IR3623MPBF Datasheet, PDF (14/26 Pages) International Rectifier – HIGH FREQUENCY 2-PHASE, SINGLE OR DUAL OUTPUT SYNCHRONOUS STEP DOWN CONTROLLER WITH OUTPUT TRACKING AND SEQUENCING

IR3623MPbF
Fault Protection
The IR3623 monitors the output voltage for over voltage protection and power good indication. It senses
the R_ds(on) of low side MOSFET for over current protection. It also protects the output for prebias
conditions. Figure below shows the IC’s operating waveforms under different fault conditions.
POR
Ph_Enable
3V
1.8V
1.0V
SS
Tri_State
PWM
90%Vfb
Vo
Set Voltage
Pre_Bias Voltage
PGood
OCP Threshold
Iout
OV_Output
t0 t1 t2 t3
t4
t5 t6
t7
t8
Fig. 12: Fault Conditions
t9 t10
t₀ – t₁: Vcc, 5V_sns and Enable signals passed their respective UVLO threshold. Ph_Enable goes high and PWM switches high
from tri-state. Soft start sequence starts.
t₁ – t₂: Power Good signal flags high.
t₁ – t₃: Output voltage ramps up and reaches the set voltage.
t₄ – t₅: OC event, SS ramps down, Ph-Enable pulls low and PWM tri-states. IC in Hiccup mode.
t₅– t₆: OC is removed, recovery sequence, fresh SS.
t₆ –t₇: Ph_Enable goes high and PWM switches high from tri-state. Output voltage reaches the set voltage.
t₈: OVP event. Ph_Enable is kept high and PWM is pulled low. OVP-Output flags high to indicate OV event.
t₉ –t₁₀: Manually recycled the Vcc after latched OVP. PreBias start up. The Ph_Enable goes high after first internal PWM pulse is
generated. The PWM output is kept in tri-state until Ph-Enable goes high.
www.irf.com
14