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dc1903af

DEMO MANUAL DC1903A

Description

LTM2889

Isolated CAN µModule

Transceiver Plus Power

Demonstration circuit 1903A is an isolated CAN μModule®

transceiver plus power featuring the LTM®2889. The demo

circuit features an EMI optimized circuit configuration and

printed circuit board layout. All components are integrated

into the μModule isolator. The demo circuit operates from

a single supply on VCC. The part generates an isolated

L

, LT, LTC, LTM, Linear Technology, µModule, and the Linear logo are registered trademarks of

Linear Technology Corporation. All other trademarks are the property of their respective owners.

performance summary

operating principles

output voltage on VCC2 and communicates all necessary

signalingacrosstheisolationbarrierthroughLTC’sisolator

µModule technology.

Design files for this circuit board are available at

http://www.linear.com/demo/DC1903A

Specifications are at TA = 25°C

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

VCC

Input Supply Range

LTM2889-3

3.0

3.3

3.6

V

LTM2889-5

4.5

5.0

5.5

V

VCC2

Regulated Output Voltage

ILOAD = 100mA, LTM2889-3

ILOAD = 150mA, LTM2889-5

4.75

5

5.25

V

fMAX

Maximum Data Rate

4

Mbps

VIORM

Maximum Working Insulation Voltage

GND to GND2

560

VDC

400

VRMS

Common Mode Transient Immunity

30

kV/µs

The LTM2889 contains an isolated DC/DC converter that

delivers power to VCC2 at 5V from the input supply VCC.

IsolationismaintainedbytheseparationofGNDandGND2

where significant operating voltages and transients can

exist without affecting the operation of the LTM2889. The

logic side ON pin enables or shuts down the LTM2889.

All logic side signals are referenced to the logic supply

pin VL, connected to the input supply voltage VCC. The

LTM2889 is available with two input voltage ranges, 3V

to 3.6V (LTM2889-3) or 4.5V to 5.5V (LTM2889-5). The

isolated side and CAN interface is capable of operating at

3.3V. The VCC2 voltage is jumper selectable for either 5V

or 3.3V operation.

CAN signaling is controlled by the logic input TXD and

the silent pin S. RE controls the RXD output. Connection

to the transceiver pins (CANL and CANH) allows for half-

duplex communication on the isolated side of the demo

circuit. Termination resistors are included on the demo

circuit, with support for split termination to reduce com-

mon mode perturbations.

Data on the TXD input is transmitted differentially on

CANH-CANL when the silent pin (S) is low. Differential

data received on CANH-CANL is delivered at the RXD

output when RE is low. The CAN driver features adjust-

able slew rate via RV1 connected to the RS pin. A jumper

easily allows selection between a fixed fast slew rate and

adjustable rate.