Intersil ISL32741EVAL1Z User Manual
User’s Manual
ISL32741EVAL1Z
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
ISL32741EIBZ
ISOLATED
RS-485
TRANSCEIVER
ISOLATED
DC-DC
CONVERTER
5V
3
ISL32741EVAL1Z
Evaluation Board
1. Overview
The ISL32741EVAL1Z board enables the evaluation of the ISL32741EIBZ reinforced isolated, half-duplex RS-485
transceiver in a typical bus node application, used in isolated industrial networks.
1.1 Key Features
• Drive capability of up to 160x1/5UL-transceivers
• Isolated 3.3V to 5V DC/DC converter with regulated output
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
Part Number Description
ISL32741EVAL1Z ISL32741EIBZ evaluation board
UG126
Rev.1.00
Aug 24, 2017
1.4 Related Literature
• For a full list of related documents, visit our website
• ISL32741E
product page
Figure 1. Block Diagram
UG126 Rev.1.00 Page 2 of 10
Aug 24, 2017
ISL32741EVAL1Z 2. Functional Description
2. Functional Description
The ISL32741E is a reinforced isolated, 40Mbps, half-duplex RS-485 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
tables in “
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 is 54kΩ minimum. The receiver includes a “full fail-safe” function that ensures a highlevel receiver output if the receiver inputs are unconnected (floating) or shorted. The receiver output is tri-statable
through the active low RE
The 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 ISL32741E is tri-statable through the active high DE input. The outputs of the ISL32741E 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
Truth Tables”.
input.
).
2.1 Truth Tables
Receiving
Inputs Output
RE
00 V
0 0 -0.05V > 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
UG126 Rev.1.00 Page 3 of 10
Aug 24, 2017
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