EXT

EXT

B

B

I

G

OUT

EXT

Hall

V

IN

Hall

V

OUT,0A

V

B

* S

* A

I * G * S

* A

V

Hall

V

S

G * S

* A

10

TMCS1100

SBOS820 – SEPTEMBER 2019

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Accuracy Parameters (continued)

8.1.4 Reference Voltage Rejection Ratio

The zero current output voltage for the TMCS1100 is derived from sampling an external voltage on the VREF

mismatches can cause minor errors. When the reference voltage deviates from half of the supply, an additional

effective output offset error is introduced into the device transfer function.

8.1.5 External Magnetic Field Errors

The TMCS1100 does not have stray field-rejection capabilities, so external magnetic fields from adjacent high-

current traces or nearby magnets can impact the output measurement. The total sensitivity (S) of the device is

comprised of the initial transformation of input current to magnetic field quantified as the magnetic coupling factor

(G), as well as the sensitivity of the Hall element and the analog circuitry that is factory calibrated to provide a

final sensitivity. The output voltage is proportional to the input current by the device sensitivity, as defined in

Equation 8.

where

•

S is the TMCS1100 sensitivity in mV/A.

•

G is the magnetic coupling factor in mT/A.

•

•

(8)

leadframe current, and is added as an extra input term in the total output voltage function:

(9)

Observable from Equation 9 is that the impact of an external field is an additional equivalent input current signal,

sensitivity, so all gain variants have equivalent input-referred current error due to external magnetic fields.

(10)