IR3504MTRPBF International Rectifier, IR3504MTRPBF Datasheet - Page 31

• Manufacturer Part Number: IR3504MTRPBF
• Description: IC CTRL XPHASE3 SVID 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3504MTRPBF

• 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

IR3504
IR3505 EXTERNAL COMPONENTS
Inductor Current Sensing Capacitor C
and Resistor R
CS
CS
The DC resistance of the inductor is utilized to sense the inductor current. Usually the resistor R
and capacitor
CS
C
in parallel with the inductor are chosen to match the time constant of the inductor, and therefore the voltage
CS
across the capacitor C
represents the inductor current. If the two time constants are not the same, the AC
CS
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
. Pre-select the capacitor C
and calculate R
as
L
CS
CS
follows.
L
R
L
R
=
(21)
CS
C
CS
Bootstrap Capacitor C
BST
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.
Page 31
July 28, 2009