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ADM2461E/ADM2463E

Data Sheet

Rev. 0 | Page 16 of 21

THEORY OF OPERATION

ROBUST LOW POWER DIGITAL ISOLATOR

The ADM2461E/ADM2463E feature a low power, digital isolator

block to galvanically isolate the primary and secondary sides of the

device. The use of coplanar transformer coils with an on or off

keying modulation scheme allows high data throughput across

the isolation barrier while minimizing any radiated emissions.

This architecture provides a robust digital isolator with immunity

to common-mode transients >250 kV/μs across the full

temperature and supply range of the device. The digital isolator

circuitry features a flexible VDD1 power supply with an input

voltage range of 1.7 V to 5.5 V.

CHANNEL 2 (VCM)

CH1 2.0V

100ns/DIV

CH3 2.0V

CH2 1kV

CHANNEL 3 (RxD)

CHANNEL 1 (TxD)

Figure 39. Switching Correctly in the Presence of >250 kV/μs

Common-Mode Transients

HIGH DRIVER DIFFERENTIAL OUTPUT VOLTAGE

The ADM2461E/ADM2463E feature a proprietary transmitter

architecture with a low driver output impedance that results in

an increased differential output voltage. This architecture is useful

when operating the device at lower data rates over long cable

runs where the dc resistance of the transmission line dominates

the signal attenuation. In these applications, the increased

differential voltage extends the reach of the device to longer

cable lengths. When operated as a 5 V transceiver (VDD2 > 4.5 V),

the ADM2461E/ADM2463E meet or exceed the Profibus

requirement of a minimum 2.1 V differential output voltage.

IEC61000-4-2 ESD PROTECTION

ESD is the sudden transfer of electrostatic charge between bodies

at different potentials, which is either caused by near contact or

induced by an electric field. ESD has the characteristics of a high

current in a short time period. The primary purpose of the

IEC61000-4-2 test is to determine system immunity to external

ESD events outside the system during operation. IEC61000-4-2

describes testing using two coupling methods: contact discharge

and air discharge. Contact discharge implies a direct contact

between the discharge gun and the equipment under test (EUT).

During air discharge testing, the charged electrode of the discharge

gun is moved toward the EUT until a discharge occurs as an arc

across the air gap. The discharge gun does not make direct contact

with the EUT during air discharge testing. Factors including

humidity, temperature, barometric pressure, distance, and rate

of approach to the EUT affect the results and repeatability of

the air discharge test. Air discharge testing is a more accurate

representation of an actual ESD event than the contact discharge

method but is not as repeatable. Therefore, contact discharge is

the preferred test method. During testing, the EUT data port is

subjected to at least 10 positive and 10 negative single discharges.

Test voltage selection depends on the system end environment.

Figure 40 shows the 8 kV contact discharge current waveform,

as described in the IEC61000-4-2 specification. Waveform

parameters include rise times of <1 ns and pulse widths of ~60 ns.

tR = 0.7ns TO 1ns

IPEAK

I30ns

I60ns

30A

90%

16A

10%

30ns

60ns

TIME

Figure 40. IEC61000-4-2 ESD Waveform (8 kV)

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