Tire Pressure Monitoring System Rev 2.0, 5/2011 Key Features Description The is tire pressure monitoring system which is designed for auto manufacturer. It is compatible with American final rule released on April 7, 2005. The would warn the driver when the pressure in one or more of the vehicle s tires, up to a total of four tires, is 25 percent or more below the vehicle manufacturer s recommended cold inflation pressure for the tires, or a minimum level of pressure specified in the American regulation, whichever pressure is higher. The is a direct tire pressure monitoring system which consists of three parts, wireless sensor, central receiver and high frequency receiving antenna. Wireless sensor is mounted on the rim with high reliability and durability. Central receiver could be mounted anywhere in the cabin. Outside high frequency receiving antenna is adopted. Antenna is mounted on the bottom side of chassis to improve RF path efficiency. The center frequency of the system is 315MHz. High efficiency communication protocol is adopted. Special coding technology is designed for higher wireless communication reliability. FMVSS138 compatible Meet SAE J2657 requirements Wireless Sensor Operating life 6 years or 100,000km Weight 45g (with valve) Central Receiver CAN-BUS communication Compliant with ISO 11898 & CAN2.0 B KWP2000 on CAN for diagnostic High Frequency Receiving Antenna Compact & robust structure High efficiency Receiving antenna inside Application Passenger car Definition Low Tire Pressure 25 percent or more below the vehicle manufacturer s recommended cold inflation pressure for the tires, or a minimum level of pressure specified in the American regulation, whichever pressure is higher. Fast Under-inflation Tire pressure loss of 0.2Bar within 60 seconds. Malfunction Sensor failure Sensor E 2 PROM failure Sensor broken wire failure Central receiver electronics failure
Wireless Sensor Absolute Maximum Ratings Storage Temperature TS -40 125 Work Conditions Operating Temperature T -40 125 Center Frequency f c 315 MHz RF Transmission Interval 2 Min Service Life 6 Years Start Working Vehicle Speed 24 km/h Pressure Monitoring Range 100 450 kpa Pressure Monitoring Accuracy -8 +8 kpa Temperature Monitoring Range -40 +125 Temperature Monitoring Accuracy -3 +3 Functional Description Block Diagram LF Transmitter Pressure Sensor Temperature Sensor RF Transmitter Centrifugal Switch Battery Sensor Conditional Circuit Battery The wireless sensor is supplied by a 3.6V coin battery. And 125kHz low frequency signal with specific frame can wake up the wireless sensor to transmit RF signal with ID information. The function is used to initiate four sensors when vehicle assembly and servicing. Storage Mode When in the depository, the wireless sensor is under power saving status. And 125kHz low frequency signal with special frame can wake up it to start to work Running Mode When vehicle speed is higher than 24km/h, the wireless sensor transmits UHF signal including pressure, temperature and battery voltage information every 2 minutes. When low Tire Pressure, fast loss or malfunction occurs, it will transmit warning signal immediately.
Stopping Mode When stationary, the wireless sensor will not transmit any warning signal and enter into power saving mode. Central Receiver Absolute Maximum Ratings Supply Voltage VDD -40 45 V Storage Temperature TS -55 125 Work Conditions Supply Voltage V DD 12 V Operating Temperature -40 85 Center Frequency f c 315 MHz Power Consumption (Wait Mode) 5 ma Power Consumption (Run Mode) 30 120 ma Functional Description Block Diagram CAN Physical Layer Module MCU UHF Power Management Module Central receiver receives 315MHz UHF signal transmitted by wireless sensor through one outside High frequency antenna which is mounted on the bottom side of chassis. MCU herein processes the data demodulated by UHF receiving circuit, and sends the useful pressure and temperature information to instrumental control module by CAN-BUS. Central receiver provides varieties of warning signal such as low tire pressure, fast loss and malfunction etc. When malfunction occurs, the central receiver will transmit warning signal on CAN-BUS within 20 minutes according to American regulation when vehicle speed is higher than 24km/h. When low tire pressure or fast loss occurs, it will provide warning signal on CAN-BUS within 2 minutes only under ignition on condition when stationary.
High Frequency Receiving Antenna Layout Diagram Installation of Wireless Sensor