STK984-090A-E

NoA2290-11/20

3. Short-Circuit Protection Circuit



The Short Circuit Protection Circuit monitors the VDS of the upper-phase MOSFET to detect short circuits. This

circuit detects a short circuit when the short circuit current flows over 3μsec (TYP) and shifts to the OFF operation

through the driver circuit. Also this circuit will output the abnormal detection signal as DIAG 1 and goes into the

latch-state.



This Short-Circuit Protection Circuit can release the latch by changing the reset signal from L to H but it may detect

a short circuit and go into the latch state again if the current Io is exceeding the short circuit detection range.



Also, the MOSFET Ron will be varied as the chip temperature is changing. VDS setting Voltage has to be changed

as temperature is changing in order to detect the setting current. To do this, place a thermistor as a temperature

detecting device on the substrate close to 3-phase MOSFET so this thermistor can sense the chip temperature of

MOSFET and detect the current that following the MOSFET Ron characteristics.

Short Circuit Protection Timing Chart

UT,VT,WT

DIAG1

Tspoff

Tspdgoff

After detect the Short-circuit

Protection, the output is

latched OFF

Motor Current Io

The Short-circuit Current

Setting Current Value

U,V,W Output Voltage

Short-circuit Current

Setting Voltage

3us(Typ)