ISL6219 Intersil Corporation, ISL6219 Datasheet - Page 16

• Manufacturer Part Number: ISL6219
• Description: Microprocessor CORE Voltage Regulator Precision Multi-Phase BUCK PWM Controller for Mobile Applications
• Manufacturer: Intersil Corporation

page 3). Figure 13 and Equation 23 are provided to assist in
the selecting the correct value for RT.
Input Capacitor Selection
The input capacitors are responsible for sourcing the ac
component of the input current flowing into the upper
MOSFETs. Their rms current capacity must be sufficient to
handle the ac component of the current drawn by the upper
MOSFETs which is related to duty cycle and the number of
active phases.
Figures 14 and 15 can be used to determine the input-
capacitor rms current as of duty cycle, maximum sustained
output current (I
peak inductor current (I
reference to demonstrate the dramatic reductions in input-
capacitor rms current upon the implementation of the
multiphase topology.
FIGURE 14. NORMALIZED INPUT-CAPACITOR RMS
1000
100
0.3
0.2
0.1
10
0
0
10
FIGURE 13. RT VS SWITCHING FREQUENCY
I
I
I
PP
PP
PP
= 0
= 0.5 I
= 0.75 I
CURRENT VS DUTY CYCLE FOR 2-PHASE
0.2
O
RT
), and the ratio of the combined peak-to-
SWITCHING FREQUENCY (KHZ)
O
O
=
10
100
DUTY CYCLE (V
L,PP
[
11.09 1.13
0.4
) to I
16
–
O
. Figure 16 is provided as a
log
0.6
O
( )
f
S
/V
1000
IN
]
)
0.8
(EQ. 23)
10000
1.0
FIGURE 15. NORMALIZED INPUT-CAPACITOR RMS
FIGURE 16. NORMALIZED INPUT-CAPACITOR RMS
0.3
0.2
0.1
0.6
0.4
0.2
0
0
0
0
I
I
PP
PP
= 0
= 0.25 I
CURRENT VS DUTY CYCLE FOR 3-PHASE
I
I
I
CURRENT VS DUTY CYCLE FOR SINGLE-PHASE
CONVERTER
PP
PP
PP
0.2
0.2
= 0
= 0.5 I
= 0.75 I
O
DUTY CYCLE (V
DUTY CYCLE (V
O
O
0.4
0.4
I
I
PP
PP
= 0.5 I
= 0.75 I
0.6
0.6
IN
IN
/ V
/ V
O
O
O
O
)
)
0.8
0.8
1.0
1.0