Operational Description

FCC ID: GQ4-54T

Operational Description

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FCCID_1753466

TRW Automotive May 21, 2012 TEE 24175 Research Dr. Farmington Hills, MI 48335-2642 Tel 248.478.7210 Fax 248.699.4241 RE: Certification for Chrysler FOBik2 RKE Transmitter Transmitter Model #: 231704-1 thru -4 FCC ID: GQ4-54T Canada IC: 1470A-35T Description of Circuit Operation The NXP PCF7953 is used for signal encoding and operational control. The switch inputs wake up the micro on change and the micro takes appropriate action depending on the switch status. If a switch is determined pressed the PCF7953 enables the NXP PCF7900 via the enable line. When enabled the PCF7900 begins driving the 13.56MHz crystal which is used for the PLL division factor and baud rate generation for the external clock on the PCF7900. The external clock out of the PCF7900 runs into the PCF7953. This signal is used to change data on the MSDA line on of the PCF7953. After a transmission ends and no more switches are pressed the device will go into a low power mode. The PCF7953 has an additional operating mode for usage in a passive entry (LF In/RF Out) system. In this instance the RF transmission is triggered by an LF Query instead of a switch input. The basic interaction between the PCF7900 and PCF7953 remain the same. Just the triggering mechanism and RF modulation are different. Legal name here


Document Created: 2012-06-26 15:57:34
Document Modified: 2012-06-26 15:57:34
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