AUIRS2336S_15 Datasheet, PDF (20/37 Pages) International Rectifier – Drives up to six IGBT/MOSFET power devices

AUIRS2336S
Fault Reporting and Programmable Fault Clear Timer
The AUIRS2336S provides an integrated fault reporting output and an adjustable fault clear timer. There are two
situations that would cause the HVIC to report a fault via the FAULT pin. The first is an undervoltage condition of
V_CC and the second is if the ITRIP pin recognizes a fault. Once the fault condition occurs, the FAULT pin is internally
pulled to V_SS. The fault clear timer is activated only if ITRIP pin recognizes a fault: in this case the fault output stays
in the low state until the fault condition has been removed and the fault clear timer expires; once the fault clear timer
expires, the voltage on the FAULT pin will return to V_CC.
The length of the fault clear time period (t_FLTCLR) is determined by exponential charging characteristics of the
capacitor where the time constant is set by R_RCIN and C_RCIN. In Figure 12 where we see that a fault condition has
occurred (UVLO or ITRIP), RCIN and FAULT are pulled to V_SS, and once the fault has been removed, the fault clear
timer begins. Figure 13 shows that R_RCIN is connected between the V_CC and the RCIN pin, while C_RCIN is placed
between the RCIN and V_SS pins.
Figure 12: RCIN and FAULT pin waveforms
Figure 13: Programming the fault clear timer
The design guidelines for this network are shown in Table 3.
C_RCIN
R_RCIN
≤1 nF
Ceramic
0.5 MΩ to 2 MΩ
>> R_ON,RCIN
Table 3: Design guidelines
The length of the fault clear time period can be determined by using the formula below.
v_C(t) = V_f(1-e^-t/RC)
t_FLTCLR = -(R_RCINC_RCIN)ln(1-V_RCIN,TH/V_CC)
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