Document Number: MPXY8000

Rev 3, 02/2006

Freescale Semiconductor

Technical Data

© Freescale Semiconductor, Inc., 2006. All rights reserved.

Tire Pressure Monitoring Sensor

Temperature Compensated

and Calibrated, Fully Integrated,

Digital Output

The Freescale Semiconductor MPXY8000 series sensor is an 8-pin tire

monitoring sensor which is comprised of a variable capacitance pressure

sensing element, a temperature sensing element, and an interface circuit (with a

wake-up feature) all on a single chip. It is housed in a Super-Small Outline

Package (SSOP), which includes a media protection filter. Specifically designed

for the low power consumption requirements of tire pressure monitoring systems,

it can combine with a Freescale Semiconductor remote keyless entry (RKE)

system to facilitate a low-cost, highly integrated system.

DETAILED DESCRIPTION

The block diagram of the MPXY8000 series sensor is shown in Figure 1. The

pressure sensor is a capacitive transducer constructed using surface

micromachining, the temperature sensor is constructed using a diffused resistor,

and the interface circuit is integrated onto the same die as the sensors using a

standard silicon CMOS process.

The conditioning of the pressure signal begins with a capacitance to voltage

conversion (C to V) followed by a switched capacitor amplifier. This amplifier has

adjustable offset and gain trimming. The offset and gain are factory calibrated,

with calibration values stored in the EEPROM trim register. This amplifier also

has temperature compensation circuits for both sensitivity and offset, which also

are factory adjusted using the EEPROM trim register.

The pressure is monitored by a voltage comparator, which compares the

measured value against an 8-bit threshold adjusted by a serial input. By adjusting

the threshold and monitoring the state of the OUT pin the external device can

check whether a low-pressure threshold has been crossed, or perform up to

8-bit A/D conversions.

The temperature is measured by a diffused resistor with a positive

temperature coefficient driven by a current source, thereby creating a voltage.

The room temperature value of this voltage is factory calibrated using the

EEPROM trim register. A two-channel multiplexer can route either the pressure

or temperature signal to a sampling capacitor that is monitored by a voltage

comparator with variable threshold adjust, providing a digital output for

temperature.

An internal low frequency, low power 5.4 kHz oscillator with a 14-stage divider

provides a periodic pulse to the OUT pin (divide by 16384 for 3 seconds). This

pulse can be used to wake up an external MCU to begin an interface with the

device. An additional 10-stage divider will provide a pulse every 52 minutes

which can be used to reset an external MCU.

The power consumption can be controlled by several operational modes

selected by external pins.

MPXY8020A

MPXY8040A

SUPER SMALL OUTLINE PACKAGE

CASE 1352-03

PIN ASSIGNMENT

TIRE PRESSURE

MONITORING SENSOR

MPXY8020A:

OPTIMIZED FOR 250 kPa – 450 kPa

MPXY8040A:

OPTIMIZED FOR 500 kPa – 900 kPa

8-pin Super Small Outline Package (SSOP)

ORDERING INFORMATION

Shipped in Rails

Shipped in Tape &

Reel

MPXY8020A6U

MPXY8040A6U

MPXY8020A6T1

MPXY8040A6T1

1

2

4

3

OUT

8

7

5

6

RST

DATA

CLK

SO