ISL6316_06 Datasheet, PDF (11/29 Pages) Intersil Corporation – Enhanced 4-Phase PWM Controller with 6-Bit VID Code Capable of Precision rDS(ON) or DCR Differential Current Sensing for VR10 Application

ISL6316
DAC and REF
The DAC pin is the output of the precision internal DAC
reference. The REF pin is the positive input of the Error Amp.
In typical applications, a 1kΩ, 1% resistor is used between
DAC and REF to generate a precision offset voltage. This
voltage is proportional to the offset current determined by the
offset resistor from OFS to ground or VCC. A capacitor is
used between REF and ground to smooth the voltage
transition during Dynamic VID™ operations.
PWM1, PWM2, PWM3, PWM4
Pulse width modulation outputs. Connect these pins to the
PWM input pins of the Intersil driver IC. The number of active
channels is determined by the state of PWM3 and PWM4. Tie
PWM3 to VCC to configure for 2-phase operation. Tie PWM4
to VCC to configure for 3-phase operation.
ISEN1+, ISEN1-; ISEN2+, ISEN2-; ISEN3+, ISEN3-;
ISEN4+, ISEN4
The ISEN+ and ISEN- pins are current sense inputs to
individual differential amplifiers. The sensed current is used
for channel current balancing, overcurrent protection, and
droop regulation. Inactive channels should have their
respective current sense inputs left open (for example, open
ISEN4+ and ISEN4- for 3-phase operation).
For DCR sensing, connect each ISEN- pin to the node
between the RC sense elements. Tie the ISEN+ pin to the
other end of the sense capacitor through a resistor, R_ISEN.
The voltage across the sense capacitor is proportional to the
inductor current. Therefore, the sense current is proportional
to the inductor current, and scaled by the DCR of the inductor
and R_ISEN.
When configured for r_DS(ON) current sensing, the ISEN1-,
ISEN2-, ISEN3-, and ISEN4- pins are grounded at the lower
MOSFET sources. The ISEN1+, ISEN2+, ISEN3+, and
ISEN4+ pins are then held at a virtual ground. Therefore, a
resistor, connected between these current sense pins and the
drain terminals of the associated lower MOSFET, will carry the
current proportional to the current flowing through that
channel. The sensed current is determined by the negative
voltage across the lower MOSFET when it is ON, which is the
channel current scaled by r_DS(ON) and R_ISEN.
PGOOD
PGOOD indicates that the soft-start is completed and the
output voltage is within the regulated range around VID
setting. It is an open-drain logic output. When OCP or OVP
occurs, PGOOD will be pulled to low. It will also be pulled low
if the output voltage is below the undervoltage threshold.
OFS
The OFS pin provides a means to program a DC offset
current for generating a DC offset voltage at the REF input.
The offset current is generated via an external resistor and
precision internal voltage references. The polarity of the offset
is selected by connecting the resistor to GND or VCC. For no
offset, the OFS pin should be left unterminated.
TCOMP
Temperature compensation scaling input. The voltage sensed
on the TM pin is utilized as the temperature input to adjust
ldroop and the overcurrent protection limit to effectively
compensate for the temperature coefficient of the current
sense element. To implement the integrated temperature
compensation, a resistor divider circuit is needed with one
resistor being connected from TCOMP to VCC of the
controller and another resistor being connected from TCOMP
to GND. Changing the ratio of the resistor values will set the
gain of the integrated thermal compensation. When integrated
temperature compensation function is not used, connect
TCOMP to GND.
IDROOP
IDROOP is the output pin of sensed average channel current
which is proportional to load current. In the application which
does not require loadline, leave this pin open. In the
application which requires load line, connect this pin to FB so
that the sensed average current will flow through the resistor
between FB and VDIFF to create a voltage drop which is
proportional to load current.
TM
TM is an input pin for VR temperature measurement. Connect
this pin through NTC themistor to GND and a resistor to VCC
of the controller. The voltage at this pin is reverse proportional
to VR temperature. ISL6316 monitors the VR temperature
based on the voltage at TM pin and outputs VR_HOT and
VR_FAN signals.
VR_HOT
VR_HOT is used as an indication of high VR temperature. It is
an open-drain logic output. It will be open when the measured
VR temperature reaches certain level.
VR_FAN
VR_FAN is an output pin with open-drain logic output. It will be
open when the measured VR temperature reaches certain
level.
Operation
Multiphase Power Conversion
Microprocessor load current profiles have changed to the
point that the advantages of multiphase power conversion are
impossible to ignore. The technical challenges associated
with producing a single-phase converter which is both cost-
effective and thermally viable have forced a change to the
cost-saving approach of multiphase. The ISL6316 controller
helps reduce the complexity of implementation by integrating
vital functions and requiring minimal output components. The
block diagrams on pages 4, 5, 6 and 7 provide top level views
of multiphase power conversion using the ISL6316 controller.
11
FN9227.1
December 12, 2006