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-

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.

________________________Applications

Battery-Powered Computers and Controllers

Embedded Controllers

Intelligent Controllers

Critical µP Power Monitoring

Portable Equipment

____________________________Features

MAX793/MAX794/MAX795

o Precision Supply-Voltage Monitor:

Fixed Reset Trip Voltage (MAX793/MAX795)

Adjustable Reset Trip Voltage (MAX794)

o Backup-Battery Power Switching—Battery

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

3.0V/3.3V Adjustable Microprocessor

Supervisory Circuits

________________________________________________________________

Maxim Integrated Products

1

MAX793

RESET

LOWLINE

WDI

CE IN

CE OUT

3.0V OR 3.3V

+5V

BATT

A0-A15

MR

+5V SUPPLY

FAILURE

BATT ON

PFI

WDO

OUT

CMOS

RAM

ADDRESS

DECODER

0.1

µF

PMOS

0.1

µF

PFO

GND

I/O

µP

NMI

RESET

0.1

µF

3.6V

BATT OK

(OPTIONAL)

Si9433DY

SILICONIX

19-0366; Rev 6; 3/10

FEATURE

Active-Low Reset

Active-High Reset

Programmable Reset

Threshold

Low-Line Early Warning

Output

MAX793







MAX794









MAX795



Backup-Battery

Switchover

External Switch Driver

Power-Fail Comparator













Battery OK Output







_____________________Selector Guide

__________Typical Operating Circuit

Watchdog Input

Battery Freshness Seal









Manual Reset Input







Chip-Enable Gating





Pin-Package

16-DIP/SO 16-DIP/SO

8-DIP/SO

Pin Configurations appear at end of data sheet.

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.

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

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.