MP1472GJ-Z [MPS]

Switching Regulator, Current-mode, PDSO8, MO-193BA, TSOT-23, 8 PIN;
MP1472GJ-Z
型号: MP1472GJ-Z
厂家: MONOLITHIC POWER SYSTEMS    MONOLITHIC POWER SYSTEMS
描述:

Switching Regulator, Current-mode, PDSO8, MO-193BA, TSOT-23, 8 PIN

开关 光电二极管 输出元件
文件: 总13页 (文件大小:451K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
MP1472  
2A, 18V Synchronous Rectified  
Step-Down Converter  
The Future of Analog IC Technology  
DESCRIPTION  
FEATURES  
The MP1472 is a monolithic synchronous buck  
regulator. The device integrates a 175mhigh-  
side MOSFET and a 115mlow-side MOSFET  
that provide 2A of continuous load current over  
a wide input voltage of 4.75V to 18V. Current  
mode control provides fast transient response  
and cycle-by-cycle current limit.  
2A Output Current  
Wide 4.75V to 18V Operating Input Range  
Integrated Power MOSFET Switches  
Output Adjustable from 0.923V to 15V  
Up to 95% Efficiency  
Programmable Soft-Start  
Stable with Low ESR Ceramic Output  
Capacitors  
An adjustable soft-start prevents inrush current  
at turn-on, and in shutdown mode the supply  
current drops to 1µA.  
Fixed 340kHz Frequency  
Cycle-by-Cycle Over Current Protection  
Input Under Voltage Lockout  
8–Pin TSOT23-8  
This device, available in an 8-pin TSOT23-8  
package, provides a very compact solution with  
minimal external components.  
APPLICATIONS  
Distributed Power Systems  
Networking Systems  
FPGA, DSP, ASIC Power Supplies  
Green Electronics/ Appliances  
Notebook Computers  
EVALUATION BOARD REFERENCE  
Board Number  
Dimensions  
EV1472GJ-00A  
2.5”X x 2.5”Y x 0.5”Z  
For MPS green status, please visit MPS website under Quality Assurance.  
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of  
Monolithic Power Systems, Inc.  
TYPICAL APPLICATION  
Efficiency vs. Load Current  
V
=3.3V  
OUT  
100  
90  
80  
70  
60  
V
=4.75V  
IN  
V
=12V  
IN  
50  
40  
30  
20  
V
=18V  
0.1  
IN  
10  
0
0.01  
1
10  
LOAD CURRENT (A)  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
1
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
ORDERING INFORMATION  
Part Number  
Package  
Top Marking  
TSOT23-8  
MP1472GJ*  
ACW  
*For Tape & Reel, add suffix –Z (e.g. MP1472GJ–Z);  
PACKAGE REFERENCE  
TOP VIEW  
SS  
EN  
BST  
IN  
1
2
3
4
8
7
6
5
COMP  
FB  
SW  
GND  
ABSOLUTE MAXIMUM RATINGS (1)  
Supply Voltage VIN ........................-0.3V to +20V  
Switch Node Voltage VSW ............................ 21V  
Boost Voltage VBS ..........VSW – 0.3V to VSW + 6V  
All Other Pins..................................-0.3V to +6V  
Junction Temperature...............................150°C  
Thermal Resistance (4)  
TSOT23-8..............................100..... 55... C/W  
θJA  
θJC  
Notes:  
1) Exceeding these ratings may damage the device.  
2) The maximum allowable power dissipation is a function of the  
maximum junction temperature TJ(MAX), the junction-to-  
ambient thermal resistance θJA, and the ambient temperature  
TA. The maximum allowable continuous power dissipation at  
any ambient temperature is calculated by PD(MAX)=(TJ(MAX)-  
TA)/ θJA. Exceeding the maximum allowable power dissipation  
will cause excessive die temperature, and the regulator will go  
into thermal shutdown. Internal thermal shutdown circuitry  
protects the device from permanent damage.  
Continuous Power Dissipation (TA = +25°C)  
(2)  
……………………………………………….1.25W  
Lead Temperature ....................................260°C  
Storage Temperature .............. -65°C to +150°C  
3) The device is not guaranteed to function outside of its  
operating conditions.  
4) Measured on JESD51-7 4-layer PCB.  
Recommended Operating Conditions (3)  
Input Voltage VIN ............................4.75V to 18V  
Output Voltage VOUT.....................0.923V to 15V  
Maximum Junction Temp. (TJ)............... +125C  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
2
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
ELECTRICAL CHARACTERISTICS  
VIN = 12V, TA = +25°C, unless otherwise noted.  
Parameter  
Symbol Condition  
Min  
Typ  
1
Max  
3.0  
Units  
μA  
mA  
V
Shutdown Supply Current  
Supply Current  
VEN = 0V  
VEN = 5.0V; VFB = 1.0V  
4.75V VIN 18V  
1.3  
1.5  
Feedback Voltage  
VFB  
0.900  
0.923  
1.1  
0.946  
Feedback Overvoltage Threshold  
Error Amplifier Voltage Gain (5)  
Error Amplifier Transconductance  
High-Side Switch On Resistance (5)  
Low-Side Switch On Resistance (5)  
High-Side Switch Leakage Current  
Upper Switch Current Limit  
Lower Switch Current Limit  
V
AEA  
400  
800  
175  
115  
V/V  
μA/V  
mΩ  
mΩ  
μA  
A
GEA  
IC = 10μA  
RDS(ON)1  
RDS(ON)2  
VEN = 0V, VSW = 0V  
Minimum Duty Cycle  
From Drain to Source  
10  
3
4.1  
1.1  
5.3  
A
COMP to Current Sense  
Transconductance  
GCS  
3.5  
A/V  
Oscillation Frequency  
Fosc1  
Fosc2  
305  
340  
100  
90  
375  
2.0  
kHz  
kHz  
%
Short Circuit Oscillation Frequency  
VFB = 0V  
Maximum Duty Cycle  
Minimum On Time (5)  
DMAX VFB = 0.8V  
220  
1.5  
ns  
EN Shutdown Threshold Voltage  
VEN Rising  
1.1  
V
EN Shutdown Threshold Voltage  
Hysteresis  
210  
mV  
EN Lockout Threshold Voltage  
EN Lockout Hysterisis  
2.2  
2.5  
2.7  
V
210  
mV  
Input Under Voltage Lockout  
Threshold  
Input Under Voltage Lockout  
Threshold Hysteresis  
VIN Rising  
3.40  
3.80  
210  
4.20  
V
mV  
Soft-Start Current  
Soft-Start Period  
VSS = 0V  
CSS = 0.1μF  
6
15  
160  
μA  
ms  
°C  
Thermal Shutdown (5)  
Note:  
5) Guaranteed by design, not tested.  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
3
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
PIN FUNCTIONS  
Pin # Name Description  
Soft-Start Control Input. SS controls the soft start period. Connect a capacitor from SS to GND  
1
2
SS  
EN  
to set the soft-start period. A 0.1μF capacitor sets the soft-start period to 15ms. To disable the  
soft-start feature, leave SS unconnected.  
Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on  
the regulator, drive it low to turn it off. Pull up with 100kresistor for automatic startup.  
Compensation Node. COMP is used to compensate the regulation control loop. Connect a  
series RC network from COMP to GND to compensate the regulation control loop. In some  
cases, an additional capacitor from COMP to GND is required. See Compensation  
Components.  
3
COMP  
Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a  
resistive voltage divider from the output voltage. The feedback threshold is 0.923V. See  
Setting the Output Voltage.  
4
5
6
FB  
GND Ground.  
Power Switching Output. SW is the switching node that supplies power to the output. Connect  
SW  
the output LC filter from SW to the output load. Note that a capacitor is required from SW to  
BS to power the high-side switch.  
Power Input. IN supplies the power to the IC, as well as the step-down converter switches.  
Drive IN with a 4.75V to 18V power source. Bypass IN to GND with a suitably large capacitor  
to eliminate noise on the input to the IC. See Input Capacitor.  
7
8
IN  
High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET  
switch. Connect a 0.01μF or greater capacitor from SW to BS to power the high side switch.  
BS  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
4
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
TYPICAL PERFORMANCE CHARACTERISTICS  
VIN = 12V, VO = 3.3V, CIN = 10µF, COUT = 22µF, L = 10µH, TA = +25°C, unless otherwise noted.  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
5
4.5  
4
3.5  
3
2.5  
0.01  
0.1  
1
10  
0.01  
0.1  
1
10  
0
20  
40  
60  
80  
100  
V
V
O/AC  
O/AC  
20mV/div.  
20mV/div.  
V
O
2V/div.  
EN  
5V/div.  
SW  
10V/div.  
SW  
10V/div.  
SW  
10V/div.  
I
I
INDUCTOR  
2A/div.  
INDUCTOR  
1A/div.  
I
INDUCTOR  
1A/div.  
V
O
2V/div.  
EN  
V
O
2V/div.  
EN  
5V/div.  
V
O
2V/div.  
EN  
5V/div.  
SW  
5V/div.  
SW  
10V/div.  
SW  
10V/div.  
10V/div.  
I
I
I
INDUCTOR  
2A/div.  
INDUCTOR  
2A/div.  
INDUCTOR  
2A/div.  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
5
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
OPERATION  
The converter uses internal N-Channel  
MOSFET switches to step-down the input  
voltage to the regulated output voltage. Since  
the high side MOSFET requires a gate voltage  
greater than the input voltage, a boost capacitor  
connected between SW and BS is needed to  
drive the high side gate. The boost capacitor is  
charged from the internal 5V rail when SW is low.  
FUNCTIONAL DESCRIPTION  
The MP1472 is a synchronous rectified,  
current-mode, step-down regulator. It regulates  
input voltages from 4.75V to 18V down to an  
output voltage as low as 0.923V, and supplies  
up to 2A of load current.  
The MP1472 uses current-mode control to  
regulate the output voltage. The output voltage  
is measured at FB through a resistive voltage  
divider and amplified through the internal  
transconductance error amplifier. The voltage at  
the COMP pin is compared to the switch current  
measured internally to control the output  
voltage.  
When the MP1472 FB pin exceeds 20% of the  
nominal regulation voltage of 0.923V, the over  
voltage comparator is tripped and the COMP  
pin and the SS pin are discharged to GND,  
forcing the high-side switch off.  
+
IN  
V
IN  
CURRENT  
SENSE  
AMPLIFIER  
V
OUT  
OVP  
+
--  
--  
+
1.1V  
0.3V  
5V  
RAMP  
CLK  
OSCILLATOR  
340kHz  
FB  
SS  
BS  
--  
0.175  
0.115  
S
Q
Q
+
--  
SW  
--  
+
+
R
CURRENT  
COMPARATOR  
ERROR  
AMPLIFIER  
0.923V  
V
OUT  
COMP  
EN  
GND  
--  
EN OK  
OVP  
IN < 3.8V  
1.2V  
LOCKOUT  
COMPARATOR  
2.5V  
1.5V  
+
+
IN  
INTERNAL  
REGULATORS  
--  
SHUTDOWN  
COMPARATOR  
Figure 1—Functional Block Diagram  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
6
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
APPLICATIONS INFORMATION  
size, higher series resistance, and/or lower  
saturation current.  
COMPONENT SELECTION  
Setting the Output Voltage  
The output voltage is set using a resistive voltage  
divider from the output voltage to FB pin. The  
voltage divider divides the output voltage down to  
the feedback voltage by the ratio:  
A good rule for determining the inductance to use  
is to allow the peak-to-peak ripple current in the  
inductor to be approximately 30% of the  
maximum switch current limit. Also, make sure  
that the peak inductor current is below the  
maximum switch current limit. The inductance  
value can be calculated by:  
R2  
VFB VOUT  
R1R2  
Where VFB is the feedback voltage and VOUT is  
the output voltage.  
VOUT  
VOUT  
VIN  
L   
1  
fS  IL  
Thus the output voltage is:  
Where VOUT is the output voltage, VIN is the input  
voltage, fS is the switching frequency, and ΔIL is  
the peak-to-peak inductor ripple current.  
R1R2  
R2  
VOUT 0.923   
R2 can be as high as 100k, but a typical value  
is 10k. Using the typical value for R2, R1 is  
determined by:  
Choose an inductor that will not saturate under  
the maximum inductor peak current. The peak  
inductor current can be calculated by:  
R1 10.83 (VOUT 0.923) (k)  
For example, for a 3.3V output voltage, R2 is  
10k, and R1 is 26.1k.  
VOUT  
VOUT  
VIN  
ILP ILOAD  
1  
2fS L  
Inductor  
Where ILOAD is the load current.  
The inductor is required to supply constant  
current to the output load while being driven by  
the switched input voltage. A larger value  
inductor will result in less ripple current that will  
result in lower output ripple voltage. However, the  
larger value inductor will have a larger physical  
Table 1 lists a number of suitable inductors from  
various manufacturers. The choice of which style  
inductor to use mainly depends on the price vs.  
size requirements and any EMI requirement.  
Table 1—Inductor Selection Guide  
Dimensions  
Part Number  
Inductance (µH) Max DCR () Current Rating (A)  
L x W x H (mm3)  
Wurth Electronics  
7440650068  
6.8  
10  
15  
0.033  
0.035  
0.050  
3.6  
3.6  
3.2  
10x10x2.8  
10x10x3.8  
10x10x3.8  
744066100  
744066150  
TDK  
SLF10165T-6R8N4R33PF  
SLF10165T-100M3R83PF  
SLF10165T-150M3R13PF  
Toko  
6.8  
10  
15  
0.014  
0.0185  
0.027  
4.3  
3.8  
3.1  
10x10x4.5  
10x10x4.5  
10x10x4.5  
#B952AS-6R8N  
#B892NAS-100M  
#B892NAS-150M  
6.8  
10  
15  
0.035  
0.0225  
0.0355  
3.1  
4.2  
3.2  
10.4x10.4x4.8  
12.3x12.3x4.5  
12.3x12.3x4.5  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
7
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
Optional Schottky Diode  
ILOAD  
VOUT  
VIN  
VOUT  
V  
1  
IN  
During the transition between high-side switch  
and low-side switch, the body diode of the low-  
side power MOSFET conducts the inductor  
current. The forward voltage of this body diode is  
high. An optional Schottky diode may be  
paralleled between the SW pin and GND pin to  
improve overall efficiency. Table 2 lists example  
Schottky diodes and their Manufacturers.  
C1fS  
V
IN  
Where C1 is the input capacitance value.  
Output Capacitor  
The output capacitor is required to maintain the  
DC output voltage. Ceramic, tantalum, or low  
ESR electrolytic capacitors are recommended.  
Low ESR capacitors are preferred to keep the  
output voltage ripple low. The output voltage  
ripple can be estimated by:  
Table 2—Diode Selection Guide  
Voltage/Current  
Part Number  
Vendor  
VOUT  
VOUT  
VIN  
1
Rating  
30V, 2A  
30V, 2A  
VOUT  
1  
RESR  
fS L  
8 fS C2  
B230  
SL23  
Diodes, Inc.  
Vishay, Inc.  
Where C2 is the output capacitance value and  
RESR is the equivalent series resistance (ESR)  
value of the output capacitor.  
International  
Rectifier  
MBRS230  
30V, 2A  
Input Capacitor  
In the case of ceramic capacitors, the impedance  
at the switching frequency is dominated by the  
capacitance. The output voltage ripple is mainly  
caused by the capacitance. For simplification, the  
output voltage ripple can be estimated by:  
The input current to the step-down converter is  
discontinuous, therefore a capacitor is required to  
supply the AC current to the step-down converter  
while maintaining the DC input voltage. Use low  
ESR capacitors for the best performance.  
Ceramic capacitors are preferred, but tantalum or  
low-ESR electrolytic capacitors may also suffice.  
Choose X5R or X7R dielectrics when using  
ceramic capacitors.  
VOUT  
VOUT  
VIN  
ΔVOUT  
1  
2
8 fS L C2  
In the case of tantalum or electrolytic capacitors,  
the ESR dominates the impedance at the  
switching frequency. For simplification, the output  
ripple can be approximated to:  
Since the input capacitor (C1) absorbs the input  
switching current it requires an adequate ripple  
current rating. The RMS current in the input  
capacitor can be estimated by:  
VOUT  
VOUT  
VIN  
ΔVOUT  
 1  
RESR  
fS L  
VOUT  
VOUT  
IC1 ILOAD  
1  
The characteristics of the output capacitor also  
affect the stability of the regulation system. The  
MP1472 can be optimized for a wide range of  
capacitance and ESR values.  
V
V
IN  
IN  
The worst-case condition occurs at VIN = 2VOUT  
,
where IC1 = ILOAD/2. For simplification, choose the  
input capacitor whose RMS current rating greater  
than half of the maximum load current.  
Compensation Components  
MP1472 employs current mode control for easy  
compensation and fast transient response. The  
system stability and transient response are  
controlled through the COMP pin. COMP pin is  
the output of the internal transconductance error  
amplifier. A series capacitor-resistor combination  
sets a pole-zero combination to control the  
characteristics of the control system.  
The input capacitor can be electrolytic, tantalum  
or ceramic. When using electrolytic or tantalum  
capacitors,  
a
small, high quality ceramic  
capacitor, i.e. 0.1μF, should be placed as close  
to the IC as possible. When using ceramic  
capacitors, make sure that they have enough  
capacitance to provide sufficient charge to  
prevent excessive voltage ripple at input. The  
input voltage ripple for low ESR capacitors can  
be estimated by:  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
8
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
The DC gain of the voltage feedback loop is  
given by:  
crossover frequencies could cause system  
instability. A good rule of thumb is to set the  
crossover frequency below one-tenth of the  
switching frequency.  
VFB  
AVDC RLOAD GCS AEA  
VOUT  
Table 3 lists the typical values of compensation  
components for some standard output voltages  
with various output capacitors and inductors. The  
values of the compensation components have  
been optimized for fast transient responses and  
good stability at given conditions.  
Where AVEA is the error amplifier voltage gain;  
GCS is the current sense transconductance and  
RLOAD is the load resistor value.  
The system has two poles of importance. One is  
due to the compensation capacitor (C3) and the  
output resistor of the error amplifier, and the  
other is due to the output capacitor and the load  
resistor. These poles are located at:  
Table 3—Compensation Values for Typical  
Output Voltage/Capacitor Combinations  
VOUT  
L1  
C2  
R3  
C3  
C6  
GEA  
22μF/6.3V  
Ceramic  
fP1  
1.8V  
6.8uH  
3.3k5.6nF None  
5.6k3.3nF None  
10k2.2nF None  
15k1.0nF None  
2  C3AVEA  
22μF/6.3V  
Ceramic  
3.3V  
5.0V  
10μH  
15μH  
1
fP2  
2  C2RLOAD  
22μF/6.3V  
Ceramic  
Where GEA is the error amplifier transconductance.  
22μF/16V  
Ceramic  
12.0V 22μH  
The system has one zero of importance, due to the  
compensation capacitor (C3) and the compensation  
resistor (R3). This zero is located at:  
To optimize the compensation components, the  
following procedure can be used.  
1
fZ1  
2C3R3  
1. Choose the compensation resistor (R3) to set  
the desired crossover frequency.  
The system may have another zero of  
importance, if the output capacitor has a large  
capacitance and/or a high ESR value. The zero,  
due to the ESR and capacitance of the output  
capacitor, is located at:  
Determine the R3 value by the following  
equation:  
2  C2 fC VOUT 2  C2 0.1fS VOUT  
R3   
GEA GCS  
VFB  
GEA GCS  
VFB  
1
fESR  
Where fC is the desired crossover frequency  
which is typically below one tenth of the switching  
frequency.  
2  C2RESR  
In this case, a third pole set by the compensation  
capacitor (C6) and the compensation resistor  
(R3) is used to compensate the effect of the ESR  
zero on the loop gain. This pole is located at:  
2. Choose the compensation capacitor (C3) to  
achieve the desired phase margin. For  
applications with typical inductor values, setting  
the compensation zero, fZ1, below one-forth of the  
crossover frequency provides sufficient phase  
margin.  
1
fP3  
2C6R3  
The goal of compensation design is to shape the  
converter transfer function to get a desired loop  
gain. The system crossover frequency where the  
feedback loop has the unity gain is important.  
Lower crossover frequencies result in slower line  
and load transient responses, while higher  
Determine the C3 value by the following equation:  
4
C3   
2  R3 fC  
where R3 is the compensation resistor.  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
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© 2011 MPS. All Rights Reserved.  
9
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
3. Determine if the second compensation  
In these cases, an external BST diode is  
recommended from the output of the voltage  
regulator to BST pin, as shown in Figure 2  
capacitor (C6) is required. It is required if the  
ESR zero of the output capacitor is located at  
less than half of the switching frequency, or the  
following relationship is valid:  
External BST Diode  
IN4148  
BST  
CBST  
fS  
2
1
MP1472  
0.01  
2C2RESR  
5V or 3.3V  
SW  
+
COUT  
L
If this is the case, then add the second  
compensation capacitor (C6) to set the pole fP3 at  
the location of the ESR zero. Determine the C6  
value by the equation:  
Figure 2—Add Optional External Bootstrap  
Diode to Enhance Efficiency  
The recommended external BST diode is IN4148,  
and the BST cap is 0.01µF.  
C2 RESR  
C6   
R3  
External Bootstrap Diode  
An external bootstrap diode may enhance the  
efficiency of the regulator, and it will be a must if  
the applicable condition is:  
VOUT=5V or 3.3V; and  
VOUT  
VIN  
duty cycle is high: D=  
>65%  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
10  
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
typical Application circuit  
Figure 3—MP1472 with 1.8V Output, 22µF/6.3V Ceramic Output Capacitor  
Figure 4—MP1472 with 5.0V Output, 22µF/6.3V Ceramic Output Capacitor  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
11  
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
2) Bypass ceramic capacitors are suggested  
PCB LAYOUT GUIDE  
PCB layout is very important to achieve stable  
operation. It is highly recommended to duplicate  
EVB layout for optimum performance.  
to be put close to the Vin Pin.  
3) Ensure all feedback connections are short  
and direct. Place the feedback resistors  
and compensation components as close to  
the chip as possible.  
If change is necessary, please follow these  
guidelines and take Figure 5 for reference.  
4) Route SW away from sensitive analog  
areas such as FB.  
1) Keep the path of switching current short and  
minimize the loop area formed by input cap,  
high-side MOSFET and low-side MOSFET.  
5) Connect IN, SW, and especially GND  
respectively to a large copper area to cool  
the chip to improve thermal performance  
and long-term reliability.  
MP1472 Typical Application Circuit  
Top Layer  
Bottom Layer  
Figure 5—MP1472 Typical Application Circuit and PCB Layout Guide  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
12  
MP1472 – 2A, 18V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER  
PACKAGE INFORMATION  
TSOT23-8  
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.  
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS  
products into any application. MPS will not assume any legal responsibility for any said applications.  
MP1472 Rev. 1.0  
9/2/2011  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2011 MPS. All Rights Reserved.  
13  

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