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PDF ISL6312 Data sheet ( Hoja de datos )
| Número de pieza | ISL6312 | |
| Descripción | 4-Phase Buck PWM Controller | |
| Fabricantes | Intersil Corporation | |
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Data Sheet
August 21, 2006
ISL6312
FN9289.1
Four-Phase Buck PWM Controller with
Integrated MOSFET Drivers for Intel VR10,
VR11, and AMD Applications
The ISL6312 four-phase PWM control IC provides a
precision voltage regulation system for advanced
microprocessors. The integration of power MOSFET drivers
into the controller IC marks a departure from the separate
PWM controller and driver configuration of previous
multiphase product families. By reducing the number of
external parts, this integration is optimized for a cost and
space saving power management solution.
One outstanding feature of this controller IC is its
multi-processor compatibility, allowing it to work with both Intel
and AMD microprocessors. Included are programmable VID
codes for Intel VR10, VR11, as well as AMD DAC tables. A
unity gain, differential amplifier is provided for remote voltage
sensing, compensating for any potential difference between
remote and local grounds. The output voltage can also be
positively or negatively offset through the use of a single
external resistor.
The ISL6312 also includes advanced control loop features
for optimal transient response to load apply and removal.
One of these features is highly accurate, fully differential,
continuous DCR current sensing for load line programming
and channel current balance. Active Pulse Positioning (APP)
modulation is another unique feature, allowing for quicker
initial response to high di/dt load transients.
This controller also allows the user the flexibility to choose
between PHASE detect or LGATE detect adaptive dead time
schemes. This ability allows the ISL6312 to be used in a
multitude of applications where either scheme is required.
Protection features of this controller IC include a set of
sophisticated overvoltage, undervoltage, and overcurrent
protection. Furthermore, the ISL6312 includes protection
against an open circuit on the remote sensing inputs.
Combined, these features provide advanced protection for the
microprocessor and power system.
Features
• Integrated Multiphase Power Conversion
- 2 or 3-Phase Operation with Internal Drivers
- 4-Phase Operation with External PWM Driver Signal
• Precision Core Voltage Regulation
- Differential Remote Voltage Sensing
- ±0.5% System Accuracy Over Temperature
- Adjustable Reference-Voltage Offset
• Optimal Transient Response
- Active Pulse Positioning (APP) Modulation
- Adaptive Phase Alignment (APA)
• Fully Differential, Continuous DCR Current Sensing
- Accurate Load Line Programming
- Precision Channel Current Balancing
• User Selectable Adaptive Dead Time Scheme
- PHASE Detect or LGATE Detect for Application
Flexibility
• Variable Gate Drive Bias: 5V to 12V
• Multi-Processor Compatible
- Intel VR10 and VR11 Modes of Operation
- AMD Mode of Operation
• Microprocessor Voltage Identification Inputs
- 8-bit DAC
- Selectable between Intel’s Extended VR10, VR11, AMD
5-bit, and AMD 6-bit DAC Tables
- Dynamic VID Technology
• Overcurrent Protection
• Multi-Tiered Overvoltage Protection
• Digital Soft-Start
• Selectable Operation Frequency up to 1.5MHz Per Phase
• Pb-Free Plus Anneal Available (RoHS Compliant)
Ordering Information
PART
NUMBER*
(Note)
PART
MARKING
TEMP.
(°C)
PACKAGE PKG.
(Pb-Free) DWG. #
ISL6312CRZ ISL6312CRZ 0 to +70 48 Ld 7x7 QFN L48.7x7
ISL6312IRZ ISL6312IRZ -40 to +85 48 Ld 7x7 QFN L48.7x7
NOTE: Intersil Pb-free plus anneal products employ special Pb-free
material sets; molding compounds/die attach materials and 100%
matte tin plate termination finish, which are RoHS compliant and
compatible with both SnPb and Pb-free soldering operations. Intersil
Pb-free products are MSL classified at Pb-free peak reflow
temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
*Add “-T” suffix for tape and reel.
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2006. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
1 page  
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ISL6312
Typical Application - ISL6312 with NTC Thermal Compensation (4-Phase)
+5V
+12V
FB IDROOP
COMP
VSEN
RGND
VCC
OFS
FS
REF
VDIFF
BOOT1
UGATE1
PHASE1
LGATE1
ISEN1-
ISEN1+
PVCC1_2
SS BOOT2
UGATE2
PHASE2
OVPSEL
VID7
VID6
VID5
VID4
VID3
VID2
VID1
VID0
VRSEL
PGOOD
ISL6312
LGATE2
ISEN2-
ISEN2+
PVCC3
BOOT3
UGATE3
PHASE3
LGATE3
ISEN3-
ISEN3+
EN
DRSEL
GND
EN_PH4
PWM4
ISEN4-
ISEN4+
+12V
+12V
+12V
+12V
BOOT
VCC UGATE
PVCC PHASE
ISL6612
LGATE
PWM GND
+12V
NTC
PLACE IN
CLOSE
PROXIMITY
LOAD
5 FN9289.1
August 21, 2006
5 Page 
www.DataSheet4U.com
ISL6312
To understand the reduction of ripple current amplitude in the
multiphase circuit, examine the equation representing an
individual channel peak-to-peak inductor current.
IPP =
(---V----I--N-----–-----V----O-----U----T---)----⋅----V----O----U-----T-
L
⋅
fS
⋅
V
IN
(EQ. 1)
In Equation 1, VIN and VOUT are the input and output
voltages respectively, L is the single-channel inductor value,
and fS is the switching frequency.
The output capacitors conduct the ripple component of the
inductor current. In the case of multiphase converters, the
capacitor current is the sum of the ripple currents from each
of the individual channels. Compare Equation 1 to the
expression for the peak-to-peak current after the summation
of N symmetrically phase-shifted inductor currents in
Equation 2. Peak-to-peak ripple current decreases by an
amount proportional to the number of channels. Output
voltage ripple is a function of capacitance, capacitor
equivalent series resistance (ESR), and inductor ripple
current. Reducing the inductor ripple current allows the
designer to use fewer or less costly output capacitors.
IC, PP=
(---V----I--N-----–-----N------⋅----V----O-----U----T----)---⋅----V----O----U-----T-
L ⋅ fS ⋅ VIN
(EQ. 2)
Another benefit of interleaving is to reduce input ripple
current. Input capacitance is determined in part by the
maximum input ripple current. Multiphase topologies can
improve overall system cost and size by lowering input ripple
current and allowing the designer to reduce the cost of input
capacitance. The example in Figure 2 illustrates input
currents from a three-phase converter combining to reduce
the total input ripple current.
The converter depicted in Figure 2 delivers 1.5V to a 36A load
from a 12V input. The RMS input capacitor current is 5.9A.
Compare this to a single-phase converter also stepping down
12V to 1.5V at 36A. The single-phase converter has 11.9A
RMS input capacitor current. The single-phase converter
must use an input capacitor bank with twice the RMS current
capacity as the equivalent three-phase converter.
INPUT-CAPACITOR CURRENT, 10A/DIV
CHANNEL 3
INPUT CURRENT
10A/DIV
CHANNEL 2
INPUT CURRENT
10A/DIV
CHANNEL 1
INPUT CURRENT
10A/DIV
1µs/DIV
FIGURE 2. CHANNEL INPUT CURRENTS AND INPUT-
CAPACITOR RMS CURRENT FOR 3-PHASE
CONVERTER
Active Pulse Positioning (APP) Modulated PWM
Operation
The ISL6312 uses a proprietary Active Pulse Positioning
(APP) modulation scheme to control the internal PWM
signals that command each channel’s driver to turn their
upper and lower MOSFETs on and off. The time interval in
which a PWM signal can occur is generated by an internal
clock, whose cycle time is the inverse of the switching
frequency set by the resistor between the FS pin and
ground. The advantage of Intersil’s proprietary Active Pulse
Positioning (APP) modulator is that the PWM signal has the
ability to turn on at any point during this PWM time interval,
and turn off immediately after the PWM signal has
transitioned high. This is important because is allows the
controller to quickly respond to output voltage drops
associated with current load spikes, while avoiding the ring
back affects associated with other modulation schemes.
The PWM output state is driven by the position of the error
amplifier output signal, VCOMP, minus the current correction
signal relative to the proprietary modulator ramp waveform
as illustrated in Figure 3. At the beginning of each PWM time
interval, this modified VCOMP signal is compared to the
internal modulator waveform. As long as the modified
VCOMP voltage is lower then the modulator waveform
voltage, the PWM signal is commanded low. The internal
MOSFET driver detects the low state of the PWM signal and
turns off the upper MOSFET and turns on the lower
synchronous MOSFET. When the modified VCOMP voltage
crosses the modulator ramp, the PWM output transitions
high, turning off the synchronous MOSFET and turning on
the upper MOSFET. The PWM signal will remain high until
the modified VCOMP voltage crosses the modulator ramp
again. When this occurs the PWM signal will transition low
again.
During each PWM time interval the PWM signal can only
transition high once. Once PWM transitions high it can not
transition high again until the beginning of the next PWM
time interval. This prevents the occurrence of double PWM
pulses occurring during a single period.
To further improve the transient response, ISL6312 also
implements Intersil’s proprietary Adaptive Phase Alignment
(APA) technique, which turns on all phases together under
transient events with large step current. With both APP and
APA control, ISL6312 can achieve excellent transient
performance and reduce the demand on the output
capacitors.
Channel-Current Balance
One important benefit of multiphase operation is the thermal
advantage gained by distributing the dissipated heat over
multiple devices and greater area. By doing this the designer
avoids the complexity of driving parallel MOSFETs and the
expense of using expensive heat sinks and exotic magnetic
materials.
11 FN9289.1
August 21, 2006
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet ISL6312.PDF ] | |
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