MAX690A/MAX692A/
MAX802L/MAX802M/
MAX805L
General Description
The MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
reduce the complexity and number of components
required for power-supply monitoring and battery-
control functions in microprocessor (μP) systems. They
significantly improve system reliability and accuracy
compared to separate ICs or discrete components.
These parts provide four functions:
1) A reset output during power-up, power-down, and
brownout conditions.
2) Battery-backup switching for CMOS RAM, CMOS μP,
or other low-power logic.
3) A reset pulse if the optional watchdog timer has not
been toggled within 1.6s.
4) A 1.25V threshold detector for power-fail warning or
low-battery detection, or to monitor a power supply
other than +5V.
The parts differ in their reset-voltage threshold levels and
reset outputs. The MAX690A/MAX802L/MAX805L generate
a reset pulse when the supply voltage drops below 4.65V,
and the MAX692A/MAX802M generate a reset below 4.40V.
The MAX802L/MAX802M guarantee power-fail accuracies
to ±2%. The MAX805L is the same as the MAX690A except
that RESET is provided instead of
RESET.
All parts are available in 8-pin DIP and SO packages.
The MAX690A/MAX802L are pin compatible with the
MAX690 and MAX694. The MAX692A/MAX802M are pin
compatible with the MAX692.
Microprocessor Supervisory Circuits
Features
● Precision Supply Voltage Monitor:
4.65V for MAX690A/MAX802L/MAX805L
4.40V for MAX692A/MAX802M
● Reset Time Delay: 200ms
● Watchdog Timer: 1.6s Timeout
● Battery-Backup Power Switching
● 200μA Quiescent Supply Current
● 50nA Quiescent Supply Current in Battery-
Backup Mode
● Voltage Monitor for Power-Fail or Low-Battery
Warning
● Power-Fail Accuracy Guaranteed to ±2%
(MAX802L/M)
● Guaranteed
RESET
Assertion to V
CC
= 1V
● 8-Pin SO and DIP Packages
Ordering Information
PART
MAX690ACPA
MAX690ACSA
MAX690AC/D
MAX690AEPA
MAX690AESA
MAX690AMJA
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
Applications
● Battery-Powered Computers and Controllers
●
Intelligent Instruments
● Critical μP Power Monitoring
Ordering Information continued at end of data sheet.
*Dice are specified at T
A
= +25°C
**Contact factory for availability and processing to MIL STD-
883. Devices in PDIP and SO packages are available in both
leaded and lead(Pb)-free packaging. Specify lead free by
adding the + symbol at the end of the part number when
ordering. Lead free not available for CERDIP package.
Typical Operating Circuit
UNREGULATED
DC
R
1
0.1µF
PFI
R
2
3.6V
LITHIUM
BATTERY
V
BATT
REGULATED +5V
V
CC
V
CC
RESET
RESET
NMI
I/O LINE GND
BUS
V
CC
CMOS
RAM
GND
µP
Pin Configurations
TOP VIEW
V
OUT
V
CC
1
2
MAX690A
MAX692A
MAX802L
MAX802M
MAX805L
MAX690A
PFO
MAX802L
WDI
8
7
6
5
V
BATT
RESET (RESET)
WDI
PFO
GND
V
OUT
GND 3
PFI 4
DIP/SO
( ) ARE FOR MAX805L ONLY.
19-4333; Rev 5; 4/15
MAX690A/MAX692A/
MAX802L/MAX802M/
MAX805L
Absolute Maximum Ratings
Terminal Voltage (with respect to GND)
V
CC
...................................................................-0.3V to +6.0V
V
BATT
...............................................................-0.3V to +6.0V
All Other Inputs (Note 1) .......................... -0.3V to (V
CC
+ 0.3V)
Input Current
V
CC
...............................................................................200mA
V
BATT
.............................................................................50mA
GND ................................................................................20mA
Output Current
V
OUT
.............................. Short-Circuit Protected for up to 10s
All Other Outputs ............................................................20mA
Microprocessor Supervisory Circuits
Rate of Rise, V
CC
, V
BATT
..............................................100V/μs
Continuous Power Dissipation
Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW
SO (derate 5.88mW/°C above +70°C) .......................
471mW
CERDIP (derate 8.00mW/°C above +70°C) ................640mW
Operating Temperature Ranges:
MAX69_AC_ _, MAX80_ _ C_ _ ........................0°C
to +70°C
MAX69_AE_ _, MAX80_ _ E_ _ ...................
-40°C to +85°C
MAX69_AMJA, MAX805LMJA .....................
-55°C to +125°C
Storage Temperature Range ............................
-65°C to +160°C
Lead Temperature (soldering, 10s) ................................
+300°C
Note 1:
The input voltage limits on PFI and WDI may be exceeded 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 MAX690A/MAX802L/MAX805L, V
CC
= 4.5V to 5.5V for MAX692A/MAX802M, V
BATT
= 2.8V, T
A
= T
MIN
to
T
MAX
, unless otherwise noted.)
PARAMETER
Operating Voltage Range,
V
CC
, V
BATT
(Note 2)
Supply Current (Excluding I
OUT
)
I
SUPPLY
in Battery-Backup
Mode (Excluding I
OUT
)
VBATT Standby Current
(Note 3)
I
SUPPLY
SYMBOL
MAX805LC
MAX69_AE/M, MAX80_ _E
MAX69_AC, MAX802_C
MAX69_AE/M, MAX802_E, MAX805LE/M
V
CC
= 0V,
V
BATT
= 2.8V
5.5V > V
CC
>
V
BATT
+0.2V
I
OUT
= 5mA
I
OUT
= 50mA
I
OUT
= 250μA, V
CC
< V
BATT
- 0.2V
V
CC
< V
RT
Power-up
Power-down
4.50
4.25
4.55
4.30
40
t
RS
140
200
280
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
-0.1
-1.0
V
CC
- 0.05
V
CC
- 0. 5
V
BATT
- 0.1
V
CC
- 0.025
V
CC
- 0. 25
V
BATT
- 0.02
20
-20
40
MAX690A, MAX802L, MAX805L
Reset Threshold
V
RT
MAX692A, MAX802M
MAX802L, T
A
= +25°C, V
CC
falling
MAX802M, T
A
= +25°C, V
CC
falling
Reset Threshold Hysteresis
Reset Pulse Width
4.65
4.40
4.75
4.50
4.70
4.45
mV
ms
V
CONDITIONS
MAX69_AC, MAX802_C
MIN
1.0
1.1
1.2
200
200
0.05
TYP
MAX
5.5
5.5
5.5
350
500
1.0
5.0
0.02
0.02
µA
µA
µA
V
UNITS
V
OUT
Output
V
V
OUT
in Battery-Backup Mode
Battery Switch Threshold, V
CC
to V
BATT
Battery Switchover Hysteresis
V
mV
mV
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2
MAX690A/MAX692A/
MAX802L/MAX802M/
MAX805L
Electrical Characteristics (continued)
Microprocessor Supervisory Circuits
(V
CC
= 4.75V to 5.5V for MAX690A/MAX802L/MAX805L, V
CC
= 4.5V to 5.5V for MAX692A/MAX802M, V
BATT
= 2.8V, T
A
= T
MIN
to
T
MAX
, unless otherwise noted.)
PARAMETER
SYMBOL
I
SINK
= 3.2mA
RESET
Output Voltage
MAX69_AC, MAX802_C, V
CC
= 1.0V
I
SINK
= 50μA
MAX69_AE/M, MAX802_E,
V
CC
= 1.2V, I
SINK
= 100μA
MAX805LC, I
SOURCE
= 4μA, V
CC
= 1.1V
RESET Output Voltage
MAX805LE/M, I
SOURCE
= 4μA, V
CC
= 1.2V
MAX805L, I
SOURCE
= 800μA
MAX805L, I
SINK
= 3.2mA
Watchdog Timeout
WDI Pulse Width
WDI Input Threshold (Note 4)
WDI Input Current
PFI Input Threshold
PFI Input Current
PFO
Output Voltage
I
SOURCE
= 800μA
I
SINK
= 3.2mA
t
WD
t
WP
V
IL
= 0.4V, V
IH
= (0.8) (V
CC
)
V
CC
= 5V
WDI = V
CC
WDI = 0V
MAX69_A, MAX805L, V
CC
= 5V
MAX802_C/E, V
CC
= 5V
-150
1.20
1.225
-25
V
CC
- 1.5
0.4
Logic low
Logic high
3.5
50
-50
1.25
1.250
0.01
1.30
1.275
25
150
1.00
50
0.8
1.60
0.8
0.9
V
CC
- 1.5
0.4
2.25
s
ns
V
µA
V
nA
V
V
CONDITIONS
I
SOURCE
= 800μA
0.4
0.3
0.3
V
MIN
TYP
MAX
UNITS
Note 2:
Either V
CC
or V
BATT
can go to 0V, if the other is greater than 2.0V.
Note 3:
“-” = battery-charging current, “+” = battery-discharging current.
Note 4:
WDI is guaranteed to be in an intermediate, non-logic level state if WDI is floating and V
CC
is in the operating voltage
range. WDI is internally biased to 35% of V
CC
with an input impedance of 50kΩ.
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MAX690A/MAX692A/
MAX802L/MAX802M/
MAX805L
Typical Operating Characteristics
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX690A-MAX805L toc01
Microprocessor Supervisory Circuits
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX690A-MAX805L toc02
MAX690A RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
V
BATT
= OV
T
A
= +25°C
5.00
4.95
4.90
4.85
SLOPE = 5Ω
4.80
4.75
V
CC
= +5V
V
BATT
= +2.8V
T
A
= +25°C
2.80
2.78
2.76
V
CC
= 0V
V
BATT
= +2.8V
T
A
= +25°C
MAX690A-MAX805L toc03
+5V
1V/div
V
CC
V
OUT
(V)
V
OUT
(V)
0V
2.74
SLOPE = 80Ω
2.72
2.70
0V
500ms/div
RESET
V
CC
V
CC
RESET
GND
2k
RESET
330pF
+5V
1V/div
0
10
20
30
40
50
0
0.2
0.4
0.6
0.8
1.0
I
OUT
(mA)
I
OUT
(mA)
MAX690A
RESET RESPONSE TIME
+5V
V
CC
MAX690A-MAX805L toc04
POWER-FAIL COMPARATOR
RESPONSE TIME
MAX690A-MAX805L toc05
POWER-FAIL COMPARATOR
RESPONSE TIME
PFI
+5V
PFO
PFO
+1.25V
30pF
1k
MAX690A-MAX805L toc06
+5V
+4V
T
A
= +25°C
1V/div
PFO
+5V
PFI
PFO
30pF
V
CC
= +5V
T
A
= +25°C
1k
V
CC
= +5V
T
A
= +25°C
+3V
+5V
V
CC
V
CC
RESET
GND
RESET
10k
RESET
30pF
+1.25V
+1.30V
PFI
0V
+0V
0V
+1.3V
PFI
+1.2V
400ns/div
+1.20V
400ns/div
2µs/div
MAX805L RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
V
CC
MAX690A-MAX805L toc07
+5V
+5V
V
CC
MAX805L
RESET RESPONSE TIME
MAX690A-MAX805L toc08
+4V
V
CC
RESET
GND
1V/div
0V
RESET
V
CC
V
BATT
RESET
GND
+5V
330
pF
10k
0V
330pF 10k
+4V
1V/div
0V
0V
500ms/div
2µs/div
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4
MAX690A/MAX692A/
MAX802L/MAX802M/
MAX805L
Pin Description
PIN
MAX690A/MAX692A
MAX802L/MAX802M
MAX805L
NAME
Microprocessor Supervisory Circuits
FUNCTION
Supply Output for CMOS RAM. When V
CC
is above the reset threshold,
V
OUT
connects to V
CC
through a P-channel MOSFET switch. When
V
CC
is below the reset threshold, the higher of V
CC
or V
BATT
will be
connected to V
OUT
.
+5V Supply Input
Ground
Power-Fail Comparator Input. When PFI is less than 1.25V,
PFO
goes
low. Connect PFI to GND or V
CC
when not used.
Power-Fail Output. When PFI is less than 1.25V,
PFO
goes low;
otherwise
PFO
stays high.
Watchdog Input. If WDI remains high or low for 1.6sec, the internal
watchdog timer runs out and reset is triggered. If WDI is left floating
or connected to a high-impedance three-state buffer, the watchdog
feature is disabled. The internal watchdog timer clears whenever reset is
asserted, WDI is three-stated, or WDI sees a rising or falling edge.
Reset Output. Whenever
RESET
is triggered, it pulses low for 200ms.
It stays low when V
CC
is below the reset threshold (4.65V in the
MAX690A/MAX802L and 4.4V in the MAX692A/MAX802M) and remains
low for 200ms after V
CC
rises above the reset threshold. A watchdog
timeout also triggers
RESET.
Active-High Reset Output is the inverse of
RESET.
When RESET is
asserted, the RESET output voltage = V
CC
or V
BATT
, whichever is
higher.
Backup-Battery Input. When V
CC
falls below the reset threshold, V
BATT
will be switched to V
OUT
if V
BATT
is 20mV greater than V
CC
. When V
CC
rises to 20mV above V
BATT
, V
OUT
will be reconnected to V
CC
. The
40mV hysteresis prevents repeated switching if V
CC
falls slowly.
1
1
V
OUT
V
CC
GND
PFI
PFO
2
3
4
5
2
3
4
5
6
6
WDI
7
7
RESET
—
—
RESET
8
8
V
BATT
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5
FPGA/CPLD
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