A1351: High Precision Linear Hall Effect Sensor IC with a Push/Pull, Pulse Width Modulated Output


This device is no longer in production. The device should not be purchased for new design applications. Samples are no longer available.

Date of status change: April 30, 2012.

Recommended substitution: For existing customer transition, and for new customers or new applications, contact Allegro Sales.

The A1351 device is a high precision, programmable linear Hall-effect sensor IC with a pulse width modulated (PWM) output. The duty cycle (DC) of the PWM output signal is proportional to an applied magnetic field. The A1351 device converts an analog signal from its internal Hall sensor element to a digitally encoded PWM output signal. The coupled noise immunity of the digitally encoded PWM output is far superior to the noise immunity of an analog output signal. A simple RC network can be used to convert the digital PWM signal back to analog signal.

The BiCMOS, monolithic circuit inside of the A1351 integrates a Hall element, precision temperature-compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element, a small-signal high-gain amplifier, proprietary dynamic offset cancellation circuits, and PWM conversion circuitry. The dynamic offset cancellation circuits reduce the residual offset voltage of the Hall element. Hall element offset is normally caused by device over molding, temperature dependencies, and thermal stress. The high frequency offset cancellation (chopping) clock allows for a greater sampling rate, which increases the accuracy of the output signal and results in faster signal processing capability.

An internal filter of approximately 150 Hz is used to achieve 11 bits of output resolution.

Key applications for the A1351 include battery current sensing, exhaust gas return (EGR), throttle position, ride height and seat belt tensioning systems.

Top Features

  • Pulse width modulated (PWM) output provides increased noise immunity compared to an analog output
  • 1 mm case thickness provides greater coupling for current sensing applications
  • Push/pull output
  • Customer-programmable offset and sensitivity
  • Factory-programmed 0%/°C Sensitivity Temperature Coefficient
  • Programmability at end-of-line
  • Selectable unipolar or bipolar quiescent duty cycles
  • Selectable sensitivity range between 0.055% and 0.095% DC/G
  • Temperature-stable quiescent duty cycle output and sensitivity
  • Precise recoverability after temperature cycling
  • Output duty cycle clamps provide short circuit diagnostic capabilities
  • Optional 50% DC calibration test mode at device power-up
  • Wide ambient temperature range: –40°C to 125°C
  • Resistant to mechanical stress

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
A1351KKTTN-T 4-lead SIP -40°C to 125°C Yes View Data Discontinued Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.


The A1351 is provided in an extremely thin case (1 mm thick), 4-pin SIP (single in-line package, suffix KT) that is lead (Pb) free, with 100% matte tin leadframe plating.

KT SIP 4 pin