datasheetbank_Logo
Integrated circuits, Transistor, Semiconductors Search and Datasheet PDF Download Site

ISL6568 View Datasheet(PDF) - Intersil

Part Name
Description
View to exact match
ISL6568 Datasheet PDF : 29 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
ISL6568
VRM9.0 codes, connect the VID12.5 pin to a +5V source
through a 50kresistor. To encode the DAC with AMD
Hammer VID codes, connect this pin to a +5V source
through a 5kresistor.
VSEN and RGND
VSEN and RGND are inputs to the precision differential
remote-sense amplifier and should be connected to the sense
pins of the remote load.
ICOMP, ISUM, and IREF
ISUM, IREF, and ICOMP are the DCR current sense
amplifier’s negative input, positive input, and output
respectively. For accurate DCR current sensing, connect a
resistor from each channel’s phase node to ISUM and
connect IREF to the summing point of the output inductors,
roughly Vout. A parallel R-C feedback circuit connected
between ISUM and ICOMP will then create a voltage from
IREF to ICOMP proportional to the voltage drop across the
inductor DCR. This voltage is referred to as the droop voltage
and is added to the differential remote-sense amplifier output.
NOTE: An optional 0.01µF ceramic capacitor can be placed from the
IREF pin to the ISUM pin to help reduce any noise affects that may
occur due to layout.
VDIFF
VDIFF is the output of the differential remote-sense amplifier.
The voltage on this pin is equal to the difference between
VSEN and RGND added to the difference between IREF and
ICOMP. VDIFF therefore represents the output voltage plus
the droop voltage.
FB and COMP
These pins are the internal error amplifier inverting input and
output respectively. FB, VDIFF, and COMP are tied together
through external R-C networks to compensate the regulator.
REF
The REF input pin is the positive input of the error amplifier. It
is internally connected to the DAC output through a 1k
resistor. A capacitor is used between the REF pin and ground
to smooth the voltage transition during Dynamic VID
operations.
OFS
The OFS pin provides a means to program a dc current for
generating an offset voltage across the resistor between FB
and VDIFF. 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 unconnected.
OCSET
This is the overcurrent set pin. Placing a resistor from OCSET
to ICOMP allows a 100µA current to flow out this pin,
producing a voltage reference. Internal circuitry compares the
voltage at OCSET to the voltage at ISUM, and if ISUM ever
exceeds OCSET, the overcurrent protection activates.
ISEN1 and ISEN2
These pins are used for balancing the channel currents by
sensing the current through each channel’s lower MOSFET
when it is conducting. Connect a resistor between the ISEN1
and ISEN2 pins and their respective phase node. This
resistor sets a current proportional to the current in the lower
MOSFET during its conduction interval.
UGATE1 and UGATE2
Connect these pins to the corresponding upper MOSFET
gates. These pins are used to control the upper MOSFETs
and are monitored for shoot-through prevention purposes.
Maximum individual channel duty cycle is limited to 66%.
BOOT1 and BOOT2
These pins provide the bias voltage for the corresponding
upper MOSFET drives. Connect these pins to appropriately-
chosen external bootstrap capacitors. Internal bootstrap
diodes connected to the PVCC pins provide the necessary
bootstrap charge.
PHASE1 and PHASE2
Connect these pins to the sources of the upper MOSFETs.
These pins are the return path for the upper MOSFET
drives.
LGATE1 and LGATE2
These pins are used to control the lower MOSFETs. Connect
these pins to the corresponding lower MOSFETs’ gates.
PGOOD
During normal operation PGOOD indicates whether the
output voltage is within specified overvoltage and
undervoltage limits. If the output voltage exceeds these limits
or a reset event occurs (such as an overcurrent event),
PGOOD is pulled low. PGOOD is always low prior to the end
of soft-start.
Operation
Multi-Phase Power Conversion
Microprocessor load current profiles have changed to the
point that the advantages of multi-phase power conversion
are impossible to ignore. The technical challenges
associated with producing a single-phase converter that is
both cost-effective and thermally viable have forced a
change to the cost-saving approach of multi-phase. The
ISL6568 controller helps simplify implementation by
integrating vital functions and requiring minimal external
components. The block diagram on page 2 provides a top
level view of multi-phase power conversion using the
ISL6568 controller.
9
FN9187.4
March 9, 2006
 

Share Link: 

datasheetbank.com [ Privacy Policy ] [ Request Datasheet ] [ Contact Us ]