IR3084AMPBF International Rectifier, IR3084AMPBF Datasheet - Page 20

• Manufacturer Part Number: IR3084AMPBF
• Description: IC XPHASE CONTROL 28-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase™r

Specifications of IR3084AMPBF

• Applications: Processor
• Current - Supply: 14mA
• Voltage - Supply: 9.5 V ~ 16 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 28-MLPQ
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Fault Modes
Under Voltage Lock Out, VID = FAULT, as well as a low signal on the ENABLE input immediately sets the fault
latch. This causes the EAOUT pin to drive low turning off the Phase IC drivers. The VRRDY pin also drives low.
The SS/DEL capacitor will discharge down to 0.215V through a 6.5uA current source. If the fault has cleared the
fault latch will be reset by the discharge comparator allowing a normal start-up sequence to occur. If a VID =
FAULT condition is latched it can only be cleared by cycling power to the IR3084A on and off.
Over−Current Protection Delay and Hiccup Mode
Figure 11 depicts the operating waveforms of the Over-Current protection. A delay is included if an over-current
condition occurs after a successful soft start sequence. This is required because over-current conditions can
occur as part of normal operation due to load transients or VID transitions. If an over-current fault occurs during
normal operation it will activate the SS/DEL discharge current of 40uA but will not set the fault latch immediately.
If the over-current condition persists long enough for the SS/DEL capacitor to discharge below the 100mV offset
of the delay comparator, the Fault latch will be set pulling the error amp’s output low inhibiting switching in the
phase ICs and de-asserting the VRRDY signal.
The SS/DEL capacitor will continue to discharge until it reaches 0.215V and the fault latch is reset allowing a
normal soft start to occur. If an over-current condition is again encountered during the soft start cycle the fault
latch will be set without any delay and hiccup mode will begin. During hiccup mode the 10.8 to 1 charge to
discharge current ratio results in a 9% hiccup mode duty cycle regardless of at what point the over-current
condition occurs.
If the voltage at the SS/DEL pin is pulled below the SS/DEL to FB Input Offset Voltage (0.85V min), the converter
can be disabled.
SS/DEL
(3.85V DURING
NORMAL
OPERATION)
VRRDY
NORMAL
OPERATION
VOUT
IOUT
Page 20 of 45
OCP
DELAY
Figure 11 – Over-Current Protection Waveforms (VID = 1.1V for simplicity)
3.75V
DISCHARGE VOLTAGE
(0.215V)
OCP THRESHOLD
HICCUP MODE
OVER-CURRENT PROTECTION
1.3V
IR3084A
3/3/2009
3.77V
RESTART
AFTER
OCP
NORMAL
OPERATION