I just received a particularly useful bit of semi-unsolicited email
from Allegro. Some time ago I had asked for (and received) some
samples of one of their hall-effect based current sensor chips that
I was hoping to build into little minimally-invasive current meters
in the lab (no isolated power requirements, as far as I can tell.)
Anyway. I got this email:
> Thank you for using the Allegro ACS704/ACS706/ACS707 Current Sensors in
> your products.
>
> I am writing to inform you that we have recently released the ACS712
> /ACS713
> , which has several improvements
> over the previous generation of current sensor. These improvements
> include:
>
> * Higher gain (185 mV/A) - Improves low current accuracy
> * Lower output noise - Improve low current resolution
> * Integrated filter pin - Further noise reduction on the output
> * Higher bandwidth - Faster response time
> * Integrated Electrostatic Shield - Significant improvement in
> immunity for high dV/dt environments
>
> The caveats to be aware of in simply dropping this new device into an
> existing design are:
>
> * Pin 6 is the new filter pin. If your application has pins 6
> and
> 7 tied together, the ACS712
> cannot drop right into the solution.
>
> * When comparing the new
> ACS712 to the previous generation of 5 A devices, the sensitivity has
> increased from 133mV/A to 185mV/A. Depending on the circuit solution
> this may require either discrete component changes to accommodate the
> new thresholds or a modification to firmware.
And I thought it was just about perfect. Reasonably identified me
as being interested, and told be a bunch of RELEVANT facts on both
upside and downside clearly and succinctly. I wish all vendors were
so ... on target and informative.
BillW
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