General Description

The MAX6391/MAX6392 microprocessor (µP) supervisory

circuits provide sequenced logic reset outputs for multi-

component or dual-voltage systems. Each device can

monitor two supply voltages and time-sequence two reset

outputs to control the order in which system components

are turned on and off. The MAX6391/MAX6392 increase

system reliability and reduce circuit complexity and cost

compared to separate ICs or discrete components.

reset supply. Both RESET1 and RESET2 are asserted

reset threshold voltage. RESET1 remains asserted as

RESET IN2 is monitored as the secondary reset supply

and is adjustable with an external resistive-divider net-

RESET IN2 is below the selected thresholds. RESET2

remains asserted 140ms (min) or a capacitor-

exceed their thresholds. RESET2 is always deasserted

after RESET1 during system power-up and is always

asserted before RESET1 during power-down.

The MAX6391 includes two internal pullup resistors for

RESET1 and RESET2 (the open-drain outputs can be

externally connected to the desired pullup voltages).

The MAX6392 includes an active-low manual reset

input (MR) that asserts both RESET1 (push-pull) and

RESET2 (open drain).

The MAX6391/MAX6392 are available in small 8-pin

SOT23 packages and are specified over the -40°C to

+85°C extended temperature range.

Applications

Computers

Controllers

Critical µP Power Monitoring

Set-Top Boxes

Printers

Servers/Workstations

Industrial Equipment

Multivoltage Monitoring

Features

o Preset VCC Reset Threshold Voltages from 1.58V

to 4.63V (master supply)

o Customer-Adjustable RESET IN2 to Monitor

Voltages Down to 625mV (secondary supply)

o Fixed (140ms min) R

RE

ES

SE

ET

T1

1 Timeout

o Fixed (140ms min) or Customer-Adjustable

R

RE

ES

SE

ET

T2

2 Timeout Period

o Active-Low Open-Drain Outputs or Push-

Pull/Open-Drain Combination

o Internal Open-Drain Pullup Resistors (for external

o Manual Reset Input (MAX6392 only)

o 15µA Typical Supply Current

o Few External Components

o Small 8-Pin SOT23 Package

Dual-Voltage µP Supervisory Circuits

with Sequenced Reset Outputs

________________________________________________________________ Maxim Integrated Products

1

R2

RESET2

GND

1

2

8

7

R1

RESET1

CSRT

RESET IN2

SOT23-8

TOP VIEW

3

4

6

5

MAX6391

Pin Configurations

Ordering Information

19-2210; Rev 1; 10/02

*Insert the desired suffix (see Selector Guide) into the blanks to

complete the part number. The MAX6391/MAX6392 require a

2.5k minimum order increment and are available in tape-and-

reel only. Samples are typically available for standard versions

(see Selector Guide for standard versions). Contact factory for

availability.

PART*

TEMP RANGE

PIN-PACKAGE

MAX6391KA_ _-T

-40

°C to +85°C

SOT23-8

MAX6392KA_ _-T

-40

°C to +85°C

SOT23-8

Pin Configurations continued at end of data sheet.

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.

Typical Operating Circuit appears at end of data sheet.