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MAX4943, MAX4944, MAX4944L, MAX4945, MAX4945L, MAX4946, MAX4949

Overvoltage-Protection Controllers with Internal FET

Provide Input Voltage Protection Up to +28V without Requiring an External nFET
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Status Explanations for product status codes

Part Number Status
MAX4943 Active: In Production. See Ordering Information for details.
MAX4944 Active: In Production.
MAX4944L Active: In Production.
MAX4945 Active: In Production.
MAX4945L Active: In Production.
MAX4946 Active: In Production.
MAX4949 Active: In Production.


The MAX4943–MAX4946/MAX4949 family of overvoltage-protection devices feature a low 80mΩ (typ) RON internal FET and protect low-voltage systems against voltage faults up to +28V. These devices also drive an optional external pFET to protect down to -28V when connected to a load with reverse current protection. When the input voltage exceeds the overvoltage threshold, the internal FET is turned off to prevent damage to the protected components.

All switches feature a minimum 1.2A current-limit protection. During a short-circuit occurrence, the MAX4944B and MAX4945B place the switch in a latchoff state where the switch turns off and remains off. For the autoretry devices, the switch turns off and continuously checks after a 15ms (typ) retry time.

The overvoltage thresholds (OVLO) are preset to 7.4V, 6.35V, 5.8V, 4.56V, or 8.9V. The undervoltage-lockout (UVLO) thresholds are preset to 2.45V and 4.15V. When the input voltage drops below the undervoltagelockout (UVLO) threshold, the devices enter a lowcurrent standby mode. (See the Ordering Information/Selector Guide in the full data sheet for more details on UVLO/OVLO).

All devices are offered in a small, 8-pin µDFN (2mm x 2mm) package and are specified for operation over the -40°C to +85°C temperature range.

Data Sheet

Download this datasheet in PDF formatDownload Rev 3 (PDF, 164kB)
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Key Features

  • Input Voltage Protection Up to +28V
  • Integrated nFET Switch
  • Preset Overvoltage Protection Trip Level
    • 7.40V (MAX4943)
    • 6.35V (MAX4944_)
    • 5.80V (MAX4945_)
    • 4.56V (MAX4946)
    • 8.90V (MAX4949)
  • Low-Current Undervoltage-Lockout Mode
  • Short-Circuit Protection (Latchoff/Autoretry)
  • Internal 15ms (typ) Startup Delay and Retry Times
  • Input Voltage Power-Good Logic Output
  • Thermal-Shutdown Protection
  • Small, 8-Pin (2mm x 2mm) µDFN Package


  • Cell Phones
  • Digital Still Cameras
  • MP3 Players
  • PDAs and Palmtop Devices

Key Specifications:

Overvoltage Protection Controllers
Part Number Channels VIN
Over Voltage Trip Level
Under Voltage Lockout
Over Volt. Flag tGATE (On)
tGATE (Off)
min max See Notes
MAX4944  1 2.2 28 6.35 4.15 Open-Drain 30.2 2 $1.19 @1k
MAX4945  5.8 4.15 $1.19 @1k
MAX4946  4.56 2.45 -
MAX4949  8.9 2.45 -
See All Overvoltage Protection Controllers (71)

Pricing Notes:

This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.


MAX4943, MAX4944, MAX4944L, MAX4945, MAX4946, MAX4949: Typical Operating Circuit
Typical Operating Circuit

More Information

Topmark Coding MAX4943
Topmark Coding MAX4944
Topmark Coding MAX4945
Topmark Coding MAX4946
Topmark Coding MAX4949
New Product Press Release   2007-08-02 ]

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Document Ref.: 19-0552 Rev 3; 2008-09-23
This page last modified: 2011-03-28