IR3523MTRPBF International Rectifier, IR3523MTRPBF Datasheet - Page 19

• Manufacturer Part Number: IR3523MTRPBF
• Description: IC XPHASE3 CTLR VR11.1 40-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3523MTRPBF

• Applications: Processor
• Current - Supply: 10mA
• Voltage - Supply: 4.75 V ~ 7.5 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 40-MLPQ
• Ic Function: Dual Output Control IC
• Supply Voltage Range: 4.75V To 7.5V
• Operating Temperature Range: 0°C To +150°C
• Digital Ic Case Style: MLPQ
• No. Of Pins: 40
• Controller Type: XPhase
• Rohs Compliant: Yes
• Package: 40-Lead MLPQ
• Circuit: X-Phase Control IC
• Switch Freq (khz): 250kHz to 1.5MHz
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Over-Current Hiccup Protection after Soft Start
The over current limit threshold is set by a resistor connected between OCSETx and VDACx pins. Figure 12 shows
the hiccup over-current protection with delay after PGx is asserted. The delay is required since over-current
conditions can occur as part of normal operation due to load transients or VID transitions.
If the IINx pin voltage, which is proportional to the average current plus VDACx voltage, exceeds the OCSETx
voltage after PGx is asserted, it will initiate the discharge of the capacitor at SS/DELx through the discharge current
47uA. If the over-current condition persists long enough for the SS/DELx capacitor to discharge below the 120mV
offset of the delay comparator, a fault latch will be set pulling the error amplifier’s output low and inhibiting switching
in the phase ICs and de-asserting the PGx signal. The SS/DEL capacitor will then continue to discharge through a
4.7uA discharge current until it reaches 200 mV, and the fault latch is reset allowing a normal soft start to occur.
The output current is not controlled during the delay time. If an over-current condition is again encountered during
the soft start cycle, the over-current action will repeat and the converter will be in hiccup mode.
VRRDY
Linear Regulator Output (VCCL)
linear regulator. The output voltage of the linear regulator can be programmed between 4.75V and 7.5V by the
resistor divider at VCCLFB pin. The regulator output powers the gate drivers and other circuits of the phase ICs
along with circuits in the control IC, and the voltage is usually programmed to optimize the converter efficiency. The
linear regulator can be compensated by a 4.7uF capacitor at the VCCL pin. As with any linear regulator, due to
stability reasons, there is an upper limit to the maximum value of capacitor that can be used at this pin and it’s a
function of the number of phases used in the multiphase architecture and their switching frequency. Figure 13
shows the stability plots for the linear regulator with 5 phases switching at 750 kHz.
ENABLE
SS/DEL
IOUT
VOUT
EA
The IR3523 has a built-in linear regulator controller, and only an external NPN transistor is needed to create a
OCP THRESHOLD
3.92V
3.88V
Page 19 of 37
4.0V
1.1V
START-UP WITH
OUTPUT SHORTED
Figure 12 - Hiccup over-current waveforms
HICCUP OVER-CURRENT
PROTECTION (OUTPUT
SHORTED)
NORMAL
START-UP
NORMAL
OPERATION
(OUTPUT
SHORTED)
OCP
DELAY
OVER-CURRENT
PROTECTION
(OUTPUT SHORTED)
NORMAL
START-UP
June 20, 2008
NORMAL
OPERATION
IR3523
POWER-DOWN