Wireless transceiver chip designed for excellent car remote control access control (RKE) system

Abstract: The RKE system allows the user to use the transmitter on the key fob to lock the car door or unlock it. In addition, the RKE also has an anti-theft function. MELEXIS wireless transceiver chip is very suitable for use in car remote control access control, it only consumes 5nA power supply current in standby mode.

RKE (Remote Keyless Entry) is the abbreviation of remote access control system / remote control door switch. The RKE system allows the user to use the transmitter on the key fob to lock the car door or unlock it. The transmitter transmits data to the car and the user presses the button switch on the key fob to trigger the system to work. In addition to the technology of opening the car brakes, RKE also has an anti-theft function.

It consists of a receiving controller mounted on the car and a transmitter carried by the user, ie the wireless remote control door key.

The composition of the RKE system

The RKE system allows the user to use the transmitter on the key fob to lock the car door or unlock it. The transmitter transmits data to the car and the user presses the button switch on the key fob to trigger the system to work. This will wake up the CPU inside the RKE key fob, and the CPU will send the data stream to the radio frequency (RF) transmitter. The data stream is typically 64 to 128 bits long and includes a preamble, a command code, and a rolling code. The data stream is typically transmitted at a rate of 2 kHz to 20 kHz. The modulation method is amplitude keying (ASK), the main purpose is to extend the battery life of the key fob.

RKE key and base station structure

The Melexis low-power 425MHz to 445MHz transmitter MLX72013 from Shiqiang is especially suitable for the RKE system, which is available in an 8-pin SCIC-8 package. Its 1.9V to 5.5V supply range allows the device to be powered from a single-cell Li-Ion battery and consumes only 5nA of supply current in standby mode.

Block diagram of Shiqiang RF transmitter MLX72013

When transmitting Manchester encoded data, the Shiqiang MLX72103 supports data rates up to 40kbps, consumes 2.9mA and 5.5mA supply current, and delivers -10dBm to +10dBm output power to 50Ω loads. The crystal-based phase-locked loop produces an accurate carrier frequency that allows the receiver to use a narrower IF bandwidth to increase the transmission distance.

For the RKE receiver, Shiqiang also offers the MLMHz7112 superheterodyne ASK receiver 315MHz to 915MHz. The MLX71121 is a highly integrated single-channel/dual-band RF receiver based on a double-conversion superheterodyne architecture. Can be used with the MLX72103.

More RKE solution information or sample applications can be obtained by logging in to the Shiqiang Component E-commerce App. Shiqiang components e-commerce intelligent hardware innovation service platform provides engineers with comprehensive coverage of technical support and quality service experience.

Shiqiang RF Receiver MLX71121 Block Diagram