Philips Magnetoresistive Sensor manual Sensor Temperature Drift

Page 26

Philips Semiconductors

Magnetoresistive sensors for

magnetic ﬁeld measurement

General

SENSOR TEMPERATURE DRIFT

The sensitivity of MR sensors is also temperature dependent, with sensitivity decreasing as temperature increases (Fig.31).The effect on sensor output is certainly

not negligible, as it can produce a difference of a factor of three within a −25 °C to +125 °C temperature range, for fields up to 0.5 kA/m. This effect is not compensated for by the flipping action described in the last section.

	15							MLC134
handbook, full pagewidth	15
handbook, full pagewidth
	VO				T	=	25oC
	(mV/V)				amb
	(mV/V)
	10							25oC
	10
								75oC
	5
								125oC
	0
	5
	10
				operating range
	15		1
	3	2	1	0	1		2	3
							H y (kA/m)

Fig.31 Output voltage ‘Vo’ as a fraction of the supply voltage for a KMZ10B sensor, as a function of transverse field ‘Hy’, at several temperatures.

2000 Sep 06

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Contents General Contents Magnetoresistive sensors for Magnetic ﬁeld measurementPhilips Semiconductors Operating principlesKMZ10 chip structure 2000 Sep Linearize Application Package Range Sensor FieldSensitivity TypeSensor characteristics FlippingEffect of temperature on behaviour 25 oC Amb MV/V 75 oC 125 oC Operating range KA/m Using magnetoresistive sensors KMZ10BFurther information for advanced users + Δ R ⎛ H For R 8 = R 2R TA1 = 1 + Positive temperature coefficient TCGiven by Magnetoresistive sensorSinφcosφ Appendix 1 the Magnetoresistive EffectResistance- ﬁeld relation Magnetization of the thin layer LinearizationSensitivity Materials Materials 10−8Ωm Δρ/ρ% ΙΙkΔ/mThis also considerably enlarges Hk. If a small temperature Appendix 2 Sensor FlippingSensor output ‘Vo’ as a function of the transverse ﬁeld Hy Appendix 3 Sensor Layout KMZ10 and KMZ11 bridge configuration 2000 Sep Fundamental measurement techniques Contents Weak Field Measurement Flipping coil T flipping current if Time Internal magnetization Sensor Temperature Drift 25 oC Flipping coil Sensor KMZ10A1 Technique Effect