MPXY8040A datasheet(5/17 Pages) FREESCALE

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Sensors

Freescale Semiconductor

MPXY8000

An analog to digital (A/D) conversion can be accomplished

with eight (8) different threshold levels in a successive

approximation algorithm; or the OUT pin can be set to trip at

some alarm level. The voltage on the sample capacitor will

maintain long enough for a single 8-bit conversion, but may

need to be refreshed with a new measured reading if the read

interval is longer than the specified hold time, tSH.

The counter that determines the number of clock pulses

into the device is reset whenever the device is placed into the

Measure Pressure or Measure Temperature Modes. This

provides a means to reset the data transfer count in case the

clock stream is corrupted during a transmission. In these two

modes the DATA and CLK pins should not be clocked to

reduce noise in the captured pressure or temperature data.

Any change in the DAR contents should be done during the

Standby or Output Read Modes.

Both the serial bit counter and the state of the DAR are

undefined following power up of the device. The serial bit

counter can be reset by cycling either the SO pin or the

S1/VPP pin to a high level and then back low. The DAR can

then be reset to the lowest level by holding the DATA pin low

while bursting the CLK pin with eight (8) clock pulses.

Figure 5. Serial Data Timing

Pressure Sensor Output

The pressure channel compares the output of its analog

measurement circuit to the D/A reference voltage. The device

is calibrated at two different nominal values depending on the

calibration option.

Temperature Sensor Output

The temperature channel compares the output of a

positive temperature coefficient (PTC) resistor driven by a

switched current source. The current source is only active

when the temperature channel is selected.

APPLICATIONS

Suggested application example is shown in Figure 6.

Figure 6. Application Example

CLK

Data

Serial Data

∗

DAR Load *

DAR *

(*) Denotes Internal Signal

MSB

Data

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

LSB

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

LSB

3.0 V

0.1

µF

MPXY8000

Series

Sensor

VDD

VSS

Optional

State Machine

or MCU

Transmitter

CLK

RST

OUT

Data

Motion

Sense

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