什么是CAN收發(fā)器？

CAN收發(fā)器在整個(gè)CAN網(wǎng)絡(luò)中所處的位置如上圖所示。CAN收發(fā)器就是一塊類似232或485的轉(zhuǎn)換芯片，它的主要功能是將CAN控制器的TTL信號(hào)轉(zhuǎn)換成CAN總線的差分信號(hào)。

CAN是控制器區(qū)域網(wǎng)絡(luò)(Controller Area Network)的縮寫，代表將“智能"設(shè)備以及同一系統(tǒng)或子系統(tǒng)內(nèi)的傳感器和執(zhí)行器等連成網(wǎng)絡(luò)而特別開(kāi)發(fā)的串行總線系統(tǒng)。

根據(jù)控制器的CAN接口電壓可選擇3.3V或5V供電的CAN模塊，隔離CAN模塊正常輸入范圍為VCC±5%，主要考慮CAN總線電平能保持在典型值范圍內(nèi)，同時(shí)也使次級(jí)的CAN芯片工作在標(biāo)稱電源電壓附近。

對(duì)于單獨(dú)的CAN收發(fā)芯片，需要對(duì)芯片的VIO引腳接入與TXD信號(hào)電平相同的參考電壓，以匹配信號(hào)電平，若沒(méi)有VIO引腳，則應(yīng)保持信號(hào)電平與VCC保持一致。使用CTM系列隔離收發(fā)器時(shí)需要匹配TXD的信號(hào)電平與供電電壓一致，即3.3V標(biāo)準(zhǔn)CAN控制器接口或5V標(biāo)準(zhǔn)CAN控制器接口。

傳輸特性

CAN收發(fā)器的傳輸特性主要為三個(gè)參數(shù)：發(fā)送延遲、接收延遲、循環(huán)延遲。

The WT1040/WT1050 is the interface between the Controller Area Network (CAN) protocol controller and the physical bus, and can be applied to the fields of trucks, buses, cars, industrial control etc. It is primarily intended for high speed applications, up to 1 MBaud, in passenger cars. The device provides differential transmit capability to the bus and differential receive capability to the CAN controller, and fully compatible with the ISO 11898 standard.

Fully compatible with the ISO 11898 standard

Thermally protected；
Input levels compatible with 3.3 V and 5 V devices；
Transmit Data (TXD) dominant time-out function；
Very low-current standby mode with remote wake-up capability via the bus（TYP. 5uA）（WT1040)；
Silent mode in which the transmitter is disabled（WT1050)；
Transceiver in unpowered state disengages from the bus (zero load)；
At least 110 nodes can be connected；
High speed (up to 1 MBaud)；
Very low Electro Magnetic Emission (EME)；