7.3 Feature Description

Table 7-1 lists the device features.

Table 7-1. Device Features

PART NUMBER

CHANNEL DIRECTION

RATED ISOLATION

MAXIMUM DATA RATE

DEFAULT OUTPUT

ISO7840

4 Forward,

5700VRMS / 8000VPK (1)

100Mbps

High

0 Reverse

ISO7840F

4 Forward,

5700VRMS / 8000VPK (1)

100Mbps

Low

0 Reverse

(1)

See Insulation Specifications for detailed isolation ratings.

7.3.1 Electromagnetic Compatibility (EMC) Considerations

Many applications in harsh industrial environment are sensitive to disturbances such as electrostatic

discharge (ESD), electrical fast transient (EFT), surge, and electromagnetic emissions. These electromagnetic

disturbances are regulated by international standards such as IEC 61000-4-x and CISPR 22. Although system-

level performance and reliability depends, to a large extent, on the application board design and layout, the

ISO7840 device incorporates many chip-level design improvements for overall system robustness. Some of

these improvements include

• Robust ESD protection cells for input and output signal pins and inter-chip bond pads.

• Low-resistance connectivity of ESD cells to supply and ground pins.

• Enhanced performance of high voltage isolation capacitor for better tolerance of ESD, EFT and surge events.

• Bigger on-chip decoupling capacitors to bypass undesirable high energy signals through a low impedance

path.

• PMOS and NMOS devices isolated from each other by using guard rings to avoid triggering of parasitic

SCRs.

• Reduced common mode currents across the isolation barrier by providing purely differential internal

operation.

7.4 Device Functional Modes

Table 7-2 lists the ISO7840 functional modes.

Table 7-2. Function Table

VCCI

VCCO

INPUT

(INx)(2)

OUTPUT

ENABLE

(EN2)

OUTPUT

(OUTx)

COMMENTS

PU

PU

H

H or open

H

Normal Operation:

A channel output assumes the logic state of the input.

L

H or open

L

Open

H or open

Default

Default mode: When INx is open, the corresponding channel output goes to

the default logic state. Default= High for ISO7840 and Low for ISO7840F.

X

PU

X

L

Z

A low value of Output Enable causes the outputs to be high-impedance

PD

PU

X

H or open

Default

Default mode: When VCCI is unpowered, a channel output assumes the

logic state based on the selected default option. Default= High for IISO7840

and Low for ISO7840F.

When VCCI transitions from unpowered to powered-up, a channel output

assumes the logic state of the input.

When VCCI transitions from powered-up to unpowered, channel output

assumes the selected default state.

X

PD

X

X

Undetermined

When VCCO is unpowered, a channel output is undetermined (1).

When VCCO transitions from unpowered to powered-up, a channel output

assumes the logic state of the input

(1)

The outputs are undetermined when 1.7V < VCCI, VCCO < 2.25V.

(2)

A strongly driven input signal can weakly power the floating VCC through an internal protection diode and cause undetermined output.

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ISO7840, ISO7840F

SLLSEN2C – JULY 2015 – REVISED JULY 2025

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