3–416
Motorola Sensor Device Data
For More Information On This Product,
Go to: www.freescale.com
TRANSFER FUNCTION
The behavior of an IPS is defined by a linear transfer
function. This transfer function applies to all Motorola’s
Integrated Pressure Sensors whatever the pressure range
and type of sensing element (absolute or differential).
Vout
V
S
(P
K1
K2)
V
S
(PE
TM
K1)
Vout : Sensor output voltage
P: Applied pressure in kPa
Vs: Sensor supply voltage in V
K1: Sensitivity constant in V/V/kPa
K2: Offset Constant inV/V
PE: Pressure error in kPa
TM: Temperature multiplier
The constants, K1, K2, PE & TM are specific to each device,
temperature and pressure encountered in the application.
The variables P and Vs are dependent on the user
application but must remain within the operating specification
of the device.
THE MPXV6115VC6U INTEGRATED
PRESSURE SENSOR
The Motorola MPXV6115VC6U gauge vacuum sensor,
designed to measure pressure below the atmospheric
pressure, is suitable for automotive application such as
vacuum pump or brake booster monitoring. The MXPV4115V
is also ideal for non–automotive applications where vacuum
control is required.
The
MPXV6115VC6U
has
characteristics (Note: Detailed characteristics of Motorola’s
pressure
sensors
can
http://www.motorola.com/semiconductors).
the
following
basic
be
found
on
MPXV6115VC6U CHARACTERISTICS
Vout
V
S
(P
0.007652
TM
0.92)
0.007652)
(PE
V
S
Figure 6. MPXV6115VC6U Transfer Function
TRANSFER FUNCTION:
Vout = 2.30 V @ P = –60 kPa
Vout = VS ([0.007652 *P] + 0.92)
–120
–100
–80
–60
–20
0
0
1
2
3
4
5
VACUUMin kPa (below atmospheric pressure)
T
20
–40
R
A
VACUUM
S
o
P is the applied vacuum to the sensor pressure port.
Pressures below atmospheric pressure have a negative
sign. For example, 50 kPa below atmospheric is P = –50
in the transfer function. For pressure higher than the
atmospheric pressure, the device will electrically satu-
rate. The sensor is designed to measure vacuum from 0
kPa (Atmospheric pressure applied to the sensor pres-
sure port) down to – 115kPa.
Since the MPXV6115VC6U is using the atmospheric
pressure as reference, –115 kPa can only be reached if the
atmospheric pressure is higher or equal than 115 kPa. The
device will electrically saturate for vacuum below –115 kPa.
PE = 1.725 kPa (1.5% of full scale span) over the entire
pressure range
TM = 1 between 0 and +85 C, 3 at –40 C and +125 C.
TM is a linear response from –40 to 0 C and from 85
to 125 C.
The real intent for the pressure–sensor user is to know the
measured pressure. In this case it is preferable to express the
transfer function as:
P
(VoutV
S
0.92) 0.007652
(PE
TM)
As an example, if Vout = 2.30 V for a 5 Vdc power supply and
at 25 C ambient temperature, the measured vacuum is P =
–60.1 kPa
1.725 kPa.
F
Freescale Semiconductor, Inc.
n
.