Data Sheet

ADM3053

Rev. E | Page 15 of 18

APPLICATIONS INFORMATION

PCB LAYOUT

The ADM3053 signal and power isolated CAN transceiver contains

an isoPower integrated dc-to-dc converter, requiring no external

interface circuitry for the logic interfaces. Power supply bypassing

is required at the input and output supply pins (see Figure 28).

The power supply section of the ADM3053 uses a 180 MHz

oscillator frequency to pass power efficiently through its chip-

scale transformers. In addition, the normal operation of the

data section of the iCoupler introduces switching transients on

the power supply pins.

Bypass capacitors are required for several operating frequencies.

Noise suppression requires a low inductance, high frequency

capacitor, whereas ripple suppression and proper regulation

require a large value capacitor. These capacitors are connected

a combination of 100 nF and 10 nF be placed as shown in Figure 28

(C6 and C4). It is recommended that a combination of two

capacitors, with values of 100 nF and 10 µF, are placed between

of 100 nF and 10 µF as shown in Figure 28 (C5 and C8). Two

(GND2) with values of 100nF and 10nF as shown in Figure 28

(C9 and C7). The best practice recommended is to use a very low

inductance ceramic capacitor, or its equivalent, for the smaller

value. The total lead length between both ends of the capacitor

and the input power supply pin must not exceed 10 mm.

The ADM3053 features an internal split paddle, lead frame on the

bus side. For the best noise suppression, filter both the GND2

to-dc converter for high frequency currents. Use surface-mount

ferrite beads in series with the signals before routing back to the

device. See Figure 28 for the recommended PCB layout.

The impedance of the ferrite bead is chosen to be about 2 kΩ

between the 100 MHz and 1 GHz frequency range, to reduce

the emissions at the 180 MHz primary switching frequency and

the 360 MHz secondary side rectifying frequency and

harmonics.

GND1

1

NC

2

GND1

3

RxD

4

TxD

5

6

GND1

7

8

GND1

9

GND1

10

ADM3053

0.01µF 0.1µF

0.1µF

10µF

0.1µF 0.01µF

10µF 0.1µF

FERRITES

Figure 28. Recommended PCB Layout

In applications involving high common-mode transients, ensure

that board coupling across the isolation barrier is minimized.

Furthermore, design the board layout such that any coupling

that does occur equally affects all pins on a given component side.

Failure to ensure this can cause voltage differentials between pins

exceeding the absolute maximum ratings for the device, thereby

leading to latch-up and/or permanent damage.

The ADM3053 dissipates approximately 650 mW of power when

fully loaded. Because it is not possible to apply a heat sink to an

isolation device, the devices primarily depend on heat dissipation

into the PCB through the GND pins. If the devices are used at

high ambient temperatures, provide a thermal path from the GND

pins to the PCB ground plane. The board layout in Figure 28 shows

enlarged pads for Pin 1, Pin 3, Pin 9, Pin 10, Pin 11, Pin 14, Pin 16,

and Pin 20. Implement multiple vias from the pad to the ground

plane to reduce the temperature inside the chip significantly. The

dimensions of the expanded pads are at the discretion of the

designer and dependent on the available board space.

EMI CONSIDERATIONS

The dc-to-dc converter section of the ADM3053 must, of necessity,

operate at very high frequency to allow efficient power transfer

through the small transformers. This creates high frequency

currents that can propagate in circuit board ground and power

planes, causing edge and dipole radiation. Grounded enclosures

are recommended for applications that use these devices. If

grounded enclosures are not possible, good RF design practices

must be followed in the layout of the PCB. See the AN-0971

Application Note, Recommendations for Control of Radiated

Emissions with isoPower Devices, for more information.