MAX5038EAI33+ [MAXIM]

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MAX5038EAI33+
型号: MAX5038EAI33+
厂家: MAXIM INTEGRATED PRODUCTS    MAXIM INTEGRATED PRODUCTS
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稳压器 开关式稳压器或控制器 电源电路 开关式控制器 光电二极管 输入元件 信息通信管理
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19-2514; Rev 3; 8/04  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Ge n e ra l De s c rip t io n  
Fe a t u re s  
The MAX5038/MAX5041 dual-phase, PWM controllers  
provide high-output-current capability in a compact  
package with a minimum number of external compo-  
nents. The MAX5038/MAX5041 utilize a dual-phase,  
average current-mode control that enables optimal use  
+4.75V to +5.5V or +8V to +28V Input Voltage  
Range  
Up to 60A Output Current  
Internal Voltage Regulator for a +12V or +24V  
of low R  
MOSFETs, eliminating the need for exter-  
DS(ON)  
Power Bus  
nal heatsinks even when delivering high output currents.  
True Differential Remote Output Sensing  
Differential sensing enables accurate control of the out-  
put voltage, while adaptive voltage positioning provides  
op timum tra ns ie nt re s p ons e . An inte rna l re g ula tor  
enables operation with input voltage ranges of +4.75V to  
+5.5V or +8V to +28V. The high switching frequency, up  
to 500kHz per phase, and dual-phase operation allow  
the use of low-output inductor values and input capacitor  
va lue s . This a c c ommod a te s the us e of PC b oa rd -  
embedded planar magnetics achieving superior reliabili-  
ty, current sharing, thermal management, compact size,  
and low system cost.  
Two Out-Of-Phase Controllers Reduce Input  
Capacitance Requirement and Distribute Power  
Dissipation  
Average Current-Mode Control  
Superior Current Sharing Between Individual  
Phases and Paralleled Modules  
Accurate Current Limit Eliminates MOSFET and  
Inductor Derating  
Integrated 4A Gate Drivers  
The MAX5038/MAX5041 a ls o fe a ture a c loc k inp ut  
(CLKIN) for synchronization to an external clock, and a  
clock output (CLKOUT) with programmable phase delay  
(relative to CLKIN) for paralleling multiple phases. The  
MAX5038 offers a variety of factory-trimmed preset output  
voltages (see Selector Guide) and the MAX5041 offers an  
adjustable output voltage from +1.0V to +3.3V.  
Selectable Fixed Frequency 250kHz or 500kHz Per  
Phase (Up to 1MHz for 2 Phases)  
Fixed (MAX5038) or Adjustable (MAX5041) Output  
Voltages  
0.5% Accurate Reference (MAX5041B)  
The MAX5038/MAX5041 operate over the extended  
industrial temperature range (-40°C to +85°C) and are  
a va ila b le in a 28-p in SSOP p a c ka g e . Re fe r to the  
MAX5037 data sheet for a VRM 9.0-compatible, VID-  
controlled output voltage controller in a 44-pin MQFP or  
QFN package.  
External Frequency Synchronization from 125kHz  
to 600kHz  
Internal PLL with Clock Output for Paralleling  
Multiple DC-DC Converters  
Thermal Protection  
Ap p lic a t io n s  
28-Pin SSOP Package  
Servers and Workstations  
Ord e rin g In fo rm a t io n  
Point-Of-Load High-Current/High-Density  
Telecom DC-DC Regulators  
PIN-  
PACKAGE  
OUTPUT  
VOLTAGE  
PART  
TEMP RANGE  
Networking Systems  
Large-Memory Arrays  
RAID Systems  
MAX5038EAI12 -40°C to +85°C 28 SSOP  
MAX5038EAI15 -40°C to +85°C 28 SSOP  
MAX5038EAI18 -40°C to +85°C 28 SSOP  
MAX5038EAI25 -40°C to +85°C 28 SSOP  
MAX5038EAI33 -40°C to +85°C 28 SSOP  
Fixed +1.2V  
Fixed +1.5V  
Fixed +1.8V  
Fixed +2.5V  
Fixed +3.3V  
High-End Desktop Computers  
Adj +1.0V to  
+3.3V  
MAX5041EAI  
-40°C to +85°C 28 SSOP  
Adj +1.0V to  
+3.3V  
MAX5041BEAI -40°C to +85°C 28 SSOP  
Pin Configuration appears at end of data sheet.  
________________________________________________________________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.  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
ABSOLUTE MAXIMUM RATINGS  
IN to SGND.............................................................-0.3V to +30V  
All Other Pins to SGND...............................-0.3V to (V + 0.3V)  
CC  
BST_ to SGND…………………………………….…-0.3V to +35V  
Continuous Power Dissipation (T = +70°C)  
A
DH_ to LX_ ................................-0.3V to [(V _ - V _) + 0.3V]  
28-Pin SSOP (derate 9.5mW/°C above +70°C) ............762mW  
Operating Temperature Range ...........................-40°C to +85°C  
Maximum Junction Temperature .....................................+150°C  
Storage Temperature Range .............................-60°C to +150°C  
Lead Temperature (soldering, 10s) .................................+300°C  
BST  
LX  
DL_ to PGND..............................................-0.3V to (V + 0.3V)  
CC  
BST_ to LX_ ..............................................................-0.3V to +6V  
V
V
CC  
to SGND............................................................-0.3V to +6V  
to PGND............................................................-0.3V to +6V  
CC  
SGND to PGND .....................................................-0.3V to +0.3V  
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 = +5V, circuit of Figure 1, T = -40°C to +85°C, unless otherwise noted. Typical specifications are at T = +25°C.) (Note 1)  
CC  
A
A
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
SYSTEM SPECIFICATIONS  
8
28  
5.5  
10  
Input Voltage Range  
V
IN  
V
Short IN and V together for +5V input  
CC  
4.75  
operation  
Quiescent Supply Current  
Efficiency  
I
EN = V or SGND  
4
mA  
%
Q
CC  
η
I
= 52A (26A per phase)  
90  
LOAD  
OUTPUT VOLTAGE  
MAX5038 only, no load  
MAX5038 only, no load, V = V  
+4.75V to +5.5V or V = +8V to +28V  
IN  
(Note 2)  
-0.8  
-1  
+0.8  
+1  
Nominal Output Voltage  
Accuracy  
=
CC  
IN  
%
V
MAX5041 only, no load  
0.992  
1.008  
MAX5041 only, no load, V = V  
=
IN  
CC  
0.990  
0.995  
1.010  
1.005  
+4.75V to +5.5V or V = +8V to +28V  
IN  
SENSE+ to SENSE- Voltage  
Accuracy  
MAX5041B only, no load  
MAX5041B only, no load,  
0.995  
1.005  
V
= +8V to +28V  
falling  
CC  
IN  
STARTUP/INTERNAL REGULATOR  
V
Undervoltage Lockout  
UVLO  
V
4.0  
4.15  
200  
5.1  
4.5  
V
mV  
V
CC  
V
Undervoltage Lockout  
CC  
Hysteresis  
V
CC  
Output Accuracy  
V
IN  
= +8V to +28V, I = 0 to 80mA  
SOURCE  
4.85  
5.30  
3
MOSFET DRIVERS  
Output Driver Impedance  
R
Low or high output  
1
4
A
ON  
Output Driver Source/Sink  
Current  
I
_, I  
_
DH  
DL  
NO  
Non-Overlap Time  
t
C
_
_ = 5nF  
60  
ns  
DH /DL  
2
_______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
ELECTRICAL CHARACTERISTICS (continued)  
(V = +5V, circuit of Figure 1, T = -40°C to +85°C, unless otherwise noted. Typical specifications are at T = +25°C.) (Note 1)  
CC  
A
A
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
OSCILLATOR AND PLL  
CLKIN = SGND  
CLKIN = V  
238  
475  
125  
250  
500  
262  
525  
600  
Switching Frequency  
f
kHz  
SW  
CC  
PLL Lock Range  
PLL Locking Time  
f
kHz  
µs  
PLL  
t
200  
120  
90  
PLL  
PHASE = V  
115  
85  
55  
3
125  
95  
65  
7
CC  
CLKOUT Phase Shift  
φCLKOUT  
degrees  
PHASE = unconnected  
PHASE = SGND  
(at f  
= 125kHz)  
SW  
60  
CLKIN Input Pulldown Current  
CLKIN High Threshold  
CLKIN Low Threshold  
I
5
µA  
V
CLKIN  
V
2.4  
CLKINH  
V
0.8  
V
CLKINL  
CLKIN High Pulse Width  
PHASE High Threshold  
PHASE Low Threshold  
PHASE Input Bias Current  
CLKOUT Output Low Level  
CLKOUT Output High Level  
CURRENT LIMIT  
t
200  
4
ns  
V
CLKIN  
V
PHASEH  
V
1
V
PHASEL  
I
-50  
4.5  
+50  
100  
µA  
mV  
V
PHASEBIA  
V
I
= 2mA (Note 2)  
CLKOUTL SINK  
V
I
= 2mA (Note 2)  
CLKOUTH SOURCE  
Average Current-Limit Threshold  
Cycle-by-Cycle Current Limit  
V
CSP_ to CSN_  
CSP_ to CSN_ (Note 3)  
45  
90  
48  
51  
mV  
mV  
CL  
V
CLPK  
112  
130  
Cycle-by-Cycle Overload  
Response Time  
t
V
CSP  
_ to V _ = +150mV  
CSN  
260  
4
ns  
R
CURRENT-SENSE AMPLIFIER  
CSP_ to CSN_ Input Resistance  
Common-Mode Range  
Input Offset Voltage  
R
_
k  
V
CS  
V
-0.3  
-1  
+3.6  
+1  
CMR(CS)  
V
mV  
V/V  
MHz  
OS(CS)  
Amplifier Gain  
A
18  
4
V(CS)  
3dB Bandwidth  
f
3dB  
CURRENT-ERROR AMPLIFIER (TRANSCONDUCTANCE AMPLIFIER)  
Transconductance  
Open-Loop Gain  
gm  
550  
50  
µS  
ca  
VOL(CE)  
A
No load  
dB  
DIFFERENTIAL VOLTAGE AMPLIFIER (DIFF)  
Common-Mode Voltage Range  
DIFF Output Voltage  
V
-0.3  
+1.0  
V
V
CMR(DIFF)  
V
V
= V = 0  
SENSE-  
0.6  
CM  
OS(DIFF)  
SENSE+  
Input Offset Voltage  
V
-1  
+1  
mV  
MAX5038/MAX5041 (+1.2V, +1.5V, +1.8V  
output versions)  
0.997  
0.495  
1
1.003  
0.505  
Amplifier Gain  
A
V/V  
V(DIFF)  
MAX5038 (+2.5Vand +3.3V output versions)  
0.5  
_______________________________________________________________________________________  
3
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
ELECTRICAL CHARACTERISTICS (continued)  
(V = +5V, circuit of Figure 1, T = -40°C to +85°C, unless otherwise noted. Typical specifications are at T = +25°C.) (Note 1)  
CC  
A
A
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
MHz  
mA  
3dB Bandwidth  
f
C
= 20pF  
DIFF  
3
3dB  
OUT(DIFF)  
Minimum Output Current Drive  
I
1.0  
50  
SENSE+ to SENSE- Input  
Resistance  
R
VS  
_
100  
kΩ  
VOLTAGE-ERROR AMPLIFIER (EAOUT)  
Open-Loop Gain  
A
70  
3
dB  
MHz  
nA  
VOL(EA)  
Unity-Gain Bandwidth  
EAN Input Bias Current  
f
UGEA  
I
V
= +2.0V  
-100  
810  
+100  
918  
B(EA)  
EAN  
Error-Amplifier Output Clamping  
Voltage  
V
With respect to V  
mV  
CLAMP(EA)  
CM  
THERMAL SHUTDOWN  
Thermal Shutdown  
T
SHDN  
150  
8
°C  
°C  
Thermal-Shutdown Hysteresis  
EN INPUT  
EN Input Low Voltage  
EN Input High Voltage  
EN Pullup Current  
V
1
V
V
ENL  
V
ENH  
3
I
EN  
4.5  
5
5.5  
µA  
Note 1: Specifications from -40°C to 0°C are guaranteed by characterization but not production tested.  
Note 2: Guaranteed by design. Not production tested.  
Note 3: See Peak-Current Comparator section.  
4
_______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s  
(Circuit of Figure 1. T = +25°C, unless otherwise noted.)  
A
EFFICIENCY vs. OUTPUT CURRENT  
AND INPUT VOLTAGE  
EFFICIENCY vs. OUTPUT CURRENT AND  
INTERNAL OSCILLATOR FREQUENCY  
EFFICIENCY vs. OUTPUT CURRENT  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
90  
80  
70  
60  
50  
40  
V
= +12V  
= +5V  
f = 500kHz  
f = 250kHz  
IN  
V
IN  
V
= +24V  
= +1.8V  
= 125kHz  
IN  
V
f
V
f
SW  
= +1.8V  
= 250kHz  
OUT  
OUT  
V
V
OUT  
= +5V  
= +1.8V  
IN  
SW  
0
4
8
12 16 20 24 28 32 36 40 44 48 52  
(A)  
0
4
8
12 16 20 24 28 32 36 40 44 48 52  
(A)  
0
4
8
12 16 20 24 28 32 36 40 44 48 52  
(A)  
I
I
OUT  
I
OUT  
OUT  
EFFICIENCY vs. OUTPUT CURRENT  
AND OUTPUT VOLTAGE  
EFFICIENCY vs. OUTPUT CURRENT  
AND OUTPUT VOLTAGE  
SUPPLY CURRENT  
vs. FREQUENCY AND INPUT VOLTAGE  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
12.0  
11.5  
11.0  
10.5  
10.0  
9.5  
V
= +24V  
V
= +1.5V  
IN  
OUT  
V
= +1.5V  
OUT  
V
OUT  
= +1.8V  
V
OUT  
= +1.8V  
V
= +1.1V  
OUT  
9.0  
V
= +1.1V  
OUT  
8.5  
V
IN  
= +12V  
8.0  
7.5  
7.0  
V
IN  
= +5V  
V
f
SW  
= +12V  
= 250kHz  
V
f
SW  
= +5V  
IN  
IN  
EXTERNALCLOCK  
NO DRIVER LOAD  
6.5  
= 500kHz  
6.0  
0
4
8
12 16 20 24 28 32 36 40 44 48 52  
(A)  
0
4
8
12 16 20 24 28 32 36 40 44 48 52  
(A)  
100 150 200 250 300 350 400 450 500 550 600  
FREQUENCY (kHz)  
I
I
OUT  
OUT  
SUPPLY CURRENT  
SUPPLY CURRENT  
SUPPLY CURRENT  
vs. TEMPERATURE AND FREQUENCY  
vs. TEMPERATURE AND FREQUENCY  
vs. LOAD CAPACITANCE PER DRIVER  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
175  
150  
125  
100  
75  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
600kHz  
500kHz  
250kHz  
125kHz  
V
= +5V  
= 22nF  
= 8.2nF  
IN  
V
= +12V  
= 22nF  
= 8.2nF  
IN  
50  
C
V = +12V  
IN  
DL_  
C
C
DL_  
C
DH_  
f
= 250kHz  
SW  
DH_  
25  
-40  
-15  
10  
35  
60  
85  
-40  
-15  
10  
35  
60  
85  
1
3
5
7
9
11  
13 15  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
C
DRIVER  
(nF)  
_______________________________________________________________________________________  
5
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )  
(Circuit of Figure 1, T = +25°C, unless otherwise noted.)  
A
OUTPUT VOLTAGE vs. OUTPUT CURRENT  
CURRENT-SENSE THRESHOLD  
vs. OUTPUT VOLTAGE  
DIFFERENTIAL AMPLIFIER BANDWIDTH  
AND ERROR AMP GAIN (R / R )  
F
IN  
MAX5038/41 toc12  
90  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0
55  
54  
53  
52  
51  
50  
49  
48  
47  
46  
45  
1.85  
1.80  
1.75  
1.70  
1.65  
1.60  
V
V
OUT  
= +12V  
= +1.8V  
IN  
45  
R / R = 15  
F
IN  
PHASE  
0
R / R = 12.5  
F
IN  
-45  
-90  
-135  
-180  
-225  
PHASE 2  
GAIN  
R / R = 7.5  
F
IN  
PHASE 1  
R / R = 10  
F
IN  
-270  
0.01  
0.1  
1
10  
1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8  
0
5
10 15 20 25 30 35 40 45 50 55  
(A)  
FREQUENCY (MHz)  
V
(V)  
I
LOAD  
OUT  
DIFF OUTPUT ERROR  
V
CC  
LOAD REGULATION  
vs. SENSE+ TO SENSE- VOLTAGE  
vs. INPUT VOLTAGE  
V
CC  
LINE REGULATION  
0.200  
0.175  
0.150  
0.125  
0.100  
0.075  
0.050  
0.025  
0
5.20  
5.15  
5.10  
5.05  
5.00  
4.95  
4.90  
4.85  
4.80  
5.25  
5.20  
5.15  
5.10  
5.05  
5.00  
4.95  
4.90  
4.85  
4.80  
4.75  
V
= +12V  
IN  
V
= +24V  
NO DRIVER  
IN  
I
= 0  
CC  
V
IN  
= +12V  
I
= 40mA  
CC  
V
IN  
= +8V  
DC LOAD  
1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0  
0
15 30 45 60 75 90 105 120 135 150  
(mA)  
8
10 12 14 16 18 20 22 24 26 28  
(V)  
V  
(V)  
I
CC  
V
IN  
SENSE  
DRIVER RISE TIME  
DRIVER FALL TIME  
V
CC  
LINE REGULATION  
vs. DRIVER LOAD CAPACITANCE  
vs. DRIVER LOAD CAPACITANCE  
120  
110  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
120  
110  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
5.25  
5.20  
5.15  
5.10  
5.05  
5.00  
4.95  
4.90  
4.85  
4.80  
4.75  
DL_  
DH_  
DL_  
DH_  
V
IN  
= +12V  
V = +12V  
IN  
f
SW  
= 250kHz  
f
SW  
= 250kHz  
I
= 80mA  
9.0  
CC  
1
6
11  
16  
21  
26  
31  
36  
1
6
11  
16  
21  
26  
31 36  
8.0  
10.0  
11.0  
(V)  
12.0  
13.0  
C
DRIVER  
(nF)  
C
DRIVER  
(nF)  
V
IN  
6
_______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )  
(Circuit of Figure 1, T = +25°C, unless otherwise noted.)  
A
PLL LOCKING TIME  
250kHz TO 350kHz AND  
350kHz TO 250kHz  
HIGH-SIDE DRIVER (DH_)  
LOW-SIDE DRIVER (DL_)  
SINK AND SOURCE CURRENT  
SINK AND SOURCE CURRENT  
MAX5038/41 toc21  
MAX5038/41 toc19  
MAX5038/41 toc20  
CLKOUT  
5V/div  
350kHz  
DH_  
1.6A/div  
PLLCMP  
200mV/div  
DL_  
1.6A/div  
250kHz  
= +12V  
0
V
IN  
V
C
DL_  
= +12V  
= 22nF  
V
C
DH_  
= +12V  
= 22nF  
IN  
IN  
NO LOAD  
100µs/div  
100ns/div  
100ns/div  
PLL LOCKING TIME  
250kHz TO 500kHz AND  
500kHz TO 250kHz  
PLL LOCKING TIME  
250kHz TO 150kHz AND  
150kHz TO 250kHz  
HIGH-SIDE DRIVER (DH_)  
RISE TIME  
MAX5038/41 toc24  
MAX5038/41 toc22  
MAX5038/41 toc23  
CLKOUT  
5V/div  
CLKOUT  
5V/div  
DH_  
2V/div  
250kHz  
PLLCMP  
200mV/div  
500kHz  
PLLCMP  
200mV/div  
150kHz  
0
250kHz  
V
C
DH_  
= +12V  
= 22nF  
V
= +12V  
V
= +12V  
IN  
IN  
IN  
NO LOAD  
NO LOAD  
0
40ns/div  
100µs/div  
100µs/div  
HIGH-SIDE DRIVER (DH_)  
FALL TIME  
LOW-SIDE DRIVER (DL_)  
RISE TIME  
LOW-SIDE DRIVER (DL_)  
FALL TIME  
MAX5038/41 toc25  
MAX5038/41 toc26  
MAX5038/41 toc27  
DH_  
2V/div  
DL_  
2V/div  
DL_  
2V/div  
V
C
DH_  
= +12V  
= 22nF  
V
C
DL_  
= +12V  
= 22nF  
IN  
IN  
V = +12V  
IN  
C
= 22nF  
DL_  
40ns/div  
40ns/div  
40ns/div  
_______________________________________________________________________________________  
7
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )  
(Circuit of Figure 1, T = +25°C, unless otherwise noted.)  
A
OUTPUT RIPPLE  
INPUT STARTUP RESPONSE  
MAX5038/41 toc29  
MAX5038/41 toc28  
V
PGOOD  
1V/div  
V
OUT  
1V/div  
V
OUT  
(AC-COUPLED)  
10mV/div  
V
IN  
5V/div  
V
= +12V  
V
= +12V  
= +1.75V  
= 52A  
IN  
IN  
V
= +1.75V  
= 52A  
V
I
OUT  
I
OUT  
OUT  
OUT  
500ns/div  
2ms/div  
ENABLE STARTUP RESPONSE  
LOAD-TRANSIENT RESPONSE  
MAX5038/41 toc30  
MAX5038/41 toc31  
V
PGOOD  
1V/div  
V
OUT  
1V/div  
V
OUT  
50mV/div  
V
2V/div  
EN  
V
= +12V  
IN  
V
IN  
= +12V  
V
= +1.75V  
= 8A TO 52A  
= 1µs  
RISE  
OUT  
V
= +1.75V  
= 52A  
I
OUT  
I
STEP  
t
OUT  
1ms/div  
40µs/div  
8
_______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
P in De s c rip t io n  
PIN  
NAME  
FUNCTION  
CSP2,  
CSP1  
Current-Sense Differential Amplifier Positive Input. Senses the inductor current. The differential voltage  
between CSP_ and CSN_ is amplified internally by the current-sense amplifier gain of 18.  
1, 13  
CSN2,  
CSN1  
2, 14  
Current-Sense Differential Amplifier Negative Input. Senses the inductor current.  
Phase-Shift Setting Input. Connect PHASE to V for 120°, leave PHASE unconnected for 90°, or connect  
PHASE to SGND for 60° of phase shift between the rising edges of CLKOUT and CLKIN/DH1.  
CC  
3
4
PHASE  
External Loop-Compensation Input. Connect compensation network for the phase lock loop (see Phase-  
Locked Loop section).  
PLLCMP  
CLP2,  
CLP1  
5, 7  
6
Current-Error Amplifier Output. Compensate the current loop by connecting an RC network to ground.  
SGND  
Signal Ground. Ground connection for the internal control circuitry.  
Differential Output Voltage-Sensing Positive Input. Used to sense a remote load. Connect SENSE+ to  
V
OUT+  
at the load. The MAX5038 regulates the difference between SENSE+ and SENSE- according to the  
8
SENSE+  
factory preset output voltage. The MAX5041 regulates the SENSE+ to SENSE- difference to +1.0V.  
Differential Output Voltage-Sensing Negative Input. Used to sense a remote load. Connect SENSE- to  
9
SENSE-  
DIFF  
V
OUT-  
or PGND at the load.  
10  
11  
Differential Remote-Sense Amplifier Output. DIFF is the output of a precision unity-gain amplifier.  
Voltage-Error Amplifier Inverting Input. Receives the output of the differential remote-sense amplifier.  
Referenced to SGND.  
EAN  
Voltage-Error Amplifier Output. Connect to the external gain-setting feedback resistor. The external error  
amplifier gain-setting resistors determine the amount of adaptive voltage positioning  
12  
15  
EAOUT  
EN  
Output Enable. A logic low shuts down the power drivers. EN has an internal 5µA pullup current.  
BST1,  
BST2  
Boost Flying-Capacitor Connection. Reservoir capacitor connection for the high-side FET driver supply.  
Connect 0.47µF ceramic capacitors between BST_ and LX_.  
16, 26  
DH1,  
DH2  
17, 25  
18, 24  
19, 23  
20  
High-Side Gate Driver Output. Drives the gate of the high-side MOSFET.  
Inductor Connection. Source connection for the high-side MOSFETs. Also serves as the return terminal for  
the high-side driver.  
LX1, LX2  
DL1, DL2  
Low-Side Gate Driver Output. Synchronous MOSFET gate drivers for the two phases.  
Internal +5V Regulator Output. V is derived internally from the IN voltage. Bypass to SGND with 4.7µF  
CC  
and 0.1µF ceramic capacitors.  
V
CC  
Supply Voltage Connection. Connect IN to V for a +5V system. Connect the VRM input to IN through an  
CC  
RC lowpass filter, a 2.2resistor and a 0.1µF ceramic capacitor.  
21  
IN  
Power Ground. Connect PGND, low-side synchronous MOSFETs source, and V bypass capacitor  
CC  
returns together.  
22  
PGND  
Oscillator Output. CLKOUT is phase-shifted from CLKIN by the amount specified by PHASE. Use CLKOUT  
to parallel additional MAX5038/MAX5041s.  
27  
CLKOUT  
CMOS Logic Clock Input. Drive the internal oscillator with a frequency range between 125kHz and 600kHz.  
The PWM frequency defaults to the internal oscillator if CLKIN is connected to V or SGND. Connect  
CLKIN to SGND to set the internal oscillator to 250kHz or connect to V to set the internal oscillator to  
CC  
CC  
28  
CLKIN  
500kHz. CLKIN has an internal 5µA pulldown current.  
_______________________________________________________________________________________  
9
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Fu n c t io n a l Dia g ra m  
EN  
+5V  
LDO  
UVLO  
POR  
IN  
REGULATOR  
TEMP SENSOR  
V
CC  
DRV_V  
SHDN  
CC  
TO INTERNAL CIRCUITS  
CSP1  
CSN1  
CLP1  
BST1  
CSP1  
CSN1  
CLP1  
DH1  
LX1  
DL1  
PHASE 1  
RAMP1  
CLK  
SGND  
CLKIN  
MAX5038  
MAX5041  
GM  
IN  
PGND  
PHASE-  
LOCKED  
LOOP  
CLKOUT  
PLLCMP  
RAMP  
GENERATOR  
DIFF  
SENSE-  
0.6V  
DIFF  
AMP  
PGND  
SENSE+  
EAOUT  
EAN  
ERROR  
AMP  
DRV_V  
SHDN  
PGND  
CC  
CLK  
V
V
REF  
= V for V 1.8V (MAX5038)  
OUT OUT  
OUT OUT  
REF  
= V /2 for V > 1.8V (MAX5038)  
V
REF  
= +1.0V (MAX5041)  
RAMP2  
DH2  
LX2  
PHASE 2  
GM  
IN  
CLP2  
CSN2  
CSP2  
CLP2  
DL2  
CSN2  
CSP2  
BST2  
10 ______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
output current capacity. For maximum ripple rejection  
De t a ile d De s c rip t io n  
at the input, set the phase shift between phases to 90°  
The MAX5038/MAX5041 (Figures 1 and 2) average cur-  
for two paralleled converters, or 60° for three paralleled  
re nt-mod e PWM c ontrolle rs d rive two out-of-p ha s e  
c onve rte rs . Pa ra lle ling the MAX5038/MAX5041s  
buck converter channels. Average current-mode con-  
improves design flexibility in applications requiring  
trol improves current sharing between the channels  
upgrades (higher load).  
while minimizing component derating and size. Parallel  
multiple MAX5038/MAX5041 regulators to increase the  
9
SENSE -  
8
SENSE +  
14  
3
CSN1  
CSP1  
PHASE  
13  
V
IN  
15  
EN  
IN  
R1  
V
IN  
= +12V  
C3–C7  
21  
C1, C2  
17  
18  
19  
C39  
DH1  
LX1  
DL1  
Q1  
R2  
L1  
V
CC  
C12  
Q2  
28  
4
CLKIN  
D1  
MAX5038  
16  
20  
BST1  
D3  
PLLCMP  
+1.8V AT 60A  
V
CC  
V
OUT  
R4  
C25  
C32  
C31  
C26  
R7  
R8  
V
CC  
10  
11  
12  
D4  
DIFF  
EAN  
V
IN  
C14,  
C15  
C16–C24,  
C33  
C8–C11  
LOAD  
R
X
EAOUT  
25  
24  
23  
DH2  
LX2  
DL2  
Q1  
Q2  
R3  
L2  
7
5
R6  
CLP1  
C29  
C13  
D2  
C30  
C28  
26  
BST2  
CLP2  
R5  
C27  
1
2
6
SGND  
PGND  
CSP2  
CSN2  
22  
NOTE: SEE TABLE 1 FOR COMPONENT VALUES.  
Figure 1. MAX5038 Typical Application Circuit, V = +12V  
IN  
______________________________________________________________________________________ 11  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Dual-phase converters with an out-of-phase locking  
arrangement reduce the input and output capacitor  
ripple current, effectively multiplying the switching fre-  
quency by the number of phases. Each phase of the  
MAX5038/MAX5041 consists of an inner average cur-  
rent loop controlled by a common outer-loop voltage-  
error amplifier (VEA) that corrects the output voltage  
errors. The MAX5038/MAX5041 utilize a single control-  
ling VEA and an average current mode to force the  
phase currents to be equal.  
9
SENSE -  
8
SENSE +  
14  
3
CSN1  
CSP1  
PHASE  
13  
V
IN  
15  
EN  
IN  
C3–C7  
R1  
V
IN  
= +12V  
21  
C1,  
C2  
17  
18  
19  
C39  
DH1  
LX1  
DL1  
Q1  
R2  
L1  
V
CC  
C12  
Q2  
28  
4
CLKIN  
D1  
MAX5041  
16  
20  
BST1  
D3  
PLLCMP  
+1.8V AT 60A  
V
OUT  
V
CC  
R4  
C25  
C32  
C31  
R
H
C26  
R7  
R8  
10  
11  
12  
D4  
R3  
DIFF  
EAN  
V
V
CC  
IN  
C14,  
C15  
C16–C24,  
C33  
C8–C11  
LOAD  
R
L
R
X
EAOUT  
25  
24  
23  
DH2  
LX2  
DL2  
Q1  
Q2  
L2  
7
5
R6  
CLP1  
C29  
C13  
D2  
C30  
C28  
26  
BST2  
CLP2  
R5  
C27  
1
2
6
SGND  
PGND  
CSP2  
CSN2  
22  
NOTE: SEE TABLE 1 FOR COMPONENT VALUES.  
Figure 2. MAX5041 Typical Application Circuit, V = +12V  
IN  
12 ______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
V
a n d V  
In t e rn a l Os c illa t o r  
The internal oscillator generates the 180° out-of-phase  
clock signals required by the pulse-width modulation  
IN  
CC  
The MAX5038/MAX5041 accept a wide input voltage  
range of +4.75V to +5.5V or +8V to +28V. All internal  
control circuitry operates from an internally regulated  
(PWM) circuits. The oscillator also generates the 2V  
P-P  
nominal voltage of +5V (V ). For input voltages of +8V  
voltage ramp signals necessary for the PWM compara-  
tors. Connect CLKIN to SGND to set the internal oscillator  
CC  
or greater, the internal V  
regulator steps the voltage  
CC  
down to +5V. The V  
output voltage regulates to +5V  
frequency to 250kHz or connect CLKIN to V to set the  
CC  
CC  
while sourcing up to 80mA. Bypass V  
to SGND with  
internal oscillator to 500kHz.  
CC  
4.7µF and 0.1µF low-ESR ceramic capacitors for high-  
frequency noise rejection and stable operation (Figures 1  
and 2).  
CLKIN is a CMOS log ic c loc k inp ut for the p ha s e -  
locked loop (PLL). When driven externally, the internal  
oscillator locks to the signal at CLKIN. A rising edge at  
CLKIN starts the ON cycle of the PWM. Ensure that the  
external clock pulse width is at least 200ns. CLKOUT  
provides a phase-shifted output with respect to the ris-  
ing e d g e of the s ig na l a t CLKIN. PHASE s e ts the  
amount of phase shift at CLKOUT. Connect PHASE to  
Calculate power dissipation in the MAX5038/MAX5041  
as a product of the input voltage and the total V reg-  
CC  
ulator output current (I ). I  
includes quiescent cur-  
CC CC  
rent (I ) and gate drive current (I ):  
Q
DD  
P
= V x I  
IN CC  
(1)  
(2)  
D
V
CC  
for 120° of phase shift, leave PHASE unconnected  
I
CC  
= I + f  
x (Q  
+ Q + Q  
+ Q  
)
G4  
Q
SW  
G1  
G2  
G3  
for 90° of phase shift, or connect PHASE to SGND for  
60° of phase shift with respect to CLKIN.  
where, Q , Q , Q  
and Q  
are the total gate  
G4  
G1  
G2  
G3,  
c ha rg e of the low-s id e a nd hig h-s id e e xte rna l  
MOSFETs, I is 4mA (typ), and f is the switching fre-  
quency of each individual phase.  
The MAX5038/MAX5041 re q uire c omp e ns a tion on  
PLLCMP even when operating from the internal oscillator.  
The device requires an active PLL in order to generate  
the proper clock signal required for PWM operation.  
Q
SW  
For applications utilizing a +5V input voltage, disable  
the V regulator by connecting IN and V together.  
CC  
CC  
Co n t ro l Lo o p  
The MAX5038/MAX5041 use an average current-mode  
control scheme to regulate the output voltage (Figures  
3a and 3b). The main control loop consists of an inner  
current loop and an outer voltage loop. The inner loop  
Un d e rvo lt a g e Lo c k o u t (UVLO)/  
P o w e r-On Re s e t (P OR)/S o ft -S t a rt  
The MAX5038/MAX5041 include an undervoltage lock-  
out with hysteresis and a power-on reset circuit for con-  
verter turn-on and monotonic rise of the output voltage.  
The UVLO threshold is internally set between +4.0V  
a nd +4.5V with a 200mV hys te re s is . Hys te re s is a t  
UVLO eliminates chattering” during startup.  
controls the output currents (I  
and I  
)
PHASE1  
PHASE2  
while the outer loop controls the output voltage. The  
inner current loop absorbs the inductor pole reducing  
the order of the outer voltage loop to that of a single-  
pole system.  
Most of the internal circuitry, including the oscillator,  
turns on whe n the inp ut volta g e re a c he s +4V. The  
MAX5038/MAX5041 draw up to 4mA of current before  
the input voltage reaches the UVLO threshold.  
The current loop consists of a current-sense resistor  
(R ), a current-sense amplifier (CA_), a current-error  
S
amplifier (CEA_), an oscillator providing the carrier  
ramp, and a PWM comparator (CPWM_). The precision  
The compensation network at the current error ampli-  
fiers (CLP1 and CLP2) provides an inherent soft-start of  
the output voltage. It includes a parallel combination of  
capacitors (C28, C30) and resistors (R5, R6) in series  
with other capacitors (C27, C29) (see Figures 1 and 2).  
The voltage at CLP_ limits the maximum current avail-  
able to charge output capacitors. The capacitor on  
CLP_ in conjunction with the finite output-drive current  
of the current-error amplifier yields a finite rise time for  
the output current and thus the output voltage.  
CA_ amplifies the sense voltage across R by a factor  
S
of 18. The inverting input to the CEA_ senses the CA_  
output. The CEA_ output is the difference between the  
voltage-error amplifier output (EAOUT) and the gained-  
up voltage from the CA_. The RC compensation net-  
work connected to CLP1 and CLP2 provides external  
frequency compensation for the respective CEA_. The  
start of every clock cycle enables the high-side drivers  
and initiates a PWM ON cycle. Comparator CPWM_  
compares the output voltage from the CEA_ with a 0 to  
+2V ramp from the oscillator. The PWM ON cycle termi-  
nates when the ramp voltage exceeds the error voltage.  
______________________________________________________________________________________ 13  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
C
CF  
R
CF  
C
CFF  
MAX5038  
CA1  
V
IN  
I
PHASE1  
R *  
F
CEA1  
CEA2  
DRIVE 1  
SENSE+  
SENSE-  
CPWM1  
R
S
R
*
IN  
DIFF  
AMP  
VEA  
V
OUT  
V
IN  
C
OUT  
R
S
V
REF  
LOAD  
I
PHASE2  
CPWM2  
DRIVE 2  
CA2  
C
CF  
R
CF  
*R AND R ARE EXTERNAL TO MAX5038  
IN  
F
C
CCF  
(R = R8, R = R7, FIGURE 1)  
F
IN  
Figure 3a. MAX5038 Control Loop  
C
CF  
R
CF  
C
CFF  
MAX5041  
CA1  
V
IN  
I
PHASE1  
R *  
F
CEA1  
DRIVE 1  
SENSE+  
CPWM1  
R
S
R
*
IN  
DIFF  
AMP  
VEA  
V
OUT  
SENSE-  
V
IN  
C
OUT  
CEA2  
V
=
REF  
+1.0V  
R
S
LOAD  
I
PHASE2  
CPWM2  
DRIVE 2  
CA2  
C
CF  
R
CF  
*R AND R ARE  
IN  
F
EXTERNAL TO MAX5041  
(R = R8, R = R7, FIGURE 2)  
C
CCF  
F
IN  
Figure 3b. MAX5041 Control Loop  
14 ______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
The outer voltage control loop consists of the differen-  
tial amplifier (DIFF AMP), reference voltage, and VEA.  
The unity-gain differential amplifier provides true differ-  
ential remote sensing of the output voltage. The differ-  
ential amplifier output connects to the inverting input  
(EAN) of the VEA. The noninverting input of the VEA is  
internally connected to an internal precision reference  
voltage. The MAX5041 reference voltage is set to +1.0V  
and the MAX5038 reference is set to the preset output  
voltage. The VEA controls the two inner current loops  
(Figures 3a and 3b). Use a resistive feedback network  
to set the VEA gain as required by the adaptive volt-  
a g e -p os itioning c irc uit (s e e the Ad a p tive Volta g e  
Positioning section).  
than the average current limit (48mV). Proper inductor  
selection ensures that only extreme conditions trip the  
peak-current comparator, such as a cracked output  
inductor. The 112mV voltage threshold for triggering  
the peak-current limit is twice the full-scale average  
current-limit voltage threshold. The peak-current com-  
parator has a delay of only 260ns.  
Current-Error Amplifier  
Each phase of the MAX5038/MAX5041 has a dedicated  
transconductance current-error amplifier (CEA_) with a  
typical g of 550µS and 320µA output sink and source  
m
current capability. The current-error amplifier outputs,  
CLP1 and CLP2, serve as the inverting input to the  
PWM c omp a ra tor. CLP1 a nd CLP2 a re e xte rna lly  
accessible to provide frequency compensation for the  
inner current loops (Figures 3a and 3b). Compensate  
CEA_ such that the inductor current down slope, which  
becomes the up slope to the inverting input of the PWM  
comparator, is less than the slope of the internally gen-  
erated voltage ramp (see the Compensation section).  
Current-Sense Amplifier  
The differential current-sense amplifier (CA_) provides a  
DC gain of 18. The maximum input offset voltage of the  
current-sense amplifier is 1mV and the common-mode  
voltage range is -0.3V to +3.6V. The current-sense ampli-  
fier senses the voltage across a current-sense resistor.  
Peak-Current Comparator  
The peak-current comparator provides a path for fast  
cycle-by-cycle current limit during extreme fault condi-  
tions such as an output inductor malfunction (Figure 4).  
Note that the average current-limit threshold of 48mV  
still limits the output current during short-circuit condi-  
tions. To prevent inductor saturation, select an output  
inductor with a saturation current specification greater  
PWM Comparator and R-S Flip-Flop  
The PWM comparator (CPWM) sets the duty cycle for  
each cycle by comparing the output of the current-error  
amplifier to a 2V  
ramp. At the start of each clock  
P-P  
cycle, an R-S flip-flop resets and the high-side driver  
(DH_) turns on. The comparator sets the flip-flop as  
soon as the ramp voltage exceeds the CLP_ voltage,  
thus terminating the ON cycle (Figure 4).  
DRV_V  
CC  
PEAK-CURRENT  
COMPARATOR  
112mV  
CLP_  
CSP_  
A = 18  
V
G =  
m
500µS  
CSN_  
BST_  
DH_  
LX_  
PWM  
COMPARATOR  
GM  
IN  
Q
Q
S
RAMP  
CLK  
2 x f (V/s)  
s
R
DL_  
SHDN  
PGND  
Figure 4. Phase Circuit (Phase 1/Phase 2)  
______________________________________________________________________________________ 15  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Differential Amplifier  
The differential amplifier (DIFF AMP) facilitates output  
voltage remote sensing at the load (Figures 3a and 3b).  
It provides true differential output voltage sensing while  
rejecting the common-mode voltage errors due to high-  
c urre nt g round p a ths . Se ns ing the outp ut volta g e  
directly at the load provides accurate load voltage  
sensing in high-current environments. The VEA pro-  
vides the difference between the differential amplifier  
output (DIFF) and the desired output voltage. The dif-  
ferential amplifier has a bandwidth of 3MHz. The differ-  
ence between SENSE+ and SENSE- regulates to the  
preset output voltage for the MAX5038 and regulates to  
+1V for the MAX5041.  
Use the following equations to calculate the value of R .  
X
For MAX5038 versions of V  
+1.8V:  
OUT(NOM)  
R
F
R
= [V (V + 0.6)]×  
NOM  
(5)  
(6)  
(7)  
X
CC  
V
NOM  
For MAX5038 versions of V  
> +1.8V:  
OUT(NOM)  
R
F
R
= [2V (V +1.2)] ×  
NOM  
X
CC  
V
NOM  
For MAX5041:  
R
F
R
= [V 1.6] ×  
X
CC  
V
REF  
The VEA output clamps to +0.9V (plus the common-  
mode voltage of +0.6V), thus limiting the average maxi-  
mum current from individual phases. The maximum  
average current-limit threshold for each phase is equal  
to the maximum clamp voltage of the VEA divided by  
the gain (18) of the current-sense amplifier. This allows  
for accurate settings for the average maximum current  
Voltage-Error Amplifier  
The VEA sets the gain of the voltage control loop and  
determines the error between the differential amplifier  
output and the internal reference voltage (V ).  
REF  
V
REF  
equals V  
for the +1.8V or lower voltage  
OUT(NOM)  
versions of the MAX5038 and V  
equals V  
/2  
REF  
OUT(NOM)  
for the +2.5V and +3.3V versions. For MAX5041, V  
REF  
for each phase. Set the VEA gain using R and R for  
F
IN  
equals +1V.  
An offs e t is a d d e d to the outp ut volta g e of the  
MAX5038/MAX5041 with a finite gain (R /R ) of the  
the amount of output voltage positioning required as  
discussed in the Adaptive Voltage Positioning section  
(Figures 3a and 3b).  
F
IN  
VEA such that the no-load output voltage is higher than  
the nomina l va lue . Choos e R a nd R from the  
Adaptive Voltage Positioning section and use the follow-  
Ad a p t ive Vo lt a g e P o s it io n in g  
Powe ring ne w-g e ne ra tion p roc e s s ors re q uire s ne w  
techniques to reduce cost, size, and power dissipation.  
Voltage positioning reduces the total number of output  
capacitors to meet a given transient response require-  
ment. Setting the no-load output voltage slightly higher  
than the output voltage during nominally loaded condi-  
tions allows a larger downward voltage excursion when  
the output current suddenly increases. Regulating at a  
lower output voltage under a heavy load allows a larger  
upward-voltage excursion when the output current sud-  
denly decreases. A larger allowed, voltage-step excur-  
sion reduces the required number of output capacitors  
or allows for the use of higher ESR capacitors.  
F
IN  
ing equations to calculate the no-load output voltage.  
MAX5038:  
R
IN  
(3)  
V
= 1+  
× V  
OUT(NOM)  
OUT(NL)  
R
F
MAX5041:  
V
R
R
+ R  
L
IN  
H
(4)  
= 1+  
×
× V  
REF  
OUT(NL)  
R
R
L
F
where R and R are the feedback resistor network  
(Figure 2).  
H
L
Voltage positioning and the ability to operate with multiple  
reference voltages may require the output to regulate  
away from a center value. Define the center value as the  
Some applications require V  
equal to V  
at  
OUT  
OUT(NOM)  
voltage where the output drops (V  
/2) at one half the  
OUT  
no load. To ensure that the output voltage does not  
exceed the nominal output voltage (V ), add a  
maximum output current (Figure 5).  
OUT(NOM)  
resistor R from V to EAN.  
CC  
X
16 ______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
P h a s e -Lo c k e d Lo o p : Op e ra t io n a n d  
Co m p e n s a t io n  
The PLL s ync hronize s the inte rna l os c illa tor to the  
e xte rna l fre q ue nc y s ourc e whe n d riving CLKIN.  
V
CNTR  
+ V /2  
OUT  
Connecting CLKIN to V  
or SGND forces the PWM  
CC  
frequency to default to the internal oscillator frequency  
of 500kHz or 250kHz, respectively. The PLL uses a  
conventional architecture consisting of a phase detec-  
tor and a charge pump capable of providing 20µA of  
output current. Connect an external series combination  
capacitor (C25) and resistor (R4) and a parallel capaci-  
tor (C26) from PLLCMP to SGND to provide frequency  
compensation for the PLL (Figure 1). The pole-zero pair  
V
CNTR  
V
CNTR  
- V /2  
OUT  
FULL LOAD  
1/2 LOAD  
LOAD (A)  
NO LOAD  
compensation provides a zero at f = 1 / [R4 x (C25 +  
Z
C26)] and a pole at f = 1 / (R4 x C26). Use the follow-  
P
ing typ ic a l va lue s for c omp e ns a ting the PLL:  
R4 = 7.5k, C25 = 4.7nF, C26 = 470pF. If changing the  
PLL frequency, expect a finite locking time of approxi-  
mately 200µs.  
Figure 5. Defining the Voltage-Positioning Window  
Set the voltage-positioning window (V  
) using the  
OUT  
resistive feedback of the VEA. Use the following equa-  
tions to calculate the voltage-positioning window for the  
MAX5038:  
The MAX5038/MAX5041 re q uire c omp e ns a tion on  
PLLCMP even when operating from the internal oscilla-  
tor. The device requires an active PLL in order to gen-  
erate the proper internal PWM clocks.  
I
× R  
IN  
OUT  
(8)  
V  
=
OUT  
MOS FET Ga t e Drive rs (DH_, DL_)  
The high-side (DH_) and low-side (DL_) drivers drive  
the gates of external N-channel MOSFETs (Figures 1  
and 2). The drivers high-peak sink and source current  
capability provides ample drive for the fast rise and fall  
times of the switching MOSFETs. Faster rise and fall  
times result in reduced cross-conduction losses. For  
modern CPU voltage-regulating module applications  
where the duty cycle is less than 50%, choose high-  
2 × G × R  
C
F
0.05  
(9)  
G
=
C
R
S
Use the following equation to calculate the voltage-posi-  
tioning window for the MAX5041:  
side MOSFETs (Q1 and Q3) with a moderate R  
DS(ON)  
a nd a ve ry low g a te c ha rg e . Choos e low-s id e  
IOUT ×R  
RH + RL  
MOSFETs (Q2 a nd Q4) with ve ry low R  
moderate gate charge.  
a nd  
DS(ON)  
IN  
(10)  
V  
=
×
OUT  
2 ×G ×R  
RL  
(
)
C
F
The driver block also includes a logic circuit that pro-  
vides an adaptive non-overlap time to prevent shoot-  
throug h c urre nts d uring tra ns ition. The typ ic a l  
non-overlap time is 60ns between the high-side and  
low-side MOSFETs.  
0.05  
(11)  
G
=
C
R
S
BS T_  
V
powers the low- and high-side MOSFET drivers.  
DD  
where R and R are the input and feedback resistors of  
IN  
F
Connect a 0.47µF low-ESR ceramic capacitor between  
BST_ and LX_. Bypass V to PGND with 4.7µF and  
0.1µF low-ESR ceramic capacitors. Reduce the PC  
board area formed by these capacitors, the rectifier  
the VEA, G is the current-loop gain and R is the cur-  
C
S
CC  
rent-sense resistor or, if using lossless inductor current  
sensing, the DC resistance of the inductor.  
d iod e s b e twe e n V  
a nd the b oos t c a p a c itor, the  
CC  
MAX5038/MAX5041, and the switching MOSFETs.  
______________________________________________________________________________________ 17  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
The examples discussed in this data sheet pertain to a  
typical application with the following specifications:  
Ove rlo a d Co n d it io n s  
Average current-mode control has the ability to limit the  
average current sourced by the converter during a fault  
condition. When a fault condition occurs, the VEA out-  
put clamps to +0.9V with respect to the common-mode  
VIN = +12V  
VOUT = +1.8V  
IOUT(MAX) = 52A  
voltage (V  
= +0.6V) and is compared with the output  
CM  
of the current-sense amplifiers (CA1 and CA2) (see  
Figures 3a and 3b). The current-sense amplifiers gain  
of 18 limits the maximum current in the inductor or  
fSW = 250kHz  
Peak-to-Peak Inductor Current (IL) = 10A  
Table 1 shows a list of recommended external compo-  
nents (Figure 1) and Table 2 provides component sup-  
plier information.  
sense resistor to I  
= 50mV/R .  
LIMIT  
S
P a ra lle l Op e ra t io n  
For applications requiring large output current, parallel  
up to three MAX5038/MAX5041s (six phases) to triple  
the available output current. The paralleled converters  
operate at the same switching frequency but different  
phases keep the capacitor ripple RMS currents to a mini-  
mum. Three parallel MAX5038/MAX5041 converters  
deliver up to 180A of output current. To set the phase  
shift of the on-board PLL, leave PHASE unconnected for  
90° of phase shift (2 paralleled converters), or connect  
PHASE to SGND for 60° of phase shift (3 converters in  
parallel). Designate one converter as master and the  
remaining converters as slaves. Connect the master and  
slave controllers in a daisy-chain configuration as shown  
in Figure 6. Connect CLKOUT from the master controller  
to CLKIN of the first slaved controller, and CLKOUT from  
the first slaved controller to CLKIN of the second slaved  
controller. Choose the appropriate phase shift for mini-  
mum ripple currents at the input and output capacitors.  
The master controller senses the output differential volt-  
age through SENSE+ and SENSE- and generates the  
DIFF voltage. Disable the voltage sensing of the slaved  
controllers by leaving DIFF unconnected (floating).  
Figure 7 shows a detailed typical parallel application cir-  
cuit using two MAX5038s. This circuit provides four  
phases at an input voltage of +12V and an output volt-  
age range of +1V to +3.3V at 104A.  
Nu m b e r o f P h a s e s  
Selecting the number of phases for a voltage regulator  
depends mainly on the ratio of input-to-output voltage  
(operating duty cycle). Optimum output-ripple cancella-  
tion depends on the right combination of operating duty  
cycle and the number of phases. Use the following  
equation as a starting point to choose the number of  
phases:  
(12)  
NPH K/D  
where K = 1, 2, or 3 and the duty cycle is D = VOUT/V  
IN.  
Choose K to make NPH an integer number. For exam-  
ple , c onve rting VIN = +12V to VOUT = +1.8V yie lds  
better ripple cancellation in the six-phase converter  
than in the four-phase converter. Ensure that the output  
load justifies the greater number of components for  
multiphase conversion. Generally limiting the maximum  
output current to 25A per phase yields the most cost-  
effective solution. The maximum ripple cancellation  
occurs when NPH = K/D.  
Single-phase conversion requires greater size and power  
dissipation for external components such as the switch-  
ing MOSFETs and the inductor. Multiphase conversion  
eliminates the heatsink by distributing the power dissipa-  
tion in the external components. The multiple phases  
operating at given phase shifts effectively increase the  
switching frequency seen by the input/output capacitors,  
thereby reducing the input/output capacitance require-  
ment for the same ripple performance. The lower induc-  
tance value improves the large-signal response of the  
converter during a transient load at the output. Consider  
all these issues when determining the number of phases  
necessary for the voltage regulator application.  
Ap p lic a t io n s In fo rm a t io n  
Each MAX5038/MAX5041 circuit drives two 180° out-of-  
p ha s e c ha nne ls . Pa ra lle l two or thre e MAX5038/  
MAX5041 circuits to achieve four- or six-phase opera-  
tion, respectively. Figure 1 shows the typical application  
circuit for a two-phase operation. The design criteria for  
a two-phase converter includes frequency selection,  
inductor value, input/output capacitance, switching  
MOSFETs, sense resistors, and the compensation net-  
work. Follow the same procedure for the four- and six-  
phase converter design, except for the input and output  
capacitance. The input and output capacitance require-  
ments vary depending on the operating duty cycle.  
In d u c t o r S e le c t io n  
The switching frequency per phase, peak-to-peak rip-  
ple current in each phase, and allowable ripple at the  
output determine the inductance value.  
18 ______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
CSN1  
CSP1  
SENSE+  
SENSE-  
V
IN  
DH1  
LX1  
DL1  
V
CC  
PHASE  
V
CC  
MAX5038/  
MAX5041  
V
IN  
CLKIN  
IN  
DH2  
LX2  
DL2  
V
IN  
DIFF  
EAN  
CSP2  
CSN2  
EAOUT  
PGND SGND CLKOUT  
CSN1  
CSP1  
CLKIN  
V
IN  
DH1  
LX1  
DL1  
V
CC  
PHASE  
MAX5038/  
MAX5041  
V
IN  
IN  
DH2  
LX2  
DL2  
*
*
DIFF  
LOAD  
EAN  
CSP2  
CSN2  
EAOUT  
PGND SGND CLKOUT  
CSN1  
CSP1  
CLKIN  
PHASE  
V
IN  
DH1  
LX1  
DL1  
V
CC  
MAX5038/  
MAX5041  
V
IN  
IN  
DH2  
LX2  
DL2  
DIFF  
EAN  
CSP2  
CSN2  
EAOUT  
*FOR MAX5041 ONLY.  
PGND SGND CLKOUT  
TO OTHER MAX5038/MAX5041s  
Figure 6. Parallel Configuration of Multiple MAX5038/MAX5041s  
______________________________________________________________________________________ 19  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
V
IN  
= +12V  
C1, C2  
2 x 47µF  
V
CC  
C31  
R4  
R3  
2.2Ω  
C32  
C39  
0.1µF  
V
IN  
C3–C7  
5 x 22µF  
PLLCMP CLKIN  
IN  
SENSE- SENSE+ CSN1 CSP1  
DH1  
LX1  
DL1  
Q1  
L1  
0.6µH  
R1  
1.35mΩ  
C12  
0.47µF  
Q2  
D1  
BST1  
D3  
V
CC  
V
CC  
EN  
C38  
4.7µF  
C40  
0.1µF  
D4  
OVPIN  
DIFF  
V
CC  
R7  
R8  
V
IN  
MAX5038  
(MASTER)  
4 x 22µF  
EAN  
C8–C11  
DH2  
LX2  
DL2  
Q3  
L2  
0.6µH  
R2  
1.35mΩ  
R
X
EAOUT  
C13  
0.47µF  
Q4  
D2  
BST2  
CLP1  
CLP2 PGND SGND CLKOUT PHASE PGOOD CSN2 CSP2  
R9  
R6  
R5  
C36  
C34  
C33  
PGOOD  
V
CC  
C35  
R18  
C26–C30,  
C37  
6 x 10µF  
C14, C15,  
C41, C42  
2 x 100µF  
V
= +1.1V TO  
OUT  
LOAD  
+3.3V AT 104A  
C62  
R13  
C16–C25,  
C43–C46  
R12  
2.2Ω  
C63  
EN  
14 x 270µF  
R19  
C47  
0.1µF  
V
IN  
C48–C51  
5 x 22µF  
PLLCMP IN  
CLKIN SENSE-SENSE+ CSN1 CSP1  
DH1  
Q5  
Q6  
L3  
0.6µH  
R10  
1.35mΩ  
LX1  
DL1  
C57  
0.47µF  
D5  
BST1  
D7  
V
CC  
C65  
C64  
D8  
4.7µF  
0.1µF  
MAX5038  
(SLAVE)  
R16  
V
CC  
V
IN  
C52–C55  
4 x 22µF  
DIFF  
EAN  
R11  
1.35mΩ  
DH2  
LX2  
DL2  
Q7  
L4  
0.6µH  
R17  
R
X
EAOUT  
C56  
0.47µF  
Q8  
D6  
BST2  
CLP1  
CLP2  
PGND SGND  
PHASE  
CSN2 CSP2  
R15  
C59  
R14  
C60  
C58  
C61  
V
CC  
Figure 7. Four-Phase Parallel Application Circuit (V = +12V, V  
= +1.1V to +3.3V at 104A)  
IN  
OUT  
20 ______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Table 1. Component List  
DESIGNATION  
C1, C2  
C3–C11  
C12, C13  
C14, C15  
C16–C24, C33  
C25  
QTY  
2
DESCRIPTION  
47µF,16V X5R input-filter capacitors TDK C5750X5R1C476M  
22µF, 16V input-filter capacitors TDK C4532X5R1C226M  
0.47µF, 16V capacitors TDK C1608X5R1A474K  
100µF, 6.3V, output-filter capacitors Murata GRM44-1X5R107K6.3  
270µF, 2V output-filter capacitors Panasonic EEFUE0D271R  
4700pF, 16V X7R capacitor Vishay-Siliconix VJ0603Y471JXJ  
470pF 16V capacitors Murata GRM1885C1H471JAB01  
0.01µF 50V X7R capacitors Murata GRM188R71H103KA01  
4.7µF 16V X5R capacitor Murata GRM40-034X5R475k6.3  
0.1µF 16V X7R capacitors Murata GRM188R71C104KA01  
Schottky diodes ON-Semiconductor MBRS340T3  
Schottky diodes ON-Semiconductor MBR0520LT1  
0.6µH, 27A inductors Panasonic ETQP1H0R6BFX  
Upper-power MOSFETs Vishay-Siliconix Si7860DP  
Lower-power MOSFETs Vishay-Siliconix Si7886DP  
2.2±1% resistor  
9
2
2
10  
1
C26, C28, C30  
C27, C29  
C31  
3
2
1
C32  
3
D1, D2  
D3, D4  
L1, L2  
2
2
2
Q1, Q3  
Q2, Q4  
R1  
2
2
1
R2, R3  
4
Current-sense resistors, use two 2.7mresistors in parallel, Panasonic ERJM1WSF2M7U  
7.5k±1% resistor  
R4  
1
R5, R6  
2
1k±1% resistors  
R7  
1
4.99k±1% resistor  
R8, R9  
2
37.4k±1% resistors  
Table 2. Component Suppliers  
SUPPLIER  
PHONE  
FAX  
WEBSITE  
www.murata.com  
Murata  
770-436-1300  
602-244-6600  
714-373-7939  
847-803-6100  
1-800-551-6933  
770-436-3030  
602-244-3345  
714-373-7183  
847-390-4405  
619-474-8920  
ON Semiconductor  
Panasonic  
www.on-semi.com  
www.panasonic.com  
www.tcs.tdk.com  
www.vishay.com  
TDK  
Vishay-Siliconix  
______________________________________________________________________________________ 21  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Selecting higher switching frequencies reduces the  
inductance requirement, but at the cost of lower efficien-  
cy. The charge/discharge cycle of the gate and drain  
capacitances in the switching MOSFETs create switching  
losses. The situation worsens at higher input voltages,  
since switching losses are proportional to the square of  
Use the following equation to determine the worst-case  
inductor current for each phase:  
I  
0.051  
L
(15)  
I
=
+
L _PEAK  
R
2
SENSE  
input voltage. Use 500kHz per phase for V = +5V and  
IN  
250kHz or less per phase for VIN > +12V.  
where RSENSE is the sense resistor in each phase.  
Although lower switching frequencies per phase increase  
the peak-to-peak inductor ripple current (IL), the ripple  
cancellation in the multiphase topology reduces the input  
and output capacitor RMS ripple current.  
S w it c h in g MOS FETs  
whe n c hoos ing a MOSFET for volta g e re g ula tors ,  
consider the total gate charge, RDS(ON), power dissipa-  
tion, and package thermal impedance. The product of  
the MOSFET gate charge and on-resistance is a figure of  
merit, with a lower number signifying better performance.  
Choose MOSFETs optimized for high-frequency switch-  
ing applications.  
Use the following equation to determine the minimum  
inductance value:  
V
V  
× V  
OUT  
(
)
INMAX  
OUT  
L
=
MIN  
The average gate-drive current from the MAX5038/  
MAX5041 output is proportional to the total capacitance  
it drives from DH1, DH2, DL1, and DL2. The power dis-  
sipated in the MAX5038/MAX5041 is proportional to the  
(13)  
V
× f  
× ∆I  
IN SW  
L
Choose IL equal to about 40% of the output current  
per phase. Since IL affects the output-ripple voltage,  
the inductance value may need minor adjustment after  
choosing the output capacitors for full-rated efficiency.  
input voltage and the average drive current. See the V  
IN  
and VCC section to determine the maximum total gate  
charge allowed from all the driver outputs together.  
Choos e ind uc tors from the s ta nd a rd hig h-c urre nt,  
surface-mount inductor series available from various  
manufacturers. Particular applications may require cus-  
tom-made inductors. Use high-frequency core material  
for custom inductors. High IL causes large peak-to-peak  
flux excursion increasing the core losses at higher fre-  
quencies. The high-frequency operation coupled with  
high IL, reduces the required minimum inductance  
and even makes the use of planar inductors possible.  
The advantages of using planar magnetics include low-  
profile design, excellent current-sharing between phas-  
es due to the tight control of parasitics, and low cost.  
The gate charge and drain capacitance (CV2) loss, the  
cross-conduction loss in the upper MOSFET due to finite  
rise/fall time, and the I2R loss due to RMS current in the  
MOSFET RDS(ON) account for the total losses in the MOS-  
FET. Estimate the power loss (PDMOS_) in the high-side  
and low-side MOSFETs using following equations:  
PD  
= Q × V × f  
+
(
)
MOSHI  
×I  
G
DD SW  
(16)  
V
× t + t × f  
(
)
IN OUT  
R
F
SW  
2
+1.4R  
DS(ON)  
×I  
RMSHI  
4
For e xa mp le , c a lc ula te the minimum ind uc ta nc e a t  
where QG, RDS(ON), tR, and tF are the upper-switching  
MOSFETs total gate charge, on-resistance at +25°C,  
rise time, and fall time, respectively.  
V
= +13.2V, VOUT = +1.8V, IL = 10A, and fSW =  
IN(MAX)  
250kHz:  
13.2 1.8 ×1.8  
(
)
(14)  
L
=
= 0.6µH  
D
MIN  
2
2
(17)  
13.2 × 250k ×10  
I
=
I
+I  
+I ×I  
PK  
×
DC  
RMSHI  
DC PK  
(
)
3
The a ve ra g e c urre nt-mod e c ontrol fe a ture of the  
MAX5038/MAX5041 limits the maximum peak inductor  
current which prevents the inductor from saturating.  
Choose an inductor with a saturating current greater  
than the worst-case peak inductor current.  
whe re D = VOUT/VIN, IDC = (IOUT - IL)/2 a nd IPK  
(IOUT + IL)/2  
=
22 ______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
In p u t Ca p a c it o rs  
PD  
= Q × V × f  
+
(
)
MOSLO  
G
DD SW  
The discontinuous input-current waveform of the buck  
c onve rte r c a use s la rge ripple c urre nts in the input  
capacitor. The switching frequency, peak inductor cur-  
rent, and the allowable peak-to-peak voltage ripple  
reflected back to the source dictate the capacitance  
requirement. Increasing the number of phases increas-  
es the effective switching frequency and lowers the  
p e a k-to-a ve ra g e c urre nt ra tio, yie ld ing lowe r inp ut  
capacitance requirement.  
2
(18)  
2 × C  
× V × f  
3
2
OSS  
IN SW  
+1.4R  
×I  
RMSLO  
DS(ON)  
1D  
(
)
2
2
(19)  
I
=
I
+I  
+I ×I  
PK  
×
DC  
RMSLO  
DC PK  
(
)
3
The input ripple is comprised of VQ (caused by the  
capacitor discharge) and VESR (caused by the ESR of  
the capacitor). Use low-ESR ceramic capacitors with  
high ripple-current capability at the input. Assume the  
contributions from the ESR and capacitor discharge are  
equal to 30% and 70%, respectively. Calculate the  
input capacitance and ESR required for a specified rip-  
ple using the following equation:  
For e xa mp le , from the typ ic a l s p e c ific a tions in the  
Applications Information section with VOUT = +1.8V, the  
high-side and low-side MOSFET RMS currents are 9.9A  
and 24.1A, respectively. Ensure that the thermal imped-  
ance of the MOSFET package keeps the junction tem-  
perature at least 25°C below the absolute maximum  
rating. Use the following equation to calculate maxi-  
mum junction temperature:  
(20)  
T = PD  
x θ  
+ T  
J-A A  
J
MOS  
V  
(
)
ESR  
ESR  
=
IN  
(21)  
I
I  
L
OUT  
N
+
2
I
OUT  
N
V × f  
×D 1D  
(
)
Table 3. Peak-to-Peak Output Ripple  
Current Calculations  
(22)  
C
=
IN  
Q
SW  
NUMBER OF  
PHASES (N)  
DUTY  
CYCLE (D)  
where IOUT is the total output current of the multiphase  
converter and N is the number of phases.  
EQUATION FOR I  
P-P  
For e xa mp le , a t VOUT = +1.8V, the ESR a nd inp ut  
capacitance are calculated for the input peak-to-peak  
ripple of 100mV or less yielding an ESR and capaci-  
tance value of 1mand 200µF.  
V (12D)  
O
I=  
2
2
4
4
4
6
< 50%  
> 50%  
L× f  
SW  
V
V 2D1  
(
)(  
)
Ou t p u t Ca p a c it o rs  
The worst-case peak-to-peak and capacitor RMS ripple  
current, the allowable peak-to-peak output ripple volt-  
age, and the maximum deviation of the output voltage  
during step loads determine the capacitance and the  
ESR requirements for the output capacitors.  
IN  
O
I=  
L× f  
SW  
V (14D)  
O
0 to 25%  
25% to 50%  
> 50%  
I=  
L× f  
SW  
In multiphase converter design, the ripple currents from  
the individual phases cancel each other and lower the  
rip p le c urre nt. The d e g re e of rip p le c a nc e lla tion  
depends on the operating duty cycle and the number of  
phases. Choose the right equation from Table 3 to calcu-  
late the peak-to-peak output ripple for a given duty  
cycle of two-, four-, and six-phase converters. The max-  
imum ripple cancellation occurs when NPH = K / D.  
V (12D)(4D1)  
O
I=  
I=  
2 ×D×L× f  
SW  
V (2D1)(3 4D)  
O
D×L× f  
SW  
V (16D)  
O
< 17%  
I=  
L× f  
SW  
______________________________________________________________________________________ 23  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
The allowable deviation of the output voltage during the  
fast transient load dictates the output capacitance and  
ESR. The output capacitors supply the load step until  
the controller responds with a greater duty cycle. The  
response time (tRESPONSE) depends on the closed-loop  
bandwidth of the converter. The resistive drop across  
the capacitor ESR and capacitor discharge causes a  
voltage drop during a step load. Use a combination of  
SP polymer and ceramic capacitors for better transient  
load and ripple/noise performance.  
Co m p e n s a t io n  
The main control loop consists of an inner current loop  
and an outer voltage loop. The MAX5038/MAX5041 use  
an average current-mode control scheme to regulate  
the output voltage (Figures 3a and 3b). IPHASE1 and  
IPHASE2 are the inner average current loops. The VEA  
output provides the controlling voltage for these current  
sources. The inner current loop absorbs the inductor  
pole reducing the order of the outer voltage loop to that  
of a single-pole system.  
Keep the maximum output voltage deviation less than  
or equal to the adaptive voltage-positioning window  
(VOUT). Assume 50% contribution each from the out-  
put capacitance discharge and the ESR drop. Use the  
following equations to calculate the required ESR and  
capacitance value:  
A resistive feedback around the VEA provides the best  
possible response, since there are no capacitors to  
charge and discharge during large-signal excursions, R  
F
and R determine the VEA gain. Use the following equa-  
IN  
tion to calculate the value for RF:  
I
× R  
IN  
OUT  
R
=
(27)  
(28)  
F
V  
N× G × ∆V  
ESR  
C
OUT  
(23)  
ESR  
=
OUT  
I
STEP  
0.05  
G
=
I
× t  
C
STEP  
RESPONSE  
R
C
=
(24)  
S
OUT  
V  
Q
where GC is the current-loop gain and N is number of  
phases.  
whe re ISTEP is the loa d s te p a nd tRESPONSE is the  
response time of the controller. Controller response  
time depends on the control-loop bandwidth.  
When designing the current-control loop ensure that the  
inductor downslope (when it becomes an upslope at the  
CEA output) does not exceed the ramp slope. This is a  
necessary condition to avoid sub-harmonic oscillations  
similar to those in peak current-mode control with insuffi-  
cient slope compensation. Use the following equation to  
Cu rre n t Lim it  
The average current-mode control technique of the  
MAX5038/MAX5041 accurately limits the maximum out-  
put current per phase. The MAX5038/MAX5041 sense  
the voltage across the sense resistor and limit the peak  
inductor current (IL-PK) accordingly. The ON cycle ter-  
minates when the current-sense voltage reaches 45mV  
(min). Use the following equation to calculate maximum  
current-sense resistor value:  
calculate the resistor RCF  
:
2
2 × f ×L×10  
SW  
(29)  
R
CF  
V
×R  
SENSE  
OUT  
For example, the maximum RCF is 12kfor RSENSE  
1.35m.  
=
0.045  
R
=
SENSE  
(25)  
I
OUT  
CCF provides a low-frequency pole while RCF provides a  
midband zero. Place a zero at fZ to obtain a phase bump  
at the crossover frequency. Place a high-frequency pole  
(fP) at least a decade away from the crossover frequency  
to achieve maximum phase margin.  
N
3  
2.5 ×10  
R
(26)  
PD =  
R
SENSE  
where PDR is the power dissipation in sense resistors.  
Select 5% lower value of RSENSE to compensate for any  
parasitics associated with the PC board. Also, select a  
non-inductive resistor with the appropriate wattage rating.  
24 ______________________________________________________________________________________  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
Use the following equations to calculate CCF and CCFF  
:
P in Co n fig u ra t io n  
1
C
C
=
CF  
(30)  
TOP VIEW  
2 × π × f ×R  
Z
CF  
CSP2  
CSN2  
1
2
3
4
5
6
7
8
9
28 CLKIN  
27 CLKOUT  
26 BST2  
25 DH2  
1
=
(31)  
CFF  
2 × π × f ×R  
P
CF  
PHASE  
PLLCMP  
CLP2  
P C Bo a rd La yo u t  
Use the following guidelines to layout the switching  
voltage regulator.  
24 LX2  
MAX5038A  
MAX5041A  
SGND  
23 DL2  
22 PGND  
21 IN  
1) Place the V and VCC bypass capacitors close to  
IN  
CLP1  
the MAX5038/MAX5041.  
SENSE+  
SENSE-  
2) Minimize the hig h-c urre nt loop s from the inp ut  
capacitor, upper switching MOSFET, inductor, and  
output capacitor back to the input capacitor nega-  
tive terminal.  
20  
V
CC  
DIFF 10  
EAN 11  
19 DL1  
18 LX1  
17 DH1  
16 BST1  
15 EN  
3) Keep short the current loop from the lower switch-  
ing MOSFET, inductor, and output capacitor and  
return to the source of the lower MOSFET.  
EAOUT 12  
CSP1 13  
CSN1 14  
4) Pla c e the Sc hottky d iod e s c los e to the lowe r  
MOSFETs and on the same side of the PC board.  
SSOP  
5) Keep the SGND and PGND isolated and connect  
them at one single point close to the negative termi-  
nal of the input filter capacitor.  
6) Run the c urre nt-s e ns e line s CS+ a nd CS- ve ry  
c los e to e a c h othe r to minimize the loop a re a .  
Simila rly, run the re mote volta g e s e ns e line s  
SENSE+ and SENSE- close to each other. Do not  
cross these critical signal lines through power cir-  
cuitry. Sense the current right at the pads of cur-  
rent-sense resistors.  
9) Distribute the power components evenly across the  
board for proper heat dissipation.  
10) Provide enough copper area at and around the  
switching MOSFETs, inductor, and sense resistors  
to aid in thermal dissipation.  
11) Use at least 4oz copper to keep the trace induc-  
tance and resistance to a minimum. Thin copper PC  
boards can compromise efficiency since high cur-  
rents are involved in the application. Also, thicker  
copper conducts heat more effectively, thereby  
reducing thermal impedance.  
7) Avoid long traces between the VCC bypass capaci-  
tors , d rive r outp ut of the MAX5038/MAX5041,  
MOSFET gates and PGND pin. Minimize the loop  
formed by the VCC bypass capacitors, bootstrap  
diode, bootstrap capacitor, MAX5038/MAX5041,  
and upper MOSFET gate.  
Ch ip In fo rm a t io n  
TRANSISTOR COUNT: 5431  
8) Place the bank of output capacitors close to the load.  
PROCESS: BiCMOS  
______________________________________________________________________________________ 25  
Du a l-P h a s e , P a ra lle la b le , Ave ra g e Cu rre n t -Mo d e  
Co n t ro lle rs  
P a c k a g e In fo rm a t io n  
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,  
go to www.maxim-ic.com/packages.  
2
1
INCHES  
MILLIMETERS  
MAX  
MAX  
1.99  
0.21  
0.38  
0.20  
DIM  
A
MIN  
0.068  
MIN  
1.73  
0.05  
0.25  
0.09  
INCHES  
MAX  
MILLIMETERS  
MAX  
6.33  
6.33  
7.33  
MIN  
MIN  
6.07  
6.07  
7.07  
8.07  
N
0.078  
14L  
16L  
20L  
D
D
D
D
D
A1  
B
0.239 0.249  
0.239 0.249  
0.278 0.289  
0.317 0.328  
0.002 0.008  
0.010 0.015  
0.004 0.008  
C
8.33 24L  
E
H
SEE VARIATIONS  
0.205 0.212 5.20  
0.0256 BSC  
D
0.397 0.407 10.07 10.33  
28L  
E
5.38  
e
0.65 BSC  
H
0.301 0.311 7.65  
0.025 0.037 0.63  
7.90  
0.95  
8  
L
0∞  
8∞  
0∞  
N
A
C
B
L
e
A1  
D
NOTES:  
1. D&E DO NOT INCLUDE MOLD FLASH.  
2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006").  
3. CONTROLLING DIMENSION: MILLIMETERS.  
4. MEETS JEDEC MO150.  
PROPRIETARY INFORMATION  
TITLE:  
PACKAGE OUTLINE, SSOP, 5.3 MM  
APPROVAL  
DOCUMENT CONTROL NO.  
REV.  
5. LEADS TO BE COPLANAR WITHIN 0.10 MM.  
1
21-0056  
C
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are  
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.  
26 ____________________Ma x im In t e g ra t e d P ro d u c t s , 1 2 0 S a n Ga b rie l Drive , S u n n yva le , CA 9 4 0 8 6 4 0 8 -7 3 7 -7 6 0 0  
© 2004 Maxim Integrated Products  
Printed USA  
is a registered trademark of Maxim Integrated Products.  

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