Sensors

10

Freescale Semiconductor, Inc.

MPL115A2

3.5

Example of Pressure Compensated Calculation in Floating-point Notation

Pressure Compensation:

Using the evaluation sequence shown in Section 3.3:

4

Solder Recommendations

1.

Use SAC solder alloy (i.e., Sn-Ag-Cu) with a melting point of about 217°C. It is recommended to use SAC305

(i.e., Sn-3.0 wt.% Ag-0.5 wt.% Cu).

2.

Reflow

• Ramp up rate: 2 to 3°C/s.

• Preheat flat (soak): 110 to 130s.

• Time above 217°C: 40 to 90s (depends on board type, thermal mass of the board/quantities in the reflow).

• Ramp down: 5 to 6°C/s.

a0 coefficient

=

2009.75

b1 coefficient

=

-2.37585

b2 coefficient

=

-0.92047

c12 coefficient

=

0.000790

Pressure

=

410 ADC counts

Temperature

=

507 ADC counts

c12x2

= c12 * Tadc

= 0.000790 * 507

= 0.40053

a1

= b1 + c12x2 = -2.37585 + 0.40053

= -1.97532

a1x1

= a1 * Padc

= -1.97532 * 410

= -809.8812

y1

= a0 + a1x1

= 2009.75 + (-809.8812)

= 1199.8688

a2x2

= b2 * Tadc

= -0.92047 * 507

= -466.67829

PComp

= y1 + a2x2

= 1199.8688 + (-466.67829)

= 733.19051

Pcomp

a0

b1

c12 Tadc

⋅

+

() Padc b c

()

+

⋅

+

=

Pressure (kPa)

P

=comp

115

50

–

1023

----------------------

50

+

⋅

733.19

=

115

50

–

1023

----------------------

50

+

⋅

96.59kPa

=