Honeywell HMC1501, HMC1512 User Manual

HMC1501

APPLICATIONS

Linear Displacement

Angular Displacement

Motor Control

Valve Position

Proximity Detection

Current Spike Detection

SENSOR PRODUCTS

Linear / Angular / Rotary

Displacement Sensors

HMC1501 / HMC1512

igh resolution, low power MR sensor

H capable of measuring the angle direction of a magnetic field from a magnet with <0.07° resolution. Advantages of measuring field direction versus field strength include: insensitivity to the tempco of the magnet, less sensitivity to shock and vibration, and the ability to withstand large variations in the gap between the sensor and magnet. These

sensors may be operated on 3 volts

Not actual size

with bandwidth response of 0-5 MHz. Output is typical Wheatstone bridge.

FEATURES AND BENEFITS

No Rare Earth Magnets	Unlike Hall effect devices which may require samarium cobalt or similar “rare earth”
	magnets, the HMC1501 and HMC1512 can function with Alnico or ceramic type magnets.
Wide Angular Range	HMC1501—Angular range of ±45° with <0.07° resolution.
	HMC1512—Angular range of ±90° with <0.05° resolution.
Effective Linear Range	Linear range of 8mm with two sensors mounted on two ends; range may be increased
	through multiple sensor arrays operating together.
Absolute Sensing	Unlike incremental “encoding” devices, sensors know the exact position and require no
	indexing for proper positional output.
Non-Contact Sensing	No moving parts to wear out; no dropped signals from worn tracks as in conventional
	contact based rotary sensors.
Small Package	Available in an 8-pin surface mount package with case dimensions (exclusive of pins), of
	5mm x 4mm x 1.2mm total mounting envelope, with pins of less than 6mm square.
Large Signal Output	Full Scale output range of 120mV with 5V of power supply.

HMC1501 / HMC1512

SENSOR PRODUCTS

PRINCIPLES OF OPERATION

Anisotropic magnetoresistance (AMR) occurs in ferrous materials. It is a change in resistance when a magnetic field is applied in a thin strip of ferrous material. The magnetoresistance is a function of cos2θ where θ is the angle between magnetization M and current flow in the thin strip. When an applied magnetic field is larger than 80 Oe, the magnetization aligns in the same direction of the applied field; this is called saturation mode. In this mode, θ is the angle between the direction of applied field and the current flow; the MR sensor is only sensitive to the direction of applied field.

The sensor is in the form of a Wheatstone bridge (Figure 1). The resistance R of all four resistors is the same. The bridge power supply VS causes current to flow through the resistors, the direction as indicated in the figure for each resistor.

Both HMC1501 and HMC1512 are designed to be used in saturation mode. HMC1501 contains one MR bridge and HMC1512 has two identical MR bridges, coexisting on a single die. Bridge B physically rotates 45° from bridge A. The HMC1501 has sensor output ∆V=-VSS sin (2θ) and the HMC1512 has sensor output ∆V=VSS sin (2θ) for sensor A and sensor B output ∆VS=-VSS cos (2θ), where VS is supply voltage, S is a constant, determined by materials. For Honeywell sensors, S is typically 12mV/V.

	Current	Metal Contact
		M
	Flow
		θ
		Permalloy
	Applied	Thin Film
	Field	(NiFe)

Applied Field Direction

M	M
R+∆R	R-∆R
∆V	I
+ -	Vs
M	M
R-∆R	R+∆R

Figure 1

PINOUT DRAWINGS

HMC1501

OUT+ 1 • θ 8 OUTGND 1 2 7 GND 2

3 6

4 5 VBRIDGE

Caution: Do not connect GND or Power to Pin 3,4 &6.

MR SENSOR CIRCUITS

VBRIDGE
R	R
OUT+	OUT-	OUT+
		A
R	R
GND 1	GND 2

HMC1512

OUT- A 1		•		8	GNDA
OUT- B 2			θ	7	GNDB
VBRIDGEB	3			6	OUT+ B
VBRIDGEA	4			5	OUT+ A

	VBRIDGE A	OUT +B		VBRIDGE B
			R
	R	R
		R	Bridge B	R
	Bridge A	OUT-
		A
	R	R	R
	GND A	GND B		OUT -B

2