ISL6566 Intersil Corporation, ISL6566 Datasheet - Page 14

• Manufacturer Part Number: ISL6566
• Description: Three-Phase Buck PWM Controller
• Manufacturer: Intersil Corporation

Voltage Regulation
In order to regulate the output voltage to a specified level,
the ISL6566 uses the integrating compensation network
shown in Figure 6. This compensation network insures that
the steady-state error in the output voltage is limited only to
the error in the reference voltage (output of the DAC) and
offset errors in the OFS current source, remote-sense and
error amplifiers. Intersil specifies the guaranteed tolerance of
the ISL6566 to include the combined tolerances of each of
these elements.
TABLE 4. VRM10 VOLTAGE IDENTIFICATION CODES (Continued)
VID4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
VID3
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
VID2
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
VID1
14
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
VID0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
VID12.5
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
1.2125
1.2250
1.2375
1.2500
1.2625
1.2750
1.2875
1.3125
1.3250
1.3375
1.3500
1.3625
1.3750
1.3875
1.4000
1.4125
1.4250
1.4375
1.4500
1.4625
1.4750
1.4875
1.5000
1.5125
1.5250
1.5375
1.5500
1.5625
1.5750
1.5875
1.6000
VDAC
1.300
ISL6566
The ISL6566 incorporates an internal differential remote-
sense amplifier in the feedback path. The amplifier removes
the voltage error encountered when measuring the output
voltage relative to the controller ground reference point,
resulting in a more accurate means of sensing output
voltage. Connect the microprocessor sense pins to the non-
inverting input, VSEN, and inverting input, RGND, of the
remote-sense amplifier. The droop voltage, V
feeds into the remote-sense amplifier. The remote-sense
output, V
voltage, V
the inverting input of the error amplifier through an external
resistor.
The output of the error amplifier, V
sawtooth waveform to generate the PWM signals. The PWM
signals control the timing of the Internal MOSFET drivers
and regulate the converter output so that the voltage at FB is
equal to the voltage at REF. This will regulate the output
voltage to be equal to Equation 4. The internal and external
circuitry that controls voltage regulation is illustrated in
Figure 6.
Load-Line (Droop) Regulation
Some microprocessor manufacturers require a precisely-
controlled output impedance. This dependence of output
voltage on load current is often termed “droop” or “load line”
regulation.
V
OUT
FIGURE 6. OUTPUT VOLTAGE AND LOAD-LINE
R
FB
=
EXTERNAL CIRCUIT
V
DIFF
+
-
V
OUT
V
V
REF
DROOP
OFS
R
OUT
+
+
-
-
C
, is therefore equal to the sum of the output
REGULATION WITH OFFSET ADJUSTMENT
, and the droop voltage. V
–
V
C
OFS
C
C
REF
ICOMP
RGND
COMP
VDIFF
VSEN
IREF
–
REF
FB
V
DROOP
ISL6566 INTERNAL CIRCUIT
COMP
1k
I
OFS
VID DAC
ERROR AMPLIFIER
DIFFERENTIAL
REMOTE-SENSE
AMPLIFIER
DIFF
+
, is compared to the
-
+
+
-
-
is connected to
DROOP
V
COMP
March 9, 2006
, also
FN9178.4
(EQ. 4)