ADuM263N datasheet(21/23 Pages) AD

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Data Sheet

ADuM260N/ADuM261N/ADuM262N/ADuM263N

Rev. 0 | Page 21 of 23

APPLICATIONS INFORMATION

PCB LAYOUT

The ADuM260N/ADuM261N/ADuM262N/ADuM263N digital

isolators require no external interface circuitry for the logic

interfaces. Power supply bypassing is strongly recommended at

the input and output supply pins (see Figure 22). Bypass

capacitors are connected between Pin 1 and Pin 8 for VDD1 and

between Pin 9 and Pin 16 for VDD2. The recommended bypass

capacitor value is between 0.01 μF and 0.1 μF. The total lead

length between both ends of the capacitor and the input power

supply pin must not exceed 10 mm.

VDD1

VIA

VIB

VIC

VID, VOD

VIE, VOE

VIF, VOF

GND1

VDD2

VOA

VOB

VOC

VID, VOD

VIE, VOE

VIF, VOF

GND2

Figure 22. Recommended Printed Circuit Board 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 of the device,

thereby leading to latch-up or permanent damage.

See the AN-1109 Application Note for board layout guidelines.

PROPAGATION DELAY RELATED PARAMETERS

Propagation delay is a parameter that describes the time it takes

a logic signal to propagate through a component. The propagation

delay to a Logic 0 output may differ from the propagation delay

to a Logic 1 output.

INPUT (VIx)

OUTPUT (VOx)

tPLH

tPHL

50%

Figure 23. Propagation Delay Parameters

Pulse width distortion is the maximum difference between these

two propagation delay values and is an indication of how

accurately the timing of the input signal is preserved.

Channel matching is the maximum amount the propagation

delay differs between channels within a single ADuM260N/

ADuM261N/ADuM262N/ADuM263N component.

Propagation delay skew is the maximum amount the propagation

delay differs between multiple ADuM260N/ADuM261N/

ADuM262N/ADuM263N components operating under the

same conditions.

JITTER MEASUREMENT

Figure 24 illustrates the eye diagram for the ADuM260N/

ADuM261N/ADuM262N/ADuM263N. The measurement was

taken using an Agilent 81110A pulse pattern generator at 150 Mbps

with pseudorandom bit sequences (PRBS) 2(n − 1), n = 14, for 5 V

supplies. Jitter was measured with the Tektronix Model 5104B

oscilloscope, 1 GHz, 10 GSPS with the DPOJET jitter and eye

diagram analysis tools. The result shows a typical measurement

on the ADuM260N/ADuM261N/ADuM262N/ADuM263N

with 490 ps p-p jitter.

TIME (ns)

–5

–10

Figure 24. ADuM260N/ADuM261N/ADuM262N/ADuM263N Eye Diagram

INSULATION LIFETIME

All insulation structures eventually break down when subjected

to voltage stress over a sufficiently long period. The rate of

insulation degradation is dependent on the characteristics of the

voltage waveform applied across the insulation as well as on the

materials and material interfaces.

The two types of insulation degradation of primary interest are

breakdown along surfaces exposed to the air and insulation wear

out. Surface breakdown is the phenomenon of surface tracking,

and the primary determinant of surface creepage requirements

in system level standards. Insulation wear out is the phenomenon

where charge injection or displacement currents inside the

insulation material cause long-term insulation degradation.

Surface Tracking

Surface tracking is addressed in electrical safety standards by

setting a minimum surface creepage based on the working voltage,

the environmental conditions, and the properties of the insulation

material. Safety agencies perform characterization testing on the

surface insulation of components that allows the components to be

categorized in different material groups. Lower material group

ratings are more resistant to surface tracking and, therefore, can

provide adequate lifetime with smaller creepage. The minimum

creepage for a given working voltage and material group is in each

system level standard and is based on the total rms voltage across

the isolation, pollution degree, and material group. The material

group and creepage for the ADuM260N/ADuM261N/

ADuM262N/ADuM263N isolators are presented in Table 9.

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