Intersil ISL32740EVAL2Z User Manual

User’s Manual

ISL32740EVAL2Z

User’s Manual: Evaluation Board

Industrial Precision

Rev 1.00 Aug 2017

USER’S MANUAL

LOGIC

I/O

RS-485

I/O

3.3V

SUPPLY

J5J2

J1

ISL32740EIAZ

ISOLATED
PROFIBUS

TRANSCEIVER

ISOLATED

DC/DC

CONVERTER

5V

3

ISL32740EVAL2Z

Evaluation Board

1. Overview

The ISL32740EVAL2Z board enables the evaluation of the ISL32740EIAZ isolated, half-duplex PROFIBUS
transceiver in a typical bus node application, used in isolated industrial networks.

1.1 Key Features

• Industry’s smallest isolated PROFIBUS transceiver

• Drive capability of up to 160 bus transceivers

• Isolated 3.3V to 5V DC/DC converter with regulated output

• Small total device footprint of 183mm

1.2 Specifications

This board has been configured and optimized for the following operating conditions:

• Up to 40Mbps data rate

•V

= 3.3V

CC

1.3 Ordering Information

2

UG125

Rev.1.00

Aug 24, 2017

Part Number Description

ISL32740EVAL2Z ISL32740EIAZ evaluation board

1.4 Related Literature

• For a full list of related documents, visit our website

• ISL32740E

product page

UG125 Rev.1.00 Page 2 of 10
Aug 24, 2017

Figure 1. Block Diagram

ISL32740EVAL2Z 2. Functional Description

2. Functional Description

The ISL32740E is an isolated, 40Mbps, half-duplex PROFIBUS transceiver. The device incorporates a patented refresh
circuit to maintain the correct output state with respect to data input. At power-up, the bus outputs follow the Truth Tables

The DE input should be held low during power-up to prevent false drive data pulses on the bus. This is accomplished by
connecting DE through a 10kΩ pull-down resistor to GND1.

This transceiver uses a differential input receiver for maximum noise immunity and common-mode rejection. Input
sensitivity is ±200mV, as required by the RS-485 specification.

The receiver input resistance meets the PROFIBUS “Unit Load” (UL) requirement of 54kΩ minimum. The receiver
includes a “fail-safe if open” function that ensures a high-level receiver output if the receiver inputs are unconnected
(floating). The receiver output is tri-statable through the active low RE

input.

The PROFIBUS driver is a differential output device that delivers at least 2.1V across a 54Ω purely differential load.
The driver features low propagation delay skew to maximize bit width and to minimize EMI.

The driver in the ISL32740E is tri-statable using the active high DE input. The outputs of the ISL32740E driver are not
slew rate limited, so faster output transition times allow data rates of at least 40Mbps.

Important Notice:

For convenience, an isolated DC/DC converter is used to provide the power supply across the isolation barrier. Its
isolation ratings, however, are lower than those of the transceiver. Therefore, ensure that the ground potential
difference between the left side (GND1, GND2) and the right side (GND3, GND4) of the board remain below 50VAC
(see Figure 2 on page 4

).

.

2.1 Truth Tables

Receiving

Inputs Outputs

RE

00 V

0 0 -0.05 > V

00 V

0 0 Inputs Open/Shorted 1

1 1 X High-Z

1 0 X High-Z*

Inputs Outputs

RE

X11101

X10110

0 0 X 0 High-Z High-Z

1 0 X 0 High-Z* High-Z*

Note: *Transceiver shutdown mode.

DE D ISODE B A

DE A-B RO

≥ -0.05V 1

AB

> -0.2V Undetermined

AB

≤ -0.2V 0

AB

Transmitting

UG125 Rev.1.00 Page 3 of 10
Aug 24, 2017