ADM2490EBRWZ Analog Devices Inc, ADM2490EBRWZ Datasheet - Page 14

• 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
APPLICATIONS INFORMATION
ISOLATED POWER SUPPLY CIRCUIT
The ADM2490E requires isolated power capable of 5 V at up
to approximately 65 mA (this current is dependent on the data
rate and termination resistors used) to be supplied between the
V
center-tapped transformer and LDO can be used to generate the
isolated 5 V supply, as shown in Figure 25. The center-tapped
transformer provides electrical isolation of the 5 V power supply.
The primary winding of the transformer is excited with a pair of
square waveforms that are 180° out of phase with each other. A
pair of Schottky diodes and a smoothing capacitor are used to
create a rectified signal from the secondary winding. The
linear voltage regulator provides a regulated power supply to the
bus-side circuitry (V
PCB LAYOUT
The ADM2490E isolated RS-485 transceiver requires no external
interface circuitry for the logic interfaces. Power supply bypass-
ing is required at the input and output supply pins (see Figure 24).
Bypass capacitors are conveniently connected between Pin 1
and Pin 2 for V
capacitor value should be between 0.01 μF and 0.1 μF. The total
DD2
and the GND
DD1
2
and between Pin 15 and Pin 16 for V
pins. A transformer driver circuit with a
DD2
) of the ADM2490E.
TRANSFORMER
DRIVER
V
CC
Figure 25. Isolated Power-Supply Circuit
ADP3330
DD2
V
CC
V
GND
V
. The
ADM2490E
DD1
CC
ISOLATION
BARRIER
Rev. A | Page 14 of 16
1
78253
V
GND
SD103C
SD103C
DD2
2
lead length between both ends of the capacitor and the input
power-supply pin should not exceed 20 mm. Bypassing between
Pin 1 and Pin 8 and between Pin 9 and Pin 16 should also be
considered unless the ground pair on each package side is
connected close to the package.
In applications involving high common-mode transients, care
should be taken to ensure that board coupling across the isola-
tion barrier is minimized. Furthermore, the board layout should
be designed such that any coupling that does occur equally affects
all pins on a given component side. Failure to ensure this could
cause voltage differentials between pins exceeding the absolute
maximum ratings of the device, thereby leading to latch-up or
permanent damage.
22µF
GND
GND
GND
V
RxD
TxD
Figure 24. Recommended Printed Circuit Board Layout
DD1
NC
NC
IN
SD
1
1
1
ADP3330
GND ERR
OUT
NC = NO CONNECT
ADM2490E
5V
10µF
V
GND
A
B
NC
Z
Y
GND
DD2
2
2