MPXY8021A FREESCALE | Alldatasheet
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Document Number: MPXY8021A Rev 2, 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, Inc. MPXY8021A 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 remote keyless entry (RKE) system to facilitate a low-cost, highly integrated system. DETAILED DESCRIPTION The block diagram of the MPXY8021A 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. MPXY8021A SUPER SMALL OUTLINE PACKAGE CASE 1352-03 PIN ASSIGNMENT TIRE PRESSURE MONITORING SENSOR MPXY8021A: OPTIMIZED FOR 250 kPA 450 kPA 8-pin Super Small Outline Package (SSOP)
ORDERING INFORMATION
Shipped in Rails Shipped in Tape & Reel MPXY8021A6U MPXY8021A6T1 S1NPP VDD VSS OUT RST DATA CLK SO
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Figure 1. MPXY8021A Sensor Block Diagram Table 1. In all the modes listed the channel multiplexers, D/A measuring circuitry is activated.
Power is supplied to the control IC through VDD and VSS. ground. The control IC operates from a single power supply. Figure 2. Recommended Power Supply Connections external device such as an MCU. Figure 3. Pulse on OUT Pin During Standby Mode Figure 4. Since the RST pin is clocked from the same divider pin when the RST pin pulses every 52 minutes. Table 1. Operating Modes
3 Sec
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Figure 4. Pulse on RST Pin the pin is left unconnected. EEPROM trim register is also supplied through the S1 pin. the threshold of the voltage comparator. Figure 5. Data is transferred into the serial shift register on threshold select bits is shown in Table 2. Table 2. D/A Threshold Bit Assignment
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VOUT within the range VSS ≤ (VIN or VOUT) ≤ VDD. Table 3. Maximum Ratings Table 4. Operating Range The limits normally expected in the application which define range of operation.
Table 5. Electrical Characteristics
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Figure 7. Temperature Error vs Temperature at VDD = 3.0 V Figure 8. Control Timing Test Load for OUT and RST Pins Table 6. Control Timing +2.1 V ≤ VDD ≤ +3.6 V, TL ≤ TA ≤ TH, unless otherwise specified.
SENSOR CHARACTERISTICS (MPXY8021A) PRESSURE TRANSFER FUNCTION kPa = 2.5 x Output ± (Pressure Error) Output = 8-bit digital pressure measurement (between 0-255) Pressure Error (±kPa): 50 kPa ≤ P < 250 kPa Pressure Error (±kPa): 250 kPa ≤ P ≤ 450 kPa Pressure Error (±kPa): 450 kPa < P ≤ 637.5 kPa Areas marked in grey indicate the typical operating range.
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Figure 9. Pressure Error vs Pressure at T = 25°C, 2.7 V ≤ VDD ≤ 3.3 V Figure 10. Pressure Error vs VDD at T = 25°C, 250 kPa ≤ P ≤ 450 kPa Figure 11. Pressure Error vs Temperature at VDD = 3.0 V, 250 kPa ≤ P ≤ 450 kPa
device can be exposed without permanently damaging it. provides limited, but not universal, media protection. that media does not come in direct contact with the sensor. rapid pressurization of the tire. Daytona sensor with their module design and application. Table 7. Maximum Ratings
- Tested for 5 minutes at 25°C.
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SUPER SMALL OUTLINE PACKAGE PAGE 1 OF 3
Freescale Semiconductor 13 PACKAGE DIMENSIONS CASE 1352-03 ISSUE C SUPER SMALL OUTLINE PACKAGE PAGE 2 OF 3
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SUPER SMALL OUTLINE PACKAGE PAGE 3 OF 3
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