19-2210; Rev 2; 12/05
Dual-Voltage µP Supervisory Circuits
with Sequenced Reset Outputs
General Description
Features
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.
♦ Preset V
Reset Threshold Voltages from 1.58V
CC
to 4.63V (master supply)
♦ Customer-Adjustable RESET IN2 to Monitor
Voltages Down to 625mV (secondary supply)
♦ Fixed (140ms min) RESET1 Timeout
♦ Fixed (140ms min) or Customer-Adjustable
RESET2 Timeout Period
The MAX6391/MAX6392 monitor V
as the master
CC
reset supply. Both RESET1 and RESET2 are asserted
whenever V drops below the selected factory-fixed
♦ Guaranteed Reset Valid to V
= 1V
CC
CC
♦ Active-Low Open-Drain Outputs or Push-
reset threshold voltage. RESET1 remains asserted as
long as V is below the threshold and deasserts
Pull/Open-Drain Combination
CC
140ms (min) after V
exceeds the thresholds.
CC
♦ Internal Open-Drain Pullup Resistors (for external
RESET IN2 is monitored as the secondary reset supply
and is adjustable with an external resistive-divider net-
V
voltage connections)
OH
♦ Manual Reset Input (MAX6392 only)
♦ Immune to Short Negative V Transients
work. RESET2 is asserted whenever either V
or
CC
RESET IN2 is below the selected thresholds. RESET2
CC
remains asserted 140ms (min) or a capacitor-
♦ 15µA Typical Supply Current
♦ Few External Components
♦ Small 8-Pin SOT23 Package
adjustable time period after V
and RESET IN2
CC
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).
Ordering Information
PART*
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
SOT23-8
MAX6391KA_ _-T
MAX6392KA_ _-T
SOT23-8
*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.
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
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
Computers
Controllers
Pin Configurations
Critical µP Power Monitoring
Set-Top Boxes
TOP VIEW
Printers
RESET IN2
1
2
3
4
8
7
6
5
R1
Servers/Workstations
Industrial Equipment
Multivoltage Monitoring
V
CC
RESET1
R2
MAX6391
CSRT
GND
RESET2
SOT23-8
Typical Operating Circuit appears at end of data sheet.
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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.