IR3521MTRPBF International Rectifier, IR3521MTRPBF Datasheet - Page 33

• Manufacturer Part Number: IR3521MTRPBF
• Description: IC CTRL XPHASE3 SVID 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3521MTRPBF

• 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: *
• Package: 32-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

IR3508 EXTERNAL COMPONENTS
Inductor Current Sensing Capacitor C
The DC resistance of the inductor is utilized to sense the inductor current. Usually the resistor R
C
across the capacitor C
component of the capacitor voltage is different from that of the real inductor current. The time constant mismatch
does not affect the average current sharing among the multiple phases, but affect the current signal ISHARE as well
as the output voltage during the load current transient if adaptive voltage positioning is adopted.
Measure the inductance L and the inductor DC resistance R
follows.
Bootstrap Capacitor C
Depending on the duty cycle and gate drive current of the phase IC, a capacitor in the range of 0.1uF to 1uF is
needed for the bootstrap circuit.
Decoupling Capacitors for Phase IC
0.1uF-1uF decoupling capacitors are required at VCC and VCCL pins of phase ICs.
CS
in parallel with the inductor are chosen to match the time constant of the inductor, and therefore the voltage
CS
BST
R
CS
represents the inductor current. If the two time constants are not the same, the AC

L
C
CS
R
L
CS
and Resistor R
Page 33
CS
L
. Pre-select the capacitor C
(19)
CS
and calculate R
IR3521
CS
V3.03
and capacitor
CS
as