MAX6749:µP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay

The MAX6746–MAX6753 low-power microprocessor (µP) supervisory circuits monitor single/dual system supply voltages from 1.575V to 5V and provide maximum adjustability for reset and watchdog functions. These devices assert a reset signal whenever the VCC supply voltage or RESET IN falls below its reset threshold or when manual reset is pulled low. The reset output remains asserted for the reset timeout period after VCC and RESET IN rise above the reset threshold. The reset function features immunity to power-supply transients. The MAX6746–MAX6753 have ±2% factory-trimmed reset threshold voltages in approximately 100mV increments from 1.575V to 5.0V and/or adjustable reset threshold voltages using external resistors. The reset and watchdog delays are adjustable with external capacitors. The MAX6746–MAX6751 contain a watchdog select input that extends the watchdog timeout period by 128x. The MAX6752/MAX6753 contain a window watchdog timer that looks for activity outside an expected window of operation. The MAX6746–MAX6753 are available with a push-pull or open-drain active-low RESET output. The MAX6746–MAX6753 are available in an 8-pin SOT23 package and are fully specified over the automotive temperature range (-40°C to +125°C).

Key Features
  • Reset and Watchdog Options EnablesWide Variety of Applications
    • Factory-Set Reset Threshold Options from 1.575V to 5V in ~ 100mV Increments
    • Adjustable Reset Threshold Options
    • Single/Dual Voltage Monitoring
    • Capacitor-Adjustable Reset Timeout
    • Capacitor-Adjustable Watchdog Timeout
    • Min/Max (Windowed) Watchdog Option
    • Manual-Reset Input Option
    • Push-Pull or Open-Drain Active-Low RESET Output Options
  • 3.7µA Supply Current Reduces System Power Consumption
  • Integrated Power Supply Protection Increases Robustness
    • Power-Supply Transient Immunity
    • Guaranteed Active-Low RESET Valid for VCC ≥ 1V
  • 8-Pin SOT23 Packages Saves Board Space
MAX6746, MAX6747, MAX6748, MAX6749, MAX6750, MAX6751: Typical Operating Circuit
MAX6746, MAX6747, MAX6748, MAX6749, MAX6750, MAX6751: Typical Operating Circuit
Applications/Uses
  • Automotive
  • Battery-Powered Computers/Controllers
  • Computers
  • Critical µP Monitoring
  • Embedded Controllers
  • Intelligent Instruments
  • Medical Equipment
  • Portable Equipment
  • Set-Top Boxes
DataSheet
titleDownload file
MAX6746-MAX6753 Data SheetMAX6746-MAX6753.pdf
Parametrics
Part NumberReset Thresh.
(V)
Reset OuttRESETWatchdog FeatureWatchdog TimeoutSupervisor FeaturesReset Thresh. Accur.
(%)
ICC
(µA)
Package/PinsBudgetary
Price
min@ +25°CmaxSee Notes
MAX67461.2 to 1.8
1.8 to 2.5
2.5 to 3.3
3.3 to 5.5
Active Low
Push-Pull
1ms to 15ms
15ms to 85ms
85ms to 300ms
300ms to 1s
<1ms
>1s
Adjustable
Cap Adjustable
Input (WDI)
1s to 2s
<1s
>2s
Adjustable
Manual Reset210SOT/8$1.77 @1k
MAX6747Active Low
Open Drain
Cap Adjustable
Input (WDI)
Manual ResetSOT/8$1.94 @1k
MAX6748Active Low
Push-Pull
Cap Adjustable
Input (WDI)
Adjustable Reset InputSOT/8$2.05 @1k
MAX6749Active Low
Open Drain
Cap Adjustable
Input (WDI)
Adjustable Reset InputSOT/8$2.05 @1k
MAX6752Active Low
Push-Pull
Cap Adjustable
Input (WDI)
Windowed
-SOT/8$2.41 @1k
MAX6753Active Low
Open Drain
Cap Adjustable
Input (WDI)
Windowed
-SOT/8$2.11 @1k

Part NumberInterfaceReset Thresh.
(V)
Reset OuttRESETWatchdog FeatureWatchdog TimeoutSupervisor FeaturesReset Thresh. Accur.
(%)
ICC
(µA)
Package/PinsBudgetary
Price
min@ +25°CmaxSee Notes
MAX6750Factory Fixed
R/C Adjustable
1.2 to 1.8
1.8 to 2.5
2.5 to 3.3
3.3 to 5.5
Active Low
Push-Pull
1ms to 15ms
15ms to 85ms
85ms to 300ms
300ms to 1s
<1ms
>1s
Adjustable
Cap Adjustable
Input (WDI)
1s to 2s
<1s
>2s
Adjustable
Adjustable Reset Input210SOT/8$2.41 @1k
MAX6751Active Low
Open Drain
SOT/8$1.94 @1k
Quality and Environmental Data
Related Products
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Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
MAX6749KA+ActiveSOT,;8 pin;9 mm²-40°C to +125°CLead Free
MAX6749KA+TActiveSOT,;8 pin;9 mm²-40°C to +125°CLead Free
MAX6749KA-TNo Longer AvailableMAX6749KA+TSOT,;8 pin;9 mm²-40°C to +125°CNo
MAX6746-MAX6753.pdf MAX6753
Simple Latching Watchdog Timer MAX6749
MAX6749.pdf MAX6749
MAX6746-MAX6753.pdf MAX6753