Views: 0 Author: Site Editor Publish Time: 2023-11-14 Origin: Site
During the use of the PEPS smart key, due to factors such as pressing or releasing the button, changes in the inductive load of the antenna, proximity of the human body, induction of the electromagnetic environment, etc., the main control IC, LF low-frequency receiving module, RF radio frequency transmitting module and other units in the smart key system It is susceptible to interference from static electricity or surges, causing abnormal operation or even damage.
Based on many years of experience in electromagnetic compatibility of automotive electronics and combined with the advantages of its own automotive grade products, Yint Electronics has proposed a comprehensive protection solution for the PEPS system vehicle base station (vehicle base station) and positioning tag (smart key) for user design reference.
The circuit protection of vehicle base stations mainly includes the following aspects:
The power PDU management in the PEPS system mainly includes the power supply for components such as the electronic steering column lock ESCL, and Yint Electronics TVS is used for surge protection.
Commonly used protective devices are:
SM8S24CA, SM8S33CA, SM8S33A, SM8S36CA, etc.
The specific selection needs to be based on the vehicle power systemand component power.
*Yint Electronics (independent patented product) SM8SxxCA device parameters
Part Number (Uni) | Reverse Stand off Voltage VR (Volts) | Breakdown Voltage VBR (Volts)@IT | Test Current IT(mA) | Maximum Reverse Leakage IR@ VR(μA) | Maximum IR@VRWM TJ=175 (uA) | Maximum Peak Pulse Current I pp (A) | Maximum Clamping Voltage VC @ Ipp (V) | |
Min .V | Max .V | |||||||
SM8S18CA | 18 | 20.00 | 22.10 | 5 | 10 | 150 | 226.0 | 29.2 |
SM8S22CA | 22 | 24.40 | 26.90 | 5 | 10 | 150 | 186.0 | 35.5 |
SM8S24CA | 24 | 26.70 | 29.50 | 5 | 10 | 150 | 170.0 | 38.9 |
SM8S26CA | 26 | 28.90 | 31.90 | 5 | 10 | 150 | 157.0 | 42.1 |
SM8S28CA | 28 | 31.10 | 34.40 | 5 | 10 | 150 | 145.0 | 45.4 |
SM8S33CA | 33 | 36.70 | 40.60 | 5 | 10 | 150 | 124.0 | 53.3 |
SM8S36CA | 36 | 40.00 | 44.20 | 5 | 10 | 150 | 114.0 | 58.1 |
The PEPS system communicates with the body control system BCM and other major components of the car through the CAN bus.
Yint Electronics provides automotive-grade CAN bus protection special device ESD24VAPB designed close to the CAN bus interface of the module.
*Some parameters of Yint Electronics ESD24VAPB
LIN bus communication is mainly used between the PEPS system and the electronic steering column lock ESCL.
LIN interface protection can use LIN special devices ESDLIN1524D3B, ESD24VAPB, etc. for protection.
2PEPS system LF low-frequency communication uses 125kHz frequency for communication. The 6 (or 8) antennas of the base station send out 125kHz signals to find the location of the tag (smart key) and match and wake it up. When the tag (smart key) is located in the car and the key is matched, the anti-theft controller IMMO and electronic steering column ESCL unlocking instructions can be given, and the driver can start the engine through the ignition button.
Changes in the antenna signal and equivalent load changes for the transmitting module require surge or electrostatic protection. It is recommended to use Yint Electronics 5V, SOD323 packaged electrostatic protection device ESD5V0D3B. The PCB layout design is recommended to be close to the antenna access port of the module.
*Some parameters of Yint Electronics ESD5V0D3B
The PEPS system controls the vehicle base station to wait for tag return instructions, and mainly uses 315MHz~433MHz radio frequency for communication. The PEPS system positioning tag (smart key) combines the door handle button switch instructions to send RF radio frequency encrypted signals to the vehicle base station. After matching, the vehicle base station will provide access control and unlock, and the occupants can enter the car.
For the RF radio frequency receiving module, we use Yint Electronics' low-capacitance electrostatic protection device ESDLC5V0D3B, SOD323, and the <1pF capacitance will not affect the normal communication of the signal. At the same time, it can clamp and protect the transient voltage at ps level. RF receiving module.
*Yint Electronics ESDLC5V0D3B device parameters
The PEPS system engine start button usually has an LED light color change indicator to indicate status information. In order to prevent static electricity from giving error information to the main control chip, the key-activated unit needs to add a small package electrostatic protection device. Yint Electronics' automotive grade electrostatic protection device ESD5V0D9B is packaged in SOD923 (dimensions: length, width and height 1.0mm, 0.5mm, 0.4mm) and can withstand up to 30kV electrostatic disturbance.
*Some parameters of Yint Electronics ESD5V0D9B
