MAX13051ASA+ Datasheet MAX13051ASA+, MAX13051ESA+, MAX13051ESA+T | P7-P9

Maxim Integrated

MAX13051

±80V Fault-Protected Can Transceiver

with Autobaud

Typical Operating Characteristics (continued)

= +5V, R

= 60Ω, C

= 100pF, T

= +25°C, unless otherwise specified.)

DRIVER PROPAGATION DELAY,

= GND)

MAX13051 toc11

200ns/div

TXD

(2V/div)

DIFF

(1V/div)

LOOPBACK PROPAGATION DELAY

vs. R

MAX13051 toc12

(kΩ)

LOOPBACK PROPAGATION DELAY (µs)

18016014012010080604020

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0 200

RECESSIVE

DOMINANT

PIN NAME FUNCTION

1 TXD Transmit Data Input. TXD is a CMOS/TTL-compatible input from a CAN controller.

2 GND Ground

Supply Voltage. Bypass V

to GND with a 0.1µF capacitor.

4 RXD

Receive Data Output. RXD is a CMOS/TTL-compatible output from the physical bus lines CANH and CANL.

AUTOBAUD

Autobaud Input. Drive AUTOBAUD low for normal operation. Drive AUTOBAUD high for autobaud

operation. When operating in autobaud mode, TXD is looped back to RXD without applying a differential

signal at CANH and CANL.

6 CANL CAN Bus Line Low

7 CANH CAN Bus Line High

8RS

Mode-Select Input. Drive RS low or connect to GND for high-speed operation. Connect a resistor between

RS and GND to control output slope. Drive RS high to put into standby mode.

Pin Description

MAX13051

±80V Fault-Protected Can Transceiver

with Autobaud

Maxim Integrated

Detail Description

±80V Fault Tolerant

The MAX13051 features ±80V fault protection. This

extended voltage range of CANH and CANL allows

communication in high-voltage systems up to 80V.

Operating Modes

High-Speed Mode

The MAX13051 can achieve transmission rates of up to

1Mbps when operating in high-speed mode. To oper-

ate in high-speed mode, short RS to ground.

Slope-Control Mode

Connect a resistor from RS to ground to select slope-

control mode (Table 1). In slope-control mode, CANH

and CANL slew rates are controlled by the resistor,

(16kΩ≤R

≤ 200kΩ), connected between RS and

GND. Controlling the rise and fall slopes reduces high-

frequency EMI and allows the use of an unshielded-

twisted pair or a parallel pair of wires as bus lines. The

slew rate can be approximated using the formula

below:

where, SR is the desired slew rate and R

is in kΩ.

Standby Mode

In standby mode (RS = high), the transmitter is

switched off and the receiver is switched to a low-cur-

rent/low-speed state. The supply current reduces to

15µA to detect and recognize a wake-up event on the

bus line. During standby mode, the bus line is moni-

tored with a low-differential comparator. Once the com-

parator detects a dominant bus level greater than

WAKE

, RXD pulls low.

Autobaud Mode

The MAX13051 logic-controlled autobaud input allows

a microcontroller to compute the incoming baud rate

without destroying CAN protocol communication. When

operating in autobaud mode, TXD is looped back to

RXD without applying a differential signal at CANH and

CANL. See Figure 4.

SR V s

/ µ

()

≈

250

DRIVER

THERMAL

SHUTDOWN

TIMEOUT

AND SLOPE-

CONTROL

MODE

WAKE-UP MODE

CONTROL

WAKE-UP

FILTER

MUX

AUTOBAUD

CIRCUITRY

MAX13051

CANH

CANL

TXD

RXD

AUTOBAUD

ENABLE

GND

Figure 3. MAX13051 Functional Diagram

Maxim Integrated

MAX13051

±80V Fault-Protected Can Transceiver

with Autobaud

Transmitter

The transmitter converts a single-ended input (TXD)

from the CAN controller to differential outputs for the

bus lines (CANH, CANL). The truth table for the trans-

mitter and receiver is given in Table 2.

TXD Dominant Timeout

The MAX13051 provides a transmitter-dominant timeout

that prevents erroneous CAN controllers from clamping

the bus to a dominant level by maintaining a continuous

low TXD signal. When the TXD remains in the dominant

state for greater than 1ms (max), the transmitter

becomes disabled, driving the bus line to a recessive

state (Figure 5). After a dominant timeout fault, the

MAX13051’s transmitter becomes enabled upon

detecting a rising edge at TXD.

Receiver

The receiver reads differential inputs from the bus lines

(CANH, CANL) and transfers this data as a single-

ended output (RXD) to the CAN controller. It consists of

a comparator that senses the difference, V

DIFF

(CANH - CANL), with respect to an internal threshold of

0.7V. If this difference is positive, (V

DIFF

> 0.9V), a

logic-low is present at RXD. If negative, (V

DIFF

< 0.5V),

a logic-high is present. The receiver always echoes the

CAN bus data when not operating in autobaud mode.

Table 1. Mode Selection Truth Table

CONDITION FORCED AT PIN RS MODE RESULTING CURRENT AT RS

≤ 0.3V x V

High Speed 200µA ≤

RS|

≤ 500µA

0.4V x V

< V

≤ 0.6V x V

Slope Control 10µA ≤

RS|

≤ 200µA

≥ 0.75V x V

Standby

RS|

≤ 10µA

TXD

RXD

CANH - CANL

TXD

RXD

AUTOBAUD

TRANSMITTER

INPUT

RECEIVER

OUTPUT

Figure 4. MAX13051 Autobaud Timing Diagram

Table 2. Transmitter and Receiver Truth Table when Not Connected to the Bus

TXD RS CANH CANL BUS STATE RXD

Low V

≤ 0.75V x V

High Low Dominant Low

High or Float V

≤ 0.75V x V

/ 2 V

/ 2 Recessive High

≥ 0.75V x V

ICM

GND R

ICM

GND Recessive High

Common-mode input resistance.

P1-P3 P4-P6 P7-P9 P10-P12

MAX13051ASA+

Mfr. #:

Buy MAX13051ASA+

Manufacturer:

Maxim Integrated

Description:

CAN Interface IC CAN Transceiver w/80V Fault Protect

Lifecycle:

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MAX13051ASA+

MAX13051ASA+

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