MAX793/MAX794/MAX795
19-0366; Rev 6; 3/10
3.0V/3.3V Adjustable Microprocessor
Supervisory Circuits
General Description ____________________________Features
MAX793/MAX794/MAX795
The MAX793/MAX794/MAX795 microprocessor (P)
supervisory circuits monitor and control the activities of
Precision Supply-Voltage Monitor:
+3.0V/+3.3V Ps by providing backup-battery switchover, Fixed Reset Trip Voltage (MAX793/MAX795)
Adjustable Reset Trip Voltage (MAX794)
among other features such as low-line indication, P
reset, write protection for CMOS RAM, and a watchdog
Guaranteed Reset Assertion to V = 1V
CC
(see the Selector Guide below). The backup-battery volt-
Backup-Battery Power SwitchingBattery
age can exceed V , permitting the use of 3.6V lithium
CC
Voltage Can Exceed V
CC
batteries in systems using 3.0V to 3.3V for V .
CC
On-Board Gating of Chip-Enable Signals7ns
The MAX793/MAX795 offer a choice of reset threshold Max Propagation Delay
voltage range (denoted by suffix letter): 3.00V to 3.15V
MAX793/MAX794 Only
(T), 2.85V to 3.00V (S), and 2.55V to 2.70V (R). The
Battery Freshness Seal
MAX794s reset threshold is set externally with a resistor
Battery OK Output (MAX793)
divider. The MAX793/MAX794 are available in 16-pin
Uncommitted Voltage Monitor for Power-Fail or
DIP and narrow SO packages, and the MAX795 comes
Low-Battery Warning
in 8-pin DIP and SO packages.
Independent Watchdog Timer (1.6s timeout)
Manual Reset Input
Ordering Information
_____________________Selector Guide
FEATURE MAX793 MAX794 MAX795
PIN-
PART* TEMP RANGE
Active-Low Reset
PACKAGE
Active-High Reset
MAX793_CPE 0C to +70C 16 Plastic DIP
Programmable Reset
MAX793_CSE 0C to +70C 16 Narrow SO
Threshold
Ordering Information continued at end of data sheet.
Low-Line Early Warning
*The MAX793/MAX795 offer a choice of reset threshold voltage.
Output
Select the letter corresponding to the desired reset threshold
Backup-Battery
voltage range (T = 3.00V to 3.15V, S = 2.85V to 3.00V, R =
Switchover
2.55V to 2.70V) and insert it into the blank to complete the part
number. The MAX794s reset threshold is adjustable.
External Switch Driver
Devices are available in both leaded and lead-free packaging.
Power-Fail Comparator
Specify lead free by adding the + symbol at the end of the part
Battery OK Output
number when ordering.
Watchdog Input
__________Typical Operating Circuit
Battery Freshness Seal
Manual Reset Input
(OPTIONAL)
Si9433DY
Chip-Enable Gating
3.0V OR 3.3V SILICONIX
Pin-Package 16-DIP/SO 16-DIP/SO 8-DIP/SO
0.1F
0.1F
PMOS
________________________Applications V BATT ON OUT
CC
CMOS
RAM
BATT
CE OUT
Battery-Powered Computers and Controllers
3.6V 0.1F
V
CC
Embedded Controllers MAX793
ADDRESS
A0-A15
CE IN
WDO
DECODER
Intelligent Controllers
MR I/O
WDI
+5V SUPPLY
FAILURE NMI
LOWLINE
Critical P Power Monitoring PFO
+5V
V
CC
P
Portable Equipment
PFI
RESET RESET
BATT OK
GND
Pin Configurations appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxims website at www.maxim-ic.com.3.0V/3.3V Adjustable Microprocessor
Supervisory Circuits
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND) Continuous Power Dissipation (T = +70C)
A
V ......................................................................-0.3V to +6.0V 8-Pin Plastic DIP (derate 9.09mW/C above +70C) .....727mW
CC
V ...................................................................-0.3V to +6.0V 8-Pin SO (derate 5.88mW/C above +70C)..................471mW
BATT
All Other Inputs ..................-0.3V to the higher of V or V 16-Pin Plastic DIP (derate 10.53mW/C above +70C) .842mW
CC BATT
Continuous Input Current 16-Pin Narrow SO (derate 9.52mW/C above +70C) ...696mW
V .................................................................................200mA Operating Temperature Ranges
CC
V ................................................................................50mA MAX793_C_ _/MAX794C_ _/MAX795_C_ _ ......... 0C to +70C
BATT
GND ..................................................................................20mA MAX793_E_ _/MAX794E_ _/MAX795_E_ _ ........-40C to +85C
Output Current Storage Temperature Range .............................-65C to +160C
V ................................................................................200mA Lead Temperature (soldering, 10s) .................................+300C
OUT
All Other Outputs ..............................................................20mA Soldering Temperature (reflow) .......................................+260C
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 = 3.17V to 5.5V for the MAX793T/MAX795T, V = 3.02V to 5.5V for the MAX793S/MAX795S, V = 2.72V to 5.5V for the
CC CC CC
MAX793R/MAX794/MAX795R, V = 3.6V, T = T to T , unless otherwise noted. Typical values are at T = +25C.)
BATT A MIN MAX A
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX79_C 1.0 5.5
Operating Voltage Range,
V
V , V (Note 1)
CC BATT
MAX79_E 1.1 5.5
V < 3.6V 46 60
CC
MAX793/MAX794,
MR = V
CC V < 5.5V 62 80
CC
V Supply Current
CC
I A
SUPPLY
(excluding I , I )
OUT CE OUT V < 3.6V 35 50
CC
MAX795 A
V < 5.5V 49 70
CC
V Supply Current in
CC
MAX793/MAX794 32 45
V = 2.1V,
CC
Battery-Backup Mode I A
SUPPLY
V = 2.3V
BATT
MAX795 24 35
(excluding I )
OUT
BATT Supply Current
1 A
(excluding I ) (Note 2)
OUT
BATT Leakage Current,
V = 0V, V = 0V 1 A
CC OUT
Freshness Seal Enabled
Battery Leakage Current
0.5 A
(Note 3)
I = 75mA V - 0.3 V - 0.125
OUT CC CC
OUT Output Voltage in
V I = 30mA (Note 4) V - 0.12 V - 0.050 V
OUT OUT CC CC
Normal Mode
I = 250A (Note 4) V - 0.001 V - 0.5mV
OUT CC CC
I = 250A V - 0.1 V - 0.034
OUT BATT BATT
OUT Output Voltage in
V V = 2.3V V
OUT BATT
Battery-Backup Mode
I = 1mA V - 0.14
OUT BATT
V -
CC
V > V > 1.75V (Note 5) 20 65 mV
SW CC
V
BATT
MAX793T/MAX795T 2.69 2.82 2.95
Battery Switch Threshold
(V falling) MAX793S/MAX795S 2.55 2.68 2.80
CC V > V
BATT CC
V V
SW
(Note 6)
MAX793R/MAX795R/
2.30 2.41 2.52
MAX794
This value is identical to the reset threshold,
V rising for V > V
Battery Switch Threshold V - CC BATT RST
CC
(V rising) (Note 7) V
CC BATT
V < V 25 65 mV
BATT RST
2 _______________________________________________________________________________________
MAX793/MAX794/MAX795