19-4333; Rev 4; 12/05
Microprocessor Supervisory Circuits
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 signifi-
cantly 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 1.6sec.
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 guaran-
tee 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.
___________________________Features
♦
Precision Supply-Voltage Monitor:
4.65V for MAX690A/MAX802L/MAX805L
4.40V for MAX692A/MAX802M
♦
Reset Time Delay – 200ms
♦
Watchdog Timer – 1.6sec 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
Automotive Systems
Critical µP Power Monitoring
Ordering Information continued on last page.
*
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-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 REGULATED +5V
O.1µF
V
CC
V
CC
PFI
R
2
3.6V
LITHIUM
BATTERY
RESET
PFO
WDI
V
BATT
V
OUT
GND
RESET
NMI
µP
_________________Pin Configurations
TOP VIEW
R
1
V
OUT
V
CC
1
2
8
V
BATT
RESET (RESET)
WDI
PFO
I/O LINE GND
BUS
V
CC
CMOS
RAM
GND
GND
3
PFI
4
MAX690A
MAX692A
MAX802L
MAX802M
MAX805L
DIP/SO
7
6
5
MAX690A
MAX802L
( ) ARE FOR MAX805L ONLY.
________________________________________________________________
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.
Microprocessor Supervisory Circuits
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 10sec
All Other Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
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, 10sec) . . . . . . . . . . . . . . . . . . +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
)
V
BATT
Standby Current (Note 3)
V
OUT
Output
V
OUT
in Battery-Backup Mode
Battery Switch Threshold, V
CC
to V
BATT
Battery Switchover Hysteresis
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
t
RS
I
SOURCE
= 800µA
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
2
_______________________________________________________________________________________
140
V
CC
- 1.5
4.50
4.25
4.55
4.30
40
200
280
0.4
0.3
0.3
V
I
SUPPLY
SYMBOL
CONDITIONS
MAX69_AC, MAX802_C
MAX805LC
MAX69_AE/M, MAX80_ _E
MAX69_AC, MAX802_C
MAX69_AE/M, MAX802_E, MAX805LE/M
T
A
= +25°C
V
CC
= 0V,
V
BATT
= 2.8V
T
A
= T
MIN
to T
MAX
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
T
A
= +25°C
T
A
= T
MIN
to T
MAX
-0.1
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
-1.0
0.02
V
CC
- 0.05 V
CC
- 0.025
V
CC
- 0.5
V
CC
- 0.25
20
-20
40
4.65
4.40
4.75
4.50
4.70
4.45
mV
ms
V
V
BATT
- 0.1 V
BATT
- 0.02
µA
µA
µA
V
V
mV
mV
UNITS
V
Microprocessor Supervisory Circuits
ELECTRICAL CHARACTERISTICS (continued)
(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
CONDITIONS
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
Logic low
Logic high
3.5
50
-50
1.25
1.250
0.01
1.30
1.275
25
0.4
150
1.00
50
0.8
1.60
MIN
0.8
0.9
V
CC
- 1.5
0.4
2.25
sec
ns
V
µA
V
nA
V
V
TYP
MAX
UNITS
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
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.
_______________________________________________________________________________________
3
Microprocessor Supervisory Circuits
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
__________________________________________Typical Operating Characteristics
OUTPUT VOLTAGE
vs. LOAD CURRENT
5.00
4.95
V
CC
= +5V
V
BATT
= +2.8V
T
A
= +25°C
V
OUT
(V)
2.80
2.78
OUTPUT VOLTAGE
vs. LOAD CURRENT
V
CC
= 0V
V
BATT
= +2.8V
T
A
= +25°C
MAX690A
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
+5V
V
BATT
= OV
T
A
= +25°C
V
CC
1V/div
V
OUT
(V)
4.90
2.76
0V
2.74
SLOPE = 80Ω
2.72
0V
0
0.2
0.4
0.6
0.8
1.0
500ms/div
I
OUT
(mA)
RESET
V
CC
V
CC
RESET
GND
2k
1V/div
RESET
330pF
+5V
4.85
SLOPE = 5Ω
4.80
4.75
0
10
20
30
40
50
I
OUT
(mA)
2.70
MAX690A
RESET RESPONSE TIME
+5V
V
CC
T
A
= +25°C
+5V
V
CC
RESET
V
CC
RESET
GND
1V/div
+5V
+4V
PFO
PFI
POWER-FAIL COMPARATOR
RESPONSE TIME
PFI
+5V
PFO
30pF
+1.25V
+1.30V
PFI
0V
V
CC
= +5V
T
A
= +25°C
+1.2V
400ns/div
+0V
0V
1k
PFO
POWER-FAIL COMPARATOR
RESPONSE TIME
+5V
PFO
30pF
+1.25V
1k
V
CC
= +5V
T
A
= +25°C
+3V
10k
RESET
30pF
+1.3V
PFI
+1.20V
400ns/div
2µs/div
MAX805L
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
+5V
V
CC
1V/div
+5V
V
CC
MAX805L
RESET RESPONSE TIME
+4V
V
CC
RESET
GND
0V
RESET
V
CC
V
BATT
RESET
GND
+5V
10k
330
pF
0V
10k
330pF
+4V
1V/div
0V
500ms/div
0V
2µs/div
4
_______________________________________________________________________________________
Microprocessor Supervisory Circuits
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
______________________________________________________________Pin Description
PIN
MAX690A/MAX692A
MAX802L/MAX802M
MAX805L
NAME
FUNCTION
1
1
V
OUT
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.
2
3
4
2
3
4
V
CC
GND
PFI
5
5
PFO
6
6
WDI
7
RESET
–
7
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.
8
8
V
BATT
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.
_______________________________________________________________________________________
5
嵌入式系统
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
