TH8055

Single Wire CAN Transceiver

2. Functional Description

2.1

2.2

TxD Input Pin

TxD Polarity

TxD = logic 1 (or floating) on this pin produce an undriven or recessive bus state (low bus voltage)

TxD = logic 0 on this pin produce either a bus normal or a bus high voltage dominant state depending on the

transceiver mode state (high bus voltage)

If the TxD pin is driven to a logic low state while the sleep mode (Mode0=0 and Mode1=0) is activated, the

transceiver not drive the CANH pin to the dominant state.

The transceiver provides an internal pull up current on the TxD pin which will cause the transmitter to default

to the bus recessive state when TxD is not driven.

TxD input signals are standard CMOS logic levels.

Timeout Feature

In case of a faulty blocked dominant TxD input signal the CANH output is switched off automatically after the

specified TxD timeout reaction time to prevent a dominant bus.

The transmission is continued by next TxD L to H transition without delay.

Mode 0 and Mode 1 pins

The transceiver provides a weak internal pull down current on each of these pins which causes the

transceiver to default to sleep mode when they are not driven. The mode input signals are standard CMOS

logic level.

M0

M1

Mode

L

L

Sleep mode

H

L

High speed mode

L

H

Wake up

H

H

Normal mode

Sleep Mode

Transceiver is in low power state, waiting for wake up via high voltage signal or by mode pins change to any

state other than 0,0. In this state, the CANH pin is not in the dominant state regardless of the state of the

TxD pin.

High Speed Mode

This mode allows high speed download with bitrates up to 100Kbit/s. The output waveshaping circuit is

disabled in this mode. Bus transmitter drive circuits for those nodes which are required to communicate in

high speed mode are able to drive reduced bus resistance in this mode (see Table Static Characteristics).

High speed communications shall utilize the normal mode signal voltage levels as specified in Static

Characteristics.

TH8055 - Datasheet

Page 4 of 20

3901008055

May 2004

Rev 005