IR3080 International Rectifier, IR3080 Datasheet - Page 17

• Manufacturer Part Number: IR3080
• Description: XPHASE VRD10 CONTROL IC WITH VCCVID & OVERTEMP DETECT
• Manufacturer: International Rectifier

The over-current delay can be reduced by adding a resistor in series with the SS/DEL capacitor. The delay
comparator’s offset voltage is reduced by the drop in the resistor caused by the discharge current. The value of the
series resistor should be 10KΩ or less to avoid interference with the soft start function.
If SS/DEL pin is pulled below 0.9V, the converter can be disabled.
Under Voltage Lockout (UVLO)
The UVLO function monitors the IR3080’s VCC supply pin and ensures that IR3080 has a high enough voltage to
power the internal circuit. The IR3080’s UVLO is set higher than the minimum operating voltage of compatible
Phase ICs thus providing UVLO protection for them as well. During power-up the fault latch is reset when VCC
exceeds 9.1V and there is no other fault. If the VCC voltage drops below 8.9V the fault latch will be set. For
converters using a separate 5V supply for gate driver bias an external UVLO circuit can be added to prevent any
operation until adequate voltage is present. A diode connected between the 5V supply and the SS/DEL pin provides
a simple 5V UVLO function. UVLO of the VIDPWR input is provided by the VID Power Good function. Adequate
voltage must be present at VIDPWR pin to allow VCCVID to reach 1.1V.
Over Current Protection (OCP)
The current limit threshold is set by a resistor connected between the OCSET and VDAC pins. If the IIN pin voltage,
which is proportional to the average current plus DAC voltage, exceeds the OCSET voltage, the over-current
protection is triggered.
VCC
(12V)
VIDPWR
(3.3V)
VCCVID
(1.2V)
VIDDEL
VIDPGD
SS/DEL
VOUT
PWRGD
IOUT
Page 17 of 41
3.91V
(VCCVID GATES
1.1V
FAULT MODE)
3.91V
1.3V
START-UP
(VOUT CHANGES DUE TO
LOAD AND VID CHANGES)
NORMAL OPERATION
OCP THRESHOLD
Figure 11. Operating Waveforms
OCP
DELAY
HICCUP OVER-CURRENT
PROTECTION
RE-START
AFTER OCP
9
/30/04
IR3080
POWER-DOWN
(VCC GATES
FAULT MODE)
8.9V
UVLO