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PDF LX1677 Data sheet ( Hoja de datos )
| Número de pieza | LX1677 | |
| Descripción | AMD64 Processor VRM Controller | |
| Fabricantes | Microsemi Corporation | |
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LX1677
TM ® AMD64 Processor VRM Controller
PRODUCTION DATA SHEET
DESCRIPTION
The LX1677 is a highly integrated maximizing regulator response.
VRM power supply controller IC A true differential input amplifier is
featuring two PWM switching used for remote voltage sensing at the
regulator stages.
processor core.
The two constant frequency A VID code generator provides an
voltage-mode PWM phases are internal reference that will set the
configured as a single biphase high output voltage. This VID code can be
current output core supply.
changed during operation and the
In biphase operation, the high reference will slew the output voltage to
current (>35A) output is generated by its new setting at a preset rate. During
a LoadSHARETM† technique that VID changes on the fly the Power Good
balances the currents in the two indication will stay valid.
phases. Power loss and noise, due to The current through the lower phase
the ESR of the input capacitors, are 1 MOSFET will be sampled using its
minimized by operating the PWMs RDS(ON) for current limit and shut
180° out of phase.
down.
A synchronized Transient For further protection, an over
Correction
Loop†
provides voltage circuit will trip at a specified
exceptional control of the output setting and clamp the output by turning
droop and overshoot during very high off the upper MOSFETs and turning on
di/dt load changes, the circuit can be the lower MOSFETs.
configured for droop only, overshoot The upper MOSFET drivers use a
only or both.
bootstrap capacitor to provide the upper
This architecture also minimizes drive voltage over the input voltage
capacitor requirements while range of 6 to 24 volts.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
† Protected By US Patents: US6292378,US6285571
‡ Protected By US Patents: US6825571, US6356063, US6605931
V in + 5 V
PRODUCT HIGHLIGHT
T ra n s ie n t C o re c tio n L o o p
V in 6 to 2 4 V
70nH
5 B it V ID
LX1677
V in 6 to 2 4 V
KEY FEATURES
High Current Biphase
Operation
Outputs As Low As 0.800V
† Biphase LoadSHARETM
‡ Transient Correction Loop™
Reduces Required
Capacitance
Differential Amplifier For
Remote Voltage Sensing
Integrated High Current
MOSFET Drivers
200KHz to 1MHz Frequency
Operation
Programmable Slew Rate
Control For Start-Up Sequence
and VID change
VID Changes On The Fly
Power Good Indicator
Short Circuit Protection
Output Over Voltage and
Under Voltage Protection
No current-sense resistors
APPLICATIONS
AMD Athlon 64™ and AMD
Opteron™ Processors
Processor Core Voltage Supply
Voltage Regulator Modules
Vout
TJ (°C)
0 to 70
PACKAGE ORDER INFO
Plastic TSSOP
PW 38-Pin
Plastic MLPQ
LQ 38-Pin
RoHS Compliant / Pb-free Transition DC: 0518 RoHS Compliant / Pb-free Transition DC: 0512
LX1677CPW
LX1677CLQ
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1677CLQ-TR)
Copyright © 2000
Rev 1.1, 2003-03-03
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
1 page  
LX1677
TM ® AMD64 Processor VRM Controller
PRODUCTION DATA SHEET
ELECTRICAL CHARACTERISTICS (CONT)
Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C ≤ TA ≤ 70°C except where
otherwise noted and the following test conditions: VCC = 5V, VCCL = 5V, VIN = 12V, Switching Frequency = 500KHz.
Parameter
Symbol
Test Conditions
` PHASE 2 DIFFERENTIAL AMPLIFIER
Input Offset Voltage
Gain
Common Mode Rejection Ratio
VOS LP1=LP2
ADA
CMRRDA Common Mode Voltage = 0 to 2 V
Input Resistance
Unity Gain Bandwidth
` TRANSIENT CONTROL LOOP
RB
UGBW
Voltage Droop Sense
Propagation Delay : FB+ and
FB- to I-MAX
Voltage Overshoot Sense
Propagation Delay : FB+ and
FB- to I-MIN
Voltage Droop Sense Threshold
Voltage Overshoot Sense
Threshold
` OUTPUT DRIVERS
VDFOUT Rising 3000pF Load
VDFOUT Falling 3000pF Load
Driver
Rise Time
Fall Time
High Side Driver Voltage:
tRISE
tFALL
CL = 3000pF, VCx - VSx = 5V
[VHOx - VVSx]
Drive High
Drive Low
Low Side Driver Voltage:
VHOx = 20mA, VCx - VSx = 5.0 V
VHOx = -20mA, VCx - VSx = 5.0 V
[VLOx – VPGN]
Drive High
Drive Low
High Side Driver Current
VLOx = 20mA, VCCL - VPGN = 5.0 V
VLOx = -20mA, VCCL - VPGN = 5.0 V
IHOx
VCx - VSx = 5.0 V, Load = 3300pf at
<500nSec
Lower MOSFET Driver Current
ILOx
` PHASE 1 OVER CURRENT PROTECTION
VCCL - PGN = 5.0 V, Load = 3300pf at
<500nSec
Current Sense Bias Current
IILIM1
Current Sense Delay
tCSD(ILIM1)
` TRANSIENT CORRECTION LOOP OVER CURRENT PROTECTION
Current Sense Bias Current
IILIM3
Current Sense Delay
tCSD(ILIM3)
` ENABLE INPUT / VOLTAGE IDENTIFICATION (VID)
Logic Low Threshold
Hysteresis
Pullup Resistance
` POWER GOOD
Low Output Voltage
VPWGD IPWGD = -3mA
LX1677
Units
Min Typ Max
-6 6 mV
0.98 1 1.02 V/V
60 dB
180 KΩ
4 MHz
50 nS
50 nS
40 mV
40 mV
50 nS
50
4.8 4.9
0.1 0.2
V
4.8 4.9
0.1 0.2
1
1.5
V
A
A
44 50 60 µA
200 400 500 nS
40 50 60 µA
200 400 500 nS
1.5 V
0.3 V
100 KΩ
0.5 V
Copyright © 2000
Rev 1.1, 2003-03-03
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
5 Page 
LX1677
TM ® AMD64 Processor VRM Controller
PRODUCTION DATA SHEET
THEORY OF OPERATION (CONTINUED)
THEORY OF OPERATION FOR A BI-PHASE,
LOADSHARETM CONFIGURATION
The basic principle used in LoadSHARETM in a multiple
phase buck converter topology is that if multiple, identical,
inductors have the same identical voltage impressed across
their leads, they must then have the same identical current
passing through them. The current that we would like to
balance between inductors is mainly the DC component
along with as much as possible the transient current. All
inductors in a multiphase buck converter topology have
their output side tied together at the output filter capacitors.
Therefore this side of all the inductors has the same
identical voltage.
If the input side of the inductors can be forced to have
the same equivalent DC potential on this lead, then they
will have the same DC current flowing. To achieve this
requirement, phase 1 will be the control phase that sets the
output operating voltage, under normal PWM operation.
To force the current of phase 2 to be equal to the current of
phase 1; a second feedback loop is used. Phase 2 has a low
pass filter connected from the input side of each inductor.
This side of the inductors has a square wave signal that is
proportional to its duty cycle. The output of each LPF is a
DC (+ some AC) signal that is proportional to the
magnitude and duty cycle of its respective inductor signal.
The second feedback loop will use the output of the
phase 1 LPF as a reference signal for an error amplifier
that will compare this reference to the output of the phase 2
LPF. This error signal will be amplified and used to
control the PWM circuit of phase 2. Therefore, the duty
cycle of phase 2 will be set so that the equivalent voltage
potential will be forced across the phase 2 inductor as
compared to the phase 1 inductor. This will force the
current in the phase 2 inductor to follow and equal the
phase 1 inductor current.
With the LoadSHARETM topology it is possible to
imbalance the phases so that one phase will supply more
current than the other under unique situations. The LX1677
will normally be used with the same supply voltages on
phase 1 and 2 PWM inputs and will have equal currents in
both phases.
LP1
DC Bias
LP2
Phase 1
Low Pass Filter
Differential Feedbach From Vout
DC Bias
+
-
Differential
Amp
EA -
Phase 1 Diff
Amp
DACOUT
DC Bias
Phase 2
Integrating
Amp
Phase 1 Error
Amp 0°
-
+
+
_
Phase 1
Comparator
_
gm
180°
+
Phase 2
Ramp .75 V to 3 V Comparator
Both PWMs
EO2
Phase 2
Low Pass Filter
Figure 5 – LoadSHARE Control Loop
HO1
LO1
HO2
LO2
Vout
Copyright © 2000
Rev 1.1, 2003-03-03
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LX1677.PDF ] | |
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