A1351 High Precision Linear Hall Effect Sensor IC with a Push/Pull, Pulse Width Modulated Output Last Time Buy This part is in production but has been determined to be LAST TIME BUY. This classification indicates that the product is obsolete and notice has been given. Sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because of obsolescence in the near future. Samples are no longer available. Date of status change: October 31, 2011 Deadline for receipt of LAST TIME BUY orders: April 27, 2012 Recommended Substitutions: For existing customer transition, and for new customers or new appli- cations, contact Allegro Sales. NOTE: For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative. Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no respon- sibility for its use nor for any infringements of patents or other rights of third parties which may result from its use.A1351 High Precision Linear Hall Effect Sensor IC with a Push/Pull, Pulse Width Modulated Output Features and Benefits Description Pulse width modulated (PWM) output provides increased noise The A1351 device is a high precision, programmable linear Hall immunity compared to an analog output effect sensor IC with a pulse width modulated (PWM) output. 1 mm case thickness provides greater coupling for current The duty cycle, D, of the PWM output signal is proportional sensing applications to an applied magnetic field. The A1351 device converts an Push/pull output analog signal from its internal Hall element to a digitally Customer-programmable offset and sensitivity encoded PWM output signal. The coupled noise immunity of Factory-programmed 0%/C Sensitivity Temperature Coefficient the digitally encoded PWM output is far superior to the noise Programmability at end-of-line immunity of an analog output signal. A simple RC network Selectable unipolar or bipolar quiescent duty cycles can be used to convert the digital PWM signal back to analog Selectable sensitivity range between 0.055% and 0.095% D/G signal. Temperature-stable quiescent duty cycle output and sensitivity The BiCMOS, monolithic circuit inside of the A1351 integrates Precise recoverability after temperature cycling a Hall element, precision temperature-compensating circuitry Output duty cycle clamps provide short circuit diagnostic to reduce the intrinsic sensitivity and offset drift of the Hall capabilities element, a small-signal high-gain amplifier, proprietary Optional 50% D calibration test mode at device power-up dynamic offset cancellation circuits, and PWM conversion Wide ambient temperature range: 40C to 125C circuitry. The dynamic offset cancellation circuits reduce Resistant to mechanical stress the residual offset voltage of the Hall element. Hall element Package: 4 pin SIP (suffix KT) offset is normally caused by device over molding, temperature dependencies, and thermal stress. The high frequency offset 1 mm case thickness cancellation (chopping) clock allows for a greater sampling rate, which increases the accuracy of the output signal and results in faster signal processing capability. Continued on the next page Not to scale Functional Block Diagram V+ V REG PWM Carrier Regulator Generation VCC PWM 1 Frequency Trim 2 2 1 C BYPASS PWM Signal Modulation Signal PWMOUT/ Chopper Conditioning Amp Logic with Recovery Programming Switches Push-Pull Output Sensitivity % Duty Temperature % Duty Cycle Cycle Trim Compensation Temperature Coefficient GND A1351-DS, Rev. 4