Power electronics · Buyer's guide
Choose the sensing function first: magnetic field, position or electric current. This guide follows Hall current measurement from the sensing element to the output circuit, with model-specific data and a separate check of what each listed supplier actually offers.
Start with your task
01
This functional BOM identifies the Hall element, conditioning circuit and package, then the additional parts used in a closed-loop current transducer. It explains the assembly; the cited sources do not supply a production bill of materials or a list of interchangeable spares. [5] [1]
The DRV5055 senses magnetic flux density at the chip and produces an analog voltage. In a window-type current transducer such as the LA 255-S, a conductor passes through the aperture and the assembly measures its current. A third construction integrates the primary conductor inside the package: TI’s TMCS1100 uses that arrangement without an external magnetic concentrator. An external core around a busbar is therefore not a requirement for every Hall current sensor. [5] [2] [6]
| Part / where it belongs | Function | Material and assembly evidence |
|---|---|---|
| Hall sensing element | Converts the local magnetic field into an electrical signal. The DRV5055 senses field perpendicular to the package’s sensing plane. [5] | The cited datasheets do not establish a universal GaAs, InSb or silicon Hall-element material. Specify the part number rather than choosing from an unsourced material list. |
| Signal-conditioning circuit | Amplifies and conditions the Hall signal; a linear IC provides an analog output, while a feedback transducer also drives its compensation winding. [5] [1] | Integrated circuitry is shown in the functional diagrams. Internal component values and repair parts are not provided as a manufacturing BOM. |
| Package / housing | Locates the sensing element and connections; a window transducer also defines the conductor aperture. [5] [2] | DRV5055: SOT-23 or TO-92. LA 255-S: insulated plastic case, stated UL 94 V-0 flammability rating. This is not a declaration of a particular polymer grade or complete-product certification. [5] [2] |
| Magnetic core and compensation winding · closed-loop window transducer | The core carries the magnetic flux; the driven winding opposes primary ampere-turns. This is the feedback path described by LEM. [1] | Core alloy, winding-wire grade and winding construction must come from the selected manufacturer; the LA 255-S sheet is not a materials drawing. |
| Primary conductor and measuring resistor · installation items | For LA 255-S, the primary bar passes through the hole; the external resistor converts the secondary current into a measurement voltage. [2] | Specify conductor geometry, temperature and resistor loading separately. Do not count them as supplied internal components without checking the order scope. |
02
In a window-type open-loop transducer, the primary current creates a magnetic field that the Hall sensing circuit amplifies. A closed-loop transducer drives a secondary winding to oppose that field. This feedback changes how the output is set and how the device responds. [1]
| Design | How it works | What it means for the buyer |
|---|---|---|
| Open loop (Hall) | The magnetic field from the primary current is sensed and amplified [1] | Sensitivity depends on the magnetic and electronic signal path. LEM describes this as the simpler, lower-cost architecture; compare actual model data before selecting it. [1] |
| Closed loop (Hall) | A secondary winding opposes the primary field; feedback holds the sensed field near zero. [1] | Sensitivity is set by N, linearity is intrinsically good and response is fast; above a few kilohertz the transformer effect takes over [1] |
| Closed loop (fluxgate) | A fluxgate replaces the Hall cell as the field detector [1] | Fluxgate detection avoids the intrinsic Hall-cell offset mechanism, but LEM also describes compensated Hall designs with comparable offset performance. The technology name alone does not rank all models. [1] |
LEM’s article compares newer Hall ASIC designs with older Hall and fluxgate families. Its offset improvements are design-specific. For small DC currents, compare the offered model’s zero-current output, drift and post-overload residual—not just “Hall” versus “fluxgate.” [1]
03
Magnetic-field ICs and assembled current sensors measure different quantities. Compare the field name, unit, model and test condition together; the two examples below have different electrical interfaces and are not interchangeable.
| Specification | Field-sensing IC · TI DRV5055 | Current transducer · LEM LA 255-S |
|---|---|---|
| Supply voltage | Two separate recommended ranges: 3–3.63 V or 4.5–5.5 V. The gap between them is not an operating range. [5] | Dual ±12 to ±18 V supplies, ±5%; use the corresponding burden table. [2] |
| Supply current | At zero field and 5 V: 3 mA typical, 5 mA maximum; at 3.3 V: 2 mA typical, 4 mA maximum. [5] | 20 mA plus secondary current at ±15 V. Include the output load in supply sizing. [2] |
| Output type | Ratiometric analog voltage; zero field gives VCC/2. [5] | Secondary current: 125 mA at 250 A primary. [2] |
| Sensitivity | A1/Z1 option: 100 mV/mT at 5 V. Other suffixes have different sensitivities and ranges. [5] | Primary-to-secondary conversion ratio 1:2000. This is an A/A ratio, not mV per unit of magnetic field. [2] |
| Magnetic-field / measuring range | A1/Z1 option: ±21 mT at 5 V. Do not substitute the absolute-maximum field entry for linear measurement range. [5] | Measures primary current, 0 to ±500 A; the datasheet does not give a user-applied magnetic-field range. [2] |
| Operating temperature | −40 to +125 °C ambient, subject to thermal limits. [5] | −10 to +85 °C ambient. [2] |
| Storage temperature | −65 to +150 °C, listed under absolute maximum ratings. [5] | −40 to +90 °C. [2] |
| Response / delay | Propagation delay 10 µs typical; sensing bandwidth 20 kHz. [5] | Response <1 µs with the step and slope conditions stated below; bandwidth DC–100 kHz. [2] |
| Output-high voltage (VOH) | A digital-switch field; this linear analog part is specified by output swing and transfer function instead. [5] | No logic-high output: this model produces a secondary current. [2] |
| Output-low voltage (VOL) | A digital-switch field; zero magnetic field is at mid-supply, not a logic-low level. [5] | No logic-low output; check secondary offset at zero primary current. [2] |
| Package / mounting | SOT-23 or TO-92; the package pin assignments and sensing directions must be checked before layout. [5] | 23 × 18 mm primary aperture, two 5.5 mm mounting holes and Faston 6.3 × 0.8 mm connections. [2] |
| Weight | Confirm the ordered package’s weight; no category-wide value is established here. | 110 g stated for this transducer. [2] |
04
These values belong to the LEM LA 255-S, a closed-loop current-output transducer. Its nominal rating, measuring range and short overload allowance describe different operating conditions. [2]
| Datasheet line | LEM LA 255-S · stated conditions | Why it matters |
|---|---|---|
| Nominal and measuring range | 250 A r.m.s. nominal; 0 to ±500 A measuring range. The separate 600 A measuring-overload allowance is limited to 3 minutes per hour at ±15 V with a 5 Ω measuring resistor. [2] | Size for your peak current and overloads, not only the average |
| Overall accuracy and linearity | ±0.8 % at nominal current and 25 °C; linearity error below 0.1 % [2] | Accuracy is stated at one current and temperature; ask for the conditions |
| Offset and thermal drift | At zero primary current and 25 °C, offset is ±0.15 mA secondary. Thermal drift is up to ±0.30 mA over −10 to +85 °C. Residual ±0.50 mA is specified after a 3 × nominal-current exposure; this test condition is not a continuous overload rating. [2] | Decides how well small currents and zero are measured |
| Response and bandwidth | Response below 1 µs to 90% of maximum primary current, measured at di/dt = 100 A/µs; separate reaction time below 500 ns at 10%. Bandwidth DC–100 kHz at −3 dB. [2] | Needed for inverter, drive and protection loops |
| Insulation | 1625 V r.m.s. rated voltage for safe separation, 3250 V for basic isolation, pollution class 2, with an uninsulated bar filling the hole [2] | Check against your system voltage and the conductor you will actually use |
| Standard and environment | The datasheet names EN 50178 and an operating range of −10 to +85 °C. This records the document’s basis, not a claim that EN 50178 is the current applicable standard for every installation. [2] | Ask which standard each test was made to and for the test list |
05
For the LA 255-S, the secondary current flows through an external measuring resistor. The permitted resistance changes with supply voltage, peak primary current and temperature. [2]
At 500 A, the 1:2000 ratio gives 0.25 A secondary. A 20 Ω resistor would produce 5 V mathematically, but it exceeds the datasheet’s 17 Ω limit at ±15 V / 70 °C and its 15 Ω limit at 85 °C. A desired ADC voltage cannot override the sensor’s burden limit. This is a calculation from the LA 255-S data, not a test result. [2]
06
Suppliers in this field offer current transducers, Hall ICs, position devices and magnetic accessories. A supplier name alone does not establish that its listed products can perform the same measurement.
07
Record the complete part number and suffix before installation. In particular, the DRV5055 package pin assignments differ, and LA 255-S output polarity follows the primary-current arrow. Check these against the wiring drawing before applying power. [5] [2]
For an existing LA 255-S installation with a shifted zero reading, compare the measured secondary offset with the datasheet conditions, including temperature and previous overload exposure. A residual-current test value is not a recommended overload procedure. These sources do not prescribe a general replacement interval or an internal field-repair procedure. [2]
08
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Product: isolated Hall-effect current sensor, [open loop / closed loop], quantity [units] Current: [DC / AC / pulsed], nominal [A], peak [A], overload [A for how long] Accuracy needed: [%] at [current] and [°C]; offset and drift limits: [values] Dynamics: response time [µs], bandwidth [kHz], di/dt [A/µs] Output: [current output, ratio 1:N / voltage output, range V]; supply [±12 / ±15 / single 5 V] Measuring resistor (current output): [Ω] at peak current Primary conductor: [bar W×H mm / cable diameter mm], conductor temperature [°C] Insulation: system voltage [V r.m.s.], required separation [safe / basic], pollution degree [2/3] Mounting: [panel / PCB], connector [type]; operating temperature [min] to [max] °C Documents: datasheet for this part number, test list and standard, test report per lot, manufacturing entity Delivery to [country], target date [date]
See source-checked manufacturers Send an enquiry through CNFX
12 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.
AHKC-E current-sensor family: real-time voltage output and true-RMS current-output variants are shown in its image tables. Confirm exact order code, supply and insulation test conditions.
Product scope checked 2026-10-09
The inspected MS-HSDM-011 listing is a permanent disc magnet used with Hall sensing circuits. It is a magnetic accessory, not the electronic current transducer described in this guide.
Product scope checked 2026-10-09
The AG-01 product page describes a reed-switch sensor for cylinder position. This inspected listing does not establish a Hall current-transducer offering.
Product scope checked 2026-10-09
The combined capacitive/Hall category lists SM8, SM12 and SM18 Hall sensors. Obtain the selected model’s sensing target and output data; this category page does not establish an isolated current transducer.
Product scope checked 2026-10-09
The Hall category lists split-core current transducers and YDG/YDKF model families for current measurement. Select the complete model and output option before using its specifications.
Product scope checked 2026-10-09
HONGFA publishes a Hall-current-sensor category for DC, AC and pulse measurement, separately from fluxgate sensors and conventional current transformers. Exact-model data are still required.
Product scope checked 2026-10-09
The inspected OMR product is an absolute angular encoder using a Hall-effect array and magnetic ring. It measures rotational position; it is not the current transducer used for the LA 255-S example.
Product scope checked 2026-10-09
The linked category lists Hall sensor ICs including RTH611 and RT118W. The website separately offers open- and closed-loop current-sensor categories; specify which assembly you need.
Product scope checked 2026-10-09
Its Hall category lists a digital magnetic count-sensor module for field-change detection. A separate current-sensor category is available; the two are not interchangeable.
Product scope checked 2026-10-09
KXRDCT21 is presented as a Hall sensor, but its page’s technical table is labelled KXRDCT40. Request a corrected model-specific datasheet before quoting the table values.
Product scope checked 2026-10-09
The Hall category lists SM8, SM12, SM14 and SM18 sensors. Confirm their sensing target and output; the category alone does not establish an isolated current-measurement product.
Product scope checked 2026-10-09
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
A magnetic-field IC such as DRV5055 measures flux density at the chip. A current sensor adds a defined current path and transfer function. LA 255-S uses an external conductor through a window, whereas TMCS1100 integrates the primary conductor in its package. Confirm isolation ratings for the selected current sensor; do not assume that a bare Hall IC provides system isolation. [5] [2] [6]
LEM explains that a closed-loop sensor cancels the primary field with a secondary current in a coil of N turns, so the sensitivity is set by N; operating at zero field gives intrinsically good linearity, and the response time is very fast. Whether that justifies a price premium depends on the actual range, offset, drift, bandwidth and supply requirements. LEM’s article also describes newer Hall designs with offset performance comparable to fluxgate designs. [1]
The LA 255-S specifies ±0.15 mA secondary offset at zero primary current and 25 °C. It separately specifies ±0.50 mA residual after exposure to three times nominal primary current. Compare secondary-output units, temperature and current history before attributing a reading to a fault; that exposure is a test condition, not its permitted continuous overload. [2]
Yes, but dynamic performance is best with a single bar filling the hole, and insulation ratings may be stated for a specific conductor arrangement; check the datasheet notes. [2]
Datasheets name their own basis; one leading closed-loop transducer lists EN 50178 with rated voltages for safe separation and basic isolation. Ask your supplier which standard and test list apply. [2]
Sources checked 2026-10-09. Standards bodies and regulations define the requirements; manufacturer pages show published ranges for those models only. CNFX does not certify products or suppliers.
Ask for use case, specification boundaries, supplier type, and RFQ preparation information for this product.
Compare manufacturer profiles with relevant product and process capability.