ADM2490EBRWZ Analog Devices Inc, ADM2490EBRWZ Datasheet - Page 12

• Manufacturer Part Number: ADM2490EBRWZ
• Description: IC TXRX RS-485 ISOLATED 16-SOIC
• Manufacturer: Analog Devices Inc
• Series: iCoupler®r

Specifications of ADM2490EBRWZ

• Inputs - Side 1/side 2: RS-485
• Number Of Channels: 1
• Isolation Rating: 5000Vrms
• Voltage - Supply: 4.75 V ~ 5.25 V
• Data Rate: 16Mbps
• Propagation Delay: 45ns
• Output Type: Logic
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Operating Temperature: -40°C ~ 105°C
• Device Type: Transceiver
• Ic Interface Type: RS485
• No. Of Drivers: 1
• Supply Voltage Range: 2.7V To 5.5V
• Driver Case Style: SOIC
• No. Of Pins: 16
• Operating Temperature Range: -40°C To +105°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADM2490E
CIRCUIT DESCRIPTION
ELECTRICAL ISOLATION
In the ADM2490E, electrical isolation is implemented on the
logic side of the interface. Therefore, the part has two main
sections: a digital isolation section and a transceiver section
(see Figure 21). The driver input signal, which is applied to the
TxD pin and referenced to logic ground (GND
across an isolation barrier to appear at the transceiver section
referenced to isolated ground (GND
input, which is referenced to isolated ground in the transceiver
section, is coupled across the isolation barrier to appear at the
RxD pin referenced to logic ground.
iCoupler Technology
The digital signals transmit across the isolation barrier using
iCoupler technology. This technique uses chip scale transformer
windings to couple the digital signals magnetically from one
side of the barrier to the other. Digital inputs are encoded into
waveforms that are capable of exciting the primary transformer
winding. At the secondary winding, the induced waveforms are
decoded into the binary value that was originally transmitted.
Positive and negative logic transitions at the input cause narrow
pulses (~1 ns) to be sent to the decoder via the transformer. The
decoder is bistable and is, therefore, either set or reset by the
pulses, indicating input logic transitions. In the absence of logic
transitions at the input for more than ~1 μs, a periodic set of
refresh pulses indicative of the correct input state are sent to
ensure dc correctness at the output. If the decoder receives no
internal pulses for more than about 5 μs, the input side is
assumed to be unpowered or nonfunctional, in which case the
output is forced to a default state (see Table 12).
RxD
TxD
2
). Similarly, the receiver
Figure 21. ADM2490E Digital Isolation and Transceiver Sections
DIGITAL ISOLATION
1
GND
V
), is coupled
ENCODE
DECODE
DD1
1
ISOLATION
BARRIER
Rev. A | Page 12 of 16
DECODE
ENCODE
TRUTH TABLES
The truth tables in this section use the abbreviations shown in
Table 10.
Table 10. Truth Table Abbreviations
Abbreviation
H
I
L
X
Table 11. Transmitting
V
On
On
Table 12. Receiving
V
On
On
On
On
On
Off
Off
DD1
DD1
Supply Status
GND
V
DD2
Supply Status
2
TRANSCEIVER
V
On
On
On
On
Off
On
Off
D
DD2
R
Description
High level
Indeterminate
Low level
Irrelevant
V
On
On
DD2
Inputs
A − B (V)
>0.2
<−0.2
−0.2 < A − B < +0.2
Inputs open
X
X
X
Y
Z
A
B
Input
TxD
H
L
Y
H
L
Outputs
Output
RxD
H
L
I
H
H
H
L
Z
L
H