19-0486; Rev 3; 12/05
+5V Microprocessor Supervisory Circuits
General Description
The MAX817/MAX818/MAX819 microprocessor (µP)
supervisory circuits simplify power-supply monitoring,
battery control, and chip-enable gating in µP systems
by reducing the number of components required.
These devices are designed for use in +5V-powered
systems. Low supply current (11µA typical) and small
package size make these devices ideal for portable
applications. The MAX817/MAX818/MAX819 are specif-
ically designed to ignore fast transients on V
CC
. Other
supervisory functions include active-low reset, backup-
battery switchover, watchdog input, battery freshness
seal, and chip-enable gating. The
Selector Guide
below
lists the specific functions available from each device.
These devices offer two pretrimmed reset threshold volt-
ages for ±5% or ±10% power supplies: 4.65V for the L
versions and 4.40V for the M versions. The MAX817/
MAX818/MAX819 are available in space-saving µMAX
packages, as well as 8-pin DIP/SO.
____________________________Features
♦
Precision Supply-Voltage Monitor:
4.65V (MAX81_L)
4.40V (MAX81_M)
♦
11µA Quiescent Supply Current
♦
200ms Reset Time Delay
♦
Watchdog Timer with 1.6sec Timeout
(MAX817/MAX818)
♦
Battery-Backup Power Switching; Battery Voltage
Can Exceed V
CC
♦
Battery Freshness Seal
♦
On-Board, 3ns Gating of Chip-Enable Signals
(MAX818)
♦
Uncommitted Voltage Monitor for Power-Fail or
Low-Battery Warning (MAX817/MAX819)
♦
Manual Reset Input (MAX819)
MAX817L/M, MAX818L/M, MAX819L/M*
_____________________Selector Guide
FEATURE
Active-Low Reset
Backup-Battery Switchover
Power-Fail Comparator
Watchdog Input
Battery Freshness Seal
Manual Reset Input
Chip-Enable Gating
Pin-Package
MAX817
L/M
✔
✔
✔
✔
✔
—
—
MAX818
L/M
✔
✔
—
✔
✔
—
✔
MAX819
L/M
✔
✔
✔
—
✔
✔
—
______________Ordering Information
PART
†
MAX817_CPA
MAX817_CSA
MAX817_CUA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
8 Plastic DIP
8 SO
8 µMAX
Ordering Information continued on last page.
†
These parts offer a choice of reset threshold voltage. From the
table below, select the suffix corresponding to the desired
threshold and insert it into the blank to complete the part number.
Devices are available in both leaded and lead-free packaging.
Specify lead free by adding the + symbol at the end of the part
number when ordering.
SUFFIX
L
M
RESET THRESHOLD (V)
4.65
4.40
8-DIP/SO/ 8-DIP/SO/ 8-DIP/SO/
µMAX
µMAX
µMAX
—
MAX703/
MAX704
Low-Power, Pin-
MAX690A/
Compatible Upgrades for: MAX692A
_________________Pin Configurations
________________________Applications
Battery-Powered Computers and Controllers
Embedded Controllers
Intelligent Instruments
Critical µP Monitoring
Portable Equipment
TOP VIEW
OUT
1
V
CC
2
GND
3
PFI
4
8
BATT
RESET
WDI
PFO
MAX817
7
6
5
Typical Operating Circuit appears at end of data sheet.
*P
DIP/SO/µMAX
Pin Configurations continued 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.
+5V Microprocessor Supervisory Circuits
MAX817L/M, MAX818L/M, MAX819L/M*
ABSOLUTE MAXIMUM RATINGS
Input Voltage
V
CC
, BATT ..........................................................-0.3V to +6.0V
All Other Pins (Note 1).............................-0.3V to (V
CC
+ 0.3V)
Input Current
V
CC
Peak ..............................................................................1A
V
CC
Continuous .............................................................250mA
BATT Peak .....................................................................250mA
BATT Continuous .............................................................50mA
GND .................................................................................25mA
Output Current
OUT................................................................................250mA
All Other Outputs .............................................................25mA
OUT Short-Circuit Duration.................................................10sec
Continuous Power Dissipation (T
A
= +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C) .............727mW
SO (derate 5.88mW/°C above +70°C) ..........................471mW
µMAX (derate 4.10mW/°C above +70°C) .....................330mW
Operating Temperature Ranges
MAX81_ _C_A ......................................................0°C to +70°C
MAX81_ _E_A ...................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Note 1:
The input voltage limits on PFI and WDI may be exceeded (up to 12V V
IN
) if the current into these pins is limited to less
than 10mA.
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
CC
= +4.75V to +5.5V for MAX81_L, V
CC
= +4.5V to +5.5V for MAX81_M, V
BATT
= 2.8V, T
A
= T
MIN
to T
MAX
, unless otherwise
noted. Typical values are at T
A
= +25°C.)
PARAMETER
Operating Voltage Range, V
CC
,
V
BATT
(Note 2)
Supply Current (excluding I
OUT
)
Supply Current in Battery-
Backup Mode (excluding I
OUT
)
I
SUPPLY
As applicable;
CE
IN = 0V,
WDI and
MR
unconnected
V
CC
= 0V
MAX81_ _C
MAX81_ _E
T
A
= +25°C
T
A
= T
MIN
to
T
MAX
T
A
= +25°C
BATT Standby Current (Note 3)
BATT Leakage Current,
Freshness Seal Enabled
5.5V > V
CC
> (V
BATT
+ 0.2V)
T
A
= T
MIN
to
T
MAX
-0.10
-1.00
SYMBOL
CONDITIONS
MIN
0
11
11
0.05
TYP
MAX
5.5
45
60
1.0
5.0
0.02
0.02
1
V
CC
-
0.05
V
CC
-
0.5
V
CC
-
0.025
V
CC
-
0.25
5
100
I
OUT
= 250µA, V
CC
< (V
BATT
- 0.2V)
V
CC
< V
RST
Power-up
Power-down
V
BATT -
V
BATT -
0.1
0.02
20
-20
40
10
µA
µA
UNITS
V
µA
V
CC
= 0V, V
OUT
= 0V
I
OUT
= 5mA
µA
V
OUT
Output
I
OUT
= 50mA
V
CC
to OUT On-Resistance
BATT to OUT On-Resistance
V
OUT
in Battery-Backup Mode
Battery Switch Threshold
(V
CC
- V
BATT
)
Battery Switchover Hysteresis
V
Ω
Ω
V
mV
mV
2
_______________________________________________________________________________________
+5V Microprocessor Supervisory Circuits
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +4.75V to +5.5V for MAX81_L, V
CC
= +4.5V to +5.5V for MAX81_M, V
BATT
= 2.8V, T
A
= T
MIN
to T
MAX
, unless otherwise
noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
MAX81_L
MAX81_M
CONDITIONS
MIN
4.50
4.25
140
V
CC
> V
RST(MAX),
I
SOURCE
= 800µA
V
CC
< V
RST(MIN),
I
SINK
= 3.2mA
RESET
Output Voltage
V
OL
MAX81_ _C, V
CC
= 1V, V
CC
falling,
V
BATT
= 0V, I
SINK
= 50µA
MAX81_ _E, V
CC
= 1.2V, V
CC
falling,
V
BATT
= 0V, I
SINK
= 100µA
V
CC
to
RESET
Delay
Watchdog Timeout Period
WDI Pulse Width
WDI Input Threshold (Note 4)
WDI Input Current (Note 5)
t
WD
t
WDI
V
IL
V
IH
V
IL
= 0.4V, V
IH
= 0.8V
CC
V
CC
= 5V
WDI = V
CC
, time average
WDI = GND, time average
V
PFT
I
PFI
V
OL
V
OH
V
PFI
< 1.20V, I
SINK
= 3.2mA, V
CC
> 4.50V
V
PFI
> 1.30V, I
SOURCE
= 40µA, V
CC
> 4.5V
V
P FO
= 0V
V
IL
V
IH
1
100
120
45
63
85
0.8
2.0
V
CC
- 1.5
250
500
-20
1.20
-25
From V
RST
, V
CC
falling at 10V/ms
1.00
50
0.8
3.5
120
-15
1.25
4
0.01
25
0.4
1.30
160
100
1.60
2.25
V
CC
- 1.5
0.4
0.3
0.3
µs
sec
ns
V
µA
V
TYP
4.65
4.40
25
t
RP
V
OH
200
280
MAX
4.75
4.50
UNITS
RESET AND WATCHDOG TIMER
Reset Threshold
Reset Threshold Hysteresis
Reset Timeout Period
V
RST
V
mV
ms
MAX817L/M, MAX818L/M, MAX819L/M*
POWER-FAIL COMPARATOR (MAX817/MAX819 only)
PFI Input Threshold
PFI Input Hysteresis
PFI Input Current
PFO
Output Voltage
PFO
Short-Circuit Current
MANUAL RESET INPUT (MAX819 only)
MR
Input Threshold
MR
Pulse Width
MR
Pulse that Would Not Cause
a Reset
MR
to Reset Delay
MR
Pull-Up Resistance
V
µs
ns
ns
kΩ
V
mV
nA
V
µA
_______________________________________________________________________________________
3
+5V Microprocessor Supervisory Circuits
MAX817L/M, MAX818L/M, MAX819L/M*
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +4.75V to +5.5V for MAX81_L, V
CC
= +4.5V to +5.5V for MAX81_M, V
BATT
= 2.8V, T
A
= T
MIN
to T
MAX
, unless otherwise
noted. Typical values are at T
A
= +25°C.)
PARAMETER
CE
IN Leakage Current
CE
IN to
CE
OUT Resistance
(Note 6)
CE
OUT Short-Circuit Current
(Reset Active)
CE
IN to
CE
OUT Propagation
Delay (Note 7)
CE
OUT Output
CE
OUT Input Threshold
RESET
to
CE
OUT Delay
Note 2:
Note 3:
Note 4:
Note 5:
V
OH
V
IH
V
IL
SYMBOL
Disable mode
Enable mode
Disable mode,
CE
OUT = 0V
50Ω source impedance driver, C
LOAD
= 50pF
I
OUT
= -100µA, V
CC
= 0V
I
OUT
= -1µA, V
CC
= 0V, V
BATT
= 2.8V
V
CC
= 5V
Power-down
V
CC
- 1V
2.7
0.8
3.5
15
0.1
CONDITIONS
MIN
TYP
±0.005
40
0.75
3
MAX
±1
150
2.0
8
UNITS
µA
Ω
mA
ns
V
V
µs
CHIP-ENABLE GATING (MAX818 only)
Either V
CC
or V
BATT
can go to 0V if the other is greater than 2.0V.
“-” = battery-charging current, “+” = battery-discharging current.
WDI is internally serviced within the watchdog timeout period if WDI is left unconnected.
WDI input is designed to be driven by a three-stated output device. To float WDI, the “high-impedance mode” of the output
device must have a maximum leakage current of 10µA and a maximum output capacitance of 200pF. The output device
must also be able to source and sink at least 200µA when active.
Note 6:
The chip-enable resistance is tested with V
CC
= +4.75V for the MAX818L and V
CC
= +4.5V for the MAX818M.
V
C E
IN
= V
C E
OUT
= V
CC
/2.
Note 7:
The chip-enable propagation delay is measured from the 50% point at
CE
IN to the 50% point at
CE
OUT.
4
_______________________________________________________________________________________
+5V Microprocessor Supervisory Circuits
MAX817L/M, MAX818L/M, MAX819L/M*
__________________________________________Typical Operating Characteristics
(V
CC
= +5V, V
BATT
= 3.0V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE (NO LOAD)
MAX817/18/19-01
BATTERY SUPPLY CURRENT
(BACKUP MODE) vs. TEMPERATURE
CE IN TO CE OUT ON-RESISTANCE (Ω)
140
120
100
80
60
40
20
0
V
BATT
= 2.8V
V
BATT
= 2.0V
V
CC
= 0V
V
BATT
= 5.0V
MAX817/18/19-02
CE IN TO CE OUT ON-RESISTANCE
vs. TEMPERATURE
90
80
70
60
50
40
30
20
10
0
-40
-20
0
20
40
60
80
100
V
CE IN
= 3V
V
CE IN
= 2V
MAX817/18/19-03
16
160
BATTERY SUPPLY CURRENT (nA)
100
V
CE IN
= 4V
SUPPLY CURRENT (µA)
14
12
10
8
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
BATT TO OUT ON-RESISTANCE
vs. TEMPERATURE
MAX817/18/19-04
V
CC
TO OUT ON-RESISTANCE
vs. TEMPERATURE
MAX817/18/19-05
RESET TIMEOUT PERIOD
vs. TEMPERATURE
MAX817/18/19-06
300
BATT TO OUT ON-RESISTANCE (Ω)
250
200
150
100
50
0
-40
V
CC
= 0V
7
V
CC
TO OUT ON-RESISTANCE (Ω)
220
RESET TIMEOUT PERIOD (ms)
V
BATT
= 2.0V
6
210
V
BATT
= 2.8V
V
BATT
= 5.0V
5
200
4
190
3
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
180
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
V
CC
TO RESET PROPAGATION DELAY
vs. TEMPERATURE
MAX817/18/19-07
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
WATCHDOG TIMEOUT PERIOD (sec)
MAX817/18/19-08
BATTERY FRESHNESS SEAL
LEAKAGE CURRENT vs. TEMPERATURE
MAX817/18/19-09
V
CC
TO RESET PROPAGATION DELAY (ms)
500
V
CC
FALLING AT:
0.25V/ms
400
1.70
20
LEAKAGE CURRENT (nA)
1.65
15
300
1V/ms
200
10V/ms
100
1.60
10
1.55
5
0
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
1.50
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
0
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
_______________________________________________________________________________________
5
DSP 与 ARM 处理器
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
