VG481V1 Back Biased Hall Effect Speed Sensor
INSTALLATION INSTRUCTIONS FOR THE
BACK-BIASED HALL-EFFECT SPEED SENSOR
32346701 Issue D
The VG481V1 contains a dual peak detecting circuit that is coupled with a Hall-effect element to detect the speed of a ferrous gear tooth target wheel. A biasing magnet provides a changing magnetic field as the target wheel moves past the senor IC. The sensor IC functions in reference to peak and slot magnetic levels. The sensor IC output is in either a high state or a low state, which corresponds to the target tooth/slot features.
ELECTROSTATIC DISCHARGE DAMAGE
Ensure proper ESD precautions are followed when handling this product.
Failure to comply with these instructions may result in product damage.
SOLDERING AND ASSEMBLY
- Ensure leads are adequately supported during any forming/shearing operation so that they are not stressed inside the plastic case.
- Limit exposure to high temperatures. Failure to comply with these instructions could result in death or serious injury.
Wave solder at 250°C to 260°C [482°F to 500°F] for a maximum of three seconds. Burrs are allowed only if the full lead length will pass through a 0,68 mm [0.027 in] dia. hole.
Do not use a pressure washer. A high-pressure stream could force contaminants into the package.
Failure to comply with these instructions may result in product damage.
Use an agitated rinse to clean the sensor.
|TABLE 1. ELECTRICAL SPECIFICATIONS (AT 4.0 V ≤ VS ≤ 24 V, -40°C ≤ TA ≤ 150°C, UNLESS OTHERWISE SPECIFIED)|
|Supply voltage||Pin 2 referenced to Pin 1||4||14||24||V|
|Reverse supply voltage||current < 10 mA||—||—||-26||V|
|Supply current||Vsupply = 24 V, with “ON” state||—||—||10||mA|
|Startup time||Supply = 4 V||—||—||10||ms|
|Output short circuit||short load||—||10||—||ms|
|Output leakage current||Supply = 24 V, with “OFF” state||—||—||10||mA|
|Output current (sinking)||continuous operation (recommended)||—||—||5||mA|
|Output saturation voltage||sinking 20 mA||—||—||360||mV|
|Switching frequency: rise time fall time||VCC = 12 V, RL=2 kOhm; CL = 20 pF VCC = 12 V, RL=2 kOhm; CL = 20 pF||—
|Power up ramp time1||0 V to 4 V, power up in high state||1||ms|
|TABLE 2. MAGNETIC SPECIFICATIONS|
|Back bias range||South pole facing back of the package||500||—||4000||Gauss|
|Peak magnetic field||for linear operation||—||—||4500||Gauss|
|Minimum signal lockout||peak to valley difference||—||38.5||—||Gauss|
|Magnetic signal||continuous operation (recommended)||75||—||—||Gauss|
|Output signal frequency||—||0||27.5||10000||Hz|
|Die placement tolerance||X and Y||-0.07||—||0.07||mm|
|TABLE 3. ENVIRONMENTAL SPECIFICATIONS|
|ESD (HBM)||JEDEC JS-001||8||—||—||kV|
|TABLE 4. ABSOLUTE MAXIMUM RATINGS|
|Storage temperature||ambient, unbiased||-55||—||150||°C|
|Soldering temperature||applied for <10 s||—||—||265||°C|
|Output current (sinking)||open collector||—||—||20||mA|
|Forward supply voltage||dc voltage for 1 hour||—||—||26||V|
|Reverse supply voltage||dc voltage for 1 hour||-26||—||—||V|
Absolute maximum ratings are the extreme limits the device will momentarily withstand without damage to the device. Electrical and mechanical characteristics are not guaranteed if the rated voltage and/or currents are exceeded, nor will the device necessarily operate at absolute maximum ratings.
SENSOR IC MOUNTING
The recommended sensor IC mounting position is in front of a gear wheel (see Figure 1). The south pole of the back bias magnet must face the back of the sensor IC package. The sensing distance is measured between the sensor IC front and the tip of the gear tooth. The sensor IC senses ferrous targets. The sensor IC contains a single Hall element and a symmetrical magnet such that the sensor IC can be rotated on its axis with no performance degradation. The input voltage is constantly compared to the voltage held at the output of the peak hold circuit. Whenever the input is higher than the peak hold value, the comparator triggers the counter to increment. This continues until the input value no longer exceeds the peak hold value.
FIGURE 1. SENSOR IC MOUNTING
Observe the following precautions when using magnetometers in general:
- The presence of ferrous materials, such as nickel-iron, steel, and cobalt near the sensor will create disturbances in the earth’s magnetic field that will distort x, y, and z axis measurements. Non-ferrous materials such as copper brass, gold, aluminum, some stainless steel, silver, tin silicon and any nonmetallic material will not distort the field
- The presence of the earth’s magnetic field must be taken into account when measuring the x, y, z fields and it varies considerably in different parts of the world. Differences in the earth’s magnetic field are quite dramatic between North America, South America, and the equator.
- Typical targets are 120 mm to 300 mm in diameter. The tooth shapes vary (square, triangular, windows). The teeth are of similar size, equally spaced, and with no signature
features. The sensing distance depends on the tooth/slot spacing and frequency due to eddy current effects.
Figure 2 shows the circuit’s high-level block diagram. During normal operation, peak maximum and valley minimum values, proportional to the magnetic signal, are tracked and held. The average of these two values is used to produce a slicing level that is compared to the input signal to produce the output transitions.
Upon transition from output low to a high state, the valley minimum value is preloaded in the positive direction, an amount equal to the difference of the previous peak and valley divided by four. Likewise, upon transition from output high to low state, the peak maximum is preloaded in the negative direction in an amount equal to the difference of the previous peak and valley divided by four (see Figure 3).
The preload values are calculated from the peak and valley counter register values. This preload function allows the sensor to track targets with run-out and other variations.
FIGURE 2. HIGH-LEVEL CIRCUIT BLOCK DIAGRAM
FIGURE 3. HIGH-LEVEL OPERATION
INTERNAL TRACK AND HOLD OPERATION (See Figures 4, 5)
The input voltage is constantly compared to the voltage held at the output of the peak hold circuit. Whenever the input is higher than the peak hold value, the comparator triggers the counter to increment. This continues until the input value no longer exceeds the peak hold value. The internal valley tracks and hold circuit work identically, except in the opposite direction. The peak hold and valley hold outputs are averaged to produce the slicing level.
FIGURE 4. INTERNAL PEAK TRACK AND HOLD BLOCK DIAGRAM
FIGURE 5. INTERNAL PEAK SAMPLE AND HOLD OPERATION
POWER ON RESET
At power up, and any time the supply voltage drops below a level that allows reliable operation, the sensor IC ceases operation and will not provide an output until the supply
voltage rises to a proper level. The output will be high until the power on reset releases, and it will remain high until the first valid high-to-low transition.
MINIMUM SIGNAL LOCKOUT
Sensor IC output is enabled when the peak-to-valley difference is greater than 38.5 Gauss typical. When the peak-to-valley difference degrades to less than 27.5 Gauss typical, the sensor IC output is disabled.
Sensor IC startup consists of three stages:
- Power on reset circuit release: This occurs once sufficient stable operating voltage is applied.
- Internal peak and valley track and hold circuits begin to fully track the input signal: This is typically less than 1 ms.
- Minimum signal lockout release: This occurs when the peakto-valley difference is greater than 38.5 Gauss.
After the three startup stages, the sensor IC output will switch normally.
FIGURE 6. MINIMUM CIRCUIT FOR OPERATION
FIGURE 7. TYPICAL OUTPUT SIGNAL RELATIVE TO MECHANICAL TARGET
FIGURE 8. PACKAGE DIMENSIONS (FOR REFERENCE ONLY: MM/[IN])
Note: Ensure the minimum hole size in the PCB is 0,68 mm [0.027] dia. based on the IPC 2222 Level B standard.
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While Honeywell may provide application assistance personally, through our literature and the Honeywell website, it is the buyer’s sole responsibility to determine the suitability of the product in the application.
Specifications may change without notice. The information we supply is believed to be accurate and reliable as of this writing. However, Honeywell assumes no responsibility for its use.
DO NOT USE these products as safety or emergency stop devices or in any other application where the failure of the product could result in personal injury. Failure to comply with these instructions could result in death or serious injury.
FOR MORE INFORMATION
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32346701-D-EN | D | 09/21
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