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
S1N
PP
V
DD
V
SS
OUT
8
7
5
6
RST
DATA
CLK
SO
