, reset asserted
= 3.2mA, reset asserted
CC
CC
SINK
SINK
≥ 4.25V, I
V
≥ 1.8V, I
= 200µA, reset not
CC
SOURCE
0.8 ✕ V
0.8 ✕ V
0.8 ✕ V
CC
CC
CC
asserted
RESET Output HIGH
(Push-Pull Only)
V
≥ 3.15V, I
= 500µA, reset not
= 800µA, reset not
CC
SOURCE
SOURCE
V
V
OH
asserted
V
≥ 4.75V, I
CC
asserted
Open-Drain RESET Output
Leakage Current (Note 1)
I
V
> V , RESET not asserted
1.0
µA
V
LKG
CC
TH
V
≥ 1.0V, I
= 1µA, reset asserted,
CC
SOURCE
0.8 ✕ V
CC
T
A
= 0°C to +85°C
RESET Output HIGH
(Push-Pull Only)
V
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
≥ 1.50V, I
≥ 2.55V, I
= 100µA, reset asserted 0.8 ✕ VCC
= 500µA, reset asserted 0.8 ✕ VCC
OH
SOURCE
SOURCE
SOURCE
≥ 4.25V, I
≥ 1.8V, I
= 800µA, reset asserted
0.8 ✕ VCC
= 500µA, reset not asserted
0.3
0.3
0.4
SINK
RESET Output LOW
(Push-Pull Only)
VOL
≥ 3.15V, I
= 1.2mA, reset not asserted
V
V
SINK
≥ 4.75V, I
= 3.2mA, reset not asserted
SINK
MANUAL RESET INPUT (MAX6821/MAX6822/MAX6823/MAX6825)
V
0.3 ✕ V
CC
IL
MR Input Voltage
V
0.7 ✕ V
IH
CC
MR Minimum Input Pulse
MR Glitch Rejection
MR to Reset Delay
1
µs
ns
ns
kΩ
100
200
50
MR Pullup Resistance
25
75
WATCHDOG INPUT (MAX6821/MAX6822/MAX6823/MAX6824)
T
A
T
A
= -40°C to +85°C
= -40°C to +125°C
1.12
0.80
50
1.60
2.40
2.60
Watchdog Timeout Period
WDI Pulse Width (Note 2)
WDI Input Voltage
t
s
ns
V
WD
t
WDI
V
0.3 ✕ V
CC
IL
V
0.7 ✕ V
IH
CC
WDI = V , time average
CC
120
-15
160
WDI Input Current
I
µA
WDI
WDI = 0, time average
-20
Note 1: Over-temperature limits are guaranteed by design and not production tested. Devices tested at T = +25°C.
A
Note 2: Guaranteed by design and not production tested.
_______________________________________________________________________________________
3
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
SUPPLY CURRENT
vs. TEMPERATURE
RESET TIMEOUT PERIOD
vs. TEMPERATURE
V
CC
TO RESET OUTPUT DELAY
vs. TEMPERATURE
13
250
240
230
220
210
200
190
180
170
160
150
35
30
25
20
15
10
5
V
FALLING, V = V - 100mV
CC TH
CC
12
V
= +5V, L VERSION
CC
11
10
9
8
V
= +3.3V, S VERSION
= +1.8V, V VERSION
CC
7
6
V
CC
5
4
0
3
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
NORMALIZED RESET THRESHOLD
DELAY vs. TEMPERATURE
MAXIMUM V TRANSIENT DURATION
CC
vs. RESET THRESHOLD OVERDRIVE
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
1.06
1.04
120
100
80
60
40
20
0
1.02
1.00
RESET OCCURS
ABOVE CURVE
0.98
0.96
0.94
-40 -20
0
20 40 60 80 100 120
-40 -20
0
20 40 60 80 100 120
0
20 40 60 80 100 120 140 160 180 200
RESET THRESHOLD OVERDRIVE (mV), V - V
TEMPERATURE (°C)
TEMPERATURE (°C)
TH
CC
VOLTAGE OUTPUT LOW
vs. SINK CURRENT
VOLTAGE OUTPUT HIGH
vs. SOURCE CURRENT
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
2.92
2.90
2.88
2.86
2.84
2.82
2.80
2.78
2.76
2.74
V
= +2.9V
V
= +2.9V
CC
CC
0
1
2
3
4
5
6
7
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
(mA)
I
(mA)
I
SOURCE
SINK
4
_______________________________________________________________________________________
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
Pin Description
PIN NUMBERS
PIN
FUNCTION
NAME
MAX6821 MAX6822 MAX6823 MAX6824 MAX6825
Active-Low Open-Drain or Push-Pull Reset Output. RESET
changes from high to low when the V input drops below the
CC
selected reset threshold, MR is pulled low, or the watchdog
triggers a reset. RESET remains low for the reset timeout period
1
1
1
1
3
RESET
after V
exceeds the device reset threshold, MR goes low to
CC
high, or the watchdog triggers a reset.
Active-High Push-Pull Reset Output. RESET changes from low to
high when the V
input drops below the selected reset threshold,
CC
MR is pulled low, or the watchdog triggers a reset. RESET remains
high for the reset timeout period after V exceeds the device
CC
reset threshold, MR goes low to high, or the watchdog triggers a
reset.
1
3
2
RESET
2
3
2
3
2
3
2
4
GND
Ground
Active-Low Manual Reset Input. Internal 50kΩ pullup to V . Pull
CC
low to force a reset. Reset remains active as long as MR is low
and for the reset timeout period after MR goes high. Leave
MR
unconnected or connect to V
if unused.
CC
Watchdog Input. If WDI remains high or low for longer than the
watchdog timeout period, the internal watchdog timer runs out and
a reset is triggered for the reset timeout period. The internal
watchdog timer clears whenever reset is asserted, the manual
reset is asserted, or WDI sees a rising or falling edge. If WDI is
left unconnected or is connected to a three-stated buffer output,
the watchdog feature is disabled.
4
5
4
5
4
5
4
5
WDI
5
V
Supply Voltage and Input for Reset Threshold Monitor
CC
returns high. MR has an internal 50kΩ pullup resistor,
so it can be left open if not used. This input can be dri-
ven with CMOS logic levels or with open-drain/collector
outputs. Connect a normally open momentary switch
from MR to GND to create a manual reset function;
external debounce circuitry is not required. If MR is dri-
ven from long cables or the device is used in a noisy
environment, connect a 0.1µF capacitor from MR to
GND to provide additional noise immunity.
Detailed Description
RESET/RESET Output
A µP’s reset input starts the µP in a known state. The
MAX6821–MAX6825 µP supervisory circuits assert a
reset to prevent code-execution errors during power-
up, power-down, and brownout conditions. Whenever
V
falls below the reset threshold, the reset output
CC
asserts low for RESET and high for RESET. Once V
CC
exceeds the reset threshold, an internal timer keeps the
reset output asserted for the specified reset timeout
Watchdog Input
In the MAX6821–MAX6824, the watchdog circuit moni-
tors the µP’s activity. If the µP does not toggle (low to
high or high to low) the watchdog input (WDI) within the
watchdog timeout period (1.6s nominal), reset asserts
for the reset timoeout period. The internal 1.6s timer
can be cleared by either a reset pulse or by toggling
WDI. The WDI can detect pulses as short as 50ns.
While reset is asserted, the timer remains cleared and
does not count. As soon as reset is released, the timer
starts counting (see Figure 3).
period (t ); after this interval, reset output returns to its
RP
original state (see Figure 2).
Manual Reset Input
Many µP-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. On the MAX6821/
MAX6822/MAX6823/MAX6825, a logic low on MR
asserts a reset. Reset remains asserted while MR is
low, and for the timeout period (140ms min) after it
_______________________________________________________________________________________
5
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
V
CC
MAX6821–
MAX6825
RESET (MAX6822–MAX6825)
RESET
GENERATOR
RESET
(MAX6821/MAX6824/MAX6825)
V
CC
1.26V
MR
(MAX6821–MAX6823,
MAX6825)
WATCHDOG
TRANSITION
DETECTOR
WATCHDOG
TIMER
WDI
(MAX6821–MAX6824)
GND
Figure 1. Functional Diagram
Disable the watchdog function by leaving WDI uncon-
nected or by three-stating the driver connected to WDI.
The watchdog input is internally driven low during the
first 7/8 of the watchdog timeout period and high for the
last 1/8 of the watchdog timeout period. When WDI is left
unconnected, this internal driver clears the 1.6s timer
every 1.4s. When WDI is three-stated or unconnected,
the maximum allowable leakage current is 10µA and the
maximum allowable load capacitance is 200pF.
V
CC
V
V
TH
TH
1V
1V
t
t
RP
RP
t
RD
RESET
t
RESET
RD
GND
Applications Information
Figure 2. Reset Timing Diagram
Watchdog Input Current
The MAX6821/MAX6822/MAX6823/MAX6824 WDI inputs
are internally driven through a buffer and series resistor
from the watchdog timer (Figure 1). When WDI is left
unconnected, the watchdog timer is serviced within the
watchdog timeout period by a low-high-low pulse from
the counter chain. For minimum watchdog input current
(minimum overall power consumption), leave WDI low for
the majority of the watchdog timeout period, pulsing it
low-high-low once within the first 7/8 of the watchdog
timeout period to reset the watchdog timer. If WDI is
externally driven high for the majority of the timeout peri-
od, up to 160µA can flow into WDI.
Interfacing to µPs with
Bidirectional Reset Pins
Since the RESET output on the MAX6822 is open drain,
it interfaces easily with µPs that have bidirectional reset
pins, such as the Motorola 68HC11. Connecting the µP
supervisor’s RESET output directly to the microcon-
troller’s RESET pin with a single pullup resistor allows
either device to assert reset (see Figure 4).
Negative-Going V
Transients
CC
These supervisors are relatively immune to short-dura-
tion, negative-going V transients (glitches), which
CC
usually do not require the entire system to shut down.
6
_______________________________________________________________________________________
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
V
CC
t
RST
V
CC
V
CC
RESET*
WDI
MAX6822
t
RP
RESET
RESET
µP
t
t
RP
WD
RESET
GENERATOR
GND
GND
*RESET IS THE INVERSE OF RESET.
Figure 3. Watchdog Timing Relationship
Figure 4. Interfacing Open-Drain RESET to µPs with
Bidirectional Reset I/O
Resets are issued to the µP during power-up, power-
down, and brownout conditions. The Typical Operating
Characteristics show a graph of the MAX6821–
START
MAX6825’s Maximum V
Transient Duration vs. Reset
CC
Threshold Overdrive, for which reset pulses are not
generated. The graph was produced using negative-
SET WDI
HIGH
going V
pulses, starting at the standard monitored
CC
voltage and ending below the reset threshold by the
magnitude indicated (reset threshold overdrive). The
graph shows the maximum pulse width that a negative-
PROGRAM
CODE
going V
transient can typically have without trigger-
CC
SUBROUTINE OR
PROGRAM LOOP
ing a reset pulse. As the amplitude of the transient
increases (i.e., goes farther below the reset threshold),
the maximum allowable pulse width decreases.
SET WDI LOW
Typically, a V
transient that goes 100mV below the
CC
reset threshold and lasts for 20µs or less will not trigger
a reset pulse.
RETURN
Watchdog Software Considerations
One way to help the watchdog timer monitor software
execution more closely is to set and reset the watch-
dog input at different points in the program, rather than
pulsing the watchdog input high-low-high or low-high-
low. This technique avoids a stuck loop, in which the
watchdog timer would continue to be reset inside the
loop, keeping the watchdog from timing out.
Figure 5. Watchdog Flow Diagram
Typical Operating Circuit
V
CC
Figure 5 shows an example of a flow diagram where
the I/O driving the watchdog input is set high at the
beginning of the program, set low at the beginning of
every subroutine or loop, then set high again when the
program returns to the beginning. If the program
should hang in any subroutine, the problem would
quickly be corrected, since the I/O is continually set
low and the watchdog timer is allowed to time out,
causing a reset or interrupt to be issued. As described
in the Watchdog Input Current section, this scheme
results in higher time average WDI input current than
does leaving WDI low for the majority of the timeout
period and periodically pulsing it low-high-low.
V
CC
V
CC
RESET
RESET
I/O
µP
MAX6823
WDI
MR
GND
MANUAL
RESET
_______________________________________________________________________________________
7
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
Selector Guide
ACTIVE-LOW
ACTIVE-HIGH
RESET
OPEN-DRAIN
WATCHDOG
INPUT
MANUAL
RESET INPUT
FUNCTION
RESET
RESET
MAX6821
MAX6822
MAX6823
MAX6824
MAX6825
—
—
✔
✔
✔
✔
—
—
✔
✔
—
✔
✔
✔
✔
✔
—
✔
✔
✔
—
✔
—
—
—
Pin Configurations (continued)
TOP VIEW
RESET
GND
1
2
3
5
4
V
CC
RESET
GND
1
2
3
5
4
V
CC
MAX6825
MAX6824
RESET
MR
RESET
WDI
SOT23-5
SOT23-5
Chip Information
TRANSISTOR COUNT: 750
PROCESS: BiCMOS
8
_______________________________________________________________________________________
Ultra-Low-Voltage SOT23 µP Supervisor with
Manual Reset and Watchdog Timer
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
PACKAGE OUTLINE, SOT-23, 5L
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21-0057
E
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
相关型号:
MAX6825WUK+T
Power Supply Management Circuit, Adjustable, 1 Channel, BICMOS, PDSO5, LEAD FREE, SOT-23, 5 PIN
MAXIM
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