Magnetic Sensors Welcome to Honeywell’s Magnetic Sensors training module. As a global leader in advanced switching and sensing technology, our breadth of components and customized engineering solutions offer unmatched value. As an engineer, you understand that choosing the right components can have a direct effect on the success of your work. So how do you know which magnetic sensor solution best suits a particular application?

Introduction A magnetic position sensor responds to the presence or the interruption of a magnetic field by producing a proportional output. Types of magnetic position sensors include: Hall-effect sensors are constructed from a thin sheet of conductive material with output connections perpendicular to the direction of the current flow. Magnetoresistive digital sensors have a built-in magnetoresistive bridge integrated on silicon and are encapsulated in a plastic package. The integrated circuit (IC) responds to low fields at large distances. Hall-effect vane sensors consist of a magnet and a Hall-effect sensor inside a rugged plastic housing; different package styles provide mounting flexibility. Gear tooth sensors use a magnetically biased Hall-effect IC to sense movement of ferrous metal targets. The specially-designed IC is sealed in a durable plastic probe-type package. Hall-effect basic switches and magnets Digital and analog Hall-effect position sensors Hall-effect sensor: A Hall-effect sensor is a transducer that varies its output voltage in response to changes in magnetic field. Hall sensors are often used for proximity switching, positioning, speed detection, and current sensing applications. In its simplest form, the sensor operates as an analog transducer, directly returning a voltage. With a known magnetic field, its distance from the Hall plate can be determined. Using groups of sensors, the relative position of the magnet can be deduced. Electricity carried through a conductor will produce a magnetic field that varies with current, and a Hall sensor can be used to measure the current without interrupting the circuit. Typically, the sensor is integrated with a wound core or permanent magnet that surrounds the conductor to be measured. Frequently, a Hall sensor is combined with circuitry that allows the device to act in a digital (on/off) mode, and may be called a switch. Commonly seen in industrial applications, they are also often used in consumer equipment. (Source: Wikipedia) Magnetoresistive (MR)sensor: A magnetoresistive digital sensor is a magnetic sensor that operates very much like a Hall effect.  However, MR is roughly 100 times more sensitive than the Hall-effect. Another advantage of MR sensors in applications that count revolutions using ring magnets is that the resolution doubles as MR sensors are omnipolar (operates with North or South pole). Hall-effect sensors respond to fields perpendicular to the sensor, and MR respond to parallel fields. Hall-effect vane sensor: A Hall-effect vane sensor is a digital output sensor consisting of a magnet and Hall-effect transducer fixed in a rigid package. The sensor has a gap through which a ferrous vane may pass. The Hall-effect transducer is designed to detect the presence or absence of the vane. Gear tooth sensor: A gear tooth sensor is a biased Hall-effect transducer. The assembly consists of a magnet and transducer packaged into a cylindrical housing.  When a ferrous material is passed by the sensing face, the gear tooth sensor is designed to detect the presence or absence of this material.

Potential Applications Appliances Door lock detection, washer arm RPM, current sensing Commercial Vending, automated teller machine, medical Consumer RPM measurement in fitness equipment HVAC Valve positioning (Variable Air Volume), fan control Instrumentation Flux meters, current sensing, remote metering, liquid level Infotech Tape drives, copiers, cooling fans, cash registers, uninterruptible power supplies Motion control Piston detection in pneumatic or hydraulic cylinders, brushless DC motor commutation, RPM measurement, magnetic encoder, variable speed drives Potential applications for magnetic sensors include appliances, commercial equipment, consumer equipment, HVAC (heating, ventilation, and air conditioning) equipment, instrumentation equipment, information technology equipment, and motion control equipment.

Magnetic Sensor Technology Vhall = Output Hall-effect voltage H = Magnetic Flux created by magnet or current-carrying conductor Ic = Constant supply current Vhall µ Ic x H Vhall For those of you who are not familiar with magnetic sensor technology, here is a quick overview: When a current carrying conductor or a semiconductor plate is placed into a magnetic field, a voltage (Vhall) is generated perpendicular to both the current and the field. This is the Hall-effect principle, discovered in 1879 by Edwin Hall, and commercialized in the mid-1960s.

Magnetic Sensor Technology Hall-effect Sensing Mechanism Magnetoresistive Sensing Mechanism A magnetic field applied parallel to the element changes its resistance and creates a current. The current source is applied through a thin sheet of semiconductor material. S N + - I V=0 A magnetic field applied perpendicular to the element creates a voltage change = Vhall. Its output is bipolar. Magnetoresistive (MR) technology also responds to a magnetic field, but it is slightly different. A Hall element requires a field perpendicular to its surface, and its output can be polar sensitive. It can vary depending on which type of integrated hall circuit is used and which pole is applied to it. An MR element will produce a current change when a field parallel to its surface is applied. It is more sensitive than Hall, and it is omnipolar, which means it will respond to either pole. I S N V=Vhall MR is omnipolar—either pole will operate the sensor. S N 2SS Magnet

Design Factors – Magnetic Types Unipolar: Only a south pole will operate the sensor. The sensor turns on with the south pole(+) and off when the south pole is removed. Bipolar: Sensor output is pole-dependent. A south pole (+) is designed to activate the sensor; a north pole(-) is designed to deactivate. It’s possible that the sensor could turn off and still be within a positive Gauss level. Latching: Specifications are tighter on latching. Sometimes it is designed to make certain that when the south pole(+) is removed from the sensor, it will stay on until it sees the opposite pole(-). Omnipolar: The sensor is designed to operate with either magnetic pole(+ or -). Ratiometric linear: Output is proportional to magnetic field strength. Output sensitivity range is 2.5 – 3.75 mV per unit of Gauss. Magnetic types include unipolar, bipolar, latching, omnipolar, and ratiometric linear. Each device has individual magnetic characteristics that allow potential end users to customize their applications and to utilize the various outputs that best fit their needs. SS461A Series Latching Hall-Effect Digital Position Sensor 2SS52M Series Omnipolar Magnetoresistive Sensor SS495A Series Standard Miniature Ratiometric Linear Hall-effect Sensor SS441A Series Unipolar Hall-Effect Digital Position Sensor SS411A Bipolar Hall-Effect Digital Position Sensor

Design Factors – Basic Magnetic Characteristics When selecting a magnetic sensor, one must consider how much magnetic field the sensor needs before it turns on or off. Gauss levels to operate the sensor: 25 Gauss for omnipolar through 400 Gauss for unipolar, and everywhere in between As these sensors are temperature-sensitive, these ranges are at room temperature. Magnetoresistive omnipolar devices are typically used where a simple on-off circuit is required. Their ability to react to lower Gauss levels enables them to be used at wider sensing distances. The Hall-effect uniploar and bipolar sensors can potentially be designed into applications where specific sensing distances and/or more precise operating parameters may be achieved. SS490 Series Miniature Ratiometric Linear Hall-effect sensors have a ratiometric output voltage set by the supply voltage that varies in proportion to the strength the magnetic field. The magnetic range of this sensor is -670 Gauss to +670 Gauss.

Design Factors – Electrical Characteristics Supply voltage 3.8 to 30 Vdc Supply current 10 mA to 30 mA Output current 1.5 through 20 mA Output voltage .40 volts max. Honeywell magnetic position sensors offer a wide range of electrical characteristics that allow the sensor to potentially be applied into a wide variety of control systems. The SS495A Series Standard Miniature Ratiometric Linear Hall-effect Sensor has a supply voltage of 4.5 to 10.5 V and an output current of 1.5 mA.

Design Factors – Output Type Ratiometric linear sinking or sourcing Digital sinking or digital sourcing Ratiometric refers to the output voltage as a ratio of the supply voltage. For example, if the input voltage is doubled, the output voltage is doubled. Ratiometric linear devices are designed to provide an output that is proportional to the strength of the magnetic field. Digital outputs act more like switches in that they are on-off devices. 103SR Series Second Level Hall-effect Sensors are ratiometric sinking/sourcing sensors. These sensors detect the proximity of an external magnet and are available with a current sourcing or and sinking output. They come in a rugged sealed, threaded aluminum housing. 4AV Series Second Level Hall-effect Sensors are digital sinking sensors. They operate via a low-cost, easy-to-fabricate ferrous vane and can be used as limit switches by operating with a single large vane; as tachometer sensors by using multiple vanes; or as synchronizing elements by using cams or sectors.

Design Factors – Package Style Standard (plastic radial) lead Leads are longer so they can be inserted into a circuit board. If the lead needs to be adjusted, it can be bent which provides flexibility when putting it on a circuit board. Plastic surface mount (SOT-89 package) This very low profile package is designed for high speed pick-and-place assembly operations. The sensor is placed on top of the circuit board and wave soldered. An assortment of packaging styles are available. SS441A Series Unipolar Hall-effect Digital Position Sensor SS541A Series Unipolar Hall-effect Sensor; SOT-89B surface mount package

Design Factors – Packaging Styles Reduced lead length Leads are cut short to allow them to be inserted into the circuit board Ceramic SIP (single inline package), ceramic with solder bumps Package style allows for increased temperature stability because they’re ceramic based, not plastic Ceramic packages with laser trimmed, thin and thick film resistors minimize sensitivity variations and compensate for temperature variations Magnetic ranges ±100 Gauss to ± 2500 Gauss Also available linearly (output proportional to magnetic field) Honeywell offers many package styles that can be implemented into a variety of applications and PC board layouts. SS441A-R Series Unipolar Hall-effect Reduced Lead Length Digital Position Sensor SS941A Series General Purpose Ratiometric Linear Sensor; Vdc supply voltage

Design Factors – Packaging Options Tape and reel Often ideal for end customers with pick-and-place manufacturing. Customers can order a surface mount version packaged for shipment on tape and reel so the reel can be put on an automated assembly machine. Tape and reel packaging is widely used in automated high speed surface mount assembly operations. Tape and reel packaging for SS500 Series Temperature Compensated Hall-effect Sensors. Any SOT-89 package sensor is available in this tape and reel package.

Design Factors – Packaging Options Bulk pack The sensors are ordered, manufactured and put into a bag for shipping Ammopack Parts are mounted on a fan fold that folds back and forth so it can be fed out of a box Ammopacks are often used in automated assembly equipment where components are placed on “through hole” style printed circuit boards. Ammopack for SS400 Series Temperature Compensated Hall-effect Sensors.

Design Factors – Operating Temperature Range An important design characteristic because a wide operating temperature range often offers the end user the ability to design into more applications Typical operating temperature range: -40 °C to 150 °C These are standard electronic component operating temperature zones. Most Honeywell magnetic sensors are designed to provide operating temperature ranges between -40 to 150 °C.

Summary Magnetic sensors are designed to provide: Digital and analog Hall-effect position, magnetoresistive, Hall-effect vane, gear tooth, and Hall-effect basic switches and magnets Unipolar, bipolar, bipolar latch, omnipolar, and linear magnetics Digital sourcing, digital sinking (open collector), digital sinking and sourcing, and ratiometric sinking or sourcing Plastic surface mount (SOT-89 style), ceramic SIP, ceramic with solder bumps, plastic radial lead IC, aluminum threaded barrel, plastic probe, plastic dual tower wire exit, plastic dual tower with connector, plastic mechanical switch Wide continuous operating temperature range Honeywell magnetic sensors are often ideal for customers requiring rugged housings for industrial environments; adjustable mounting; cable options; non-contact sensing; high-speed, enhanced response time; wide operating temperature range; bipolar, unipolar, latching, omnipolar, and linear magnetics; enhanced sensitivity; laser trimming for enhanced interchangeability; low power consumption; and tape and reel versions for automated pick-and-place assembly.

Engineered Excellence Part Innovation A global leader in cost-effective, problem-solving sensors and switches Part Engineering Over 50,000 products ranging from humidity, position, speed, pressure, torque and airflow sensors to snap action, limit, toggle, pushbutton and pressure switches Total Solutions 75 years of developing solutions to meet millions of customers’ needs In addition to the information covered in this training module, when you are selecting and specifying a magnetic sensor you should also take into consideration elements such as the enhanced functionality, repeatability, and stability built into every Honeywell Sensing and Control magnetic sensor. Honeywell solutions can be tailored to your exact specifications. We offer extensive application assistance based on meeting millions of customers’ needs. For help in choosing the right sensor, please contact your Honeywell representative.

Warranty and Remedies

Warranties and Remedies