19-2498; Rev 1; 10/02
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
AMD Hammer, 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.
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Features
±0.75% Output Voltage Accuracy
Instant Load-Transient Response
Up to 90% Efficiency Eliminates Heatsinks
Up to 60A Output Current
8V to 24V Input Range
User-Programmable Voltage Positioning
Controlled VID Voltage Transition
500kHz Effective Switching Frequency
MAX1937: AMD Hammer Compatible
MAX1938: Intel VRM 9.0/9.1 Compatible
MAX1939: AMD Athlon Mobile Compatible
Soft-Start
Power-Good (PWRGD) Output
Cycle-by-Cycle Current Limit
Output Overvoltage Protection (OVP)
R
DS(ON)
or R
SENSE
Current Sensing
Remote Voltage Sensing
28-Pin QSOP Package
MAX1937/MAX1938/MAX1939
Ordering Information
PART
MAX1937EEI
MAX1938EEI
MAX1939EEI
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
28 QSOP
28 QSOP
28 QSOP
Applications
Notebook and Desktop Computers
Servers and Workstations
Blade Servers
High-End Switches
High-End Routers
Macro Base Stations
TOP VIEW
VID0 1
VID1 2
TIME 3
VID2 4
VID3 5
VID4 6
VPOS 7
V
DD
8
ILIM 9
28 V
CC
27 BST1
26 DH1
25 LX1
24 CS1
Pin Configuration
MAX1937
MAX1938
MAX1939
23 DL1
22 VLG
21 PGND
20 DL2
19 CS2
18 LX2
17 DH2
16 BST2
15 PWRGD
Typical Application Circuits and Functional Diagram appear
at end of data sheet.
GND 10
GNDS 11
REF 12
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.
EN 13
FB 14
QSOP
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Two-Phase Desktop CPU Core Supply Controllers
with Controlled VID Change
MAX1937/MAX1938/MAX1939
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND ............................................................-0.3V to +28V
V
DD
, PWRGD, ILIM, FB to GND ...............................-0.3V to +6V
EN, GNDS, VPOS, REF, VID_,
TIME to GND ............................................0.3V to V
VDD
+ 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 V
BST1
+ 0.3V
DH2 to LX2.................................................-0.3V to V
BST2
+ 0.3V
DL1, DL2 to PGND ......................................-0.3V to V
VLG
+ 0.3V
Continuous Power Dissipation (T
A
= +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
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.
ELECTRICAL CHARACTERISTICS
(V
CC
= 12V, V
EN
= V
VDD
= 5V, PGND = GNDS = GND = 0, VID_ = GND, C
VPOS
= 47pF, C
REF
= 0.1µF, V
ILIM
= 1V,
T
A
= 0°C to
+85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
GENERAL
V
CC
Operating Range
V
DD
Operating Range
VLG Operating Range
V
CC
Operating Supply Current
V
DD
Operating Supply Current
VLG Operating Supply Current
V
CC
Shutdown Current
V
DD
Shutdown Current
VLG Shutdown Current
TIME Output Voltage
ILIM Input Bias
VPOS Output Voltage
REFERENCE
Reference Voltage
SOFT-START
MAX1937
Ramp Period
Soft-Start Voltage Step
ERROR AMPLIFIER
FB Input Resistance
GNDS Input Bias Current
Output Regulation Voltage
Accuracy
Resistance from FB to GND
-5
-0.75
180
+5
+0.75
kΩ
µA
%
MAX1938
MAX1939
1.1
1.5
1.3
25
5.5
6.2
6.5
mV
ms
-50µA
≤
I
REF
≤
50µA
1.987
2.000
2.013
V
V
ILIM
= 1.5V
CS_= GND, VPOS connected to REF through a 75kΩ
resistor
V
VLG
> V
VDD
FB above threshold (no switching)
FB above threshold (no switching)
FB above threshold (no switching)
EN = GND
EN = GND, VID_ not connected
EN = GND
1.96
-250
1.96
2.0
20
<1
50
<1
2.00
MAX1937
MAX1938/MAX1939
6
8
4.5
4.5
20
1.4
5
24
24
5.5
6.5
40
2.5
60
5
100
5
2.04
+250
2.04
V
V
V
µA
mA
µA
µA
µA
µA
V
nA
V
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Two-Phase Desktop CPU Core Supply Controllers
with Controlled VID Change
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 12V, V
EN
= V
VDD
= 5V, PGND = GNDS = GND = 0, VID_ = GND, C
VPOS
= 47pF, C
REF
= 0.1µF, V
ILIM
= 1V,
T
A
= 0°C to
+85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
FAULT PROTECTION
V
DD
Undervoltage Lockout
(UVLO) Threshold
V
DD
UVLO Hysteresis
VLG UVLO Threshold
VLG UVLO Hysteresis
Thermal Shutdown
Reference UVLO Threshold
Output Overvoltage Fault
Threshold
Output UVLO Threshold
CURRENT LIMIT
PGND to CS_, V
ILIM
= 1.5V
Current-Limit Threshold
CS Input Offset Voltage
CS_ Input Bias Current
VOLTAGE POSITIONING
VPOS Input Offset Voltage
VPOS Gain
VPOS Gain
TIMER AND DRIVERS
On-Time
Minimum Off-Time
LX1 = LX2 = CS1 = CS2 = GND, V
FB
= 1.5V
DH1 low to DH2 high, and DH2 low to DH1 high
DH_ low to DL_ high
Break-Before-Make Time
DL_ low to DH_ high
MAX1937/MAX1938
MAX1939
MAX1937/MAX1938
MAX1939
420
260
525
325
60
60
85
70
ns
630
390
ns
ns
From CS_ to FB; V
CS1
, V
CS2
= 0, -100mV; R
VPOS
= 75kΩ
From CS1, CS2 to FB; V
CS1
, V
CS2
= +13mV, -113mV;
R
VPOS
= 75kΩ
-3
72.5
68
75.0
75
+3
77.5
82
mV
%/V
%/V
PGND to CS_, V
ILIM
= 1V
PGND to CS_, V
ILIM
= 0.5V
CS_ = GND
CS_ = GND
135
90
45
-3
-5
150
100
50
165
110
55
+3
+5
mV
µA
mV
Rising temperature, typical hysteresis = 15°C
Rising edge
Falling edge
Rising and falling
MAX1937/MAX1938
MAX1939
1.97
2.215
65
Rising or falling VLG
4.00
Rising or falling V
DD
4.00
4.25
80
4.25
40
160
1.600
1.584
2.00
2.250
70
2.03
2.285
75
4.45
4.45
V
mV
V
mV
°C
V
V
%
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1937/MAX1938/MAX1939
Rising and falling percentage of the nominal
regulation voltage
_______________________________________________________________________________________
3
Two-Phase Desktop CPU Core Supply Controllers
with Controlled VID Change
MAX1937/MAX1938/MAX1939
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 12V, V
EN
= V
VDD
= 5V, PGND = GNDS = GND = 0, VID_ = GND, C
VPOS
= 47pF, C
REF
= 0.1µF, V
ILIM
= 1V,
T
A
= 0°C to
+85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
DH_ On-Resistance in Low State
DL_ On-Resistance in Low State
DL_ On-Resistance in High State
BST_ Leakage Current
LX_ Leakage Current
EN AND VID
Low Level Threshold
High Level Threshold
Pullup Resistance
PWRGD
PWRGD Upper Trip Level
PWRGD Lower Trip Level
Output Low Level
Output High Leakage
CONTROLLED VID CHANGE
On-the-Fly VID Change Slew
Rate
VID_ Change Frequency Range
PWRGD Blanking Time
V
VDD
= 4.5V to 5.5V
R
TIME
= 120kΩ
25mV per step
R
TIME
= 47kΩ
R
TIME
= 470kΩ
6.17
2.35
23.5
38
125
200
6.67
2.63
26.3
7.25
2.99
29.9
380
350
kHz
µs
µs
10.0
-15
12.5
-12.5
15.0
-10
0.4
1
%
%
V
µA
Internally pulled up to V
DD
1.6
50
100
200
0.8
V
V
kΩ
V
BST_
= 30V, V
LX_
= 24V
V
BST_
= 30V, V
LX_
= 24V
CONDITIONS
V
BST1
= V
BST2
= 6V, LX1 = LX2 = GND
MIN
TYP
1.5
1.5
0.5
1.5
MAX
3.0
3.0
1.7
3.0
50
50
UNITS
Ω
Ω
Ω
Ω
µA
µA
DH_ On-Resistance in High State V
BST_
= 6V, LX_ = GND
4
_______________________________________________________________________________________
Two-Phase Desktop CPU Core Supply Controllers
with Controlled VID Change
ELECTRICAL CHARACTERISTICS
(V
VCC
= 12V, V
EN
= V
VDD
= 5V, PGND = GNDS = GND, VID_= GND, C
VPOS
= 47pF, C
REF
= 0.1µF, V
ILIM
= 1V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
GENERAL
V
CC
Operating Range
V
DD
Operating Range
VLG Operating Range
V
CC
Operating Supply Current
V
DD
Operating Supply Current
VLG Operating Supply Current
V
CC
Shutdown Current
V
DD
Shutdown Current
VLG Shutdown Current
TIME Output Voltage
ILIM Input Bias
VPOS Output Voltage
REFERENCE
Reference Voltage
SOFT-START
MAX1937
Ramp Period
ERROR AMPLIFIER
GNDS Input Bias Current
Output Regulation Voltage
Accuracy
FAULT PROTECTION
V
DD
UVLO Threshold
VLG UVLO Threshold
Output Overvoltage Fault
Threshold
Output UVLO Threshold
CURRENT LIMIT
PGND to CS_, V
ILIM
= 1.5V
Current-Limit Threshold
PGND to CS_, V
ILIM
= 1V
PGND to CS_, V
ILIM
= 0.5V
135
90
45
165
110
55
mV
Rising or falling V
DD
Rising or falling VLG
Rising and falling
MAX1937/MAX1938
MAX1939
4.00
4.00
1.97
2.215
65
4.45
4.45
2.03
2.285
75
V
V
V
%
-5
-1
+5
+1
µA
%
MAX1938
MAX1939
1.1
1.5
1.3
5.5
6.6
7.0
ms
-50µA
≤
I
REF
≤
50µA
1.98
2.02
V
V
ILIM
= 1V
CS_ = GND, VPOS connected to REF through a 75kΩ
resistor
V
VLG
≥
V
VDD
FB above threshold (no switching)
FB above threshold (no switching)
FB above threshold (no switching)
EN = GND
EN = GND, VID_ not connected
EN = GND
1.96
-250
1.96
20
MAX1937
MAX1938/MAX1939
6
8
4.5
4.5
24
24
5.5
6.5
40
2.5
60
5
100
5
2.04
+250
2.04
V
V
V
µA
mA
µA
µA
µA
µA
V
nA
V
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1937/MAX1938/MAX1939
Rising and falling percentage of the nominal
regulation voltage
_______________________________________________________________________________________
5
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