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General Description

The MAX6365–MAX6368 supervisory circuits simplify

power-supply monitoring, battery-backup control func-

tions, and memory write protection in microprocessor

(µP) systems. The circuits significantly improve the size,

accuracy, and reliability of modern systems with an ultra-

small integrated solution.

These devices perform four basic system functions:

1) Provide a µP reset output during V

supply power-

up, power-down, and brownout conditions.

2) Internally control V

to backup-battery switching to

maintain data or low-power operation for CMOS

RAM, CMOS µPs, real-time clocks, and other digital

logic when the main supply fails.

3) Provide memory write protection through internal

chip-enable gating during supply or processor faults.

4) Include one of the following options: a manual reset

input (MAX6365), a watchdog timer function

(MAX6366), a battery-on output (MAX6367), or an

auxiliary user-adjustable reset input (MAX6368).

The MAX6365–MAX6368 operate from V

supply volt-

ages as low as 1.2V. The factory preset reset threshold

voltages range from 2.32V to 4.63V (see the

Ordering

Information

). In addition, each part is offered in three

reset output versions: push-pull active low, open-drain

active low, or open-drain active high (see the

Selector

Guide

). The MAX6365–MAX6368 are available in minia-

ture 8-pin SOT23 packages.

Applications

Critical µP/µC Power Portable/Battery-

Monitoring Powered Equipment

Fax Machines Set-Top Boxes

Industrial Control POS Equipment

Computers/Controllers

Features

o Low +1.2V Operating Supply Voltage (V

or V

BATT

)

o Precision Monitoring of +5.0V, +3.3V, +3.0V, and

+2.5V Power-Supply Voltages

o On-Board Gating of Chip-Enable Signals, 1.5ns

Propagation Delay

o Debounced Manual Reset Input (MAX6365)

o Watchdog Timer, 1.6s Timeout (MAX6366)

o Battery-On Output Indicator (MAX6367)

o Auxiliary User-Adjustable RESET IN (MAX6368)

o Low 10µA Quiescent Supply Current

o Three Available Output Structures

Push-Pull RESET

Open-Drain RESET

o RESET/RESET Valid Down to 1.2V Guaranteed

or V

BATT

)

o Power-Supply Transient Immunity

o 150ms min Reset Timeout Period

o Miniature 8-Pin SOT23 Package

MAX6365–MAX6368

SOT23, Low-Power µP Supervisory Circuits

with Battery Backup and Chip-Enable Gating

________________________________________________________________

Maxim Integrated Products

OUT

CE OUT

BATTCE IN

GND

RESET, RESET

SOT23

TOP VIEW

MAX6365

Pin Configurations

19-1658; Rev 5; 10/11

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

These parts offer a choice of reset threshold voltages. From the

Reset Threshold Ranges table, insert the desired threshold volt-

age code in the blank to complete the part number. SOT parts

come in tape and reel only and must be ordered in 2500-piece

increments. See Device Marking Codes for a complete parts list,

including SOT top marks and standard threshold versions. See

Selector Guide for a listing of device features.

Devices are available in both leaded and lead(Pb)-free packaging.

Specify lead-free by replacing “-T” with “+T” when ordering.

Denotes a package containing lead(Pb).

= Tape and reel.

/V Denotes an automotive qualified part.

Pin Configurations continued at end of data sheet.

Typical Operating Circuit appears at end of data sheet.

PART*

TEMP RANGE

PIN-PACKAGE

M A X6 3 6 5 LK A_ _-T

-40°C to +85°C

8 SOT23

MAX6365PKA_ _-T

-40°C to +85°C

8 SOT23

MAX6365HKA_ _-T

-40°C to +85°C

8 SOT23

M A X6 3 6 6 LK A_ _-T

-40°C to +85°C

8 SOT23

M A X 6 36 6P K A_ _-T

-40°C to +85°C

8 SOT23

M A X 6 36 6H K A_ _-T

-40°C to +85°C

8 SOT23

M A X6 3 6 7 LK A_ _-T

-40°C to +85°C

8 SOT23

M A X 6 36 7P K A_ _-T

-40°C to +85°C

8 SOT23

M A X 6 36 7P K A_ _/V-T

-40°C to +85°C

8 SOT23

M A X 6 36 7H K A_ _-T

-40°C to +85°C

8 SOT23

M A X6 3 6 8 LK A_ _-T

-40°C to +85°C

8 SOT23

M A X 6 36 8P K A_ _-T

-40°C to +85°C

8 SOT23

M A X 6 36 8H K A_ _-T

-40°C to +85°C

8 SOT23

Summary of content (15 pages)

PAGE 1
9-1658; Rev 5; 10/11 SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating Features The MAX6365–MAX6368 supervisory circuits simplify power-supply monitoring, battery-backup control functions, and memory write protection in microprocessor (µP) systems. The circuits significantly improve the size, accuracy, and reliability of modern systems with an ultrasmall integrated solution.
PAGE 2
MAX6365–MAX6368 SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating ABSOLUTE MAXIMUM RATINGS Terminal Voltages (with respect to GND) VCC, BATT, OUT.......................................................-0.3V to +6V RESET (open drain), RESET (open drain) ................-0.3V to +6V BATT ON, RESET (push-pull), RESET IN, WDI, CE IN, CE OUT ...........................-0.3V to (VOUT + 0.3V) MR ..............................................................-0.3V to (VCC + 0.
PAGE 3
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating (VCC = +2.4V to +5.5V, VBATT = +3.0V, CE IN = VCC, reset not asserted, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER Reset Active Timeout Period SYMBOL VOL RESET Output Voltage MIN TYP 150 Reset asserted, VBATT = 0V MAX UNITS 280 ms ISINK = 1.6mA, VCC > 2.1V 0.3 ISINK = 100µA, VCC > 1.2V 0.
PAGE 4
ELECTRICAL CHARACTERISTICS (continued) (VCC = +2.4V to +5.5V, VBATT = +3.0V, CE IN = VCC, reset not asserted, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1.185 1.235 1.285 V ±0.01 ±25 nA RESET IN (MAX6368 only) RESET IN Threshold VRTH RESET IN Leakage Current RESET IN to Reset Delay VOD = 50mV, RESET IN falling 1.
PAGE 5
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating 0.6 VCC = 3.0V IOUT = 65mA 0.4 VCC = 4.5V IOUT = 150mA 0.2 195 0 20 40 60 MAX6365/8-06 1V/ms 10V/ms -20 0 20 40 60 -40 80 -20 0 20 40 60 80 TEMPERATURE (°C) TEMPERATURE (°C) RESET THRESHOLD vs. TEMPERATURE MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE BATTERY SUPPLY CURRENT vs. SUPPLY VOLTAGE 4.0 3.5 3.0 MAX636_ 26 (VTH = 2.63V) 2.5 350 300 MAX636_ 46 (VTH = 4.
PAGE 6
Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) MAX6368 RESET IN TO RESET PROPAGATION DELAY vs. TEMPERATURE PROPAGATION DELAY (µs) 1.235 VOD = 50mV 5 2.5 2.2 1.9 1.6 -20 0 20 40 60 -40 80 -20 0 20 40 60 2 VCC = 5V 0 80 50 100 CLOAD (pF) MAX6366 WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE CE IN TO CE OUT ON-RESISTANCE vs. TEMPERATURE VCC = 3.0V 15 10 VCC = 5.0V 5 VCE IN = VCC/2 VBATT = 0V MAX6365/8-14 20 2.0 1.
PAGE 7
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating PIN NAME FUNCTION RESET Active-High Reset Output. RESET asserts high continuously when VCC is below the reset threshold (VTH), MR is low, or RESET IN is low. It asserts in pulses when the internal watchdog times out.
PAGE 8
MAX6365–MAX6368 SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating Functional Diagram BATT ON (MAX6367 ONLY) 1.235V MAX6365 MAX6366 MAX6367 MAX6368 VCC OUT CHIP-ENABLE OUTPUT CONTROL BATT CE IN CE OUT 20k RESET GENERATOR MR (MAX6365 ONLY) WATCHDOG TRANSITION DETECTOR WDI (MAX6366 ONLY) RESET IN (MAX6368 ONLY) RESET (RESET) WATCHDOG TIMER 1.235V GND Detailed Description The Typical Operating Circuit shows a typical connection for the MAX6365–MAX6368.
PAGE 9
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating Backup-Battery Switchover In a brownout or power failure, it may be necessary to preserve the contents of the RAM. With a backup battery installed at BATT, the MAX6365–MAX6368 automatically switch the RAM to backup power when VCC falls. The MAX6367 has a BATT ON output that goes high in battery-backup mode.
PAGE 10
MAX6365–MAX6368 SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating WDI tRP tWD tRP tWD RESET tWD = WATCHDOG TIMEOUT PERIOD tRP = RESET TIMEOUT PERIOD Figure 2. MAX6366 Watchdog Timeout Period and Reset Active Time Watchdog Input (MAX6366 Only) The watchdog monitors µP activity through the watchdog input (WDI). If the µP becomes inactive, reset asserts. To use the watchdog function, connect WDI to a bus line or µP I/O line.
PAGE 11
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating Replacing the Backup Battery When VCC is above VTH, the backup power source can be removed without danger of triggering a reset pulse. The device does not enter battery-backup mode when VCC stays above the reset threshold voltage. Negative-Going VCC Transients These supervisors are relatively immune to short-duration, negative-going VCC transients.
PAGE 12
MAX6365–MAX6368 SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating Reset Threshold Ranges SUFFIX 46 44 31 29 26 23 RESET THRESHOLD RANGES (V) MIN TYP MAX 4.50 4.63 4.75 4.25 4.38 4.50 3.00 3.08 3.15 2.85 2.93 3.00 2.55 2.63 2.70 2.25 2.32 2.
PAGE 13
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating MANUAL RESET INPUT PART MAX6365LKA__ MAX6365PKA__ MAX6365HKA__ WATCHDOG INPUT BATT ON RESET PUSHPULL RESET IN RESET OPENDRAIN RESET OPENDRAIN MAX6366LKA__ MAX6366PKA__ MAX6366HKA__ MAX6367PKA__ MAX6367HKA__ MAX6368PKA__ MAX6368HKA__ MAX6368LKA__ MAX6367LKA__ CHIPENABLE GATING Pin Configurations (continued)
PAGE 14
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating MAX6365–MAX6368 Typical Operating Circuit +2.4V TO +5.5V CMOS RAM 0.1µF CE VCC BATT OUT MAX6366 MAX6368 SECONDARY DC VOLTAGE REALTIME CLOCK 0.1µF A0–A15 RESET RESET R1 µP I/O RESET IN* WDI** R2 CE IN CE OUT GND ADDRESS DECODE *RESET IN APPLIES TO MAX6368 ONLY. **WDI APPLIES TO MAX6366 ONLY.
PAGE 15
SOT23, Low-Power µP Supervisory Circuits with Battery Backup and Chip-Enable Gating REVISION NUMBER REVISION DATE 4 5/09 Added automotive part number to Ordering Information table 1 5 10/11 Updated the Electrical Characteristics. 2 DESCRIPTION PAGES CHANGED Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.