19-0366; Rev 6; 3/10
3.0V/3.3V Adjustable Microprocessor
Supervisory Circuits
The MAX793/MAX794/MAX795 microprocessor (µP)
supervisory circuits monitor and control the activities of
+3.0V/+3.3V µPs by providing backup-battery switchover,
among other features such as low-line indication, µP
reset, write protection for CMOS RAM, and a watchdog
(see the Selector Guide below). The backup-battery voltage can exceed VCC, permitting the use of 3.6V lithium
batteries in systems using 3.0V to 3.3V for VCC.
The MAX793/MAX795 offer a choice of reset threshold
voltage range (denoted by suffix letter): 3.00V to 3.15V
(T), 2.85V to 3.00V (S), and 2.55V to 2.70V (R). The
MAX794’s reset threshold is set externally with a resistor
divider. The MAX793/MAX794 are available in 16-pin
DIP and narrow SO packages, and the MAX795 comes
in 8-pin DIP and SO packages.
____________________________Features
MAX793/MAX794/MAX795
o Precision Supply-Voltage Monitor:
Fixed Reset Trip Voltage (MAX793/MAX795)
Adjustable Reset Trip Voltage (MAX794)
o Guaranteed Reset Assertion to VCC = 1V
o Backup-Battery Power Switching—Battery
Voltage Can Exceed VCC
o On-Board Gating of Chip-Enable Signals—7ns
Max Propagation Delay
MAX793/MAX794 Only
o Battery Freshness Seal
o Battery OK Output (MAX793)
o Uncommitted Voltage Monitor for Power-Fail or
Low-Battery Warning
o Independent Watchdog Timer (1.6s timeout)
o Manual Reset Input
Ordering Information
_____________________Selector Guide
FEATURE
Active-Low Reset
MAX793
MAX794
MAX795
Active-High Reset
MAX793_CPE
0°C to +70°C
16 Plastic DIP
MAX793_CSE
0°C to +70°C
16 Narrow SO
Programmable Reset
Threshold
Low-Line Early Warning
Output
Backup-Battery
Switchover
External Switch Driver
Power-Fail Comparator
Battery OK Output
Watchdog Input
Battery Freshness Seal
Manual Reset Input
Chip-Enable Gating
Pin-Package
16-DIP/SO 16-DIP/SO 8-DIP/SO
PART*
PINPACKAGE
Ordering Information continued at end of data sheet.
*The MAX793/MAX795 offer a choice of reset threshold voltage.
Select the letter corresponding to the desired reset threshold
voltage range (T = 3.00V to 3.15V, S = 2.85V to 3.00V, R =
2.55V to 2.70V) and insert it into the blank to complete the part
number. The MAX794’s reset threshold is adjustable.
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.
__________Typical Operating Circuit
(OPTIONAL)
Si9433DY
SILICONIX
3.0V OR 3.3V
0.1µF
0.1µF
________________________Applications
Battery-Powered Computers and Controllers
Embedded Controllers
Intelligent Controllers
Critical µP Power Monitoring
Portable Equipment
TEMP RANGE
0.1µF
3.6V
PMOS
VCC BATT ON OUT
BATT
CE OUT
VCC
MAX793
WDO
+5V SUPPLY
FAILURE
+5V
CMOS
RAM
CE IN
MR
WDI
PFO
ADDRESS
DECODER
LOWLINE
PFI
I/O
NMI
VCC
RESET
BATT OK
GND
A0-A15
µP
RESET
Pin Configurations appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
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MAX793/MAX794/MAX795
General Description
