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MAX791ESE+

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P19
MAX791
Microprocessor Supervisory Circuit
________________________________________________________________ Maxim Integrated Products 1
19-0075; Rev. 7; 11/05
General Description
The MAX791 microprocessor (µP) supervisory circuit
reduces the complexity and number of components need-
ed to monitor power-supply and battery-control functions
in µP systems. The 50µA supply current makes the
MAX791 ideal for use in portable equipment, while the 6ns
chip-enable propagation delay and 250mA output capa-
bility (25mA in battery-backup mode) make it suitable for
larger, higher-performance equipment.
The MAX791 comes in 16-pin DIP, TSSOP, and narrow SO
packages and provides the following functions:
•µP reset.
–
R
—
E
—
S
—
E
—
T
–
output is asserted during power-up,
power-down, and brownout conditions, and is guaran-
teed to be in the correct state for V
CC
down to 1V,
even with no battery in the circuit.
• Manual-reset input.
•A 1.25V threshold detector provides for power-fail
warning and low-battery detection, or monitors a
power supply other than +5V.
• Two-stage power-fail warning. A separate low-line
comparator compares V
CC
to a threshold 150mV
above the reset threshold.
• Backup-battery switchover for CMOS RAM, real-time
clocks, µPs, or other low-power logic.
• Software monitoring of backup-battery voltage.
•A watchdog-fault output is asserted if the watchdog
input has not been toggled within either a preset or
an adjustable timeout period.
• Write protection of CMOS RAM or EEPROM.
• Pulsed watchdog output to give advance warning of
impending
–
W
—
D
—
O
–
assertion caused by watchdog timeout.
Applications
Computers Critical µP Power Monitoring
Controllers Intelligent Instruments
Portable/Battery-
Powered Equipment
Features
♦ Precision 4.65V Voltage Monitoring
♦ 200ms Power-OK/Reset Time Delay
♦ Independent Watchdog Timer—Preset or Adjustable
♦ 1µA Standby Current
♦ Power Switching
250mA Output in V
CC
Mode
25mA Output in Battery-Backup Mode
♦ On-Board Gating of Chip-Enable Signals
Memory Write-Cycle Completion
6ns CE Gate Propagation Delay
♦ MaxCap
or SuperCap
Compatible
♦ Voltage Monitor for Power-Fail or Low-Battery Warning
♦ Backup-Battery Monitor
♦ Guaranteed
–
R
—
E
—
S
—
E
—
T
–
Valid to V
CC
= 1V
Ordering Information
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
WDPO
RESET
WDO
CE IN
GND
V
CC
V
OUT
VBATT
TOP VIEW
MAX791
CE OUT
WDI
LOWLINE
MR
SWT
PFI
PFO
BATT ON
DIP/SO/TSSOP
CMOS
RAM
MAX791
RESET
LOWLINE
WDI
CE IN
CE OUT
+5V
OTHER SYSTEM
RESET SOURCES
+12V
V
OUT
VBATT
*
MaxCap
A0–A15
MR
+12V SUPPLY
FAILURE
BATT
ON
SWT
ADDRESS
DECODE
0.1µF
0.1µF
0.47F*
V
CC
PFI
PFO
GND
I/O
µP
NMI
INT
RESET
WDO
Pin Configuration
Typical Operating Circuit
PART TEMP RANGE PIN-PACKAGE
MAX791CPE 0°C to +70°C 16 Plastic DIP
MAX791CSE 0°C to +70°C 16 Narrow SO
MAX791C/D 0°C to +70°C Dice*
MAX791EPE -40°C to +85°C 16 Plastic DIP
MAX791ESE -40°C to +85°C 16 Narrow SO
MAX791EJE -40°C to +85°C 16 CERDIP
MAX791MJE -55°C to +125°C 16 CERDIP
MaxCap is a registered trademark of Cesiwid Inc. SuperCap is a registered trademark of Baknor Industries.
* Dice are specified at T
A
= +25°C.
Devices in PDIP, SO and TSSOP 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.
MAX791CUE 0°C to +70°C 16 TSSOP
MAX791EUE -40°C to +85°C 16 TSSOP
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.
MAX791
Microprocessor Supervisory Circuit
2 _______________________________________________________________________________________
Input Voltage (with respect to GND)
V
CC
.......................................................................-0.3V to +6V
VBATT..................................................................-0.3V to + 6V
All Other Inputs.....................................-0.3V to (V
OUT
+ 0.3V)
Input Current
V
CC
Peak ..........................................................................1.0A
V
CC
Continuous ............................................................250mA
VBATT Peak ..................................................................250mA
VBATT Continuous ..........................................................25mA
GND, BATT ON .............................................................100mA
All Other Outputs ............................................................25mA
Continuous Power Dissipation (T
A
= +70°C)
Plastic DIP (derate 10.53mW/°C above +70°C) ..........842mW
Narrow SO (derate 8.70mW/°C above +70°C) ............696mW
CERDIP (derate 10.00mW/°C above +70°C)...............800mW
TSSOP (derate 6.70mW/°C above +70°C) ..................533mW
Operating Temperature Ranges
MAX791C_ _ ......................................................O°C to +70°C
MAX791E_ _ ....................................................-40°C to +85°C
MAX791MJE ..................................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(V
CC
= 4.75V to 5.5V, VBATT = 2.8V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
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.
ABSOLUTE MAXIMUM RATINGS
PARAMETER CONDITIONS
Supply Current in Battery-Backup
Mode (excludes I
OUT
) (Note 2)
MIN TYP MAX UNITS
VBATT = 4.5V, I
OUT
= 20mA VBATT - 0.3
Operating Voltage Range
V
CC
, VBATT (Note 1)
0 5.5 V
V
CC
- 0.3 V
CC
- 0.2
V
CC
- 0.05 V
CC
- 0.02
VBATT-to-V
OUT
On-Resistance
5
VBATT = 2.0V
µA
17 30
Ω
Battery-Switchover Threshold
Power down VBATT - 0.03
V
V
OUT
in Normal
Operating Mode
V
CC
= 3V, VBATT = 2.8V, I
OUT
= 100mA V
CC
- 0.2 V
CC
- 0.12
V
V
CC
= 4.5V
0.8 1.6
0.8 1.2
V
CC
= 4.5V
V
CC
- 0.40
VBATT = 2.8V, I
OUT
= 10mA VBATT - 0.25
0.04 1
Supply Current in Normal
Operating Mode (excludes I
OUT
)
V
CC
> VBATT - 1V 50 150 µA
V
CC
-to-V
OUT
On-Resistance
V
CC
= 3V 1.2 2.0
Ω
VBATT = 4.5V 815
VBATT = 2.8V
Power up
13 25
VBATT + 0.03
V
OUT
in Battery-Backup Mode
VBATT = 2.0V, I
OUT
= 5mA VBATT - 0.15
V
Battery-Switchover Hysteresis 60 mV
Low-Battery Detector Threshold 2 V
I
OUT
= 250mA
I
OUT
= 25mA
MAX791C/E
MAX791M
MAX791C/E
MAX791M
V
CC
< VBATT - 1.2V,
VBATT = 2.8V
T
A
= +25°C
T
A
= T
MIN
to T
MAX
VBATT Standby Current
(Note 3)
T
A
= T
MIN
to T
MAX
T
A
= +25°C
-1.0 0.02
µAVBATT + 0.2V ≤ V
CC
-0.1 0.02
ns
MAX791
Microprocessor Supervisory Circuit
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 4.75V to 5.5V, VBATT = 2.8V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
0.7 1.5I
SINK
= 25mA
mA720Output source current
–
W
—
D
—
P
—
O
–
Output
Short-Circuit Current
V
0.1 0.4I
SINK
= 3.2mA
BATT ON Output
Low Voltage
ms104.7nF capacitor connected from SWT to GND
Minimum Watchdog
Timeout Period
ms1
–
W
—
D
—
P
—
O
–
Pulse Width
ns100V
IL
= 0.8V, V
IH
= 0.75 x V
CC
Minimum Watchdog Input
Pulse Width
µs80Power downV
CC
-to-
–
L
—
O
—
W
— —
L
—
I
—
N
—
E
–
Delay
s1.0 1.6 2.25SWT connected to V
OUT
V4.50 4.65 4.75
–
R
—
E
—
S
—
E
—
T
–
Threshold Voltage
mV150
–
L
—
O
—
W
— —
L
—
I
—
N
—
E
–
-to-
–
R
—
E
—
S
—
E
—
T
–
Threshold Voltage
µs100Power downV
CC
-to-
–
R
—
E
—
S
—
E
—
T
–
Delay
mV15
–
R
—
E
—
S
—
E
—
T
–
Threshold Hysteresis
Watchdog Timeout Period
ns70
–
W
—
D
—
P
—
O
–
-to-
–
W
—
D
—
O
–
Delay
µA
ms
115100Source current
BATT ON Output
Short-Circuit Current
mA60Sink current
140 200 280Power up
UNITSMIN TYP MAX
–
R
—
E
—
S
—
E
—
T
–
Active Timeout Period
CONDITIONSPARAMETER
0.004 0.3MAX791E/M, I
SINK
= 50µA, V
CC
= 1.2V, V
CC
falling
0.1 0.4I
SINK
= 3.2mA, V
CC
= 4.25V
V
3.5I
SOURCE
= 1.6mA, V
CC
= 5V
–
R
—
E
—
S
—
E
—
T
–
Output Voltage
mA720Output source current
–
R
—
E
—
S
—
E
—
T
–
Output
Short-Circuit Current
0.4I
SINK
= 3.2mA, V
CC
= 4.25V
µA15 100Output source current
–
L
—
O
—
W
— —
L
—
I
—
N
—
E
–
Output
Short-Circuit Current
V
3.5I
SOURCE
= 1µA, V
CC
= 5V
–
L
—
O
—
W
— —
L
—
I
—
N
—
E
–
Output Voltage
0.4I
SINK
= 3.2mA
mA310Output source current
–
W
—
D
—
O
–
Output Short-Circuit Current
V
3.5I
SOURCE
= 500µA, V
CC
= 5V
–
W
—
D
—
O
–
Output Voltage
0.4I
SINK
= 3.2mA
V
3.5I
SOURCE
= 1mA
–
W
—
D
—
P
—
O
–
Output Voltage
0.004 0.3MAX791C, I
SINK
= 50µA, V
CC
= 1.0V, V
CC
falling
RESET, LOW-LINE, AND WATCHDOG TIMER
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P19

MAX791ESE+

Mfr. #:
Buy MAX791ESE+
Manufacturer:
Maxim Integrated
Description:
Supervisory Circuits MPU Supervisor
Lifecycle:
New from this manufacturer.
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