MAX20006 [MAXIM]

36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters;
MAX20006
型号: MAX20006
厂家: MAXIM INTEGRATED PRODUCTS    MAXIM INTEGRATED PRODUCTS
描述:

36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters

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Click here for production status of specific part numbers.  
MAX20004/MAX20006/  
MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
General Description  
Benefits and Features  
Multiple Functions for Small Size  
The MAX20004/MAX20006/MAX20008 are small, synchro-  
nous, automotive buck converter devices with integrated  
high-side and low-side MOSFETs. The device family can  
deliver up to 8A with input voltages from 3.5V to 36V, while  
using only 25μA quiescent current at no load. Voltage qual-  
ity can be monitored by observing the RESET signal. The  
devices can operate in dropout by running at 98% duty  
cycle, making them ideal for automotive applications.  
• Operating V Range of 3.5V to 36V  
IN  
• 25µA Quiescent Current in Skip Mode  
• Synchronous DC-DC Converter with  
Integrated FETs  
220kHz to 2.2MHz Adjustable Frequency  
• Fixed 5ms Internal Soft-Start  
Programmable 1V to 10V Output, or 3.3V and  
5.0V Fixed-Output Options Available  
98% Duty-Cycle Operation with Low Dropout  
RESET Output  
The devices offer fixed output voltages of 5V and 3.3V,  
along with the ability to program the output voltage between  
1V and 10V. Frequency is resistor programmable from  
220kHz to 2.2MHz. The devices offer a forced fixed-fre-  
quency PWM mode (FPWM) and skip mode with ultra-low  
quiescent current. The devices can be factory programmed  
to enable spread-spectrum switching to reduce EMI.  
● High Precision  
• ±2% Output-Voltage Accuracy  
Good Load-Transient Performance  
Robust for the Automotive Environment  
Current-Mode, Forced-PWM and Skip Operation  
Overtemperature and Short-Circuit Protection  
3.5mm x 3.75mm 17-Pin FC2QFN  
• -40°C to +125°C Operating Temperature Range  
40V Load-Dump Tolerant  
The MAX20004/MAX20006/MAX20008 are available in a  
small, 3.5mm x 3.75mm, 17-pin FC2QFN package and use  
very few external components.  
Applications  
● Point-of-Load (PoL) Applications in Automotive  
AEC-Q100 Qualified  
● Distributed DC Power Systems  
Navigation and Radio Head Units  
Ordering Information appears at end of data sheet.  
Typical Application Circuit  
12k  
SUPSW  
FOSC  
SUP  
SYNC  
C
4.7µF  
IN1  
C
0.1µF  
IN2  
R
RESET  
20kΩ  
BIAS  
EN  
RESET  
OUT  
BST  
LX  
C
BST  
COMP  
0.1µF  
L
1µH  
22kΩ  
1nF  
4.7pF  
FB  
V
OUT  
C
BIAS  
C
BIAS  
OUT  
2.2µF  
PGND  
GND  
19-100239; Rev 8; 11/19  
MAX20004/MAX20006/  
MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
Absolute Maximum Ratings  
SUP, EN, SUPSW to PGND..................................-0.3V to +40V  
Output Short-Circuit Duration....................................Continuous  
LX to PGND (Note 1) ........................ -0.3V to (V  
+ 0.3V)  
Continuous Power Dissipation (T = +70°C)  
SUPSW  
A
BIAS, RESET to GND..........................................-0.3V to +6.0V  
17-Pin FC2QFN (derate 29.4mW/°C > 70°C) .......... 2553mW  
Operating Temperature Range......................... -40°C to +125°C  
Junction Temperature......................................................+150°C  
Storage Temperature Range............................ -65°C to +150°C  
Lead Temperature Range................................................+300°C  
Soldering Temperature (reflow).......................................+260°C  
FOSC, COMP to GND............................-0.3V to (V  
SYNC, FB to GND..................................-0.3V to (V  
+ 0.3V)  
+ 0.3V)  
BIAS  
BIAS  
GND to PGND......................................................-0.3V to +0.3V  
OUT to PGND .......................................................-0.3V to +12V  
BST to LX ...............................................................-0.3V to +6V  
LX Continuous RMS Current ..................................................8A  
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.  
Note 1: Self-protected from transient voltages exceeding these limits in circuit under normal operation.  
Package Information  
17 FC2QFN  
Package Code  
F173A3FY+1  
21-100155  
90-100056  
Outline Number  
Land Pattern Number  
Thermal Resistance, Four-Layer Board:  
Junction to Ambient (θ  
)
27°C/W  
2.6°C/W  
JA  
Junction to Case (θ  
)
JC  
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,  
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing  
pertains to the package regardless of RoHS status.  
Package thermal resistances were obtained using the EV kit. For detailed information on package thermal considerations, refer to  
www.maximintegrated.com/thermal-tutorial.  
Electrical Characteristics  
(V  
= V  
= V  
= 14V. T = T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C under normal  
SUP  
SUPSW  
EN  
A
J
A
conditions, unless otherwise noted.) (Note 2)  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
V
,
SUP  
Supply Voltage Range  
3.5  
36  
V
V
SUPSW  
V
,
SUP  
Supply Voltage Range  
Supply Current  
After startup  
3.0  
V
V
SUPSW  
V
V
= 3.3V  
= 5.0V  
25  
30  
5
32  
42  
10  
OUT  
OUT  
I
Skip mode, no load  
µA  
SUP  
Shutdown Supply Current  
BIAS Regulator Voltage  
I
V
V
= 0V  
µA  
V
SHDN  
EN  
= V  
= 6V to 40V I  
< 10mA,  
SUP  
SUPSW  
BIAS  
OUT  
V
5
3
BIAS  
BIAS not switched over to V  
BIAS Undervoltage  
Lockout  
V
V
rising  
2.7  
3.3  
V
UVBIAS  
BIAS  
Maxim Integrated  
2  
www.maximintegrated.com  
MAX20004/MAX20006/  
MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
Electrical Characteristics (continued)  
(V  
= V  
= V  
= 14V. T = T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C under normal  
SUP  
SUPSW  
EN  
A
J
A
conditions, unless otherwise noted.) (Note 2)  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
BIAS Undervoltage  
Lockout  
V
V
falling  
2.5  
2.9  
V
UVBIAS  
BIAS  
Thermal-Shutdown  
Temperature  
T
T rising  
175  
15  
°C  
°C  
SHDN  
J
Thermal-Shutdown  
Hysteresis  
T
HYST  
OUTPUT VOLTAGE  
PWM-Mode Output  
Voltage (Note 3)  
V
V
V = 6V to 28V  
4.9  
4.9  
5
5
5.1  
5.15  
3.37  
3.4  
V
V
V
OUT_5V  
SUP = SUPSW  
Skip-Mode Output Voltage  
(Note 4)  
V
Skip mode, no load, FB = BIAS  
= 6V to 28V  
SKIP_5V  
PWM-Mode Output  
Voltage  
V
V
V
3.23  
3.23  
3.3  
OUT_3.3V  
SUP = SUPSW  
Skip-Mode Output Voltage  
(Note 4)  
V
Skip mode, no load, FB = BIAS  
3.3  
0.6  
V
SKIP_3.3V  
V
= V  
, 30mA < I  
< 6A, PWM mode,  
FB  
BIAS  
LOAD  
Load Regulation  
LN  
LD  
%
REG  
5V  
Line Regulation  
V
= V  
, 6V < V  
< 36V, PWM mode  
0.02  
1.5  
0.1  
7
%/V  
mA  
µA  
REG  
FB  
BIAS  
SUPSW  
BST Input Current  
BST Input Current  
I
High-side MOSFET on, V  
- V = 5V  
LX  
BST_ON  
BST  
IBST_OFF High-side MOSFET off, V  
- V = 5V  
LX  
BST  
MAX20004 (4A)  
5.25  
7.5  
8.75  
12.5  
17.5  
LX Current Limit  
I
MAX20006 (6A)  
MAX20008 (8A)  
10  
A
LX  
10.5  
14  
LX Rise Time (Note 4)  
t
2
ns  
%
LX_TR  
Spread Spectrum  
SS  
Spread spectrum enabled  
= 5V, I = 2A  
±3  
High-Side Switch  
On-Resistance  
R
HS  
V
38  
1
76  
5
mΩ  
µA  
BIAS  
LX  
High-side MOSFET off, V  
= 36V,  
= 36V,  
SUPSW  
High-Side Switch Leakage  
I
HS_LKG  
V
= 0V, T = +25°C  
A
LX  
Low-Side Switch  
On-Resistance  
R
V
= 5V, I = 2A  
18  
36  
mΩ  
LS  
BIAS  
LX  
Low-side MOSFET off, V  
= 36V, T = +25°C  
SUPSW  
Low-Side Switch Leakage  
FB Input Current  
I
1
5
µA  
nA  
V
LS_LKG  
V
LX  
A
I
T
= +25°C  
30  
100  
1.01  
FB  
A
FB connected to an external resistive divider,  
6V < V < 36V  
FB Regulation Voltage  
V
FB  
0.99  
500  
1.00  
SUPSW  
Transconductance  
(from FB to COMP)  
g
V
= 1V, V = 5V  
BIAS  
780  
75  
1000  
µS  
ns  
m
FB  
Minimum On-Time  
(Note 4)  
t
Load 500mA (Note 4)  
ON_MIN  
Maxim Integrated  
3  
www.maximintegrated.com  
MAX20004/MAX20006/  
MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
Electrical Characteristics (continued)  
(V  
= V  
= V  
= 14V. T = T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C under normal  
SUP  
SUPSW  
EN  
A
J
A
conditions, unless otherwise noted.) (Note 2)  
PARAMETER  
Maximum Duty Cycle  
Oscillator Frequency  
Oscillator Frequency  
Soft-Start Time  
SYMBOL  
DC  
CONDITIONS  
MIN  
97  
TYP  
98  
MAX  
UNITS  
%
MAX  
f
f
R
R
= 73.2kΩ  
360  
2.0  
400  
2.2  
5
440  
2.4  
kHz  
MHz  
ms  
SW1  
SW2  
FOSC  
= 12kΩ  
FOSC  
t
SS  
EN, SYNC  
External Input Clock  
Frequency  
R
= 12kΩ (Note 5)  
1.8  
1.4  
2.6  
MHz  
FOSC  
SYNC High Threshold  
SYNC Low Threshold  
SYNC Leakage Current  
EN High Threshold  
EN Low Threshold  
EN Hysteresis  
V
V
V
SYNC_HI  
V
0.4  
1
SYNC_LO  
I
T
= +25°C  
0.1  
µA  
V
SYNC  
A
A
V
2.4  
EN_HI  
V
0.6  
2
V
EN_LO  
V
0.2  
0.1  
V
EN_HYS  
EN Leakage Current  
I
T
= +25°C  
µA  
EN  
RESET  
UV Threshold  
UV  
Falling  
89  
91  
3
93  
%
%
ACC  
UV Hysteresis  
Hold Time (Note 6)  
UV Debounce Time  
OV Protection Threshold  
OV Protection Threshold  
Leakage Current  
t
(Note 6)  
0.2  
25  
ms  
µs  
%
HOLD1  
t
DEB  
OVP  
Rising  
Falling  
104  
107  
105  
110  
THR  
THF  
OVP  
%
I
V
in regulation, T = +25°C  
A
1
µA  
V
RST_LKG  
OUT  
Output Low Level  
V
I
= 5mA  
0.4  
ROL  
SINK  
Note 2: All units are 100% production tested at T = +25˚C. All temperature limits are guaranteed by design.  
A
Note 3: Device not in dropout condition.  
Note 4: Guaranteed by design. Not production tested.  
Note 5: Contact factory for SYNC frequency outside the specified range.  
Note 6: Contact factory for additional options.  
Maxim Integrated  
4  
www.maximintegrated.com  
MAX20004/MAX20006/  
MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
Typical Operating Characteristics  
(V  
= V  
= 14V, V  
= 14V, V  
= 5V, V  
= 0V, R  
= 12kΩ, T = +25°C, unless otherwise noted.)  
SUP  
SUPSW  
EN  
OUT  
FSYNC  
FOSC  
A
EFFICIENCY vs. LOAD CURRENT  
EFFICIENCY vs. LOAD CURRENT  
toc02  
toc01  
100  
100  
90  
80  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
70  
SKIP MODE  
PWM MODE  
SKIP MODE  
60  
PWM MODE  
50  
40  
30  
20  
V
V
f
= 12V  
V
V
f
= 12V  
= 5V  
= 400kHz  
IN  
IN  
= 3.3V  
OUT  
10  
OUT  
= 400kHz  
SW  
SW  
0
0.001  
0.01  
0.1  
LOAD CURRENT (A)  
1
10  
0.001  
0.01  
0.1  
LOAD CURRENT (A)  
1
10  
EFFICIENCY vs. LOAD CURRENT  
EFFICIENCY vs. LOAD CURRENT  
toc04  
toc03  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
SKIP MODE  
SKIP MODE  
PWM MODE  
PWM MODE  
V
V
f
= 12V  
= 5V  
= 2.2MHz  
V
V
f
= 12V  
IN  
IN  
= 3.3V  
OUT  
OUT  
= 2.2MHz  
SW  
SW  
0.001  
0.01  
0.1  
LOAD CURRENT (A)  
1
10  
0.001  
0.01  
0.1  
LOAD CURRENT (A)  
1
10  
NO LOAD SUPPLY CURRENT  
vs. SUPPLY VOLTAGE  
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE  
toc05  
toc06  
10  
9
8
7
6
5
4
3
2
1
0
35  
30  
25  
20  
15  
10  
5
VEN = 0V  
V
f
= 3.3V  
= 2.2MHz  
OUT  
SW  
SKIP MODE  
0
6
9
12 15 18 21 24 27 30 33 36  
SUPPLY VOLTAGE (V)  
6
9
12 15 18 21 24 27 30 33 36  
SUPPLY VOLTAGE (V)  
Maxim Integrated  
5  
www.maximintegrated.com  
MAX20004/MAX20006/  
MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
Typical Operating Characteristics  
(V  
= V  
= 14V, V  
= 14V, V  
= 5V, V  
= 0V, R  
= 12kΩ, T = +25°C, unless otherwise noted.)  
SUP  
SUPSW  
EN  
OUT  
FSYNC  
FOSC  
A
SWITCHING FREQUENCY vs. RFOSC  
SYNC FUNCTION  
toc07  
toc08  
2500  
2250  
2000  
1750  
1500  
1250  
1000  
750  
5V/div  
1V/div  
V
LX  
V
SYNC  
500  
250  
0
10  
30  
50  
70  
90  
110 130 150  
200ns/div  
R
(kΩ)  
OSC  
VBIAS vs. VSUP  
DROPOUT VOLTAGE vs. IOUT  
toc09  
toc10  
6.0  
5.5  
5.0  
4.5  
4.0  
3.5  
3.0  
2.5  
2.0  
0.50  
0.45  
0.40  
0.35  
0.30  
0.25  
0.20  
0.15  
0.10  
0.05  
0.00  
V
= 95% of V  
SET  
OUT  
IOUT = 0.1A  
VOUT = 3.3V  
fSW= 2.2MHz  
L = COILCRAFT XAL6030-102  
V
= 3.3V  
SET  
IOUT = 6A  
V
= 5V  
SET  
0
1
2
3
4
5
6
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0  
VSUP (V)  
I
(A)  
OUT  
LOAD REGULATION  
LOAD REGULATION  
toc11  
toc12  
5.20  
5.15  
5.10  
5.05  
5.00  
4.95  
4.90  
4.85  
4.80  
5.20  
5.15  
5.10  
5.05  
5.00  
4.95  
4.90  
4.85  
4.80  
V
= 14V  
VIN = 14V  
SKIP MODE  
IN  
PWM MODE  
400kHz  
400kHz  
2.2MHz  
2.2MHz  
0
1
2
3
4
5
6
7
8
0
1
2
3
4
5
6
7
8
IOUT (A)  
I
(A)  
OUT  
Maxim Integrated  
6  
www.maximintegrated.com  
MAX20004/MAX20006/  
MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
Typical Operating Characteristics  
(V  
= V  
= 14V, V  
= 14V, V  
= 5V, V  
= 0V, R  
= 12kΩ, T = +25°C, unless otherwise noted.)  
SUP  
SUPSW  
EN  
OUT  
FSYNC  
FOSC  
A
ENABLE STARTUP BEHAVIOR  
VOUT vs. VIN  
toc14  
toc13  
5.05  
5.04  
5.03  
5.02  
5.01  
5.00  
4.99  
V
= 14V  
IN  
PWM MODE  
= 0A  
I
5V/div  
2V/div  
LOAD  
V
EN  
400kHz  
V
OUT  
2A/div  
5V/div  
I
OUT  
2.2MHz  
V
RESET  
4ms/div  
6
12  
18  
24  
30  
36  
V
(V)  
IN  
SHORT CIRCUIT AND RECOVERY  
VIN STARTUP BEHAVIOR  
toc15  
toc16  
10V/div  
2V/div  
2V/div  
V
IN  
V
OUT  
10V/div  
V
LX  
V
OUT  
2A/div  
5V/div  
I
OUT  
I
OUT  
20A/div  
V
RESET  
EN = V  
IN  
4ms/div  
20ms/div  
TJ_RISE vs. IOUT  
TJ_RISE vs. IOUT  
toc18  
toc17  
80  
70  
60  
50  
40  
30  
20  
10  
0
140  
130  
120  
110  
100  
90  
fSW = 400kHz  
VIN = 14V  
PWM MODE  
TA = 25°C  
f
V
= 2.2MHz  
= 14V  
SW  
IN  
PWM MODE  
= 25°C  
T
A
V
= 5V  
OUT  
80  
70  
V
= 3.3V  
OUT  
60  
50  
40  
30  
V
= 3.3V  
V
= 5V  
5
OUT  
5
OUT  
20  
10  
0
1
2
3
4
I
6
7
8
1
2
3
4
I
6
7
8
(A)  
OUT  
(A)  
OUT  
Maxim Integrated  
7  
www.maximintegrated.com  
MAX20004/MAX20006/  
MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
Pin Configuration  
TOP VIEW  
17  
16  
15  
14  
13  
12  
11  
10  
EN  
OUT  
RESET  
BST  
1
2
SUP  
3
9
8
7
SUPSW  
PGND  
PGND  
4
5
PGND  
PGND  
6
FC2QFN  
3.5mm x 3.75mm  
Pin Description  
PIN  
NAME  
FUNCTION  
Switching Regulator Output. OUT also provides power to the internal circuitry under certain conditions (see the  
Linear Regulator Output (BIAS) section for details).  
1
OUT  
2
3
RESET  
Open-Drain, Active-Low RESET Output. To obtain a logic signal, pullup RESET with an external resistor.  
BST  
High-Side Driver Supply. Connect a 0.1μF capacitor between LX and BST for proper operation.  
4, 5,  
7, 8  
PGND  
LX  
Power Ground. Connect all PGND pins together.  
6
Inductor Connection. Connect LX to the switched side of the inductor.  
Internal High-Side Switch Supply Input. SUPSW provides power to the internal switch. Bypass SUPSW to  
9
SUPSW PGND with 0.1μF and 4.7μF ceramic capacitors. Place the 0.1μF capacitor as close as possible to the SUPSW  
and PGND pins, followed by the 4.7μF capacitor.  
Voltage Supply Input. SUP supplies the internal linear regulator. Connect SUP directly to SUPSW as close as  
possible to the IC. SUP and SUPSW are connected together internally.  
10  
11  
SUP  
SUP Voltage-Compatible Enable Input. Drive EN low to disable the device. Drive EN high to enable the device.  
EN  
For a safe startup, ensure that V  
> 7.5V when EN is toggled high.  
SUP  
Connect SYNC to GND or leave unconnected to enable skip-mode operation under light loads. Connect SYNC  
to BIAS or to an external clock to enable fixed-frequency forced-PWM-mode operation. When driving SYNC  
externally, do not exceed the BIAS or OUT voltage.  
12  
SYNC  
Linear Regulator Output. BIAS supplies the internal circuitry. Bypass with a minimum 2.2 µF ceramic capacitor  
13  
14  
BIAS  
GND  
to ground. The BIAS pin can transition from 5V to V  
after startup.  
OUT  
Analog Ground  
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Pin Description (continued)  
PIN  
NAME  
FUNCTION  
Error-Amplifier Output. Connect an RC network from COMP to GND for stable operation. See the  
Compensation Network section for more details.  
15  
COMP  
Feedback Input. Connect an external resistive divider from OUT to FB and GND to set the output voltage.  
Connect FB to BIAS to set the output voltage to 5V or 3.3V.  
16  
17  
FB  
Resistor-Programmable Switching Frequency Setting Control Input. Connect a resistor from FOSC to GND to  
set the switching frequency.  
FOSC  
Internal Block Diagram  
CURRENT-SENSE  
AMP  
MAX20004  
SUPSW  
MAX20006  
MAX20008  
SKIP CURRENT  
COMP  
BST  
LX  
CLK  
PEAK CURRENT  
COMP  
RAMP  
GENERATOR  
LX  
CONTROL LOGIC  
BIAS  
PWM  
COMP  
PGND  
COMP  
VREF  
ERROR  
AMP  
FPWM CLK  
SOFT-START  
GENERATOR  
PGOOD  
COMP  
ZX  
COMP  
PGND  
OUT  
FB  
POK  
FEEDBACK  
SELECT  
SYNC  
FOSC  
SUP  
CLK  
OTP  
TRIMBITS  
OSC  
POK  
BIAS LDO  
FPWM  
BIAS  
VOLTAGE  
REFERENCE  
V
REF  
RESET  
MAIN  
CONTROL  
LOGIC  
EN  
GND  
SEL  
GND  
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The input voltage at which the device enters dropout can  
be approximated as:  
Detailed Description  
The MAX20004/MAX20006/MAX2008 are 4A, 6A, and  
8A current-mode step-down converters, respectively,  
with integrated high-side and low-side MOSFETs. The  
low-side MOSFET enables fixed-frequency FPWM opera-  
tion in light-load applications. The devices operate with  
3.5V to 36V input voltages, while using only 25μA (typ)  
quiescent current at no load. The switching frequency  
is resistor programmable from 220kHz to 2.2MHz and  
can be synchronized to an external clock. The devices’  
output voltage is available as fixed 5V or 3.3V, or adjust-  
able between 1V and 10V. The wide input voltage range,  
along with the ability to operate at 99% duty cycle during  
undervoltage transients, make these devices ideal for  
automotive applications.  
VOUT  
VSUP  
=
+ IOUT ×RHS  
0.98  
where R  
is the high-side switch on-resistance, which  
HS  
should also include the inductor DC resistance for better  
accuracy.  
Linear Regulator Output (BIAS)  
The devices include a 5V linear regulator (V  
) that  
BIAS  
provides power to the internal circuit blocks. Connect  
a 2.2μF ceramic capacitor from BIAS to GND. Under  
certain conditions, the BIAS regulator turns off and the  
BIAS pin switches to OUT (i.e., switches over) after  
startup to increase efficiency. For IC versions that are  
factory trimmed for 3.3V fixed output, BIAS switches to  
OUT under light load conditions in skip mode only. For IC  
versions that are factory trimmed for 5V fixed output, the  
BIAS pin switches to OUT after startup regardless of load  
or skip/PWM mode. In any case, BIAS only switches over  
if OUT is between 2.8V and 5.6V. In summary, BIAS can  
transition from 5V to VOUT after startup depending on  
load, mode and IC version.  
In light-load applications, a logic input (SYNC) allows  
the devices to operate either in skip mode for reduced  
current consumption, or fixed-frequency FPWM mode  
to eliminate frequency variation and help minimize EMI.  
Protection features include cycle-by-cycle current limit,  
and thermal shutdown with automatic recovery.  
Thermal Considerations  
The devices are available in 4A, 6A, or 8A versions; how-  
ever, the average output-current capability is dependent on  
several factors. Some of the key factors include the maxi-  
Soft-Start  
mum ambient temperature (T  
), switching frequency  
The devices include a fixed, internal soft-start. Soft-start  
limits startup inrush current by forcing the output voltage  
to ramp up towards its regulation point.  
A(MAX)  
(f ), and the number of layers and the size of the PCB.  
SW  
See the Typical Operating Characteristics for a guideline.  
Wide Input Voltage Range  
The devices include two separate supply inputs (SUP and  
SUPSW) specified for a wide 3.5V to 36V input voltage  
Reset Output (RESET)  
The devices feature an open-drain reset output (RESET).  
RESET asserts when V  
drops below the specified  
OUT  
range. V  
provides power to the device and V  
falling threshold. RESET deasserts when V  
rises  
SUP  
SUPSW  
OUT  
provides power to the internal switch. When the device is  
operating with a 3.5V input supply, conditions such as cold  
crank can cause the voltage at the SUP and SUPSW pins  
to drop below the programmed output voltage. Under such  
conditions, the devices operate in a high duty-cycle mode  
to facilitate minimum dropout from input to output.  
above the specified rising threshold after the specified  
hold time. Connect RESET to the output or I/O voltage  
of choice (within pin voltage limits) with a pullup resistor.  
Synchronization Input (SYNC)  
SYNC is a logic-level input used for operating-mode  
selection and frequency control. Connecting SYNC to  
BIAS or to an external clock enables forced fixed-frequen-  
cy (FPWM) operation. Connecting SYNC to GND enables  
automatic skip-mode operation for light load efficiency.  
The external clock frequency at SYNC can be higher or  
lower than the internal clock by 20%. If the external clock  
frequency is greater than 120% of the internal clock, con-  
tact the factory to verify the design. The devices synchro-  
nize to the external clock in two cycles. When the external  
clock signal at SYNC is absent for more than two clock  
cycles, the devices use the internal clock. There is a diode  
Maximum Duty-Cycle Operation  
The devices have an effective maximum duty cycle of 98%  
(typ). The IC continuously monitors the time between low-  
side FET switching cycles in both PWM and skip modes.  
Whenever the low-side FET has not switched for more than  
13.5µs (typ), the low-side FET is forced on for 150ns (typ)  
to refresh the BST capacitor. The input voltage at which  
the device enters dropout changes depending on the input  
voltage, output voltage, switching frequency, load current,  
and the efficiency of the design.  
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between SYNC and BIAS, so it is important when driving  
SYNC with an external source that the voltage be less  
than or equal to BIAS (or OUT in the case of switchover).  
If this cannot be guaranteed, place a series resistor in-line  
with SYNC ≥ 20kΩ to limit the input current. If EN is low,  
BIAS is turned off so a voltage should not be present on  
SYNC without the series resistor.  
graph in the Typical Operating Characteristics section or  
the following equation:  
29,600  
RFOSC  
=
1.48  
fSW  
where f  
is in kHz and RFOSC is in kΩ. For example, a  
SW  
400kHz switching frequency is set with R  
= 72.5kΩ.  
System Enable (EN)  
FOSC  
An enable control input (EN) activates the devices from  
their low-power shutdown mode. EN is compatible with  
inputs from automotive battery level down to 3.5V.  
Higher frequencies allow designs with lower inductor  
values and less output capacitance at the expense of  
reduced efficiency and higher EMI.  
EN turns on the internal linear (BIAS) regulator. Once  
Thermal-Shutdown Protection  
V
BIAS  
is above the internal lockout threshold (V  
=
UVBIAS  
Thermal shutdown protects the device from excessive  
operating temperature. When the junction temperature  
exceeds the specified threshold, an internal sensor shuts  
down the internal bias regulator and the step-down con-  
verter, allowing the IC to cool. The sensor turns the IC on  
again after the junction temperature cools by the specified  
hysteresis.  
3V (typ)), the converter activates and the output voltage  
ramps up with the programmed soft-start time.  
A logic-low at EN shuts down the device. During shut-  
down, the BIAS regulator and gate drivers turn off.  
Shutdown is the lowest power state and reduces the  
quiescent current to 5μA (typ). Drive EN high to bring the  
device out of shutdown.  
Current Limit/Short-Circuit Protection  
For safe startup, ensure that V  
> 7.5V when EN is  
SUP  
The devices feature a current limit that protects them  
against short-circuit and overload conditions at the out-  
put. In the event of a short-circuit or overload condition,  
the high-side MOSFET remains on until the inductor  
current reaches the specified LX current-limit threshold.  
The converter then turns the high-side MOSFET off and  
the low-side MOSFET on to allow the inductor current to  
ramp down. Once the inductor current crosses below the  
current-limit threshold, the converter turns on the high-  
side MOSFET again. This cycle repeats until the short or  
overload condition is removed.  
toggled high. In all applications, BIAS capacitance guide-  
lines must be followed to ensure safe operation of the IC.  
Note: In all applications, BIAS must start from < 0.3V or  
> 1.6V during startup.  
Spread-Spectrum Option  
The devices can be ordered with spread spectrum  
enabled. See the Ordering Information/Selector Guide  
section. When the spread spectrum is factory enabled,  
the operating frequency is varied ±3% centered on FOSC.  
The modulation signal is a triangular wave with a fre-  
quency of 4.5kHz at 2.2MHz.  
A hard short is detected when the output voltage falls  
below 50% of the target while in current limit. If this  
occurs, hiccup mode activates, and the output turns off  
for four times the soft-start time. The output then enters  
soft-start and powers back up. This repeats indefinitely  
while the short circuit is present. Hiccup mode is disabled  
during soft-start.  
For operations at FOSC values other than 2.2MHz, the  
modulation signal scales proportionally (e.g., at 400kHz,  
the modulation frequency reduces by 0.4MHz/2.2MHz).  
The internal spread spectrum is disabled if the devices  
are synchronized to an external clock. However, the  
devices do not filter the input clock on the SYNC pin and  
pass any modulation (including spread spectrum) present  
driving the external clock.  
Overvoltage Protection  
If the output voltage exceeds the OV protection rising  
threshold, the high-side MOSFET turns off and the low-  
side MOSFET turns on. Normal operation resumes when  
Internal Oscillator (FOSC)  
The switching frequency (f ) is set by a resistor  
SW  
the output voltage goes below the falling OV threshold.  
(R  
) connected from FOSC to GND. To determine  
FOSC  
the approximate value of RFOSC for a given fSW, use the  
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Forced-PWM and Skip Modes  
Applications Information  
In forced-PWM (FPWM) mode, the devices switch at a  
constant frequency with variable on-time. In skip mode,  
the converter’s switching frequency is load-dependent.  
At higher load current, the switching frequency becomes  
fixed and operation is similar to PWM mode. Skip mode  
helps improve efficiency in light-load applications by  
allowing switching only when the output voltage falls  
below a set threshold. Since the effective switching  
frequency is lower in skip mode at light load, gate charge  
and switching losses are lower and efficiency is increased.  
Maximum Output Current  
While there are device versions that supply up to 8A,  
there are many factors that may limit the average output  
current to less than the maximum. The devices can be  
thermally limited based on the selected f , number of  
SW  
PCB layers, PCB size, and the maximum ambient tem-  
perature. See the Typical Operating Characteristics sec-  
tion for guidance on the maximum average current. For a  
more precise value, the θ needs to be measured in the  
JA  
application environment.  
Inductor Selection  
Three key parameters must be considered when select-  
ing an inductor: inductance value (L), inductor saturation  
Setting the Output Voltage  
Connect FB to BIAS for a fixed 5V or 3.3V output volt-  
age. To set the output to other voltages between 1V and  
10V, connect a resistive divider from output (OUT) to FB  
current (I  
), and DC resistance (R  
SAT  
). The devises  
DCR  
are designed to operate with the ratio of inductor peak-  
to-peak AC current to DC average current (LIR) between  
15% and 30% (typ). The switching frequency, input volt-  
age, and output voltage then determine the inductor value  
as follows:  
(Figure 1). Select R  
(FB to GND resistor) less than or  
FB2  
equal to 100kΩ. Calculate R  
the following equation:  
(OUT to FB resistor) with  
FB1  
V
OUT  
R
= R  
1  
FB2  
FB1  
V
V
V  
× V  
OUT OUT  
(
)
FB   
SUP  
L
=
MIN1  
V
× f  
× I × 30%  
MAX  
SUP  
SW  
where V  
is the feedback regulation voltage. See the  
FB  
Electrical Characteristics table.  
where V  
and V  
are typical values (so that effi-  
OUT  
SUP  
Add a capacitor, C , as shown to compensate the pole  
ciency is optimum for typical conditions) and IMAX is 4A  
FB1  
formed by the divider resistance and FB pin capacitance  
for MAX20004, 6A for MAX20006, and 8A for MAX20008,  
as follows:  
and f  
is the switching frequency set by R  
Note  
SW  
FOSC.  
RFB2  
that IMAX is the maximum rated output current for the  
device, not the maximum load current in the application.  
CFB1 = 10pf ×  
RFB1   
The next equation ensures that the internal compensating  
slope is greater than 50% of the inductor current down slope:  
Note: Applications that use a resistor divider to set  
output voltages below 4.5V should use IC versions  
that are factory trimmed for 3.3V fixed output voltage  
to ensure full output current capability.  
m2  
m ≥  
2
where m is the internal compensating slope and m2 is the  
sensed inductor current down-slope as follows:  
VOUT  
V
OUT  
m2 =  
×RCS  
L
where R  
and 0.21 for MAX20008.  
is 0.38 for MAX20004, 0.28 for MAX20006,  
CS  
R
R
FB1  
FB2  
C
FB1  
FB  
V
fSW  
m = 1.35  
×
µs 2.2MHz  
Solving for L and using a 1.3 multiplier to account for  
tolerances in the system:  
R
CS  
L
= V  
×
OUT  
×1.3  
MIN2  
2×m  
Figure 1. Adjustable Output-Voltage Setting  
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To satisfy both L  
larger of the two as follows:  
and L  
, L must be set to the  
MIN2 MIN  
input capacitance and ESR required for a specified input  
voltage ripple using the following equations:  
MIN1  
V  
ESR  
L
= max L  
, L  
MIN1 MIN2  
(
)
ESRIN  
=
MIN  
IL  
2
IOUT  
+
The maximum nominal inductor value recommended is 2  
times the chosen value from the above formula:  
where:  
and:  
V
VOUT × V  
OUT  
(
)
SUP  
IL  
=
LMAX = 2×LMIN  
VSUP × fSW ×L  
Select a nominal inductor value based on the following  
formula:  
IOUT ×D 1D  
(
)
CIN  
=
LMIN < LNOM < LMAX  
VQ × fSW  
The best choice of inductor is usually the standard induc-  
V
tor value closest to L  
.
NOM  
OUT  
D =  
VSUPSW  
Input Capacitor  
The input filter capacitor reduces peak currents drawn  
from the power source and reduces noise and voltage  
ripple on the input due to high speed switching.  
where:  
I
is the maximum output current and D is the duty  
OUT  
cycle.  
Place a 0.1μF capacitor as close as possible to the  
SUPSW and PGND pins, followed by a 4.7μF (or larger)  
ceramic capacitor. A bulk capacitor with higher ESR  
(such as an electrolytic capacitor) is normally required as  
well to lower the Q of the front-end circuit and provide the  
remaining capacitance needed to minimize input voltage  
ripple.  
Output Capacitor  
The output filter capacitor must have enough capacitance  
and sufficiently low ESR to meet output-ripple require-  
ments. In addition, the output capacitance must be high  
enough to maintain the output voltage within specification  
while the control loop responds to load changes.  
The input capacitor RMS current requirement (I  
defined by the following equation:  
) is  
When using high-capacitance, low-ESR capacitors, the  
filter capacitor’s ESR dominates the output-voltage ripple,  
so the size of the output capacitor depends largely on the  
maximum ESR allowed to meet the output-voltage ripple  
specifications as follows:  
RMS  
VOUT × V  
VOUT  
(
)
SUP  
IRMS = ILOAD(MAX)  
×
VSUP  
V
= ESR× ∆I  
L
RIPPLE(PP)  
I
has a maximum value when the input voltage  
RMS  
equals twice the output voltage:  
When using low-ESR (e.g. ceramic) output capacitors,  
size is usually determined by the capacitance required  
to maintain the output voltage within specification during  
load transients and can be estimated as follows:  
VSUP = 2× VOUT  
therefore:  
I  
I
LOAD MAX  
COUT =  
(
)
I
=
V × 2π × fC  
RMS  
2
where ∆I is the load change, ∆V is the allowed voltage  
droop, and f is the loop crossover frequency, which can  
Choose an input capacitor that exhibits less than +10°C  
self-heating temperature rise at the RMS input current for  
optimal long-term reliability.  
C
be assumed to be the lesser of f /10 or 100kHz. Any  
SW  
calculations involving C  
should consider capacitance  
OUT  
The input-voltage ripple is composed of ∆V (caused by  
Q
tolerance, temperature, and voltage derating.  
the capacitor discharge) and ∆V  
(caused by the ESR  
ESR  
of the capacitor). Use low-ESR ceramic capacitors with  
high ripple-current capability at the input. Calculate the  
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V
V
V
V
OUT  
REF  
ERR  
COMP  
+
C(s)  
M(s)  
-
V
FB  
F(s)  
Figure 2. Control System  
A simplified condition for stability is that the denominator  
of the transfer function never equals zero. Accordingly,  
the loop transfer function should never equal -1, which  
correspondingly means that the phase must not equal  
-180 degrees when the magnitude equals 1. In addition,  
the loop gain should be much less than zero when the  
phase equals -180 degrees. The frequency at which the  
magnitude of the loop gain equals 1 (or 0dB) is defined as  
Compensation Network  
The devices use a transconductance amplifier for external  
frequency compensation. The compensation network in  
conjunction with the output capacitance primarily deter-  
mine the loop stability and response. The inductor and the  
output capacitor are chosen based on performance, size,  
and cost. The compensation network is used to optimize  
the loop stability and response.  
the crossover frequency (f ). The difference between the  
c
The converter uses a peak current mode control scheme  
that regulates the output voltage by forcing the required  
peak current through the external inductor. The devices  
use the voltage drop across the high-side MOSFET to  
sense inductor current. Current-mode control eliminates  
the double pole in the feedback loop caused by the induc-  
tor and output capacitor, resulting in a smaller phase shift  
and requiring less elaborate error-amplifier compensation  
than voltage-mode control.  
loop phase at the crossover frequency and -180 degrees  
is defined as the phase margin. The phase margin rep-  
resents the additional loop phase lag that must occur at  
the crossover frequency for the system to be unstable.  
In addition to stability, phase margin is also related to  
the transient response of the system. Insufficient phase  
margin causes overshoot and ringing, whereas excessive  
phase margin causes slow response.  
The goal of the system is to have a high crossover fre-  
quency, so there is adequate gain to regulate against load  
transients and other variations in the relevant frequency  
range, while maintaining adequate phase margin to guard  
against instability, overshoot, and ringing. In practice,  
these are fundamentally conflicting criteria that must be  
managed along with other design goals. According to  
sampling theory, the crossover frequency cannot exceed  
one half the switching frequency. In practice, noise and  
phase margin considerations limit crossover frequency to  
below one tenth the switching frequency with a practical  
limit of approximately 100kHz.  
The final control system can be modeled according to  
Figure 2 from which the following transfer function is  
derived:  
VOUT(s)  
VREF  
C(s)M(s)  
=
1+ F(s)C(s)M(s)  
where M(s), C(s) and F(s) are the modulator, compensator  
and feedback transfer functions, respectively, V is the  
OUT  
regulated output voltage and V  
is the internal voltage  
REF  
reference. The product of the modulator, compensator and  
feedback transfer functions is typically referred to as the  
loop transfer function.  
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The modulator control (COMP) to output transfer function  
of a current-mode buck regulator can be approximated  
as follows:  
V
OUT  
s
ωz_esr  
1+  
VOUT  
s
( )  
ROUT  
RCS  
=
×
g
m
2
VCOMP  
s
( )  
s
s
s
COMP  
1+  
1+  
+
2
ωp_load  
ωnQ  
ωn  
V
REF  
The first term is the DC gain, which is the quotient of the  
equivalent load resistance (R ) and the current-sense  
R
C
C
C
C
F
OUT  
gain (R ). The numerator is the zero due to the output  
CS  
capacitance (C  
) and its equivalent series resistance  
OUT  
(R  
), which occurs at the following frequency:  
ESR  
1
fz_esr =  
2π ×RESR × COUT  
Figure 3. Compensation Network  
The first term in the denominator is the pole due to the  
load resistance and output capacitance, and occurs at the  
following frequency:  
where G and R (1.5MΩ typ) are the transconductance  
EA  
EA  
1
and output resistance of the error amplifier, respectively, and  
the frequency of the poles and zeros are approximately as  
follows:  
fpload =  
2π ×ROUT × COUT  
The last term in the denominator is the sampling double  
pole, which occurs at 1/2 of the switching frequency  
1
fz_comp =  
2π ×RC × CC  
(f /2). The sampling double pole typically occurs at  
SW  
1
high frequency relative to the crossover frequency and  
can generally be ignored if there is adequate slope com-  
pensation (i.e., low Q). In the typical application, where  
the ESR is very low due to ceramic output capacitors,  
the ESR zero also occurs at high frequency and can be  
ignored as well. In these cases, the transfer function  
simplifies to the low-frequency dominate pole model as  
follows:  
fp1_comp =  
2π ×REA × CC  
1
fp2_comp =  
2π ×RC × CF  
VOUT  
s
( )  
ROUT  
RCS  
1
=
×
VCOMP  
s
( )  
s
1+  
Compensation resistor, R , primarily determines the com-  
C
ωp_load  
pensator gain and, thus, crossover frequency, while the  
separation of the compensator zero and high-frequency  
pole determine the phase margin. The high-frequency  
compensator pole is used to cancel the ESR zero or, in  
the case of very high ESR zero frequency, limit the band-  
width for noise immunity. The low frequency compensator  
pole is then placed to achieve adequate phase margin  
and response, typically at the load pole frequency. The  
The type 2 compensation network (Figure 3) introduces  
a zero, a low-frequency pole, and a high frequency pole  
according to the simplified transfer function below:  
s
ωz_comp  
  
1+  
VCOMP  
s
( )  
s
= GEA × REA  
×
VERR  
s
s
( )  
selection of C , therefore, becomes a tradeoff between  
1+  
1+  
C
  
ωp1_comp  
ωp2_comp  
  
phase margin and response.The complete loop transfer  
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Step-Down Converters  
function is the product of the product of the modulator,  
compensator, and feedback transfer functions as follows:  
Setting the compensator zero frequency equal to the load  
pole frequency and solving for R yields:  
C
1
1
=
VREF ROUT  
2π ×RC × CC 2π ×ROUT × COUT  
F(s)C(s)M(s) =  
×
× GEA ×REA  
VOUT RCS  
s
  
s
1+  
1+  
2π × COUT ×RCS × VOUT × fC  
  
ωz_esr  
ωz_comp  
RC  
=
  
s
×
VREF × GEA  
s
  
  
s
1+  
1+  
  
1+  
  
ωp_load  
ωp1_comp  
  
ωp2_comp  
  
The above leads to an alternative equation for C as  
C
follows:  
ROUT × COUT  
The goal of compensation design is to reduce the loop  
transfer function to an approximate single-pole system  
with -20dB/decade gain slope and 90 degrees phase  
margin at the crossover frequency. To achieve this, the  
compensator zero is used to cancel the load pole, and  
the compensator high frequency pole is used to cancel  
the ESR zero. Assuming these cancellations, the loop  
transfer function reduces to the following:  
CC  
=
RC  
Finally, setting the high-frequency compensator pole  
equal to the minimum of the ESR zero frequency or 1/2  
the switching frequency and solving for C yields:  
F
1
fSW  
2
1
= Min  
,
2π ×RC × CF  
2π ×RESR × COUT   
VREF ROUT  
F(s)C(s)M(s) =  
×
1
,
VOUT RCS  
CF  
=
fSW  
2
1
1
s
2π ×RC ×Min  
× GEA ×REA  
×
2π ×RESR × COUT   
1+  
ωp1_comp  
The above equation leads to the following compensation  
design procedure:  
To derive the compensation components, the magnitude  
of the loop gain at the crossover frequency is set equal to  
1) Select a crossover frequency equal to one tenth of  
the switching frequency (f /10) or 100kHz, which-  
ever is lower.  
SW  
1 and solved for C as follows (assuming the magnitude of  
C
the compensator pole at the crossover frequency is >>1):  
2) Calculate and select the compensation resistor, R .  
VREF ROUT  
C
×
× GEA ×REA  
VOUT RCS  
3) Calculate and select the compensation capacitor, C .  
C
1
4) Calculate and select compensation capacitor C .  
F
×
= 1  
2π × fC ×REA × CC  
(
)
5) Evaluate the gain and phase of the final loop transfer  
function at the crossover frequency and adjust cross-  
over frequency and/or compensation as required.  
VREF ×ROUT × GEA  
2π × fC × VOUT ×RCS  
CC  
=
6) Verify the final design with transient line/load response  
testing and gain-phase measurements and adjust as  
required.  
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4) Use a contiguous copper GND plane on the layer  
next to the IC to provide an image plane and shield  
the entire circuit. GND should also be poured around  
the entire circuit on the top side. Use a single GND:  
do not separate or isolate PGND and GND connec-  
tions with separate planes or copper areas. Ensure  
that all heat-dissipating components have adequate  
connections to copper for cooling. Use multiple vias  
to interconnect GND planes/areas for low impedance  
and maximum heat dissipation. Place vias at the GND  
terminals of the IC, input/output/bypass capacitors,  
and other components.  
PCB Layout Guidelines  
Careful PCB layout is critical for stability, low-noise/  
EMI and overall performance. Use a multilayer board  
whenever possible for better noise immunity and power  
dissipation. See Figure 4 for the following guidelines for  
good PCB layout:  
1) Use the correct footprint for the IC and place as  
many copper planes as possible under the IC foot-  
print to ensure efficient heat transfer.  
2) Place the ceramic input bypass capacitors (C and  
BP  
C ) as close as possible to the SUPSW and PGND  
IN  
pins on the same side as the IC. Use low-impedance  
connections (no vias or other discontinuities) be-  
5) Place the compensation network (CF, CC, RC) near  
the COMP pin so that the ground connections are as  
short as possible to the GND pin. Keep high frequency  
signals away from these components.  
tween the capacitors and IC pins. C should be  
BP  
located closest to the IC and should have very good  
high-frequency performance (small package size,  
low inductance, and high. Use flexible terminations  
or other technologies instead of series capacitors  
for these functions if failure modes are a concern.  
This approach provides the best EMI rejection and  
minimizes internal noise on the device, which can  
degrade performance.  
6) Place the oscillator set resistor (RF) near the FSET  
pin so that the ground connection is as short as  
possible to the GND pin. Keep high-frequency signals  
away from this component.  
7) Place the feedback resistor-divider (if used) near  
the IC and route the feedback and OUT connections  
away from the inductor and LX node and other noisy  
signals.  
3) Place the inductor (L), output capacitors (C  
),  
OUT  
boost capacitor (C  
) and BIAS capacitor (C ) on  
BST  
B
the same side as the IC in such a way as to minimize  
the area enclosed by the current loops. Place the  
inductor (L) as close as possible to the IC LX pin and  
minimize the area of the LX node. Place the output  
capacitors (COUT) near the inductor and the ground  
side of COUT near the CIN ground connection so as  
to minimize the current the loop area. Place the BIAS  
capacitor (CB) next to the BIAS pin.  
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CC  
RC  
CF  
CB  
RF  
VIN  
CBST  
CBP  
CIN  
LX  
COUT  
COUT  
VOUT  
Figure 4. Simplified Layout Example  
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MAX20008  
36V, 220kHz to 2.2MHz, 4A/6A/8A  
Fully Integrated Automotive  
Step-Down Converters  
Ordering Information/Selector Guide  
V
MAXIMUM  
OPERATING  
CURRENT (A)  
OUT  
V
T
(ms)  
SPREAD  
SPECTRUM  
OUT  
HOLD  
PART  
(EXTERNAL RESISTOR-  
DIVIDER) (V)  
(FB TIED TO BIAS)  
MAX20004AFOA/VY+  
MAX20004AFOB/VY+  
MAX20004AFOC/VY+  
MAX20004AFOD/VY+  
MAX20006AFOA/VY+  
MAX20006AFOB/VY+  
MAX20006AFOC/VY+  
MAX20006AFOD/VY+  
MAX20008AFOA/VY+  
MAX20008AFOB/VY+  
MAX20008AFOC/VY+  
MAX20008AFOD/VY+  
5.0  
3.3  
5.0  
3.3  
5.0  
3.3  
5.0  
3.3  
5.0  
3.3  
5.0  
3.3  
4.5–10  
1–10  
4
4
4
4
6
6
6
6
8
8
8
8
0.2  
0.2  
0.2  
0.2  
0.2  
0.2  
0.2  
0.2  
0.2  
0.2  
0.2  
0.2  
Off  
Off  
On  
On  
Off  
Off  
On  
On  
Off  
Off  
On  
On  
4.5–10  
1–10  
4.5–10  
1–10  
4.5–10  
1–10  
4.5–10  
1–10  
4.5–10  
1–10  
For variants with different options, contact factory.  
/V Denotes an automotive-qualified part.  
+Denotes a lead(Pb)-free/RoHS-compliant package.  
Chip Information  
PROCESS: BiCMOS  
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Step-Down Converters  
Revision History  
REVISION REVISION  
PAGES  
CHANGED  
DESCRIPTION  
NUMBER  
DATE  
0
3/18  
Initial release  
Removed future product status from MAX20006AFOA/VY+ and  
MAX20008AFOC/VY+ variants in the Ordering Information/Selector Guide table  
1
2
5/18  
8/18  
19  
Updated the Package Information table, and Reset Output (RESET), Setting  
the Output Voltage, Output Capacitor, and Compensation Network sections  
; reformatted the Typical Operating Characteristics charts; replaced TOC17  
and TOC18; and removed future product designation from MAX2006AFOB/  
VY+, MAX2006AFOB/VY+, MAX2006AFOB/VY+, MAX2006AFOB/VY+,  
MAX2006AFOB/VY+, and MAX2006AFOB/VY+  
2, 5–7, 10  
12–16, 19  
Removed future product status from MAX20004AFOA/VY+, MAX20004AFOB/  
VY+, MAX20004AFOC/VY+, and MAX20004AFOD/VY+ variants in the Ordering  
Information/Selector Guide table  
3
4
5
11/18  
1/19  
1/19  
19  
2
Updated land pattern number in Package Information table  
Updated thermal resistance values in Package Information table and added V  
OUT  
2, 19  
(external resistor-divider) column to Ordering Information/Selector Guide table  
6
2/19  
Added “automotive” to product description  
1–19  
7
8
9/19  
Updated Typical Application Circuit, Pin Description, and Detailed Description  
Updated Pin Description, and Detailed Description  
1, 8, 11  
8, 11  
11/19  
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.  
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses  
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)  
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.  
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.  
2018 Maxim Integrated Products, Inc.  
20  

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