IR3504MPBF International Rectifier, IR3504MPBF Datasheet - Page 11
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IR3504MPBF
Manufacturer Part Number
IR3504MPBF
Description
IC CTRL XPHASE AMD SVID 32-MLPQ
Manufacturer
International Rectifier
Series
XPhase3™r
Datasheet
1.IR3504MTRPBF.pdf
(42 pages)
Specifications of IR3504MPBF
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
PWM Operation
The PWM comparator is located in the phase IC. Upon receiving the falling edge of a clock pulse, the PWM latch is
set; the PWM ramp voltage begins to increase; the low side driver is turned off, and the high side driver is then
turned on after the non-overlap time. When the PWM ramp voltage exceeds the error amplifier’s output voltage, the
PWM latch is reset. This turns off the high side driver and then turns on the low side driver after the non-overlap
time; it activates the ramp discharge clamp, which quickly discharges the internal PWM ramp capacitor to the output
voltage of share adjust amplifier in phase IC until the next clock pulse.
The PWM latch is reset dominant allowing all phases to go to zero duty cycle within a few tens of nanoseconds in
response to a load step decrease. Phases can overlap and go up to 100% duty cycle in response to a load step
increase with turn-on gated by the clock pulses. An error amplifier output voltage greater than the common mode
input range of the PWM comparator results in 100% duty cycle regardless of the voltage of the PWM ramp. This
arrangement guarantees the error amplifier is always in control and can demand 0 to 100% duty cycle as required.
It also favors response to a load step decrease which is appropriate given the low output to input voltage ratio of
most systems. The inductor current will increase much more rapidly than decrease in response to load transients.
This control method is designed to provide “single cycle transient response” where the inductor current changes in
response to load transients within a single switching cycle maximizing the effectiveness of the power train and
minimizing the output capacitor requirements. An additional advantage of the architecture is that differences in
ground or input voltage at the phases have no effect on operation since the PWM ramps are referenced to VDAC.
Figure 6 depicts PWM operating waveforms under various conditions.
Page 11
Control IC CLKOUT
(Phase IC CLKIN)
Control IC PHSOUT
(Phase IC1 PHSIN)
Phase IC1
PWM Latch SET
Phase IC 1 PHSOUT
(Phase IC2 PHSIN)
Phase IC 2 PHSOUT
(Phase IC3 PHSIN)
Phase IC 3 PHSOUT
(Phase IC4 PHSIN)
Phase IC4 PHSOUT
(Control IC PHSIN)
Figure 5 Four Phase Oscillator Waveforms
July 28, 2009
IR3504