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How Does the ADM3252EABCZ Digital Isolator Work?

Integrated Circuits (ICs) come in different forms and usually have one role to play – to improve the overall functions of the applications or devices. Today, these ICs have been modeled into different forms, with each of these variants offering unique attributes to the target applications.

One of such models is the digital isolator, of which the ADM3252EABCZ is one them. In this article, you will learn how this digital isolator works.

What is a Digital Isolator?

According to Digi-Key, a digital isolator is an electrically-separating Integrated Circuit (IC), which helps in transferring digital signals among the separated circuits.

You want to rely on ADM3252EABCZ to separate signals coming to the circuits, while maintaining the status quo of improving the workings of the target applications.

The Isolation in Force

Is there any need to isolate the electronic signals? Yes, it helps in keeping each of the circuits fully functional and independent.

For this to work effectively, ADM3252EABCZ has been optimized with a series of isolation technologies, one of which is the isoPower integrated technology. The highpoint of this technology is the support for Digital-to-Digital (dc-to-dc) conversion.

This is imperative, seeing that at the core of the isoPower technology is the separation or isolation of the circuits. Thus, it may be impossible for an analog circuit to interface with a digital circuit and vice-versa. Therefore, the dc-to-dc isolated converter is a welcome development.

The 3.3-V Logic Receiver

ADM3252EABCZ uses a variety of logics, one of which is the 3.3-V logic receiver. But before delving into this, we want to mention that this circuit isolator has a dedicated transmitter driver that converts the 3.3-volts logic input levels into the corresponding RS-232 output levels.

For the 3.3-volts logic receiver, it is tied to the EIA/TIA-232E specifications. As such, it provides for the acceptance of the RS-232 input levels via its dedicated inverting level shifter. This inverting level shifter is responsible for the translation or conversion of the RS-232 input levels into the corresponding 3.3-volts output levels.

ADM3252EABCZ’s 3.3-volts logic receiver also works well with the noise impedance, irrespective of the density. For example, its logic receiver uses the Schmitt trigger input with a hysteresis level of 0.1-volt to keep the noisy input and the slow transition input free from errors.

Overvoltage or an excessive supply of current could potentially reduce the potentials of a circuit. That is why the ADM3252EABCZ’s pull-down resistor measured at 5 kΩ is in place. It helps to protect the logic receiver against overvoltage, especially if it measures above ±30 V.

Data Rate

The speed of transferring data to, from and across the circuits is an important consideration when choosing a digital isolator. ADM3252EABCZ has an estimated data rate of 460 kilobytes per second. This is in conformation to the EIA/TIA-232E and the ITU-T V.28 specifications.

Although this is the maximum data rate, as per the datasheet, it is tied to one factor. For the data rate to clock up to that figure, it is expected that the higher data rates of 460 kbps are feasible, only when the ADM3252EABCZ is running at a reduced RS-232 capacitive load levels.

Below is a list of the additional technical specifications of this ADM3252EABCZ, represented in a table:

Technical SpecificationsDescription
Type of ChannelUnidirectional
Technology UsedMagnetic Coupling Technology
Common Mode Transient Immunity (minimum)25kV/µ
Typical Rise and Fall TimeMaximum of 2.5 nanoseconds (ns)
Number of Channels Used4
Power IsolationYes
Operating Temperature (minimum to maximum)Between 40˚C and 85˚C
Voltage (isolation)2500Vrms
Types of Packages44-LBGA and CSPBGA
Voltage Supply (minimum to maximum)3 volts to 5.5 volts

ADM3252EABCZ’s Power Transfer Process

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Since ADM3252EABCZ uses the digital isolator framework and combines it with the magnetic coupling technology, how then does it transfer power?

The power, voltage or current transmission process is enabled by the isoPower technology. It uses a set of high-frequency switching elements to transfer, move or return power to the different “isolated” circuits. All these are done via the dedicated transformer.

The Commonplace for Total Isolation

Even though the separated circuits get power transmitted to and from them with ease, ADM3252EABCZ still maintains the isolation capabilities. To keep this running, it uses the chip-scale iCoupler technology to enable a total isolation solution. This isolation involves the separation or isolation of the dedicated dc-to-dc converter from the logic signals.

Digital Isolator Protection Features

ADM3252EABCZ complies with the Electrostatic Discharge (ESD) standards of protecting circuits, and in extension, consumer electronics.

The highpoint of the protection is the fine-tuning of the target device’s security framework in line with the IEC 61000-4-2 system-level testing specifications for ESD devices. The specifications highlight the subjection of the device to a system-level test to confirm the viability to survive normal operations.

To that end, both the Contact Discharge and the Air Gap Discharge have been designed to shore up these specifications.

ADM3252EABCZ uses these two discharge options to meet the ESD system-level testing specifications.

The Air Gap Discharge, according to Maxim Integrated, is a “method of testing ESD-protection structures in which the ESD generator is discharged through an air gap.”

Typically, the discharge takes place between the Device Under Test (DUT), which, in this case, is the ADM3252EABCZ; and the generator. Therefore, the DUT is to be placed close to the ESD test gun to confirm a discharge.

On the other hand, the Contact Discharge has to do with the ESD system-level testing that involves the discharge of the Electrostatic Discharge (ESD) pulse from the ESD test gun. The pulse is discharged directly to the Device Under Test (DUT).

By default, the ESD system-level testing process specifies the equivalenting of these discharge processes. For that purpose, the Level standard is used to make a Contact Discharge of 8 kV to be equivalent to the 15 kV Air Discharge.

That is exactly the ESD protection rating on ADM3252EABCZ. The Contact Discharge is pegged at ±8 kV, while the Air Discharge is pegged at ±15 kV.

Conclusion

ADM3252EABCZ isolates or separates circuits (electrically) to help them function independently, while using a total of 4 channels to switch the signals unidirectionally.