8 Detailed Description

8.1 Overview

The ISO1044B device is a digitally isolated CAN transceiver that offers ±58-V DC bus fault protection and ±12-V

common-mode voltage range. The device supports up to 5-Mbps data rate in CAN FD mode allowing much

faster transfer of payload compared to classic CAN. The ISO1044B device has an isolation withstand voltage of

3000 VRMS with a surge isolation voltage of 5kVPK. The device can operate from 1.8-V, 2.5-V, 3.3-V, and 5-V

supplies on side 1 and a 5-V supply on side 2. This supply range is of particular advantage for applications

operating in harsh industrial environments because the low voltage on side 1 enables the connection to low-

voltage microcontrollers for power conservation, whereas the 5 V on side 2 maintains a high signal-to-noise ratio

of the bus signals.

8.2 Functional Block Diagram

+

±

RXD

TXD

VCC1

GND1

VCC2

GND2

CANH

CANL

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8.3 Feature Description

8.3.1 CAN Bus States

The CAN bus has two states during operation: dominant and recessive. A dominant bus state, equivalent to logic

low, is when the bus is driven differentially by a driver. A recessive bus state is when the bus is biased to a

common mode of VCC / 2 through the high-resistance internal input resistors of the receiver, equivalent to a logic

high. The host microprocessor of the CAN node uses the TXD pin to drive the bus and receives data from the

bus on the RXD pin. See Figure 8-1 and Figure 8-2.

ISO1044

SLLSFB0A – MARCH 2020 – REVISED JULY 2020

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