Hall Magnetic Circuit Selection Tool

Enter magnet dimensions, material grade and operating temperature to directly compute the Hall operate stroke, release stroke and hysteresis; the dual-Hall ring scheme gives a quadrature phase-error budget and breaks the error into four items - air gap, mounting, threshold mismatch and ring pole pitch - so you know where the tolerance budget should go.

Kernel: surface-charge method; cross-checked against the axial closed-form solution with error < 0.1%; valid for near-field cases without magnetic return path.

Device

Part NumberUnipolar/omnipolar only

Mounting style

magnet

Material

Diameter D

Thickness L

Duty

Temperature lower limit

Temperature upper limit

Customer required stroke

Geometry sketch

Stroke result

Operating stroke S_op—mm

Release stroke S_rp—mm

Hysteresis ΔS—mm

Full-temp stroke band—mm

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Stroke–field curve

The horizontal axis is the magnet-to-chip travel, far on the left and near on the right. The horizontal dashed lines are the operate threshold Bop and release threshold Brp; the red dot marks the operate-stroke point and the green one the release-stroke point.

SC245X four-grade comparison

Part Number	Bop range (Gs)	S_op(mm)	S_rp(mm)	Full-temp band (mm)	decision

Compare grades under the same magnet and mounting. Higher-sensitivity parts give longer operating stroke but are also more sensitive to stray fields.

Device (two of same type)

Part NumberLatch type only

Sensing mode

Multipole ring

Pole pairs P

Material

Outer radius Ro

Inner radius Ri

Thickness L

air gap

Tolerance budget

PCB mounting position

Air-gap deviation

Ring pole-pitch error

Ambient temperature

Quadrature accuracy target

Geometry sketch

Quadrature result

Mounting angle—° mech

Two-device spacing—mm

Air-gap field peak—Gs

Worst quadrature error—° elec

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Error-source breakdown

Error source	Error (° elec)	Share	Conduction mechanism

Two output waveforms

The horizontal axis is one full ring revolution = 360 deg mechanical. The upper half is the field‘s sensing component at the air gap; the two dashed lines are the operate thresholds +/-Bop. The lower half is the digitized output of the A/B comparators - the two quadrature high/low levels seen on a scope. One revolution holds P electrical periods (2P poles), so each channel shows P high and P low levels per turn; a larger P packs the pulses denser. The rising edges of the two square waves occur when the field crosses +/-Bop, ideally 90 deg electrical apart.

Pole-pair sweep

P	Mounting angle (° mech)	Amplitude (Gs)	Mismatch °	Placement °	Air gap °	Worst °	Two-device spacing (mm)	decision

Pole-pair count is the parameter customers change most often, and the same mechanical tolerance is amplified P times - this table directly judges whether a given ring scheme meets the target quadrature accuracy. The "two-device spacing" is the chord at 90 deg electrical; if it is smaller than the package footprint width it is flagged red, meaning the two devices cannot be placed side by side at that radiuscannot be placed side by side physically.

Device

Part NumberGroup by type

Structure

magnet

Material

Diameter D

Thickness L

air gap

offset

Air-gap tolerance

Temperature lower limit

Temperature upper limit

Result

Decision component—Gs

Room-temp margin—%

Worst-case margin over full temp range—%

Room-temp decision—

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Temperature sweep

Scan temperature at the tolerance upper-limit air gap. The solid line also serves as the vertical position; the red line toward -Bop is the worst-case threshold including tolerance.

Demo type

Device

Part Number—

magnet

Material

Diameter D

Thickness L

Stroke range

Duty

temperature

Position-relation animation

Manual positioning

Playback speed

Below the position view is the field scale: the horizontal axis is the sensing component in Gauss (Gs); darker blocks mean stronger field and the sign shows field direction. The two vertical lines are the operate threshold Bop and release threshold Brp; the white dot is the measured field at the magnet‘s current position. The block beside the Hall in the figure shares the same colour scale as the ruler, so you can read them off directly.

Field & output state

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Worked examples (static, citable)

Results below are computed by the same kernel at build time with identical parameters — use them to cross-check trend and magnitude.

Proximity-switch example

φ10×5 mm cylindrical NdFeB 42SH, full temperature range -40 to 150 °C, stroke boundary under air-gap tolerance.

Part Number	Bop typ. / max (Gs)	Mounting style	Operating stroke (mm)	Release stroke (mm)	Hysteresis (mm)	Full-temp stroke band (mm)
SC2450	25 / 35	Face-on	29.09	35.04	5.96	24.14 ~ 36.13
SC2451	100 / 120	Face-on	17.13	18.27	1.14	14.88 ~ 19.35
SC2452	180 / 200	Face-on	13.46	15.41	1.95	11.98 ~ 14.65
SC2455	220 / 250	Face-on	12.34	13.78	1.44	10.84 ~ 13.63
SC2450	25 / 35	Lateral sweep	23.40	28.49	5.09	18.91 ~ 29.40
SC2451	100 / 120	Lateral sweep	7.84	7.96	0.11	7.57 ~ 13.29
SC2452	180 / 200	Lateral sweep	7.34	7.64	0.30	7.06 ~ 7.53
SC2455	220 / 250	Lateral sweep	7.14	7.39	0.25	6.81 ~ 7.37

Dual-Hall quadrature example

Multi-pole ring Ro 20 / Ri 14 / L 6 mm, air gap 2 mm, both Hall devices are SC2943, Mounting tolerance +/-0.1 mm, air-gap deviation +/-0.2 mm, ring pole-pitch error +/-1 deg, target quadrature accuracy +/-10 deg electrical.

Pole pairs P	Sensing mode	Mounting angle (° mech)	Field peak (Gs)	Threshold mismatch (°)	Placement error (°)	Air-gap deviation (°)	Worst total (°)	Quadrature ±10°
2	Radial	45.00	3187	0.04	0.52	1.40	2.96	PASS
2	Axial	45.00	2936	0.04	0.67	1.52	3.24	PASS
4	Radial	22.50	3221	0.07	1.04	2.98	5.09	PASS
4	Axial	22.50	3061	0.09	1.35	3.31	5.75	PASS
6	Radial	15.00	3063	0.11	1.56	4.98	7.65	PASS
6	Axial	15.00	2915	0.13	2.02	5.94	9.08	PASS
8	Radial	11.25	2779	0.14	2.08	7.24	10.47	FAIL
8	Axial	11.25	2582	0.17	2.70	8.93	12.80	FAIL
10	Radial	9.00	2449	0.18	2.60	9.62	13.41	FAIL
10	Axial	9.00	2195	0.22	3.37	12.03	16.62	FAIL
12	Radial	7.50	2118	0.23	3.13	12.08	16.43	FAIL
12	Axial	7.50	1820	0.29	4.04	15.13	20.46	FAIL

Magnet material temp drift

Magnet material	Br@20°C (T)	Br@150°C (T)	Drop	Max operating temperature
NdFeB N42	1.300	1.097	-15.6%	80 °C
NdFeB 42SH	1.300	1.114	-14.3%	150 °C
NdFeB N52	1.445	1.220	-15.6%	80 °C
Ferrite Y30	0.390	0.294	-24.7%	250 °C
Ferrite Y35	0.410	0.309	-24.7%	250 °C
SmCo YXG-26H	1.035	0.988	-4.5%	350 °C

If margin still worries you, or you want parameters tailored to your magnet and structure, just send the magnet drawing and mounting dimensions.

Submit a selection request