ISL6266AIRZ-T Intersil, ISL6266AIRZ-T Datasheet - Page 23

• Manufacturer Part Number: ISL6266AIRZ-T
• Description: IC CORE CTRLR 2PHASE 48-QFN
• Manufacturer: Intersil

Specifications of ISL6266AIRZ-T

• Applications: Converter, Intel IMVP-6
• Voltage - Input: 5 ~ 25 V
• Number Of Outputs: 1
• Voltage - Output: 0.3 ~ 1.5 V
• Operating Temperature: -40°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 48-VQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Static Mode of Operation - Processor Die Sensing
Die sensing is the ability of the controller to regulate the core
output voltage at a remotely sensed point. This allows the
voltage regulator to compensate for various resistive drops
in the power path and ensure that the voltage seen at the
CPU die is the correct level independent of load current.
The VSEN and RTN pins of the ISL6266A are connected to
Kelvin sense leads at the die of the processor through the
processor socket. These signal names are V
V
tightly control the processor voltage at the die, independent
of layout inconsistencies and voltage drops. This Kelvin
sense technique provides for extremely tight load line
regulation.
These traces should be treated as noise sensitive traces.
For optimum load line regulation performance, the traces
connecting these two pins to the Kelvin sense leads of the
processor must be laid out away from rapidly rising/falling
voltage nodes (switching nodes) and other noisy traces. To
achieve optimum performance, place common mode and
differential mode RC filters to analog ground on VSEN and
RTN as shown in Figure 37. The filter resistors should be
10Ω so that they do not interact with the 50kΩ input
resistance of the differential amplifier. The filter resistor may
be inserted between V
Another option is to place to the filter resistor between
Vcc_sense and VSEN pin and between V
RTN pin. The need for RC filters really depends on the
actual board layout and noise environment.
SS_SENSE
ISEN1
OC
VDIFF
INTERNAL TO
ISL6266
ISEN1
0.018µF
FIGURE 37. SIMPLIFIED SCHEMATIC FOR DROOP AND DIE SENSING WITH INDUCTOR DCR CURRENT SENSING
-
+
respectively. This allows the voltage regulator to
+
+
ISEN2
10µA
R
OPN2
RTN
1
1
+
+
-
-
CC_SENSE
ISEN2
0.018µF
82nF
DROOP
VSEN
23
+
-
DROOP
and the VSEN pin.
OCSET
VSUM
10
DFB
R
V
opn1
V
VO'
CC_SENSE
SS_SENSE
SS_SENSE
R
drp2
CC_SENSE
R
OCSET
R
TO V
drp1
ISL6266, ISL6266A
TO PROCESSOR
SOCKET KELVIN
CONNECTIONS
and
OUT
R
and
VO'
SERIES
Cn
R
NTC
VSUM
R
PAR
Intersil recommends the use of the R
connected to V
These resistors provide voltage feedback in the event that
the system is powered up without a processor installed.
These resistors typically range from 20Ω to 100Ω.
Setting the Switching Frequency - FSET
The R
architecture. The switching frequency can increase during
the application of a load to improve transient performance.
It also varies slightly due to changes in input and output
voltage and output current, but this variation is normally less
than 10% in continuous conduction mode.
See Figure 32. The resistor connected between the VW and
COMP pins of the ISL6266A adjusts the switching window,
and therefore adjusts the switching frequency. The R
resistor that sets up the switching frequency of the converter
operating in CCM can be determined using Equation 7,
where R
Equation 7 is only a rough estimate of actual frequency. It
should be used to choose an R
the desired switching frequency. Empirical fine tuning may
be necessary to achieve the actual frequency target. In
addition, droop amplifier gain may slightly affect the
switching frequency. Equation 7 is derived using the droop
gain seen on the ISL6266AEVAL1Z REV A evaluation
board.
R
VO'
FSET
VSUM
VSUM
3
(
kΩ
modulator scheme is not a fixed frequency PWM
FSET
I
I
PHASE1
PHASE2
)
=
RS
RS
is in kΩ and the switching frequency is in kHz.
⎛
⎝
OUT
F
---------------------------- -
SW
2232
(
and ground as shown in Figure 37.
kHz
ISEN2
ISEN1
R
)
L
L2
⎞
⎠
R
2
–
L1
1.1202
L 1
FSET
VO'
+
Vdcr
C
C L1
L2
VO'
OPN1
value in the vicinity of
+
2
DCR
Vdcr
DCR
-
RO1
1
-
and R
R
O2
OPN2
June 14, 2010
ESR
C
V
BULK
OUT
FSET
(EQ. 7)
FN6398.3