8.4 Device Functional Modes

Table 8-2 and Table 8-3 list the driver and receiver functions. Table 8-4 lists the functional modes for the

ISO1044B device.

Table 8-2. Driver Function Table

INPUT

OUTPUTS

DRIVEN BUS STATE

TXD(1)

CANH(1)

CANL(1)

L

H

L

Dominant

H

Z

Z

Recessive

(1)

H = high level, L = low level, Z = common mode (recessive) bias to VCC / 2. See Figure 8-1 and

Figure 8-2 for bus state and common mode bias information.

Table 8-3. Receiver Function Table

DEVICE MODE

CAN DIFFERENTIAL INPUTS

VID = VCANH – VCANL (3)

BUS STATE

RXD PIN(1)

Normal

VID ≥ VIT(MAX)

Dominant

L

VIT(MIN) < VID < VIT(MAX)

Undefined

Undefined

VID ≤ VIT(MIN)

Recessive

H

Open (VID ≈ 0 V)

Open

H

(1)

H = high level, L = low level

Table 8-4. Function Table

DRIVER(1)

RECEIVER

INPUTS

OUTPUTS

BUS STATE

DIFFERENTIAL INPUTS

VID = CANH–CANL(3)

OUTPUT

RXD

BUS STATE

TXD

CANH

CANL

L(2)

H

L

DOMINANT

VID ≥ VIT(MAX)

L

DOMINANT

H

Z

Z

RECESSIVE

VIT(MIN) < VID < VIT(MAX)

Undefined

Undefined

Open

Z

Z

RECESSIVE

VID ≤ VIT(MIN)

H

RECESSIVE

X if VCC1 supply

< UVVCC1

Z

Z

RECESSIVE

Open (VID ≈ 0 V)

H

RECESSIVE

(1)

H = high level; L = low level; X = irrelevant; Z = high impedance

(2)

Logic low pulses to prevent dominant time-out.

(3)

See Receiver Electrical Characteristics section for input thresholds.

ISO1044

SLLSFB0A – MARCH 2020 – REVISED JULY 2020

www.ti.com

22

Submit Document Feedback

Copyright © 2020 Texas Instruments Incorporated

Product Folder Links: ISO1044