1V to 16V, Single-Channel, Hot-Swap Controllers with Precision Current-Sensing Output

1V to 16V, Hot-Swap Controller with Precision Current-Sense Output

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The MAX5977A/MAX5977B hot-swap controllers provide complete protection for systems with a 1V to 16V single-supply voltage.

During the initial insertion, the hot-swap controllers limit the inrush current from damaging the board or from shorting out the backplane. When the input voltage is above the undervoltage threshold and below the overvoltage threshold, a 5µA current source powered from the internal 5V charge pump drives the gate of an external n-channel MOSFET providing a slow turn-on response. An internal current-sense amplifier in the IC monitors the current across an external shunt resistor providing current sensing for wide input-sense voltage range. The devices provide two levels of overcurrent circuit-breaker protections: a fast-trip threshold for a fast turn-off and a lower slow-trip threshold for a delayed turn-off.

Exceeding either of the overcurrent circuit-breaker thresholds will force the device into fault mode where the external n-channel MOSFET is disabled. The MAX5977 is available in two versions which provide a latched off (MAX5977A) or autoretry (MAX5977B) output when the device is in fault mode.

A calibration mode allows further calibration of the integrated transconductance amplifier for production testing of the final design. The devices are offered in a 20-pin, 4mm x 4mm, TQFN-EP package and are fully specified from -40°C to +85°C.
MAX5977A, MAX5977B: Typical Operating Circuit MAX5977A, MAX5977B: Typical Operating Circuit Enlarge+

Key Features

  • 1% Accurate Current-Sense Amplifier Output
  • Hot-Swap Monitors Operation from 1V to 16V
  • Integrated Charge Pump Fully Enhances the External n-Channel FET (VGATE = VIN + 5V)
  • VariableSpeed/BiLevel™ Fault Protection Provides Electronic Circuit-Breaker Function
  • Output Latched Off After Fault Condition (MAX5977A)
  • Autoretry After Fault Condition (MAX5977B)
  • Power-Good Indicator
  • Calibration Mode
  • Small, 20-Pin, 4mm x 4mm, TQFN-EP Package


  • General Hot-Swap
  • Network Switches and Routers
  • Servers
  • Storage Systems
Part NumberVIN
Circuit Breaker/ Current LimitCircuit Breaker/Current Limit Threshold
Fault Condition ControlChannelsPositive/Negative RailFeaturesPackage/PinsBudgetary
minmaxSee Notes
MAX5977A 116Circuit BreakerAdjustableLatched Off1Positive
On-Board Charge Pumps to Drive External
VariableSpeed/BiLevel Current Limit
$1.52 @1k
MAX5977B Periodic Retry
$2.21 @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.

MAX5977AEVKIT: Evaluation Kit for the MAX5977A and MAX5977B

Technical Documents

App Note 5882 Guidelines for the MAX5977’s Critical Component Placement and Routing

Quality and Environmental Data

Request Reliability Report for: MAX5977B 
Lead-Free Package Tin (Sn) Whisker Reports

CAD Symbols and Footprints

  • MAX5977BETP+
  • MAX5977BETP+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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