DOCUMENT 301900, REVISION D
EPISENSOR USER GUIDE 49
Table 10: Current requirements
Sensor Quiescent Current
Dual "12V
Supply
Single 12V
Supply
Low-power unit 12 mA 65 mA
Unit with low low-noise amplifiers enabled 35 mA 130 mA
Sensor Full-scale Output Current 1 Axis 3 Axes
Restoring current for coils per g 2.5 mA/g 7.5 mA/g
Output amplifier load at "2.5V single-ended
or "5V differential full-scale
0.7 mA 2.1 mA
Output amplifier load at "10V single-ended
or "20V differential full-scale
6.6 mA 20 mA
To calculate the worst case maximum current required, take the full-scale
range that the unit is set at and multiply by 7.5mA. This will give the
current required to "balance" the applied acceleration.
Add to this the output amplifier load for the output you have selected.
For a dual supply add this number to the quiescent current to get the worst
case current.
For a single supply option, multiply the current by 4 to account for the 50%
efficiency of the DC to DC converter and voltage ratio and then add this
current to the quiescent current.
The maximum current load on a dual supply for an EpiSensor set to a 2g
full-scale range with a 20V differential low-noise output is calculated as
below:
(7.5 mA x 2) + 20 mA + 35 mA = 70 mA
For the single supply option:
((7.5 mA x 2) + 20 mA) x 4) + 130 mA = 270 mA
These values are very conservative because in normal situations all three
axis of the EpiSensor are unlikely to see 2g of acceleration at the same time.
Further examples are found in Table 11:
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