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3517 Datasheet(PDF) 6 Page - Allegro MicroSystems |
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3517 Datasheet(HTML) 6 Page - Allegro MicroSystems |
6 / 13 page ![]() 3517 AND 3518 RATIOMETRIC, LINEAR HALL-EFFECT SENSORS FOR HIGH-TEMP. OPERATION www.allegromicro.com 5 CHARACTERISTICS DEFINITIONS Ratiometry. The A3517xUA and A3518xUA feature a ratiometric output. The quiescent voltage output and sensitivity are proportional to the supply voltage (ratiometric). The per cent ratiometric change in the quiescent voltage output is defined as ∆V OQ( ∆V) = V OQ(VCC) / VOQ(5V) x 100% (4) V CC / 5 V and the per cent ratiometric change in sensitivity is defined as ∆Sens ( ∆V) = Sens (VCC) / Sens(5V) x 100% (5) V CC / 5 V Linearity and Symmetry. The on-chip output stage is designed to provide a linear output to within 500 mV of either rail with a supply voltage of 5 V. This is equivalent to approximately ±800 gauss of ambient field. Although application of stronger magnetic fields will not damage these devices, it will force the output into a non-linear region. Linearity in per cent is measured and defined as Lin+ = V O(500G) – VOQ x 100% (6) 2 (V O(250G) – VOQ) Lin– = V O(-500G) – VOQ x 100% (7) 2 (V O(-250G) – VOQ) and output symmetry as Sym = V O(500G) – VOQ x 100% (8) V OQ – VO(-500G) Quiescent Voltage Output. In the quiescent state (no magnetic field), the output is ideally equal to one-half of the supply voltage over the operating voltage and tem- perature range (V OQ ≈ VCC/2). Due to internal component tolerances and thermal considerations, there is a tolerance on the quiescent voltage output and on the quiescent voltage output as a function of supply voltage and ambient temperature. For purposes of specification, the quiescent voltage output as a function of temperature is defined as ∆V OQ( ∆T) = V OQ(TA) – VOQ(25 °C) (1) Sens (25 °C) This calculation yields the device’s equivalent accuracy, over the operating temperature range, in gauss. Sensitivity. The presence of a south-pole magnetic field perpendicular to the package face (the branded surface) will increase the output voltage from its quiescent value toward the supply voltage rail by an amount proportional to the magnetic field applied. Conversely, the application of a north pole will decrease the output voltage from its quiescent value. This proportionality is specified as the sensitivity of the device and is defined as Sens = V O(500G) – VO(-500G) (2) 1000 G The stability of sensitivity as a function of tempera- ture is defined as ∆Sens ( ∆T) = Sens (TA) – Sens(25 °C) x 100% (3) Sens (25 °C) |