MAX1939 Fast Delivery |IC PHOENIX CO.,LIMITED

MAX1939 ,Two-Phase Desktop CPU Core Supply Controllers with Controlled VID ChangeFeaturesThe MAX1937/MAX1938/MAX1939 comprise a family of ♦ ±0.75% Output Voltage Accuracysynchronou ..
MAX1939EEI ,Two-Phase Desktop CPU Core Supply Controllers with Controlled VID ChangeApplicationsNotebook and Desktop ComputersPin ConfigurationServers and WorkstationsBlade Servers TO ..
MAX1939EEI ,Two-Phase Desktop CPU Core Supply Controllers with Controlled VID ChangeMAX1937/MAX1938/MAX193919-2498; Rev 1; 10/02Two-Phase Desktop CPU Core Supply Controllerswith Contr ..
MAX1940EEE ,Triple USB Switch with Autoreset and Fault BlankingELECTRICAL CHARACTERISTICS(V = 5V, C = 0.1µF, C = 1µF, T = 0°C to +85°C, unless otherwise noted. Ty ..
MAX1945REUI ,2.6 V to 5.5 V, 1 MHz, 1% accurate, 6A internal switch step-down regulatorApplicationsLow-Voltage, High-Density Distributed PowerTypical Operating CircuitSuppliesASIC, CPU, ..
MAX1945REUI+ ,1MHz, 1% Accurate, 6A Internal Switch Step-Down RegulatorsApplicationsLow-Voltage, High-Density Distributed PowerTypical Operating CircuitSuppliesASIC, CPU, ..
MAX4906EFELB+T ,High-/Full-Speed USB 2.0 Switches with High ESDApplications+Denotes a lead(Pb)-free/RoHS-compliant package.USB Switching Relay ReplacementsT = Tap ..
MAX4906ELB+ ,High-/Full-Speed USB 2.0 SwitchesFeaturesThe MAX4906/MAX4906F/MAX4907/MAX4907F analog♦ Fully Specified for a Single +3.0V to +3.6V s ..
MAX4906FELB ,High-/Full-Speed USB 2.0 Switchesapplications at480Mbps. These switches will also handle all the 7pF (max) On-Capacitance (C )ONrequ ..
MAX4906FELB+ ,High-/Full-Speed USB 2.0 SwitchesApplications MAX4907ELA 8 µDFN L822-1MAX4907FELA 8 µDFN L822-1Cell Phones USB SwitchingPDAs Etherne ..
MAX4906FELB+T ,High-/Full-Speed USB 2.0 Switchesapplications. These devices are♦ MAX4907/MAX4907F Ultra-Low 4pF (typ), designed for USB 2.0 high-sp ..
MAX4907ELA+ ,High-/Full-Speed USB 2.0 SwitchesELECTRICAL CHARACTERISTICS(V+ = +3V to +3.6V, T = T to T , unless otherwise noted. Typical values a ..

MAX1939
Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change
General Description
The MAX1937/MAX1938/MAX1939 comprise a family of
synchronous, two-phase, step-down controllers capable
of delivering load currents up to 60A. The controllers uti-
lize Quick-PWM™ control architecture in conjunction with
active load-current voltage positioning. Quick-PWM con-
trol provides instantaneous load-step response, while
programmable voltage positioning allows the converter
to utilize full transient regulation limits, reducing the out-
put capacitance requirement. The two phases operate
180°out-of-phase with an effective 500kHz switching fre-
quency, thus reducing input and output current ripple, as
well as reducing input filter capacitor requirements.
The MAX1937/MAX1938/MAX1939 are compliant with
AMDHammer, Intel®‚Voltage-Regulator Module (VRM)
9.0/9.1, and AMD Athlon™Mobile VID code specifica-
tions (see Table 1 for VID codes). The internal DAC pro-
vides ultra-high accuracy of ±0.75%. A controlled VID
voltage transition is implemented to minimize both
undervoltage and overvoltage overshoot during VID
input change.
Remote sensing is available for high output-voltage
accuracy. The MOSFET switches are driven by a 6V
gate-drive circuit to minimize switching and crossover
conduction losses to achieve efficiency as high as
90%. The MAX1937/MAX1938/MAX1939 feature cycle-
by-cycle current limit to ensure that the current limit is
not exceeded. Crowbar protection is available to pro-
tect against output overvoltage.
Applications
Notebook and Desktop Computers
Servers and Workstations
Blade Servers
High-End Switches
High-End Routers
Macro Base Stations
Features±0.75% Output Voltage AccuracyInstant Load-Transient ResponseUp to 90% Efficiency Eliminates HeatsinksUp to 60A Output Current8V to 24V Input RangeUser-Programmable Voltage PositioningControlled VID Voltage Transition500kHz Effective Switching FrequencyMAX1937: AMD Hammer CompatibleMAX1938: Intel VRM 9.0/9.1 CompatibleMAX1939: AMD Athlon Mobile CompatibleSoft-StartPower-Good (PWRGD) OutputCycle-by-Cycle Current LimitOutput Overvoltage Protection (OVP)RDS(ON)or RSENSECurrent SensingRemote Voltage Sensing28-Pin QSOP Package
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
VCC
BST1
DH1
LX1
CS1
DL1
PWRGD
VLG
PGND
DL2
CS2
LX2
DH2
BST2
REF
GNDS
GND
ILIM
VDD
VPOS
VID4
VID3
VID2
TIME
VID1
VID0
QSOP
TOP VIEW
MAX1937
MAX1938
MAX1939
Pin Configuration
Ordering Information
19-2498; Rev 1; 10/02
EVALUATION KIT
AVAILABLEPART TEMP RANGE PIN-PACKAGEMAX1937EEI -40°C to +85°C 28 QSOPMAX1938EEI -40°C to +85°C 28 QSOPMAX1939EEI -40°C to +85°C 28 QSOP
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Athlon is a trademark of Advanced Micro Devices, Inc.
Intel is a registered trademark of Intel Corp.
Typical Application Circuits and Functional Diagram appear
at end of data sheet.
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VCCto GND............................................................-0.3V to +28V
VDD, PWRGD, ILIM, FB to GND...............................-0.3V to +6V
EN, GNDS, VPOS, REF, VID_,
TIME to GND............................................0.3V to VVDD + 0.3V
PGND to GND.......................................................-0.3V to +0.3V
CS1, CS2 to GND......................................................-2V to +28V
VLG to GND..............................................................-0.3V to +7V
BST1, BST2 to GND...............................................-0.3V to +35V
LX1 to BST1..............................................................-7V to +0.3V
LX2 to BST2..............................................................-7V to +0.3V
DH1 to LX1.................................................-0.3V to VBST1 + 0.3V
DH2 to LX2.................................................-0.3V to VBST2 + 0.3V
DL1, DL2 to PGND......................................-0.3V to VVLG + 0.3V
Continuous Power Dissipation (TA= +70°C)
28-Pin QSOP (derate 20.8mW/°C above +70°C)......860.2mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
ELECTRICAL CHARACTERISTICS
(VCC= 12V, VEN= VVDD= 5V, PGND = GNDS = GND = 0, VID_ = GND, CVPOS= 47pF, CREF= 0.1µF, VILIM= 1V, TA= 0°C to
+85°C, unless otherwise noted. Typical values are at TA= +25°C.)PARAMETER CONDITIONS MIN TYP MAX UNITSGENERAL MAX1937 6 24 VCC Operating Range MAX1938/MAX1939 8 24 VVDD Operating Range 4.5 5 5.5 VVLG Operating Range VVLG > VVDD 4.5 6.5 VVCC Operating Supply Current FB above threshold (no switching) 20 40 µAVDD Operating Supply Current FB above threshold (no switching) 1.4 2.5 mAVLG Operating Supply Current FB above threshold (no switching) 20 60 µAVCC Shutdown Current EN = GND <1 5 µAVDD Shutdown Current EN = GND, VID_ not connected 50 100 µAVLG Shutdown Current EN = GND <1 5 µATIME Output Voltage 1.96 2.00 2.04 VILIM Input Bias VILIM = 1.5V -250 +250 nAVPOS Output Voltage CS_= GND, VPOS connected to REF through a 75kΩ
resistor 1.96 2.0 2.04 VREFERENCE Reference Voltage -50µA ≤ IREF ≤ 50µA 1.987 2.000 2.013 VSOFT-START MAX1937 1.1 5.5MAX1938 1.5 6.2 Ramp PeriodMAX1939 1.3 6.5msSoft-Start Voltage Step 25 mVERROR AMPLIFIER FB Input Resistance Resistance from FB to GND 180 kΩGNDS Input Bias Current -5 +5 µAOutput Regulation Voltage
Accuracy -0.75 +0.75 %
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
ELECTRICAL CHARACTERISTICS (continued)
(VCC= 12V, VEN= VVDD= 5V, PGND = GNDS = GND = 0, VID_ = GND, CVPOS= 47pF, CREF= 0.1µF, VILIM= 1V, TA= 0°C to
+85°C, unless otherwise noted. Typical values are at TA= +25°C.)PARAMETER CONDITIONS MIN TYP MAX UNITSFAULT PROTECTION VDD Undervoltage Lockout
(UVLO) Threshold Rising or falling VDD 4.00 4.25 4.45 VVDD UVLO Hysteresis 80 mVVLG UVLO Threshold Rising or falling VLG 4.00 4.25 4.45 VVLG UVLO Hysteresis 40 mVThermal Shutdown Rising temperature, typical hysteresis = 15°C 160 °CRising edge 1.600 Reference UVLO Threshold Falling edge 1.584 V
MAX1937/MAX1938 1.97 2.00 2.03 Output Overvoltage Fault
ThresholdRising and fallingMAX1939 2.215 2.250 2.285 VOutput UVLO ThresholdRising and falling percentage of the nominal
regulation voltage 65 70 75 %CURRENT LIMIT
PGND to CS_, VILIM = 1.5V 135 150 165
PGND to CS_, VILIM = 1V 90 100 110 Current-Limit Threshold
PGND to CS_, VILIM = 0.5V 45 50 55mVCS Input Offset VoltageCS_ = GND -3 +3 mVCS_ Input Bias CurrentCS_ = GND -5 +5 µAVOLTAGE POSITIONING VPOS Input Offset Voltage -3 +3 mVVPOS GainFrom CS_ to FB; VCS1, VCS2 = 0, -100mV; RVPOS = 75kΩ 72.5 75.0 77.5 %/VVPOS GainFrom CS1, CS2 to FB; VCS1, VCS2 = +13mV, -113mV;
RVPOS = 75kΩ 68 75 82 %/VTIMER AND DRIVERS On-TimeLX1 = LX2 = CS1 = CS2 = GND, VFB = 1.5V 420 525 630 nsMinimum Off-TimeDH1 low to DH2 high, and DH2 low to DH1 high 260 325 390 ns
MAX1937/MAX1938 60 DH_ low to DL_ highMAX1939 60
MAX1937/MAX1938 85 Break-Before-Make Time
DL_ low to DH_ highMAX1939 70 ns
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
ELECTRICAL CHARACTERISTICS (continued)
(VCC= 12V, VEN= VVDD= 5V, PGND = GNDS = GND = 0, VID_ = GND, CVPOS= 47pF, CREF= 0.1µF, VILIM= 1V, TA= 0°C to
+85°C, unless otherwise noted. Typical values are at TA= +25°C.)PARAMETER CONDITIONS MIN TYP MAX UNITSDH_ On-Resistance in Low State VBST1 = VBST2 = 6V, LX1 = LX2 = GND 1.5 3.0 ΩDH_ On-Resistance in High State VBST_ = 6V, LX_ = GND 1.5 3.0 ΩDL_ On-Resistance in Low State 0.5 1.7 ΩDL_ On-Resistance in High State 1.5 3.0 ΩBST_ Leakage Current VBST_ = 30V, VLX_ = 24V 50 µALX_ Leakage Current VBST_ = 30V, VLX_ = 24V 50 µAEN AND VID Low Level Threshold 0.8 VHigh Level Threshold 1.6 VPullup Resistance Internally pulled up to VDD 50 100 200 kΩPWRGD PWRGD Upper Trip Level 10.0 12.5 15.0 %PWRGD Lower Trip Level -15 -12.5 -10 %Output Low Level 0.4 VOutput High Leakage 1 µACONTROLLED VID CHANGE RTIME = 120kΩ 6.17 6.67 7.25RTIME = 47kΩ 2.35 2.63 2.99 On-the-Fly VID Change Slew
Rate 25mV per stepRTIME = 470kΩ 23.5 26.3 29.9µsVID_ Change Frequency Range 38 380 kHzPWRGD Blanking Time VVDD = 4.5V to 5.5V 125 200 350 µs
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
ELECTRICAL CHARACTERISTICS
(VVCC= 12V, VEN= VVDD= 5V, PGND = GNDS = GND, VID_= GND, CVPOS = 47pF, CREF= 0.1µF, VILIM= 1V, TA= -40°C to +85°C,
unless otherwise noted.) (Note 1)PARAMETER CONDITIONS MIN TYP MAX UNITSGENERAL MAX1937 6 24 VCC Operating Range MAX1938/MAX1939 8 24 VVDD Operating Range 4.5 5.5 VVLG Operating Range VVLG ≥ VVDD 4.5 6.5 VVCC Operating Supply Current FB above threshold (no switching) 40 µAVDD Operating Supply Current FB above threshold (no switching) 2.5 mAVLG Operating Supply Current FB above threshold (no switching) 20 60 µAVCC Shutdown Current EN = GND 5 µAVDD Shutdown Current EN = GND, VID_ not connected 100 µAVLG Shutdown Current EN = GND 5 µATIME Output Voltage 1.96 2.04 VILIM Input Bias VILIM = 1V -250 +250 nAVPOS Output Voltage CS_ = GND, VPOS connected to REF through a 75kΩ
resistor 1.96 2.04 VREFERENCE Reference Voltage -50µA ≤ IREF ≤ 50µA 1.98 2.02 VSOFT-START MAX1937 1.1 5.5MAX1938 1.5 6.6 Ramp PeriodMAX1939 1.3 7.0msERROR AMPLIFIER GNDS Input Bias Current -5 +5 µAOutput Regulation Voltage
Accuracy -1 +1 %FAULT PROTECTION VDD UVLO Threshold Rising or falling VDD 4.00 4.45 VVLG UVLO Threshold Rising or falling VLG 4.00 4.45 V
MAX1937/MAX1938 1.97 2.03 Output Overvoltage Fault
ThresholdRising and fallingMAX1939 2.215 2.285 VOutput UVLO ThresholdRising and falling percentage of the nominal
regulation voltage 65 75 %CURRENT LIMIT
PGND to CS_, VILIM = 1.5V 135 165
PGND to CS_, VILIM = 1V 90 110 Current-Limit Threshold
PGND to CS_, VILIM = 0.5V 45 55mV
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
ELECTRICAL CHARACTERISTICS (continued)
(VVCC= 12V, VEN= VVDD= 5V, PGND = GNDS = GND, VID_= GND, CVPOS = 47pF, CREF= 0.1µF, VILIM= 1V, TA= -40°C to +85°C,
unless otherwise noted.) (Note 1)PARAMETER CONDITIONS MIN TYP MAX UNITSCS Input Offset VoltageCS_ = GND -5 +5 mVCS_ Input Bias CurrentCS_ = GND -5 +5 µAVOLTAGE POSITIONING VPOS Input Offset Voltage -5 +5 mVVPOS GainFrom CS_ to FB; VCS1, VCS2 = 0, -100mV; RVPOS = 75kΩ 72.5 77.5 %/VVPOS GainFrom CS1, CS2 to FB; VCS1, VCS2 = +13mV, -113mV;
RVPOS = 75kΩ 68 82 %/VTIMER AND DRIVERS On-TimeLX1 = LX2 = CS1 = CS2 = GND, VFB = 1.5V 420 630 nsMinimum Off-TimeDH1 low to DH2 high, and DH2 low to DH1 high 260 390 nsDH_ On-Resistance in Low State VBST1 = VBST2 = 6V, LX1 = LX2 = GND 3 ΩDH_ On-Resistance in High State VBST_ = 6V, LX_ = GND 3 ΩDL_ On-Resistance in Low State 1.7 ΩDL_ On-Resistance in High State 3 ΩBST_ Leakage Current VBST_ = 30V, VLX_ = 24V 50 µALX_ Leakage Current VBST_ = 30V, VLX_ = 24V 50 µAEN AND VID_ Low Level Threshold 0.8 VHigh Level Threshold 1.6 VPullup Resistance Internally pulled up to VDD 50 200 kΩPWRGD PWRGD Upper Trip Level 10 15 %PWRGD Lower Trip Level -15 -10 %Output Low Level 0.4 VOutput High Leakage 1 µACONTROLLED VID CHANGE RTIME = 120kΩ 6.17 7.25RTIME = 47kΩ 2.35 2.99 On-the-Fly VID Change Slew
Rate 25mV per stepRTIME = 470kΩ 23.5 29.9µsVID_ Change Frequency Range 38 380 kHzPWRGD Blanking Time VVDD = 4.5V to 5.5V 125 350 µs
Note 1:Specifications to -40°C are guaranteed by design and not production tested.
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
EFFICIENCY vs. LOAD CURRENT
AT 1.45V OUTPUT
MAX1937 toc01
LOAD CURRENT (A)
EFFICIENCY (%)100
VIN = 8V
VIN = 14V
VIN = 12V
VOUT = 1.45V10100
EFFICIENCY vs. LOAD CURRENT
AT 1.85V OUTPUT
MAX1937 toc02
LOAD CURRENT (A)
EFFICIENCY (%)
VIN = 12V
VIN = 14V
VOUT = 1.85V
VIN = 8V
FREQUENCY vs. LOAD CURRENT
MAX1937 toc03
LOAD CURRENT (A)
FREQUENCY (kHz)40302010
VIN = 12V
VOUT = 1.45V
FREQUENCY vs. INPUT VOLTAGE
MAX1937 toc04
INPUT VOLTAGE (V)
FREQUENCY (kHz)1211109
ILOAD = 46A
VOUT = 1.45V
ILOAD = 1A
FREQUENCY vs. TEMPERATURE
MAX1937 toc05
TEMPERATURE (°C)
FREQUENCY (kHz)60-2002040
VIN = 12V
VOUT = 1.45V
ILOAD = 10A
VCC INPUT CURRENT
vs. INPUT VOLTAGE
MAX1937 toc06
INPUT VOLTAGE (V)
INPUT CURRENT (1211109
VOUT = 1.45V
VDD CURRENT vs. VDD VOLTAGE
MAX1937 toc07
VDD VOLTAGE (V)
CURRENT (mA)
Typical Operating Characteristics
(VIN= 12V, VOUT= 1.45V, TA= +25°C, unless otherwise noted.)
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
Typical Operating Characteristics (continued)
(VIN= 12V, VOUT= 1.45V, TA= +25°C, unless otherwise noted.)
CURRENT SHARING
MAX1937 toc10
LOAD CURRENT (A)
INDUCTOR CURRENTS (A)302010
VIN = 12V
VOUT = 1.45V
TA = +25°C
CURRENT SHARING
MAX1937 toc11
LOAD CURRENT (A)
INDUCTOR CURRENTS (A)302010
VIN = 12V
VOUT = 1.45V
TA = +80°C
VIN = 12V
VOUT = 1.45V
IOUT = 0A
OUTPUT INDUCTOR
CURRENTS:
10A/div
OUTPUT RIPPLE
VOLTAGE:
20mV/div
2μs/div
MAX1937 toc12
INDUCTOR CURRENT WAVEFORMS
WITH 0A LOAD
VIN = 12V
VOUT = 1.45V
IOUT = 40A
OUTPUT INDUCTOR
CURRENTS:
10A/div
OUTPUT RIPPLE
VOLTAGE:
20mV/div
2μs/div
MAX1937 toc13
INDUCTOR CURRENT WAVEFORMS
WITH 40A LOAD
OUTPUT VOLTAGE vs. LOAD CURRENT
AT 1.45V OUTPUT
MAX1937 toc09
LOAD CURRENT (A)
OUT302010
RVPOS = 90.9kΩ
VIN = 12V
RVPOS = 120kΩ
VDD CURRENT vs. VDD VOLTAGE
IN SHUTDOWN
MAX1937 toc08
VDD VOLTAGE (V)
DD
CURRENT (mA)
VID_ NOT CONNECTED
ENABLE SIGNAL
OUTPUT VOLTAGE:
0.5V/div
POK SIGNAL
20ms/div
MAX1937 toc18
SHUTDOWN WAVEFORM
WITH 40A LOAD
INDUCTOR CURRENT:
10A/div
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
CURRENT-SENSE THRESHOLD vs. VILIM
MAX1937 toc19
VILIM (V)
CURRENT-SENSE THRESHOLD (mV)
VIN = 12V
VOUT = 1.45V
TA = +25°C
TA = +80°Cypical Operating Characteristics (continued)
(VIN= 12V, VOUT= 1.45V, TA= +25°C, unless otherwise noted.)
ENABLE SIGNAL
OUTPUT VOLTAGE:
0.5V/div
POK SIGNAL
1ms/div
MAX1937 toc16
SOFT-START WAVEFORMS
WITH 40A LOAD
INDUCTOR CURRENT:
10A/div
ENABLE SIGNAL
OUTPUT VOLTAGE:
0.5V/div
POK SIGNAL
20ms/div
MAX1937 toc17
SHUTDOWN WAVEFORM
WITH NO LOAD
INDUCTOR CURRENT:
10A/div
40μs/div
MAX1937 toc14
LOAD TRANSIENT
1A TO 40A TO 1A
TRANSIENT CONTROL
SIGNAL:
C6 = 47pF
R2 = 91.1kΩ
INDUCTOR CURRENTS:
10A/div
OUTPUT VOLTAGE:
50mV/div
ENABLE SIGNAL
OUTPUT VOLTAGE:
0.5V/div
POK SIGNAL
1ms/div
MAX1937 toc15
SOFT-START WAVEFORMS
WITH NO LOAD
INDUCTOR CURRENT:
10A/div
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
REFERENCE VOLTAGE vs. TEMPERATURE
MAX1937 toc22
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)6040200-20
VIN = 12V
VOUT = 1.45V
NO LOAD
FB VOLTAGE vs. TEMPERATURE
MAX1937 toc23
TEMPERATURE (°C)
FB VOLTAGE (V)3510-15
VIN = 12V
NO LOAD
VOUT = 0.8V
FB VOLTAGE vs. TEMPERATURE
MAX1937 toc24
TEMPERATURE (°C)
FB VOLTAGE (V)6040200-20
VIN = 12V
NO LOAD
VOUT = 1.45V
OUTPUT VOLTAGE:
200mV/div
POK SIGNAL
40μs/div
MAX1937 toc20
VID CODE CHANGE ON-THE-FLY WITH 40A
LOAD 1.2V TO 1.45V TO 1.2V
VID CODE CHANGE
CONTROL SIGNAL
OUTPUT VOLTAGE:
200mV/div
POK SIGNAL
40μs/div
MAX1937 toc21
VID CODE CHANGE ON-THE-FLY WITH 1A
LOAD 1.2V TO 1.45V TO 1.2V
VID CONTROL
SIGNALypical Operating Characteristics (continued)
(VIN= 12V, VOUT= 1.45V, TA= +25°C, unless otherwise noted.)
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
Pin DescriptionPIN NAME FUNCTION1 VID0 Voltage Identification Input Bit 0. See Table 1. Internal 100kΩ pullup resistor to VDD.2 VID1 Voltage Identification Input Bit 1. See Table 1. Internal 100kΩ pullup resistor to VDD.3 TIME Connect to an external resistor (47kΩ to 470kΩ) for VID change slew-rate control.4 VID2 Voltage Identification Input Bit 2. See Table 1. Internal 100kΩ pullup resistor to VDD.5 VID3 Voltage Identification Input Bit 3. See Table 1. Internal 100kΩ pullup resistor to VDD.6 VID4 Voltage Identification Input Bit 4. See Table 1. Internal 100kΩ pullup resistor to VDD.7 VPOS Voltage Positioning. Connect a resistor between VPOS and REF to set the output voltage-positioning
droop, or connect directly to REF for no output voltage positioning. Connect a 47pF capacitor from
VPOS to GND.8 VDD IC Analog Power-Supply Input. Connect a 5V supply to VDD.9 ILIM Current-Limit Threshold per Phase. Connect ILIM to VDD to set a default current limit of 120mV, or
connect to a voltage-divider from REF to GND to adjust the current limit. See the Setting the Current
Limit section.10 GND Ground11 GNDS Remote Ground Sense. Connect GNDS to the output ground at the load. For VRM applications, also
connect a 100Ω resistor from GNDS to PGND locally.12 REF Reference Output. Connect a 0.1µF capacitor from REF to GND.13 EN Enable Input. Leave unconnected or drive high for normal operation. Drive low for shutdown.14 FB Remote Feedback Sense. Connect FB to the output at the load. For VRM applications, also connect
a 100Ω resistor from FB to the output locally.15 PWRGDPower-Good Output. Open-drain output is high impedance when the output is in regulation and
pulled low when the output deviates more than 12.5% from the voltage set by the VID code. PWRGD
is also low in shutdown or during any fault condition. To use as a logic output, connect a pullup
resistor from PWRGD to the logic supply.16 BST2 High-Side MOSFET Gate-Driver Bootstrap Input. Connect 0.22µF or higher value bypass capacitor
from BST2 to LX2. Keep trace length as short as possible. Connect a Schottky diode between BST2
and VLG. See the Selecting a BST Capacitor section.17 DH2 High-Side MOSFET Gate-Drive Output. Connect to the high-side MOSFET gate. DH2 is pulled low in
shutdown.18 LX2 Inductor Connection. Connect to the switched side of the inductor.19 CS2 Negative Current-Sense Input. Connect to a current-sense resistor in series with the low-side
MOSFET, or connect to LX2 to use the low-side MOSFET’s on-resistance for current sensing.20 DL2 Low-Side MOSFET Gate-Driver Output. Connect to the low-side MOSFET gate. DL2 is pulled low in
shutdown.21 PGND Power Ground. Connect to power ground at the point where the current-sense resistors or low-side
MOSFET sources connect. PGND is used as the positive current-sense connection.
MAX1937/MAX1938/MAX1939wo-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
Detailed Description
The MAX1937/MAX1938/MAX1939 is a family of syn-
chronous, two-phase step-down controllers capable of
delivering load currents up to 60A. The controllers use
Quick-PWM control architecture in conjunction with
active load current voltage positioning. Quick-PWM
control provides instantaneous load-step response,
while programmable voltage positioning allows the con-
verter to utilize full transient regulation limits, reducing
the output capacitance requirement. Furthermore, the
two phases operate 180°out-of-phase with an effective
500kHz switching frequency, thus reducing input and
output current ripple, as well as reducing input filter
capacitor requirements.
The MAX1937/MAX1938/MAX1939 are compliant with
the AMD Hammer, Intel VRM 9.0/VRM 9.1, and AMD
Athlon Mobile VID code specifications (see Table 1 for
VID codes). The internal DAC provides ultra-high accu-
racy of ±0.75%. A controlled VID voltage transition is
implemented to minimize both undervoltage and over-
voltage overshoot during VID input change.
Remote sensing is available for high output-voltage
accuracy. The MOSFET switches are driven by with a
6V gate-drive circuit to minimize switching and
crossover conduction losses to achieve efficiency as
high as 90%. The MAX1937/MAX1938/ MAX1939 fea-
ture cycle-by-cycle current limit to ensure current limit
is not exceeded. Crowbar protection is available to pro-
tect against output overvoltage.
On-Time One-Shot
The heart of the Quick-PWM core is the one-shot that
sets the high-side switch on-time. This fast, low-jitter,
one-shot circuitry varies the on-time in response to the
input and output voltages. The high-side switch on-time
is inversely proportional to the voltage applied to VCC
and directly proportional to the output voltage. This
algorithm results in a nearly constant switching fre-
quency, despite the lack of a fixed-frequency clock
generator. The benefits of a constant switching fre-
quency are twofold: the frequency selected avoids
noise-sensitive regions, and the inductor ripple current
operating point remains relatively constant, resulting in
easy design methodology and predictable output volt-
age ripple:
where the constant K is 4µs and VDROPis the voltage
drop across the low-side MOSFET’s on-resistance plus
the drop across the current-sense resistor (VDROP≈
75mV), if used.
The on-time one-shot has good accuracy at the operat-
ing point specified in the Electrical Characteristics. On-
times at operating points far removed from the
conditions specified in the Electrical Characteristicscan
vary over a wide range. For example, the regulators run
slower with input voltages greater than 12V because of
the very short on-times required.VON
OUTDROP
VCC=+()
Pin Description (continued)PIN NAME FUNCTION22 VLG DL_ Driver Power-Supply Input. Connect to a 4.5V to 6.5V supply for powering the low-side MOSFET
gate drive, and the bootstrap circuit for driving the high-side MOSFETs. Ensure that VVLG is greater
than or equal to VVDD.23 DL1 Low-Side MOSFET Gate-Driver Output. Connect to the low-side MOSFET gate. DL1 is pulled low in
shutdown.24 CS1 Negative Current-Sense Input. Connect to a current-sense resistor in series with the low-side
MOSFET or connect to LX1 to use the low-side MOSFET’s on-resistance for current sensing.25 LX1 Inductor Connection. Connect to the switched side of the inductor.26 DH1 High-Side MOSFET Gate-Drive Output. Connect to the high-side MOSFET gate. DH1 is pulled low in
shutdown.27 BST1 High-Side MOSFET Gate-Driver Bootstrap Input. Connect 0.22µF or higher value bypass capacitor
from BST1 to LX1. Keep trace length as short as possible. Connect a Schottky diode between BST1
and VLG. See the Selecting a BST Capacitor section.28 VCC Input Voltage Sense. Connect to the input supply at the high-side MOSFET drain. The voltage
sensed at VCC is used to set the on-time.

Partno	Mfg	Dc	Qty	Available	Descript
MAX1939	MAXIM	N/a	79	avai	Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change