ISL6569A Intersil Corporation, ISL6569A Datasheet - Page 8

• Manufacturer Part Number: ISL6569A
• Description: Multi-Phase PWM Controller
• Manufacturer: Intersil Corporation

Interleaving
The switching of each channel in a multi-phase converter is
timed to be symmetrically out of phase with the other
channel. In a 2-phase converter, channel-2 switches half a
cycle after channel-1. As a result, the converter has a ripple
frequency twice that of either phase. Figure 2 illustrates the
multiplicative effect on output ripple frequency. The two
channel currents (IL1 and IL2), combine to form the AC
ripple current and the DC load current. The ripple
component has twice the ripple frequency of either channel
current. Each PWM pulse is terminated half of a cycle, or
2.0µs, after the PWM pulse of the previous phase. The peak-
to-peak current waveform for each phase is about 7A, and
the dc components of the inductor currents combine to feed
the load.
IOUT
VDIFF
FB
COMP
I
OUT
REFERENCE
100µA
x0.1
x 1
+
+
-
DAC
OFS
&
+
-
VSEN
AMPLIFIER
ERROR
8
FIGURE 1. SIMPLIFIED BLOCK DIAGRAM OF A ISL6569A CONVERTER
RGND
+
+
+
+
-
-
-
-
ISL6569A
AVERAGE
CURRENT
CURRENT
CIRCUIT
CIRCUIT
SENSE
SENSE
PWM
PWM
FIGURE 2. PWM AND INDUCTOR-CURRENT WAVEFORMS
PWM1, 5V/DIV
PWM1
PWM2
ISEN1
ISEN2
FOR 2-PHASE CONVERTER
IL1 + IL2, 7A/DIV
IL1, 7A/DIV
R
R
ISEN1
ISEN2
VIN
VIN
1µs/DIV
L
L
1
2
C
PWM2, 5V/DIV
O
IL2, 7A/DIV
LOAD
V
µP
OUT