2.2 Device Behavior

The following tables show the truth tables for the Si8285 and Si8286.

Table 2.1. Si8285 Truth Table

IN+

IN–

VDDA State

VDDB–VMID

State

Desaturation

State

VH

VL

RDY

FLTb

H

H

Powered

Powered

Undetected

Hi-Z

Pull-down

H

H

H

L

Powered

Powered

Undetected

Pull-up

Hi-Z

H

H

L

X

Powered

Powered

Undetected

Hi-Z

Pull-down

H

H

X

X

Powered

Unpowered

—

—

—

L

H

X

X

Powered

Powered

Detected

Hi-Z

Pull-down1

H

L

Note:

1. Driver state after soft shutdown.

2. This table is valid if RSTb is deactivated (high). For further information please refer to Reset (RSTb) Pin description.

Table 2.2. Si8286 Truth Table

IN+

IN–

VDDA State

VDDB–VMID State

Desaturation State

VO

FLTb

H

H

Powered

Powered

Undetected

Low

H

H

L

Powered

Powered

Undetected

High

H

L

X

Powered

Powered

Undetected

Low

H

X

X

Powered

Powered

Detected

Low1

L

Note:

1. Driver state after soft shutdown.

2.3 Main Features

Input

The IN+ and IN– inputs to the Si828x devices act as a complementary pair. If IN– is held low, then IN+ will act as an active-high input

for driver control. Alternatively, if IN+ is held high, then IN– can be used as an active-low input for driver control. When IN– is used as

the control signal, taking IN+ low will hold the output driver low.

Output

The Si8285 and Si8286 devices are different in how the driver output is presented. The Si8285 has separate pins for gate drive high

(VH) and gate drive low (VL). This makes it simple to use different gate resistors to control IGBT VCE or SiC FET VDS rise and fall

time. The Si8286 has both actions combined in the single VO pin. A weak internal pulldown resistor of about 200 kΩ is provided to

ensure that the driver output defaults to low if power on the secondary side is interrupted.

Desaturation Detection

The Si828x provides sufficient voltage and current to drive and keep the SiC FET or IGBT in saturation during on time to minimize

power dissipation and maintain high efficiency operation. However, abnormal load conditions can force the SiC FET or IGBT out of

saturation and cause permanent damage to the switch.

To protect the SiC FET or IGBT during abnormal load conditions, the Si828x detects a switch desaturation condition, shuts down the

driver upon detecting a fault, and provides a fault indication to the controller. These integrated features provide desaturation protection

with minimum external BOM cost.

Si8285/86 Data Sheet • Product Overview

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

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Rev. 2.0 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • October 12, 2021

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