ACS70331 datasheet(22/26 Pages) ALLEGRO

22 / 26 page

High Sensitivity, 1 MHz, GMR-Based Current Sensor IC

in Space-Saving, Low Resistance QFN and SOIC-8 Packages

ACS70331

Allegro MicroSystems, LLC

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

Sensitivity Error (ESENS). The variation of the sensitivity from

its ideal, nominal value, Sens, expressed in percent. Sensitivity

error contributes directly to the Total Output Error, percent for

percent.

Zero-Current Output Voltage (VIOUT(Q)). The output of the

sensor when the primary current is zero. For a bidirectional

device (measures current in both directions), it is nominally 1.5 V,

and for a unidirectional device, it is nominally 0.25 V.

Offset Voltage (VOE). The deviation of the device output from its

ideal quiescent value of 1.5 V (bidirectional) or 0.25 V (unidirec-

tional). To convert this voltage to amperes, divide by the device

sensitivity, Sens.

Total Output Error (ETOT). The difference between the cur-

rent measurement from the sensor IC and the actual current (IP),

relative to the actual current. This is equivalent to the difference

between the ideal output voltage and the actual output voltage,

divided by the ideal sensitivity, relative to the current flowing

through the primary conduction path:

E(I)

TOTP

V(I) –V (I )

IOUT_ideal

PIOUTP

Sens (I )× I

idealP

× 100 (%)

The Total Output Error incorporates all sources of error and is a

function of IP. At relatively high currents, ETOT will be mostly

due to sensitivity error, and at relatively low currents, ETOT will

be mostly due to Offset Voltage (VOE). In fact, at IP = 0, ETOT

approaches infinity due to the offset. This is illustrated in Figure

8 and Figure 9. Figure 8 shows a distribution of output voltages

versus IP at 25°C and across temperature. Figure 9 shows the cor-

responding ETOT versus IP.

ACS70331 Datasheet(PDF) 22 Page - Allegro MicroSystems