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PDF ISL62873 Data sheet ( Hoja de datos )
| Número de pieza | ISL62873 | |
| Descripción | PWM DC/DC Controller with VID Inputs | |
| Fabricantes | Intersil | |
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®
Data Sheet
June 30, 2009
ISL62873
www.DataSheet4U.com
FN6930.0
PWM DC/DC Controller with VID Inputs for
Portable GPU Core-Voltage Regulator
The ISL62873 is a Single-Phase Synchronous-Buck PWM
voltage regulator featuring Intersil’s Robust Ripple Regulator
(R3) Technology™. The wide 3.3V to 25V input voltage range
is ideal for systems that run on battery or AC-adapter power
sources. The ISL62873 is a low-cost solution for applications
requiring dynamically selected slew-rate controlled output
voltages. The soft-start and dynamic setpoint slew-rates are
capacitor programmed. Voltage identification logic-inputs
select two resistor-programmed setpoint reference voltages
that directly set the output voltage of the converter between
0.5V to 1.5V, and up to 3.3V using a feedback voltage divider.
Optionally, an external reference such as the DAC output from
a microcontroller, can be used by either IC to program the
setpoint reference voltage, and still maintain the controlled
slew-rate features. Robust integrated MOSFET drivers and
Schottky bootstrap diode reduce the implementation area and
lower component cost.
Intersil’s R3 Technology™ combines the best features of
both fixed-frequency and hysteretic PWM control. The PWM
frequency is 300kHz during static operation, becoming
variable during changes in load, setpoint voltage, and input
voltage when changing between battery and AC-adapter
power. The modulators ability to change the PWM switching
frequency during these events in conjunction with external
loop compensation produces superior transient response.
For maximum efficiency, the converter automatically enters
diode-emulation mode (DEM) during light-load conditions
such as system standby.
Pinout
ISL62873
(16 LD 2.6X1.8 µTQFN)
TOP VIEW
GND 1
EN 2
VID0 3
SREF 4
12 BOOT
11 UGATE
10 PHASE
9 OCSET
Features
• Input Voltage Range: 3.3V to 25V
• Output Voltage Range: 0.5V to 3.3V
• Output Load up to 30A
• Flexible Output Voltage Programmability
- 1-Bit VID Selects Two Independent Setpoint Voltages
- Simple Resistor Programming of Setpoint Voltages
- Accepts External Setpoint Reference such as DAC
• ±0.75% System Accuracy: -10°C to +100°C
• One Capacitor Programs Soft-start and Setpoint Slew-rate
• Fixed 300kHz PWM Frequency in Continuous Conduction
• External Compensation Affords Optimum Control Loop
Tuning
• Automatic Diode Emulation Mode for Highest Efficiency
• Integrated High-current MOSFET Drivers and Schottky
Boot-Strap Diode for Optimal Efficiency
• Choice of Overcurrent Detection Schemes
- Lossless Inductor DCR Current Sensing
- Precision Resistive Current Sensing
• Power-Good Monitor for Soft-Start and Fault Detection
• Fault Protection
- Undervoltage
- Overcurrent (DCR-Sense or Resistive-Sense Capability)
- Over-Temperature Protection
- Fault Identification by PGOOD Pull-Down Resistance
• Pb-Free (RoHS compliant)
Applications
• Mobile PC Graphical Processing Unit VCC Rail
• Mobile PC I/O Controller Hub (ICH) VCC Rail
• Mobile PC Memory Controller Hub (GMCH) VCC Rail
• Built-In Voltage Margin for System-Level Test
Ordering Information
PART
NUMBER
(Note)
TEMP
RANGE
(°C)
PACKAGE
(Pb-Free)
PKG.
DWG. #
ISL62873HRUZ-T* -10 to +100 16 Ld 2.6x1.8 µTQFN L16.2.6x1.8A
Tape and Reel
*Please refer to TB347 for details on reel specifications.
NOTE: These Intersil Pb-free plastic packaged products employ
special Pb-free material sets; molding compounds/die attach
materials and NiPdAu plate - e4 termination finish, which is 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.
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. 2009. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
1 page  
ISL62873
www.DataSheet4U.com
Absolute Maximum Ratings
VCC, PVCC, PGOOD to GND . . . . . . . . . . . . . . . . . . -0.3V to +7.0V
VCC, PVCC to PGND . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +7.0V
GND to PGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +0.3V
EN, SET0, VO,
VID0, FB, OCSET, SREF. . . . . . . . . . . . -0.3V to GND, VCC + 0.3V
BOOT Voltage (VBOOT-GND). . . . . . . . . . . . . . . . . . . . . -0.3V to 33V
BOOT To PHASE Voltage (VBOOT-PHASE) . . . . . . -0.3V to 7V (DC)
-0.3V to 9V (<10ns)
PHASE Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . GND - 0.3V to 28V
GND -8V (<20ns Pulse Width, 10µJ)
UGATE Voltage . . . . . . . . . . . . . . . . VPHASE - 0.3V (DC) to VBOOT
VPHASE - 5V (<20ns Pulse Width, 10µJ) to VBOOT
LGATE Voltage . . . . . . . . . . . . . . . GND - 0.3V (DC) to VCC + 0.3V
GND - 2.5V (<20ns Pulse Width, 5µJ) to VCC + 0.3V
Thermal Information
Thermal Resistance (Typical, Note 1)
θJA (°C/W)
16 Ld µTQFN Package . . . . . . . . . . . . . . . . . . . . . .
84
Junction Temperature Range. . . . . . . . . . . . . . . . . .-55°C to +150°C
Operating Temperature Range . . . . . . . . . . . . . . . .-10°C to +100°C
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . .see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Recommended Operating Conditions
Ambient Temperature Range. . . . . . . . . . . . . . . . . .-10°C to +100°C
Converter Input Voltage to GND . . . . . . . . . . . . . . . . . . 3.3V to 25V
VCC, PVCC to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5V ±5%
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and
result in failures not covered by warranty.
NOTES:
1. θJA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See
Tech Brief TB379.
Electrical Specifications
These specifications apply for TA = -10°C to +100°C, unless otherwise stated.
All typical specifications TA = +25°C, VCC = 5V. Parameters with MIN and/or MAX limits are 100% tested at
+25°C, unless otherwise specified. Temperature limits established by characterization and are not production
tested.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN TYP MAX UNIT
VCC and PVCC
VCC Input Bias Current
VCC Shutdown Current
PVCC Shutdown Current
VCC POR THRESHOLD
IVCC
IVCCoff
IPVCCoff
EN = 5V, VCC = 5V, FB = 0.55V, SREF < FB
EN = GND, VCC = 5V
EN = GND, PVCC = 5V
- 1.1 1.5 mA
- 0.1 1.0 µA
- 0.1 1.0 µA
Rising VCC POR Threshold Voltage
Falling VCC POR Threshold Voltage
REGULATION
VVCC_THR
VVCC_THF
4.40
4.10
4.49
4.22
4.60
4.35
V
V
Reference Voltage
System Accuracy
VREF(int)
VID0 = VID1 = GND, PWM Mode = CCM
- 0.50 -
-0.75 - +0.75
V
%
PWM
Switching Frequency
VO
FSW PWM Mode = CCM
270 300 330 kHz
VO Input Voltage Range
VO Input Impedance
VO Reference Offset Current
VO Input Leakage Current
ERROR AMPLIFIER
VVO
RVO
IVOSS
IVOoff
EN = 5V
VENTHR < EN, SREF = Soft-Start Mode
EN = GND, VO = 3.6V
0 - 3.6 V
- 600 - kΩ
- 10 - µA
- 0.1 - µA
FB Input Bias Current
SREF
IFB EN = 5V, FB = 0.50V
-20 - +50 nA
SREF Operating Voltage Range
Soft-Start Current
Voltage Step Current
VSREF
ISS
IVS
Nominal SREF Setting with 1% Resistors
SREF = Soft-Start Mode
SREF = Setpoint-Stepping Mode
0.5 - 1.5 V
10 20 30 µA
±60 ±100 ±140 µA
5 FN6930.0
June 30, 2009
5 Page 
ISL62873
www.DataSheet4U.com
converter. The fault will remain latched until the EN pin has
been pulled below the falling EN threshold voltage VENTHF
or if VCC has decayed below the falling POR threshold
voltage VVCC_THF.
Over-Temperature
When the temperature of the IC increases above the rising
threshold temperature TOTRTH, it will enter the OTP state
that suspends the PWM, forcing the LGATE and UGATE
gate-driver outputs low. The status of the PGOOD pin does
not change nor does the converter latch-off. The PWM
remains suspended until the IC temperature falls below the
hysteresis temperature TOTHYS at which time normal PWM
operation resumes. The OTP state can be reset if the EN pin
is pulled below the falling EN threshold voltage VENTHF or if
VCC has decayed below the falling POR threshold voltage
VVCC_THF. All other protection circuits remain functional
while the IC is in the OTP state. It is likely that the IC will
detect an UVP fault because in the absence of PWM, the
output voltage decays below the undervoltage threshold
VUVTH.
The negative slope of VR can be written as Equation 20:
VRNEG = gm ⋅ VOUT ⁄ CR
(EQ. 20)
Where, gm is the gain of the transconductance amplifier.
A window voltage VW is referenced with respect to the error
amplifier output voltage VCOMP, creating an envelope into
which the ripple voltage VR is compared. The amplitude of
VW is controlled internally by the IC. The VR, VCOMP, and
VW signals feed into a window comparator in which VCOMP
is the lower threshold voltage and VW is the higher threshold
voltage. Figure 7 shows PWM pulses being generated as VR
traverses the VW and VCOMP thresholds. The PWM
switching frequency is proportional to the slew rates of the
positive and negative slopes of VR; it is inversely
proportional to the voltage between VW and VCOMP.
RIPPLE CAPACITOR VOLTAGE CR
WINDOW VOLTAGE VW
Theory of Operation
The modulator features Intersil’s R3 Robust-Ripple-
Regulator technology, a hybrid of fixed frequency PWM
control and variable frequency hysteretic control. The PWM
frequency is maintained at 300kHz under static
continuous-conduction-mode operation within the entire
specified envelope of input voltage, output voltage, and
output load. If the application should experience a rising load
transient and/or a falling line transient such that the output
voltage starts to fall, the modulator will extend the on-time
and/or reduce the off-time of the PWM pulse in progress.
Conversely, if the application should experience a falling
load transient and/or a rising line transient such that the
output voltage starts to rise, the modulator will truncate the
on-time and/or extend the off-time of the PWM pulse in
progress. The period and duty cycle of the ensuing PWM
pulses are optimized by the R3 modulator for the remainder
of the transient and work in concert with the error amplifier
VERR to maintain output voltage regulation. Once the
transient has dissipated and the control loop has recovered,
the PWM frequency returns to the nominal static 300kHz.
Modulator
The R3 modulator synthesizes an AC signal VR, which is an
analog representation of the output inductor ripple current.
The duty-cycle of VR is the result of charge and discharge
current through a ripple capacitor CR. The current through
CR is provided by a transconductance amplifier gm that
measures the input voltage (VIN) at the PHASE pin and
output voltage (VOUT) at the VO pin. The positive slope of
VR can be written as Equation 19:
VRPOS = (gm) ⋅ (VIN – VOUT) ⁄ CR
(EQ. 19)
ERROR AMPLIFIER VOLTAGE VCOMP
PWM
FIGURE 7. MODULATOR WAVEFORMS DURING LOAD
TRANSIENT
Synchronous Rectification
A standard DC/DC buck regulator uses a free-wheeling
diode to maintain uninterrupted current conduction through
the output inductor when the high-side MOSFET switches off
for the balance of the PWM switching cycle. Low conversion
efficiency as a result of the conduction loss of the diode
makes this an unattractive option for all but the lowest
current applications. Efficiency is dramatically improved
when the free-wheeling diode is replaced with a MOSFET
that is turned on whenever the high-side MOSFET is turned
off. This modification to the standard DC/DC buck regulator
is referred to as synchronous rectification, the topology
implemented by the ISL62873 controller.
Diode Emulation
The polarity of the output inductor current is defined as
positive when conducting away from the phase node, and
defined as negative when conducting towards the phase
node. The DC component of the inductor current is positive,
but the AC component known as the ripple current, can be
either positive or negative. Should the sum of the AC and
DC components of the inductor current remain positive for
the entire switching period, the converter is in
11 FN6930.0
June 30, 2009
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet ISL62873.PDF ] | |
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