IR3510MTRPBF International Rectifier, IR3510MTRPBF Datasheet - Page 22

• Manufacturer Part Number: IR3510MTRPBF
• Description: IC XPHASE CONTROL 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase™r

Specifications of IR3510MTRPBF

• Applications: Processor
• Mounting Type: Surface Mount
• Package / Case: 32-MLPQ
• Package: 32-Lead MLPQ
• Circuit: X-Phase Control IC
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Voltage - Supply: -
• Operating Temperature: -
• Other names: IR3510MTRPBFTR

Figure 9 depicts the start-up sequence of the voltage regulator. If there is no fault, the SS pin will start charging
when the enable crosses the threshold. The current error amplifier output EAOUT is clamped low until SS
reaches 1.35V. The error amplifier will then regulate the voltage regulator’s output voltage to match the SS
voltage less the 1.35V offset until the output reaches the set voltage. The SS voltage continues to increase until it
rises above 3.7V and allows the VRRDY signal to be asserted. SS finally settles at 3.8V, indicating the end of the
soft start.
If a higher than the second enable threshold voltage is
applied to the “Enable” pin when the input FET is OFF, a
consecutive two-stage soft-start cycle is started. The
input FET is first turned on, and immediately follows the
soft-start of the voltage regulator, as seen in the Fig.10
waveform.
If the P12V takes longer time to ramp up than the soft-
start cap voltage in the first soft-start cycle, the soft-start
cap will hold its charge until the P12V voltage ramps up
across the UVLO threshold of P12V voltage, then it
starts the 2
Input Fault Latch Q1
VRM Fault Latch Q2
SS Discharge
OPEN-SENSE CHECK
12V IN
Enable
VRRDY
Page 22 of 36
Vss
P12V
EAOUT
Vout
nd
soft-start cycle.
UVLO2 Vth
Figure 9 Start-up sequence of converter
IR Confidential
1.3V
Fig. 10 Two-stage soft-start
May 18, 2009
IR3510