isl62883c Intersil Corporation, isl62883c Datasheet - Page 19

• Manufacturer Part Number: isl62883c
• Description: Multiphase Pwm Regulator For Imvp-6.5? Mobile Cpus And Gpus
• Manufacturer: Intersil Corporation

Current balancing (I
when there is R
R
Since the slave ripple capacitor voltages mimic the
inductor currents, R
excellent current balancing during steady state and
dynamic operations. Figure 15 shows current balancing
performance of the ISL62883C evaluation board with load
transient of 12A/51A at different rep rates. The inductor
currents follow the load current dynamic change with the
output capacitors supplying the difference. The inductor
currents can track the load current well at low rep rate,
but cannot keep up when the rep rate gets into the
hundred-kHz range, where it’s out of the control loop
bandwidth. The controller achieves excellent current
balancing in all cases installed.
CCM Switcing Frequency
The R
sets the sets the VW windows size, therefore sets the
switching frequency. When the ISL62883C is in
continuous conduction mode (CCM), the switching
frequency is not absolutely constant due to the nature of
the R
Modulator section, the effective switching frequency will
increase during load insertion and will decrease during
load release to achieve fast response. On the other hand,
the switching frequency is relatively constant at steady
state. Variation is expected when the power stage
condition, such as input voltage, output voltage, load,
etc. changes. The variation is usually less than 15% and
doesn’t have any significant effect on output voltage
ripple magnitude. Equation 17 gives an estimate of the
frequency-setting resistor R
approximately 300kHz switching frequency. Lower
resistance gives higher switching frequency.
pcb3
R
fset
3
fset
(
™ modulator. As explained in the Multiphase R
will not have any effect.
kΩ
)
resistor between the COMP and the VW pins
=
(
Period μs
dcr1
3
(
™ modulator can naturally achieve
= R
L1
) 0.29
= I
–
dcr2
19
L2
fset
)
= R
= I
×
2.65
value. 8kΩ R
L3
dcr3
) will be achieved
. R
pcb1
fset
, R
pcb2
gives
(EQ. 17)
ISL62883C
and
3
™
FIGURE 15. ISL62883 EVALUATION BOARD CURRENT
BALANCING DURING DYNAMIC
OPERATION. CH1: IL1, CH2: I
IL2, CH4: IL3
REP RATE = 100kHz
REP RATE = 200kHz
REP RATE = 10kHz
REP RATE = 25kHz
REP RATE = 50kHz
LOAD
March 18, 2010
, CH3:
FN7557.1