Data Sheet

ADXL335 Preliminary Technical Data
Rev. PrA | Page 8 of 11
The ADXL335 output is ratiometric, therefore, the output
sensitivity (or scale factor) varies proportionally to the
supply voltage. At V
S
= 3.6 V, the output sensitivity is
typically 360 mV/g. At V
S
= 2 V, the output sensitivity is
typically 195 mV/g.
The zero g bias output is also ratiometric, so the zero g output is
nominally equal to V
S
/2 at all supply voltages.
The output noise is not ratiometric but is absolute in volts;
therefore, the noise density decreases as the supply voltage
increases. This is because the scale factor (mV/g) increases
while the noise voltage remains constant. At V
S
= 3.6 V, the
X- and Y-axis noise density is typically 120 µg/√Hz, while at
V
S
= 2 V, the X- and Y-axis noise density is typically 270 g/√Hz.
Self test response in g is roughly proportional to the square of
the supply voltage. However, when ratiometricity of sensitivity
is factored in with supply voltage, the self test response in volts
is roughly proportional to the cube of the supply voltage. For
example, at V
S
= 3.6 V, the self test response for the ADXL335 is
approximately −275 mV for the X-axis, +275 mV for the Y-axis,
and −100 mV for the Z-axis.
At V
S
= 2 V, the self test response is approximately −60 mV for
the X-axis, +60 mV for the Y-axis, and −25 mV for the Z-axis.
The supply current decreases as the supply voltage decreases.
Typical current consumption at V
S
= 3.6 V is 375 µA, and
typical current consumption at V
S
= 2 V is 200 µA.
AXES OF ACCELERATION SENSITIVITY
05677-030
A
Z
A
Y
A
X
T
O
P
Figure 5. Axes of Acceleration Sensitivity, Corresponding Output Voltage
Increases When Accelerated Along the Sensitive Axis
05677-031
X
OUT
= –1g
Y
OUT
= 0g
Z
OUT
= 0g
GRAVITY
X
OUT
= 0g
Y
OUT
= 1g
Z
OUT
= 0g
X
OUT
= 0g
Y
OUT
= –1g
Z
OUT
= 0g
X
OUT
= 1g
Y
OUT
= 0g
Z
OUT
= 0g
X
OUT
= 0g
Y
OUT
= 0g
Z
OUT
= 1g
X
OUT
= 0g
Y
OUT
= 0g
Z
OUT
= –1g
TOP
TOP
TOP
TOP
T
O
P
Figure 6. Output Response vs. Orientation to Gravity
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