Supervisory Circuits. MAX795 Datasheet

MAX795 Datasheet PDF, Equivalent


Part Number

MAX795

Description

3.0V/3.3V Adjustable Microprocessor Supervisory Circuits

Manufacture

Maxim

Total Page 20 Pages
PDF Download
Download MAX795 Datasheet PDF


MAX795 Datasheet
19-0366; Rev 1; 1/96
3.0V/3.3V Adjustable Microprocessor
Supervisory Circuits
_______________General Description
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 volt-
age 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. For similar devices
designed for 5V systems, see the µP Supervisory
Circuits table at the back of this data sheet.
_____________________Selector Guide
FEATURE
Active-Low Reset
Active-High Reset
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
Pins-Package
MAX793 MAX794 MAX795
16-DIP/SO 16-DIP/SO 8-DIP/SO
________________________Applications
Battery-Powered Computers and Controllers
Embedded Controllers
Intelligent Controllers
Critical µP Power Monitoring
Portable Equipment
Pin Configurations appear at end of data sheet.
____________________________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 (1.6sec timeout)
o Manual Reset Input
______________Ordering Information
PART*
TEMP. RANGE
PIN-PACKAGE
MAX793_CPE
0°C to +70°C
16 Plastic DIP
MAX793_CSE
0°C to +70°C
16 Narrow SO
MAX793_EPE
-40°C to +85°C
16 Plastic DIP
MAX793_ESE
-40°C to +85°C
16 Narrow SO
Ordering Information continued on last page.
* 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.
__________Typical Operating Circuit
3.0V OR 3.3V
0.1µF
3.6V 0.1µF
+5V SUPPLY
+5V FAILURE
(OPTIONAL)
Si9433DY
SILICONIX
PMOS
VCC BATT ON OUT
BATT CE OUT
0.1µF
CMOS
RAM
MAX793
WDO CE IN
MR WDI
PFO LOWLINE
ADDRESS
DECODER
VCC
VCC
A0-A15
I/O
NMI
µP
PFI RESET
BATT OK
GND
RESET
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

MAX795 Datasheet
3.0V/3.3V Adjustable Microprocessor
Supervisory Circuits
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND)
VCC ........................................................................-0.3V to 6.0V
VBATT .....................................................................-0.3V to 6.0V
All Other Inputs ..................-0.3V to the higher of VCC or VBATT
Continuous Input Current
VCC .................................................................................200mA
VBATT ................................................................................50mA
GND ..................................................................................20mA
Output Current
VOUT................................................................................200mA
All Other Outputs ..............................................................20mA
Continuous Power Dissipation (TA = +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) .....727mW
8-Pin SO (derate 5.88mW/°C above +70°C)..................471mW
16-Pin Plastic DIP (derate 10.53mW/°C above +70°C) .842mW
16-Pin Narrow SO (derate 9.52mW/°C above +70°C) ...696mW
Operating Temperature Ranges
MAX793_C_ _/MAX794C_ _/MAX795_C_ _ ......... 0°C to +70°C
MAX793_E_ _/MAX794E_ _/MAX795_E_ _ ........-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
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
(VCC = 3.17V to 5.5V for the MAX793T/MAX795T, VCC = 3.02V to 5.5V for the MAX793S/MAX795S, VCC = 2.72V to 5.5V for the
MAX793R/MAX794/MAX795R, VBATT = 3.6V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
Operating Voltage Range,
VCC, VBATT (Note 1)
VCC Supply Current
(excluding IOUT, ICE OUT)
VCC Supply Current in
Battery-Backup Mode
(excluding IOUT)
BATT Supply Current
(excluding IOUT) (Note 2)
SYMBOL
CONDITIONS
MAX79_C
MAX79_E
ISUPPLY
MAX793/MAX794,
MR = VCC
MAX795
VCC < 3.6V
VCC < 5.5V
VCC < 3.6V
VCC < 5.5V
ISUPPLY
VCC = 2.1V,
VBATT = 2.3V
MAX793/MAX794
MAX795
MIN
1.0
1.1
TYP MAX UNITS
5.5
V
5.5
46 60
62 80
µA
35 50
µA
49 70
32 45
µA
24 35
1 µA
BATT Leakage Current,
Freshness Seal Enabled
VCC = 0V, VOUT = 0V
1 µA
Battery Leakage Current
(Note 3)
OUT Output Voltage in
Normal Mode
OUT Output Voltage in
Battery-Backup Mode
Battery Switch Threshold
(VCC falling)
Battery Switch Threshold
(VCC rising) (Note 7)
VOUT
VOUT
VCC -
VBATT
VSW
VCC -
VBATT
0.5
IOUT = 75mA
IOUT = 30mA (Note 4)
IOUT = 250µA (Note 4)
VBATT = 2.3V
IOUT = 250µA
IOUT = 1mA
VCC - 0.3
VCC - 0.12
VCC - 0.001
VBATT - 0.1
VCC - 0.125
VCC - 0.050
VCC - 0.5mV
VBATT - 0.034
VBATT - 0.14
VSW > VCC > 1.75V (Note 5)
20 65
MAX793T/MAX795T
VBATT > VCC
(Note 6)
MAX793S/MAX795S
MAX793R/MAX795R/
MAX794
This value is identical to the reset threshold,
VCC rising for VBATT > VRST
VBATT < VRST
2.69
2.55
2.30
2.82
2.68
2.41
25
2.95
2.80
2.52
65
µA
V
V
mV
V
mV
2 _______________________________________________________________________________________


Features Datasheet pdf 19-0366; Rev 1; 1/96 3.0V/3.3V Adjustab le Microprocessor Supervisory Circuits _______________General Description The MAX793/MAX794/MAX795 microprocessor (µ P) supervisory circuits monitor and con trol the activities of +3.0V/+3.3V µPs by providing backup-battery switchover , among other features such as low-line indication, µP reset, write protectio n for CMOS RAM, and a watchdog (see the Selector Guide below). The backup-batt ery voltage can exceed VCC, permitting the use of 3.6V lithium batteries in sy stems using 3.0V to 3.3V for VCC. The M AX793/MAX795 offer a choice of reset th reshold voltage range (denoted by suffi x 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 exte rnally with a resistor divider. The MAX 793/MAX794 are available in 16-pin DIP and narrow SO packages, and the MAX795 comes in 8-pin DIP and SO packages. For similar devices designed for 5V system s, see the µP Supervisory Circuits table at the back of this data sh.
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