Current-Regulating Hot-Swap Controller with DualSpeed/BiLevel Fault Protection

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The MAX4370 is a circuit-breaker IC designed to offer protection in hot-swap applications using Maxim's DualSpeed/BiLevel™ detection. This controller, designed to reside either on the backplane or on the removable card, is used to protect a system from start-up damage when a card or board is inserted into a rack with the main system power supply turned on. The card's discharged filter capacitors provide a low impedance that can momentarily cause the main power supply to collapse. The MAX4370 prevents this start-up condition by providing inrush current regulation during a programmable start-up period, allowing the system to stabilize safely. In addition, two on-chip comparators provide DualSpeed/BiLevel short-circuit protection and overcurrent protection during normal operation.

The MAX4370 provides protection for a +3V to +12V single supply. An internal charge pump generates the controlled gate drive for an external N-channel MOSFET power switch. The MAX4370 latches the switch off after a fault condition until an external reset signal clears the device. Other features include a status pin to indicate a fault condition, an adjustable overcurrent response time, and a power-on reset comparator.

The MAX4370 is specified for the extended-industrial temperature range (-40°C to +85°C) and is available in an 8-pin SO package.
MAX4370: Typical Operating Circuit MAX4370: Typical Operating Circuit Enlarge+

Key Features

  • DualSpeed/BiLevel Protection During Normal Operation
  • Inrush Current Regulated at Start-Up
  • Resides Either on the Backplane or on the Removable Card
  • Programmable Start-Up Period and Response Time
  • Allows Safe Board Insertion and Removal from Live Backplane
  • Protection for +3V to +12V Single Supplies
  • Latched Off After Fault Condition
  • Status Output Pin
  • Internal Charge Pump Generates Gate Drive for External N-Channel MOSFET


  • Hot Board Insertion
  • Solid-State Circuit Breakers
Part NumberVIN
Circuit Breaker/ Current LimitCircuit Breaker/Current Limit Threshold
Fault Condition ControlChannelsPositive/Negative RailFeaturesPackage/PinsBudgetary
minmaxSee Notes
MAX4370 2.713.2Current Limit50Latched Off1PositiveDualSpeed/BiLevel Current Limit
$3.25 @1k
See All Hot Swap Controllers (49)
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.

Technical Documents

Reference Schematic 2765 Flexible Fault Protection
App Note 2602
Reference Schematic 2378 Handy Circuit Gives Systems Flexible Fault Protection
Tutorial 2158 Advantages of IC-Based Hot-Swap Circuit Protection
App Note 1785 Flexible Hot-Swap Current Limiter Allows Thermal Protection

Quality and Environmental Data

Product Reliability Reports: MAX4370.pdf 
Lead-Free Package Tin (Sn) Whisker Reports

CAD Symbols and Footprints

  • MAX4370ESA
  • MAX4370ESA+
  • MAX4370ESA+T
  • MAX4370ESA-T
  • Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

    Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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