Datasheet A1321, A1322, A1323 (Allegro) - 7

A1321, A1322, Ratiometric Linear Hall Effect Sensor ICs and A1323 for High-Temperature Operation
Characteristic Defi nitions
Quiescent Voltage Output.
In the quiescent state (no
Ratiometric.
The A132X family features a ratiometric output. magnetic fi eld), the output equals one half of the supply voltage The quiescent voltage output and sensitivity are proportional to over the operating voltage range and the operating temperature the supply voltage (ratiometric). range. Due to internal component tolerances and thermal con- The percent ratiometric change in the quiescent voltage output is siderations, there is a tolerance on the quiescent voltage output defi ned as: both as a function of supply voltage and as a function of ambient temperature. For purposes of specifi cation, the quiescent voltage Vout(q)(VCC) Vout(q)(5V) ΔV (4) output as a function of temperature is defi ned in terms of mag- out(q)(ΔV) = × 100% VCC 5 V netic fl ux density, B, as: and the percent ratiometric change in sensitivity is defi ned as: V – Δ out(q)(ΤΑ) Vout(q)(25ºC) Vout(q)(ΔΤ) = (1) Sens(25ºC) Sens(VCC) Sens(5V) (5) This calculation yields the device’s equivalent accuracy, ΔSens( = ΔV) × 100% V over the operating temperature range, in gauss (G). CC 5 V
Linearity and Symmetry.
The on-chip output stage
Sensitivity.
The presence of a south-pole magnetic fi eld per- is designed to provide a linear output with a supply voltage of pendicular to the package face (the branded surface) increases 5 V. Although application of very high magnetic fi elds will not the output voltage from its quiescent value toward the supply damage these devices, it will force the output into a non-linear voltage rail by an amount proportional to the magnetic fi eld region. Linearity in percent is measured and defi ned as: applied. Conversely, the application of a north pole will decrease the output voltage from its quiescent value. This proportionality V – out(+B) Vout(q) (6) is specifi ed as the sensitivity of the device and is defi ned as: Lin+ = × 100% 2(Vout(+B / 2) – Vout(q) – Vout(–B) Vout(+B) (2) Sens = 2 V – (7) B out(–B) Vout(q) Lin– = × 100% The stability of sensitivity as a function of temperature is 2(Vout(–B / 2) – Vout(q) defi ned as: and output symmetry as: Sens – Δ (ΤΑ) Sens(25ºC) Sens (3) (ΔΤ) = × 100% V –V Sens out(+B) out(q) (8) (25ºC) Sym = × 100% Vout(q) – Vout(–B) Allegro MicroSystems, Inc. 6 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com