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A4942: Three-Phase Sensorless Fan Driver

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A4942 Datasheet
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Description

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Packaging

The A4942 three phase motor driver incorporates BEMF sensing to eliminate the requirement for Hall sensors in fan applications.

A closed loop speed control system is integrated into the IC. This allows accurate setting of maximum and minimum speeds via selection of external resistors. The speed is controlled by duty cycle demand applied to the PWM input.

The PWM input is allowed to operate over a wide frequency range.

Current limiting is integrated to allow saving the cost and PCB space of an external sense resistor. The current limit function includes an adjustable soft start to minimize load on the power supply while the fan is ramping up to speed.

The A4942 is supplied in a 20-contact 4 mm × 4 mm QFN package (suffix ES) with exposed pad for enhanced thermal dissipation. The package is lead (Pb) free, with 100% matte tin leadframe plating.

  • Sensorless (no Hall sensors required)
  • Closed loop speed control
  • Minimal external components
  • PWM speed input
  • FG speed output
  • Lock detection
  • Soft start
  • Overcurrent protection
  • Soft switching for reduced audible noise
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Part Number Specifications and Availability

Part Number
Description
Status
Architecture
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Integrated MOSFET
Control Interface
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RDS (ON) (Ohms)
Commutation
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Trapezoidal
Motor Positioning Method
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Hall-Based
Sleep Current
Current Sense Amplifiers
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Integrated
Supply Voltage Min (V)
5
55
5
≥
≤
Supply Voltage Max (V)
16
1616
16
≥
≤
Peak Output Current (A)
1
12
2
≥
≤
Number of Bridges
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Package
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20-Pin QFN
Market
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Consumer
Industrial
 
Samples
Part Composition / RoHS DataCheck StockECAD
A4942GESTR-TIntegrated MOSFET-TrapezoidalHall-Based5.0016.001.600-20-Pin QFNConsumer, IndustrialView DataCheck Distributor StockECAD model image
Part Number
Architecture
Control Interface
Commutation
Motor Positioning Method
Supply Voltage Min
(V)
Supply Voltage Max
(V)
Peak Output Current
(A)
Number of Bridges
Package
Market
A4942GESTR-TIntegrated MOSFETTrapezoidalHall-Based5.0016.001.60020-Pin QFNConsumerIndustrial

Documentation and Resources

Documentation

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Improve Server Efficiency with Advanced Control Electronics
Selection Guide
Allegro Product Selection Guide