ADM2582EBRWZ Analog Devices Inc, ADM2582EBRWZ Datasheet - Page 14

• Manufacturer Part Number: ADM2582EBRWZ
• Description: IC TXRX RS485 ISOLATED 20SOIC
• Manufacturer: Analog Devices Inc
• Series: isoPower®r

Specifications of ADM2582EBRWZ

• Inputs - Side 1/side 2: 1/1
• Number Of Channels: 3
• Isolation Rating: 2500Vrms
• Voltage - Supply: 3 V ~ 5.5 V
• Data Rate: 16Mbps
• Propagation Delay: 63ns
• Output Type: Differential
• Package / Case: 20-SOIC (7.5mm Width)
• Operating Temperature: -40°C ~ 85°C
• Device Type: Transceiver
• Ic Interface Type: RS485
• No. Of Drivers: 1
• Supply Voltage Range: 3V To 5.5V
• Driver Case Style: SOIC
• No. Of Pins: 20
• Operating Temperature Range: -40°C To +85°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADM2582E/ADM2587E
CIRCUIT DESCRIPTION
SIGNAL ISOLATION
The ADM2582E/ADM2587E signal isolation is implemented on
the logic side of the interface. The part achieves signal isolation
by having a digital isolation section and a transceiver section
(see Figure 1). Data applied to the TxD and DE pins and
referenced to logic ground (GND
isolation barrier to appear at the transceiver section referenced
to isolated ground (GND
output signal, referenced to isolated ground in the transceiver
section, is coupled across the isolation barrier to appear at the
RXD pin referenced to logic ground.
POWER ISOLATION
The ADM2582E/ADM2587E power isolation is implemented
using an isoPower integrated isolated dc-to-dc converter. The
dc-to-dc converter section of the ADM2582E/ADM2587E works
on principles that are common to most modern power supplies.
It is a secondary side controller architecture with isolated pulse-
width modulation (PWM) feedback. V
an oscillating circuit that switches current into a chip-scale air
core transformer. Power transferred to the secondary side is
rectified and regulated to 3.3 V. The secondary (V
controller regulates the output by creating a PWM control
signal that is sent to the primary (V
iCoupler data channel. The PWM modulates the oscillator
circuit to control the power being sent to the secondary side.
Feedback allows for significantly higher power and efficiency.
TRUTH TABLES
The truth tables in this section use the abbreviations found in
Table 12.
Table 12. Truth Table Abbreviations
Letter
H
L
X
Z
NC
Table 13. Transmitting (see Table 12 for Abbreviations)
DE
H
H
L
X
Inputs
Description
High level
Low level
Don’t care
High impedance (off )
Disconnected
TxD
H
L
X
X
2
). Similarly, the single-ended receiver
1
) are coupled across an
CC
Y
H
L
Z
Z
) side by a dedicated
CC
power is supplied to
Outputs
ISO
Z
L
H
Z
Z
) side
Rev. B | Page 14 of 20
Table 14. Receiving (see Table 12 for Abbreviations)
A − B
> −0.03 V
< −0.2 V
−0.2 V < A − B < −0.03 V
Inputs open
X
THERMAL SHUTDOWN
The ADM2582E/ADM2587E contain thermal shutdown circuitry
that protects the parts from excessive power dissipation during
fault conditions. Shorting the driver outputs to a low impedance
source can result in high driver currents. The thermal sensing
circuitry detects the increase in die temperature under this
condition and disables the driver outputs. This circuitry is
designed to disable the driver outputs when a die temperature
of 150°C is reached. As the device cools, the drivers are reenabled
at a temperature of 140°C.
OPEN- AND SHORT-CIRCUIT, FAIL-SAFE RECEIVER
INPUTS
The receiver inputs have open- and short-circuit, fail-safe
features that ensure that the receiver output is high when the
inputs are open or shorted. During line-idle conditions, when no
driver on the bus is enabled, the voltage across a terminating
resistance at the receiver input decays to 0 V. With traditional
transceivers, receiver input thresholds specified between −200 mV
and +200 mV mean that external bias resistors are required on the
A and B pins to ensure that the receiver outputs are in a known
state. The short-circuit, fail-safe receiver input feature eliminates
the need for bias resistors by specifying the receiver input
threshold between −30 mV and −200 mV. The guaranteed negative
threshold means that when the voltage between A and B decays
to 0 V, the receiver output is guaranteed to be high.
Inputs
RE
L or NC
L or NC
L or NC
L or NC
H
RxD
H
L
X
H
Z
Output