Rev. D 09/19

5

SIC1182K

www.power.com

Figure 7.

Primary-Side of Example Circuitry.

Application Example

This example describes how to set up the SIC1182K to use overvoltage

limitation with a chain of TVS-diodes between the SiC MOSFET device

Drain and SIC1182K SNS pin as well as a short-circuit detection via a

resistive network also connected to the SNS pin.

Primary-Side

For the input the circuitry of Figure 6 is recommended, when using

15 V input logic. R

1 and R2 represent a voltage divider to get a 5 V

signal at the IN pin. If additional filtering is required a capacitor C

F can

be placed in parallel to R

2 as depicted in Figure 7. The time constant

τ can be calculated by Equation (1). In case direct 5 V logic is used at

the IN pin, R

2 can be omitted and R1 can be reduced to 100 Ω.

(1)

t

RR

RR

CF

12

12

#

#

=

+

The pull up resistor R

SO shall be connected to VCC and SO, with a

value of 1 kΩ, to provide at least 5 mA to SO (open drain) in a fault

condition. The primary-side power supply is connected to VCC and

COM, where C1 is buffering V

VCC and C2 acts as high frequency filter.

Secondary-Side

The secondary-side power supply is connected to VISO and COM as

shown in Figure 8. It is for instance recommended for SiC MOSFET

to use V

TOT = 20 V, to get VGH = 15 V for turn-on referenced to VEE

and V

GL = -5 V referenced to VEE for turn-off, to avoid additional

components.

For each µC of semiconductor’s gate charge a buffer capacitor of at

least 3 µF shall be placed at VEE to COM (C

S1) as well as between

VISO and VEE (C

S2). A 10 nF capacitor is connected between GH and

VGXX.

To ensure gate voltage stabilization and drain current limitation

during short-circuit the gate is connected to V

VISO through Schottky

diode D

STO.

To avoid parasitic turn-on during system power-on, the gate is

connected to COM via a 22 kΩ resistor R

DIS.

The SNS pin has an alternating function that can be used for an

overvoltage limitation, the so called Advanced Active Clamping,

via a TVS-diodes chain during the turn-off transient as well as for

a short-circuit detection via a resistive network during the turn-on

transient.

The Advanced Active Clamping is triggered with the current I

SNS

flowing into the SNS pin of the SIC1182K which gradually reduces the

GL-current down to typically 20 mA with increased I

SNS. This increas-

es the effectiveness of the Basic Active Clamping function provided

by the TVS-diodes drastically. The total voltage limit of the TVS chain

is set to 900 V for a 1200 V-SiC MOSFET device.

During the turn-on transient the SNS pin serves the short-circuit

detection and shut-down is triggered by a detection level referenced

to VEE of V

SNS. The resistor chain to the Drain of the SiC MOSFET

consisting of the resistors from R

CE2 to RCE10 has a total resistance of

2.43 MΩ for a 1200 V-SiC MOSFET device.

If the SiC MOSFET has a sense terminal referenced to VEE which pro-

vide a fraction of the actual Source current this signal can also be fed

back to the SNS pin via a shunt resistor. If here the SNS detection

level of V

SNS is reached the SIC1182K will turn-off the SiC MOSFET and

thus provide an over-current detection.

Figure 8. Secondary-Side of Example Circuitry.

PI-8771-071718

SCALE-iDriver

IN

SO

VCC

GND

RSO

R2

R1

C1

CF

C2

PI-8896-011119

SCALE-iDriver

SNS

GH

VISO

VGXX

GL

VEE

COM

VTOT

+

-

CS2

CGXX

RGON

RCE1

S1

D

S2

G

RGOFF

DSTO

DACC3

DACC2

RDIS

RACC2

RCETH

DACC1

RACC1

CS1

CCOMPS

CAAC1

RCE2

RCE3

DTVS1

DTVS2

DTVS3

DTVS4

DTVS5

DTVS6

RCE4

RCE5

RCE6

RCE7

RCE8

RCE9

RCE10