MIC28513 [MICROCHIP]

45V, 4A Synchronous Buck Regulator;
MIC28513
型号: MIC28513
厂家: MICROCHIP    MICROCHIP
描述:

45V, 4A Synchronous Buck Regulator

文件: 总34页 (文件大小:1514K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
MIC28513  
45V, 4A Synchronous Buck Regulator  
Features  
General Description  
• 4.6V to 45V Operating Input Voltage Supply  
• Up to 4A Output Current  
The MIC28513 is a synchronous step-down switching  
regulator with internal power switches capable of  
providing up to 4A output current from a wide input  
supply range from 4.6V to 45V. The output voltage is  
adjustable down to 0.8V with a guaranteed accuracy of  
• Integrated High-Side and Low-Side N-Channel  
MOSFETs  
• HyperLight Load (MIC28513-1) and Hyper Speed  
Control (MIC28513-2) Architecture  
±1%.  
A
constant switching frequency can be  
programmed from 200 kHz to 680 kHz. The  
MIC28513’s Hyper Speed Control® and HyperLight  
• Enable Input and Power Good (PGOOD) Output  
Load® architectures allow for high VIN (low VOUT  
)
• Programmable Current-Limit and Foldback  
“Hiccup” Mode Short-Circuit Protection  
operation and ultra-fast transient response while  
reducing the required output capacitance. The  
MIC28513-1’s HyperLight Load architecture also  
provides very good light load efficiency.  
• Built-In 5V Regulator for Single-Supply Operation  
• Adjustable 200 kHz to 680 kHz Switching  
Frequency  
The MIC28513 offers a full suite of features to ensure  
protection under fault conditions. These include  
undervoltage lockout to ensure proper operation under  
power sag conditions, internal soft-start to reduce  
inrush current, foldback current limit, “hiccup” mode  
short-circuit protection, and thermal shutdown.  
• Fixed 5 ms Soft-Start  
• Internal Compensation and Thermal Shutdown  
• Thermally-Enhanced 24-Pin 3 mm x 4 mm FQFN  
Package  
• –40°C to +125°C Junction Temperature Range  
Applications  
• Industrial Power Supplies  
• Distributed Supply Regulation  
• Base Station Power Supplies  
• Wall Transformer Regulation  
• High-Voltage Single-Board Systems  
Package Type  
MIC28513  
24-Pin 3 mm x 4 mm FQFN (FL)  
23  
22  
21  
24  
20  
1
2
3
4
5
DL  
PVDD  
19  
18  
PGND  
DH  
VDD  
ILIM  
PVIN  
LX  
17 VIN  
16  
EN  
6
7
8
BST  
PGOOD  
15  
14  
PVIN  
FB  
AGND  
13  
PVIN  
9
10  
11  
12  
2016 Microchip Technology Inc.  
DS20005522A-page 1  
MIC28513  
Typical Application Circuit  
MIC28513  
3x4 FQFN  
2.2μF  
VDD  
PVDD  
BST  
10Ω  
0.1μF  
6.8μH  
MIC28513  
2.2kΩ  
ILIM  
VOUT  
VIN  
EN  
5V (0A to 4A)  
5.5V to 45V  
SW  
LX  
PVIN  
VIN  
100kΩ  
10.0kΩ  
470pF  
100kΩ  
100kΩ  
0.1μF  
47μF x2  
FREQ  
FB  
1.91kΩ  
AGND  
PGND  
Functional Block Diagram  
VIN  
CIN  
DBST  
CVDD  
VIN  
VDD PVDD  
PVIN  
17  
19  
20  
4, 7, 8, 9, 25  
BST  
LINEAR  
REGULATOR  
6
UVLO  
RBST  
DH  
3
THERMAL  
SHUTDOWN  
M1  
CBST  
OFF  
ON  
L
12, SW  
21,  
16  
24  
VOUT  
R3  
R4  
27  
EN  
FIXED T  
LX  
5
ESTIMATIOONN  
ZCD  
CONTROL  
LOGIC  
FREQ  
SOFT-START  
COUT  
1
DL  
RLIM  
PGND  
10,  
PVDD  
M2  
3.3V  
RPGOOD  
POWER GOOD  
COMPARATOR  
11,  
22,  
23,  
26  
15  
CURRENT  
LIMIT  
DETECTION  
PGOOD  
RINJ  
X90%  
2
PGND  
ILIM  
VREF  
0.8V  
CINJ  
18  
R1  
13  
AGND  
14  
CFF  
FB  
R2  
DS20005522A-page 2  
2016 Microchip Technology Inc.  
MIC28513  
1.0  
ELECTRICAL CHARACTERISTICS  
Absolute Maximum Ratings †  
PVIN, VIN to PGND..................................................................................................................................... –0.3V to +50V  
V
V
DD, PVDD to PGND..................................................................................................................................... –0.3V to +6V  
BST to VSW, VLX ......................................................................................................................................... –0.3V to +6V  
VBST to PGND......................................................................................................................................0.3V to (VIN + 6V  
VSW, VLX to PGND...........................................................................................................................–0.3V to (VIN + 0.3V)  
VFREQ, VILIM, VEN to AGND.............................................................................................................–0.3V to (VIN + 0.3V)  
VLX, VFB, VPG, VFREQ, VILIM, VEN to AGND................................................................................... –0.3V to (VDD + 0.3V)  
PGND to AGND ........................................................................................................................................ –0.3V to +0.3V  
ESD Rating(1) (HBM) ..............................................................................................................................................1.5 kV  
ESD Rating(1) (MM) ..................................................................................................................................................150V  
Operating Ratings ‡  
Supply Voltage (PVIN, VIN)......................................................................................................................... +4.6V to +45V  
Enable Input (VEN)..............................................................................................................................................0V to VIN  
VSW, VFREQ, VILIM, VEN ......................................................................................................................................0V to VIN  
† Notice: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.  
This is a stress rating only and functional operation of the device at those or any other conditions above those indicated  
in the operational sections of this specification is not intended. Exposure to maximum rating conditions for extended  
periods may affect device reliability.  
‡ Notice: The device is not guaranteed to function outside its operating ratings.  
Note 1: Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5 kin series  
with 100 pF.  
2016 Microchip Technology Inc.  
DS20005522A-page 3  
MIC28513  
TABLE 1-1:  
ELECTRICAL CHARACTERISTICS  
Electrical Characteristics: VIN = 12V, TA = 25°C, unless noted. Bold values indicate –40°C TJ +125°C.  
(Note 1).  
Parameters  
Min.  
Typ.  
Max.  
Units  
Conditions  
Power Supply Input  
Input Voltage Range (PVIN,  
VIN)  
4.6  
45  
V
Quiescent Supply Current  
0.4  
0.7  
0.1  
0.75  
1.5  
10  
mA  
VFB = 1.5V (MIC28513-1)  
VFB = 1.5V (MIC28513-2)  
SW unconnected, VEN = 0V  
Shutdown Supply Current  
VDD Supply  
µA  
VDD Output Voltage  
4.8  
3.8  
5.2  
4.2  
400  
2
5.4  
4.6  
V
V
VIN = 7V to 45V, IVDD = 10 mA  
V
DD UVLO Threshold  
DD UVLO Hysteresis  
VDD rising  
V
mV  
%
Load Regulation at 40 mA  
Reference  
0.6  
4.0  
Feedback Reference Voltage  
0.792  
0.784  
0.8  
0.8  
5
0.808  
0.816  
500  
V
nA  
V
25°C (±1%)  
–40°C TJ +125°C (±2%)  
FB Bias Current  
Enable Control  
EN Logic Level High  
EN Logic Level Low  
EN Hysteresis  
VFB = 0.8V  
1.8  
0.6  
200  
5
mV  
µA  
EN Bias Current  
Oscillator  
40  
V
EN = 12V  
Switching Frequency  
450  
680  
340  
85  
800  
kHz  
%
V
FREQ = VIN  
VFREQ = 50% VIN  
Maximum Duty Cycle  
Minimum Duty Cycle  
Minimum Off-Time  
Internal MOSFET  
0
VFB > 0.8V  
110  
200  
270  
ns  
High-Side NMOS  
On-Resistance  
37  
20  
mꢀ  
Low-Side NMOS  
On-Resistance  
Short-Circuit Protection  
Current-Limit Threshold  
Short-Circuit Threshold  
–30  
–24  
50  
–14  
–7  
0
8
mV  
µA  
V
FB = 0.79V  
VFB = 0V  
FB = 0.79V  
VFB = 0V  
Current-Limit Source Current  
Short-Circuit Source Current  
70  
90  
43  
V
25  
36  
Note 1: Specification for packaged product only.  
DS20005522A-page 4  
2016 Microchip Technology Inc.  
MIC28513  
TABLE 1-1:  
ELECTRICAL CHARACTERISTICS (CONTINUED)  
Electrical Characteristics: VIN = 12V, TA = 25°C, unless noted. Bold values indicate –40°C TJ +125°C.  
(Note 1).  
Parameters  
Min.  
Typ.  
Max.  
Units  
Conditions  
Leakage  
SW, BST Leakage Current  
Power Good (PGOOD)  
PGOOD Threshold Voltage  
PGOOD Hysteresis  
50  
µA  
85  
90  
6
95  
%VOUT Sweep VFB from low to high  
Sweep VFB from high to low  
PGOOD Delay Time  
100  
70  
µs  
Sweep VFB from low to high  
FB < 90% x VNOM, IPGOOD = 1 mA  
PGOOD Low Voltage  
Thermal Protection  
200  
mV  
V
Overtemperature Shutdown  
160  
15  
°C  
°C  
TJ Rising  
Overtemperature Shutdown  
Hysteresis  
Soft-Start  
Soft-Start Time  
5
ms  
Note 1: Specification for packaged product only.  
2016 Microchip Technology Inc.  
DS20005522A-page 5  
MIC28513  
TEMPERATURE SPECIFICATIONS  
Parameters  
Temperature Ranges  
Sym.  
Min.  
Typ.  
Max.  
Units  
Conditions  
Junction Operating Temperature  
Storage Temperature Range  
Junction Temperature  
TJ  
TS  
TJ  
–40  
–65  
+125  
+150  
+150  
+300  
°C  
°C  
°C  
°C  
Note 1  
Lead Temperature  
Soldering, 10s  
Package Thermal Resistances  
Thermal Resistance 3 mm x 4 mm  
FQFN-24LD  
JA  
30  
°C/W  
Note 1: The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable  
junction temperature and the thermal resistance from junction to air (i.e., TA, TJ, JA). Exceeding the  
maximum allowable power dissipation will cause the device operating junction temperature to exceed the  
maximum +125°C rating. Sustained junction temperatures above +125°C can impact the device reliability.  
DS20005522A-page 6  
2016 Microchip Technology Inc.  
MIC28513  
2.0  
TYPICAL PERFORMANCE CURVES  
Note: The graphs and tables provided following this note are a statistical summary based on a limited number of  
samples and are provided for informational purposes only. The performance characteristics listed herein  
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified  
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.  
FIGURE 2-1:  
Switching Frequency vs.  
FIGURE 2-4:  
V
Voltage vs. Input  
DD  
Output Voltage (MIC28513-1).  
Voltage.  
FIGURE 2-2:  
Feedback Voltage vs.  
FIGURE 2-5:  
V
UVLO Threshold vs.  
DD  
Temperature (MIC28513-1).  
Temperature (MIC28513-1).  
FIGURE 2-3:  
Temperature (MIC28513-2).  
Feedback Voltage vs.  
FIGURE 2-6:  
vs. V ).  
Line Regulation Error (V  
OUT  
IN  
2016 Microchip Technology Inc.  
DS20005522A-page 7  
MIC28513  
.
FIGURE 2-7:  
Enable Threshold vs. Input  
FIGURE 2-10:  
Output Voltage vs. Output  
Voltage.  
Current (MIC28513-2).  
FIGURE 2-11:  
Output Current (MIC28513-2).  
Switching Frequency vs.  
FIGURE 2-8:  
Current vs. Input Voltage (MIC28513-1).  
V
Operating Supply  
IN  
FIGURE 2-12:  
Output Peak Current Limit  
FIGURE 2-9:  
V
Operating Supply  
IN  
vs. Temperature (MIC28513-1).  
Current vs. Input Voltage (MIC28513-2).  
DS20005522A-page 8  
2016 Microchip Technology Inc.  
MIC28513  
FIGURE 2-13:  
Output Peak Current Limit  
FIGURE 2-16:  
Efficiency (V = 36V) vs.  
IN  
vs. Temperature (MIC28513-2).  
Output Current (MIC28513-1).  
FIGURE 2-14:  
Efficiency (V = 12V) vs.  
FIGURE 2-17:  
IC Power Dissipation vs.  
IN  
Output Current (MIC28513-1).  
Output Current (V = 12V).  
IN  
FIGURE 2-15:  
Efficiency (V = 24V) vs.  
FIGURE 2-18:  
IC Power Dissipation vs.  
IN  
Output Current (MIC28513-1).  
Output Current (V = 24V).  
IN  
2016 Microchip Technology Inc.  
DS20005522A-page 9  
MIC28513  
FIGURE 2-19:  
IC Power Dissipation vs.  
FIGURE 2-22:  
36V Input Thermal Derating.  
Output Current (V = 36V).  
IN  
FIGURE 2-20:  
12V Input Thermal Derating.  
FIGURE 2-23:  
Efficiency (V = 12V) vs.  
IN  
Output Current (MIC28513-2).  
FIGURE 2-24:  
Output Current (MIC28513-2).  
Efficiency (V = 24V) vs.  
IN  
FIGURE 2-21:  
24V Input Thermal Derating.  
DS20005522A-page 10  
2016 Microchip Technology Inc.  
MIC28513  
VEN  
(10V/div)  
VIN = 12V  
VOUT = 5V  
VOUT  
(2V/div)  
I
OUT = 4A  
IIL  
(5A/div)  
Time (2ms/div)  
FIGURE 2-25:  
Efficiency (V = 36V) vs.  
FIGURE 2-28:  
Enable Turn-On.  
IN  
Output Current (MIC28513-2).  
VEN  
(10V/div)  
VIN  
(10V/div)  
VOUT  
VIN = 12V  
VOUT = 5V  
OUT = 4A  
(2V/div)  
I
VOUT  
(2V/div)  
VIN = 12V  
VOUT = 5V  
I
OUT = 4A  
V
(5V/diSvW)  
IIL  
(5A/div)  
IIL  
(5A/div)  
Time (400μs/div)  
Time (2ms/div)  
FIGURE 2-29:  
Enable Turn-Off.  
FIGURE 2-26:  
Turn-On.  
VIN  
(10V/div)  
VOUT  
VIN = 12V  
VOUT = 5V  
OUT = 0A  
VPRE-BIAS = 2V  
I
(2V/div)  
VIN = 12V  
VOUT = 5V  
V
I
OUT = 4A  
(5V/diSvW)  
VOUT  
(2V/div)  
V
(10V/diSvW)  
IIL  
(5A/div)  
Time (1ms/div)  
Time (200μs/div)  
FIGURE 2-30:  
MIC28513-1 V Start-Up  
IN  
FIGURE 2-27:  
Turn-Off.  
with Pre-Biased Output.  
2016 Microchip Technology Inc.  
DS20005522A-page 11  
MIC28513  
VIN = 12V  
VOUT = 5V  
I
OUT = NL  
VPRE-BIAS = 2V  
VOUT = 3.3V  
IOUT = 0.5A  
VEN = 5V  
VOUT  
(2V/div)  
VIN  
(2V/div)  
VOUT  
(2V/div)  
V
(10V/diSvW)  
Time (2ms/div)  
Time (20ms/div)  
FIGURE 2-31:  
MIC28513-2 V Start-Up  
FIGURE 2-34:  
V
UVLO Thresholds.  
IN  
IN  
with Pre-Biased Output.  
VIN = 12V  
VOUT = 5V  
VIN  
I
OUT = 4A  
(10V/div)  
VPRE-BIAS = 2V  
VOUT  
(2V/div)  
VIN = 12V  
VOUT = short  
VOUT  
(2V/div)  
V
(5V/diSvW)  
IL  
V
(10V/diSvW)  
(5A/div)  
Time (1ms/div)  
Time (1ms/div)  
FIGURE 2-35:  
Turn-On Into Short-Circuit.  
FIGURE 2-32:  
MIC28513-1 V Start-Up  
IN  
with Pre-Biased Output.  
VIN = 12V  
VOUT = 5V  
VIN = 12V  
VOUT = 5V  
VEN  
(2V/div)  
I
OUT = 4A  
I
OUT = short  
VPRE-BIAS = 2V  
VOUT  
(100mV/div)  
VOUT  
(2V/div)  
V
(10V/diSvW)  
IL  
V
(10V/diSvW)  
(5A/div)  
Time (4ms/div)  
Time (2ms/div)  
FIGURE 2-36:  
Enabled Into Short-Circuit.  
FIGURE 2-33:  
MIC28513-2 V Start-Up  
IN  
with Pre-Biased Output.  
DS20005522A-page 12  
2016 Microchip Technology Inc.  
MIC28513  
VIN = 12V  
VOUT = 5V  
VOUT  
(2V/div)  
VOUT  
(2V/div)  
IOUT  
(5A/div)  
V
V
(10V/diSvW)  
(5V/diSvW)  
Time (20μs/div)  
Time (4ms/div)  
FIGURE 2-37:  
Overcurrent Protection.  
FIGURE 2-40:  
Output Recovery from  
Thermal Shutdown.  
VIN = 12V  
VOUT = 5V  
IOUT = 0A  
VOUT  
(50mV/div)  
AC-Coupled  
VOUT  
(2V/div)  
IL  
(5A/div)  
V
V
(10V/diSvW)  
(10V/diSvW)  
Time (100μs/div)  
Time (200μs/div)  
FIGURE 2-38:  
Overcurrent Protection  
FIGURE 2-41:  
MIC28513-1 Switching  
Retry.  
Waveforms (I  
= 0A).  
OUT  
VIN = 12V  
VOUT = 5V  
VOUT  
(20mV/div)  
AC-Coupled  
I
OUT = 0A  
VOUT  
(2V/div)  
IL  
(5A/div)  
V
V
(10V/diSvW)  
(10V/diSvW)  
Time (4ms/div)  
Time (1μs/div)  
FIGURE 2-39:  
Thermal Shutdown.  
Output Recovery from  
FIGURE 2-42:  
Waveforms (I  
MIC28513-2 Switching  
= 0A).  
OUT  
2016 Microchip Technology Inc.  
DS20005522A-page 13  
MIC28513  
VIN = 12V  
VOUT = 5V  
VOUT  
(200mV/div)  
AC-Coupled  
VOUT  
(20mV/div)  
AC-Coupled  
I
OUT = 4A  
VIN = 12V  
VOUT = 5V  
I
OUT = 0A to 4A  
V
IOUT  
(2A/div)  
(10V/diSvW)  
Time (1μs/div)  
Time (1ms/div)  
FIGURE 2-43:  
MIC28513-1 Switching  
= 4A).  
FIGURE 2-46:  
Response (0A to 4A).  
MIC28513-2 Transient  
Waveforms (I  
OUT  
VIN = 12V  
VOUT = 5V  
VOUT  
(200mV/div)  
AC-Coupled  
I
OUT = 4A  
VOUT  
(20mV/div)  
AC-Coupled  
V
IL  
(10V/diSvW)  
(1A/div)  
Time (1μs/div)  
Time (1ms/div)  
FIGURE 2-44:  
MIC28513-2 Switching  
= 4A).  
FIGURE 2-47:  
Response (0A to 1.3A).  
MIC28513-1 Transient  
Waveforms (I  
OUT  
VOUT  
(200mV/div)  
AC-Coupled  
VOUT  
(200mV/div)  
AC-Coupled  
VIN = 12V  
VOUT = 5V  
I
OUT = 0A to 1.3A  
IL  
IOUT  
(1A/div)  
(2A/div)  
Time (1ms/div)  
Time (1ms/div)  
FIGURE 2-45:  
MIC28513-1 Transient  
FIGURE 2-48:  
MIC28513-2 Transient  
Response (0A to 4A).  
Response (0A to 1.3A).  
DS20005522A-page 14  
2016 Microchip Technology Inc.  
MIC28513  
VOUT  
(100mV/div)  
AC-Coupled  
VOUT  
(100mV/div)  
AC-Coupled  
VIN = 12V  
VOUT = 5V  
I
OUT = 2.6 to 4A  
IL  
IOUT  
(2A/div)  
(1A/div)  
Time (1ms/div)  
Time (1ms/div)  
FIGURE 2-49:  
MIC28513-1 Transient  
FIGURE 2-52:  
MIC28513-2 Transient  
Response (1.3A to 2.6A).  
Response (2.6A to 4A).  
VOUT  
(100mV/div)  
AC-Coupled  
VOUT  
(50mV/div)  
AC-Coupled  
VIN = 12V  
VOUT = 5V  
VIN = 12V to 60V  
VOUT = 5V  
I
OUT = 1.3A to 2.6A  
I
OUT = 3A  
VIN  
(10V/div)  
IOUT  
(1A/div)  
V
(20V/diSvW)  
Time (1ms/div)  
Time (4ms/div)  
FIGURE 2-50:  
MIC28513-2 Transient  
FIGURE 2-53:  
Input Voltage Transient  
Response (1.3A to 2.6A).  
Response.  
VOUT  
(100mV/div)  
AC-Coupled  
VOUT  
(50mV/div)  
AC-Coupled  
VIN = 12V to 60V  
VOUT = 5V  
I
OUT = 3A  
VIN  
(10V/div)  
IL  
V
(2A/div)  
(20V/diSvW)  
Time (1ms/div)  
Time (4ms/div)  
FIGURE 2-51:  
MIC28513-1 Transient  
FIGURE 2-54:  
Input Voltage Transient  
Response (2.6A to 4A).  
Response.  
2016 Microchip Technology Inc.  
DS20005522A-page 15  
MIC28513  
3.0  
PIN DESCRIPTIONS  
The descriptions of the pins are listed in Table 3-1.  
TABLE 3-1:  
Pin Number  
PIN FUNCTION TABLE  
Symbol  
Description  
1
2
3
DL  
PGND  
DH  
Low-Side Gate Drive. Internal low-side power MOSFET gate connection. This pin must  
be left unconnected or floating.  
PGND is the return path for the low-side driver circuit. Connect to the source of low-side  
MOSFET (PGND, pins 10, 11 22, 23, and 26) through a low-impedance path.  
High-Side Gate Drive. Internal high-side power MOSFET gate connection. This pin  
must be left unconnected or floating.  
4, 7, 8, 9, 25  
(25 is ePad)  
PVIN  
Power Input Voltage. The PVIN pins supply power to the internal power switch. Connect  
all PVIN pins together and bypass locally with ceramic capacitors. The positive terminal  
of the input capacitor should be placed as close as possible to the PVIN pins, the  
negative terminal of the input capacitor should be placed as close as possible to the  
PGND pins 10,11, 22, 23, and 26.  
5
6
LX  
The LX pin is the return path for the high-side driver circuit. Connect the negative  
terminal of the bootstrap capacitor directly to this pin. Also connect this pin to the SW  
pins 12, 21, and 27, with a low-impedance path. The controller monitors voltages on this  
and PGND for zero current detection.  
BST  
Bootstrap Pin. This pin provides bootstrap supply for the high-side gate driver circuit.  
Connect a 0.1 µF capacitor and an optional resistor in series from the LX (pin 5) to the  
BST pin.  
10, 11, 22, 23,  
26  
(26 is ePad)  
PGND  
Power Ground. These pins are connected to the source of the low-side MOSFET. They  
are the return path for the step-down regulator power stage and should be tied together.  
The negative terminal of the input decoupling capacitor should be placed as close as  
possible to these pins.  
12, 21, 27  
(27 is ePad)  
SW  
AGND  
FB  
Switch Node. The SW pins are the internal power switch outputs. These pins should be  
tied together and connected to the output inductor.  
13  
Analog Ground. The analog ground for VDD and the control circuitry. The analog ground  
return path should be separate from the power ground (PGND) return path.  
14  
Feedback Input. The FB pin sets the regulated output voltage relative to the internal  
reference. This pin is connected to a resistor divider from the regulated output such that  
the FB pin is at 0.8V when the output is at the desired voltage.  
15  
16  
17  
PGOOD The power good output is an open drain output requiring an external pull-up resistor to  
external bias. This pin is a high impedance open circuit when the voltage at FB pin is  
higher than 90% of the feedback reference voltage (typically 0.8V).  
EN  
Enable Input. The EN pin enables the regulator. When the pin is pulled below the  
threshold, the regulator will shut down to an ultra-low current state. A precise threshold  
voltage allows the pin to operate as an accurate UVLO. Do not tie EN to VDD  
VIN  
Supply voltage for the internal LDO. The VIN operating voltage range is from 4.6V to  
45V. A ceramic capacitor from VIN to AGND is required for decoupling. The decoupling  
capacitor should be placed as close as possible to the supply pin.  
18  
19  
ILIM  
Current Limit Setting. Connect a resistor from this pin to the SW pin node to allow for  
accurate current limit sensing programming of the internal low-side power MOSFET.  
VDD  
Internal +5V Linear Regulator: VDD is the internal supply bus for the IC. Connect to an  
external 1 µF bypass capacitor. When VIN is <5.5V, this regulator operates in drop-out  
mode. Connect VDD to VIN.  
20  
24  
PVDD  
A 5V supply input for the low-side N-channel MOSFET driver circuit, which can be tied  
to VDD externally. A 1 μF ceramic capacitor from PVDD to PGND is recommended for  
decoupling.  
FREQ  
Switching Frequency Adjust pin. Connect this pin to VIN to operate at 680 kHz. Place a  
resistor divider network from VIN to the FREQ pin to program the switching frequency.  
DS20005522A-page 16  
2016 Microchip Technology Inc.  
MIC28513  
EQUATION 4-2:  
DMAX = 1 tOFFMINfSW  
4.0  
FUNCTIONAL DESCRIPTION  
The MIC28513 is an adaptive on-time synchronous  
buck regulator with integrated high-side and low-side  
MOSFETs suitable for high-input voltage to low-output  
voltage conversion applications. It is designed to  
operate over a wide input voltage range, from 4.6V to  
45V, which is suitable for automotive and industrial  
applications. The output is adjustable with an external  
resistive divider. An adaptive on-time control scheme is  
employed to produce a constant switching frequency in  
continuous-conduction mode and reduced switching  
frequency in discontinuous-operation mode, improving  
light-load efficiency. Overcurrent protection is  
implemented by sensing the low-side MOSFET’s  
RDS(ON). The device features internal soft-start, enable,  
UVLO, and thermal shutdown.  
It is not recommended to use MIC28513 with an  
OFF-time close to tOFF(MIN) during steady-state  
operation.  
The adaptive ON-time control scheme results in a  
constant switching frequency in the MIC28513. The  
actual ON-time and resulting switching frequency will  
vary with the different rising and falling times of the  
external MOSFETs. Also, the minimum tON results in a  
lower switching frequency in high VIN to VOUT  
applications. During load transients, the switching  
frequency is changed due to the varying OFF-time.  
Figure 4-1 shows the allowable range of the output  
voltage versus the input voltage. The minimum output  
voltage is 0.8V which is limited by the reference  
voltage. The maximum output voltage is 24V which is  
limited by the internal circuitry.  
4.1  
Theory of Operation  
As illustrated in the Functional Block Diagram, the  
output voltage is sensed by the feedback (FB) pin via  
voltage dividers R1 and R2, and compared to a 0.8V  
reference voltage VREF at the error comparator through  
a low-gain transconductance (gM) amplifier. If the  
feedback voltage decreases and the amplifier output is  
below 0.8V, then the error comparator will trigger the  
control logic and generate an ON-time period. The  
ON-time period length is predetermined by the fixed  
tON estimator circuitry:  
30  
25  
fSW = 600kHz  
20  
fSW = 400kHz  
fSW = 200kHz  
15  
10  
5
ALLOWABLE RANGE  
0.8V (MINIMUM)  
EQUATION 4-1:  
VOUT  
tONESTIMATED= -----------------------  
VIN fSW  
0
5
45  
15  
35  
55  
25  
INPUT VOLTAGE (V)  
Where:  
FIGURE 4-1:  
Range vs. Input Voltage.  
Allowable Output Voltage  
VOUT  
VIN  
Output Voltage  
Power Stage Input Voltage  
Switching Frequency  
To illustrate the control loop operation, both the  
steady-state and load transient scenarios will be  
analyzed.  
fSW  
At the end of the ON-time period, the internal high-side  
driver turns off the high-side MOSFET and the low-side  
driver turns on the low-side MOSFET. The OFF-time  
period length depends upon the feedback voltage in  
most cases. When the feedback voltage decreases  
and the output of the gM amplifier is below 0.8V, then  
the ON-time period is triggered and the OFF-time  
period ends. If the OFF-time period determined by the  
feedback voltage is less than the minimum OFF-time  
Figure 4-2 shows the MIC28513 control loop timing  
during steady-state operation. During steady-state, the  
gM amplifier senses the feedback voltage ripple, which  
is proportional to the output voltage ripple and the  
inductor current ripple, to trigger the ON-time period.  
The ON-time is predetermined by the tON estimator.  
The termination of the OFF-time is controlled by the  
feedback voltage. At the valley of the feedback voltage  
ripple, which occurs when VFB falls below VREF, the  
OFF period ends and the next ON-time period is  
triggered through the control logic circuitry.  
tOFF(MIN)  
, which is about 200 ns (typical), the  
MIC28513 control logic will apply the tOFF(MIN) instead.  
The tOFF(MIN) is required to maintain enough energy in  
the boost capacitor (CBST) to drive the high-side  
MOSFET.  
The maximum duty cycle is obtained from  
Equation 4-2.  
2016 Microchip Technology Inc.  
DS20005522A-page 17  
MIC28513  
current ripple if the ESR of the output capacitor is large  
enough. The MIC28513 control loop has the advantage  
of eliminating the need for slope compensation.  
IL  
IOUT  
¨IL(PP)  
In order to meet the stability requirements, the  
MIC28513 feedback voltage ripple should be in phase  
with the inductor current ripple and large enough to be  
sensed by the gM amplifier and the error comparator.  
The recommended feedback voltage ripple is 20 mV ~  
100 mV.  
VOUT  
¨VOUT(PP) = ESRCOUT× ¨IL(PP)  
VFB  
R2  
¨VFB(PP) = ¨VOUT(PP)  
×
VREF  
R1 + R2  
If a low-ESR output capacitor is selected, then the  
feedback voltage ripple may be too small to be sensed  
by the gM amplifier and the error comparator. Also, if  
the ESR of the output capacitor is very low, the output  
voltage ripple and the feedback voltage ripple are not  
necessarily in phase with the inductor current ripple. In  
these cases, ripple injection is required to ensure  
proper operation. Please refer to the Ripple Injection  
subsection for more details about the ripple injection  
technique.  
HSD  
TRIGGER ON-TIME IF VFB IS BELOW VREF  
ESTIMATED ON-TIME  
FIGURE 4-2:  
Timing.  
MIC28513 Control Loop  
Figure 4-3 shows the operation of the MIC28513 during  
a load transient. The output voltage drops due to the  
sudden load increase, which causes the VFB to be less  
than VREF. This will cause the error comparator to  
trigger an ON-time period. At the end of the ON-time  
period, a minimum OFF-time tOFF(MIN) is generated to  
charge CBST because the feedback voltage is still  
below VREF. Then, the next ON-time period is triggered  
due to the low feedback voltage. Therefore, the  
switching frequency changes during the load transient,  
but returns to the nominal fixed frequency once the  
output has stabilized at the new load current level. With  
the varying duty cycle and switching frequency, the  
output recovery time is fast and the output voltage  
deviation is small in MIC28513 converter.  
4.2  
Discontinuous Mode (MIC28513-1  
Only)  
In continuous mode, the inductor current is always  
greater than zero; however, at light loads the  
MIC28513-1 is able to force the inductor current to  
operate in discontinuous mode. Discontinuous mode  
occurs when the inductor current falls to zero, as  
indicated by trace (IL) shown in Figure 4-4. During this  
period, the efficiency is optimized by shutting down all  
the non-essential circuits and minimizing the supply  
current. The MIC28513-1 wakes up and turns on the  
high-side MOSFET when the feedback voltage VFB  
drops below 0.8V.  
FULL LOAD  
IOUT  
The MIC28513-1 has a zero crossing comparator that  
monitors the inductor current by sensing the voltage  
drop across the low-side MOSFET during its ON-time.  
If the VFB > 0.8V and the inductor current goes slightly  
negative, then the MIC28513-1 automatically powers  
down most of the IC circuitry and goes into a low-power  
mode.  
NO LOAD  
VOUT  
Once the MIC28513-1 goes into discontinuous mode,  
both DH and DL are low, which turns off the high-side  
and low-side MOSFETs. The load current is supplied  
by the output capacitors and VOUT drops. If the drop of  
VOUT causes VFB to go below VREF, then all the circuits  
will wake up into normal continuous mode. First, the  
bias currents of most circuits reduced during the  
discontinuous mode are restored, and then a tON pulse  
is triggered before the drivers are turned on to avoid  
any possible glitches. Finally, the high-side driver is  
turned on. Figure 4-4 shows the control loop timing in  
discontinuous mode.  
VFB  
VREF  
HSD  
TOFF(MIN)  
FIGURE 4-3:  
Response.  
MIC28513 Load Transient  
Unlike true current-mode control, the MIC28513 uses  
the output voltage ripple to trigger an ON-time period.  
The output voltage ripple is proportional to the inductor  
DS20005522A-page 18  
2016 Microchip Technology Inc.  
MIC28513  
4.5  
Current Limit  
IL CROSSES 0 AND VFB > 0.8.  
DISCONTINUOUS MODE STARTS  
The MIC28513 uses the RDS(ON) of the internal  
low-side power MOSFET to sense overcurrent  
conditions. In each switching cycle, the inductor current  
is sensed by monitoring the low-side MOSFET during  
its ON period. The sensed voltage, V(ILIM), is compared  
with the power ground (PGND) after a blanking time of  
150 ns.  
V
< 0.8. WAKEUP FROM  
IL  
DFISB CONTINUOUS MODE.  
0
VFB  
The voltage drop of the resistor RILIM is compared with  
the low-side MOSFET voltage drop to set the  
overcurrent trip level. The small capacitor connected  
from the ILIM pin to PGND can be added to filter the  
switching node ringing, allowing a better short limit  
measurement. The time constant created by RILIM and  
the filter capacitor should be much less than the  
minimum off time.  
VREF  
ZC  
VHSD  
The overcurrent limit can be programmed by using  
Equation 4-3:  
ESTIMATED ON-TIME  
EQUATION 4-3:  
VLSD  
ICLIM – 0.5  ILPP  RDSON+ VCL  
RILIM = ----------------------------------------------------------------------------------------------------  
ICL  
Where:  
ICLIM  
Desired Current Limit  
FIGURE 4-4:  
MIC28513-1 Control Loop  
Timing (Discontinuous Mode).  
IL(PP)  
Inductor Current Peak-to-Peak  
Use Equation 4-4 to calculate the  
inductor ripple current  
During discontinuous mode, the bias current of most  
circuits are reduced. As a result, the total power supply  
current during discontinuous mode is only about  
450 μA, allowing the MIC28513-1 to achieve high  
efficiency in light load applications.  
RDS(ON)  
VCL  
On-Resistance of Low-Side MOSFET  
Current-limit threshold.  
14 mV (typical absolute value).  
ICL  
Current-limit source current.  
80 µA (typical).  
4.3  
VDD Regulator  
The MIC28513 provides a 5V regulated VDD to bias  
internal circuitry for VIN ranging from 5.5V to 45V.  
When VIN is less than 5.5V, VDD should be tied to VIN  
pins to bypass the internal linear regulator.  
The peak-to-peak inductor current ripple is calculated  
with Equation 4-4.  
EQUATION 4-4:  
4.4  
Soft-Start  
VOUT  VINMAXVOUT  
ILPP= -------------------------------------------------------------------  
INMAXfSW L  
V
Soft-start reduces the power supply inrush current at  
startup by controlling the output voltage rise time while  
the output capacitor charges.  
The MOSFET RDS(ON) varies 30% to 40% with  
temperature; therefore, it is recommended to use the  
RDS(ON) at maximum junction temperature with a 20%  
margin to calculate RILIM in Equation 4-3.  
The MIC28513 implements an internal digital soft-start  
by ramping up the 0.8V reference voltage (VREF) from  
0 to 100% in about 5 ms with 9.7 mV steps. This  
controls the output voltage rate of rise at turn on,  
minimizing inrush current and eliminating output  
voltage overshoot. Once the soft-start cycle ends, the  
related circuitry is disabled to reduce current  
consumption.  
In case of hard short, the current-limit threshold is  
folded down to allow an indefinite hard short on the  
output without any destructive effect. It is mandatory to  
make sure that the inductor current used to charge the  
output capacitor during soft-start is under the folded  
short limit; otherwise the supply will go into hiccup  
mode and may not be finishing the soft-start  
successfully.  
2016 Microchip Technology Inc.  
DS20005522A-page 19  
MIC28513  
4.6  
Power Good (PGOOD)  
The power good (PGOOD) pin is an open-drain output  
that indicates logic-high when the output is nominally  
90% of its steady-state voltage.  
4.7  
MOSFET Gate Drive  
The Functional Block Diagram shows a bootstrap  
circuit, consisting of DBST, CBST, and RBST. This circuit  
supplies energy to the high-side drive circuit. Capacitor  
CBST is charged, while the low-side MOSFET is on,  
and the voltage on the SW pin is approximately 0V.  
When the high-side MOSFET driver is turned on,  
energy from CBST is used to turn the MOSFET on. As  
the high-side MOSFET turns on, the voltage on the SW  
pin increases to approximately VIN. Diode DBST is  
reverse-biased and CBST floats high while continuing to  
bias the high-side gate driver. The bias current of the  
high-side driver is less than 10 mA, so a 0.1 μF to 1 μF  
capacitor is sufficient to hold the gate voltage with  
minimal droop for the power stroke (high-side  
switching) cycle, i.e. BST = 10 mA x 1.25 μs/0.1 μF =  
125 mV. When the low-side MOSFET is turned back  
on, CBST is then recharged through the boost diode. A  
30resistor RBST, which is in series with the BST pin,  
is required to slow down the turn-on time of the  
high-side N-channel MOSFET.  
DS20005522A-page 20  
2016 Microchip Technology Inc.  
MIC28513  
5.2  
Setting the Switching Frequency  
5.0  
5.1  
APPLICATION INFORMATION  
The MIC28513 switching frequency can be adjusted by  
changing the resistor divider network from VIN.  
Output Voltage Setting  
Components  
The MIC28513 requires two resistors to set the output  
voltage as shown in Figure 5-1.  
R1  
FB  
gM AMP  
R2  
VREF  
FIGURE 5-2:  
Switching Frequency  
Adjustment.  
FIGURE 5-1:  
Configuration.  
Voltage Divider  
Equation 5-3 gives the estimated switching frequency.  
The output voltage is determined by Equation 5-1.  
EQUATION 5-3:  
EQUATION 5-1:  
R17  
R17 + R19  
-------------------------  
fSW = f0   
R1  
R2  
VOUT = VFB 1 + ------  
Where:  
f0  
Where:  
VFB  
Switching frequency when R17 is open;  
typically 600 kHz.  
0.8V  
Figure 5-3 shows the switching frequency versus the  
resistor R17 when R19 = 100 k.  
A typical value of R1 used on the standard evaluation  
board is 10 k. If R1 is too large, it may allow noise to  
be introduced into the voltage feedback loop. If R1 is  
too small in value, it will decrease the efficiency of the  
power supply, especially at light loads. Once R1 is  
selected, R2 can be calculated using Equation 5-2:  
EQUATION 5-2:  
VFB R1  
R2 = -----------------------------  
VOUT VFB  
FIGURE 5-3:  
Switching Frequency vs.  
R17.  
5.3  
Inductor Selection  
Values for inductance, peak, and RMS currents are  
required to select the output inductor. The input and  
output voltages and the inductance value determine  
the peak-to-peak inductor ripple current. Generally,  
higher inductance values are used with higher input  
voltages. Larger peak-to-peak ripple currents will  
increase the power dissipation in the inductor and  
2016 Microchip Technology Inc.  
DS20005522A-page 21  
MIC28513  
MOSFETs. Larger output ripple currents will also  
require more output capacitance to smooth out the  
larger ripple current. Smaller peak-to-peak ripple  
EQUATION 5-7:  
PLCU= ILRMS2 DCR  
currents require  
a larger inductance value and  
therefore a larger and more expensive inductor. A good  
compromise between size, loss and cost is to set the  
inductor ripple current to be equal to 20% of the  
maximum output current. The inductance value is  
calculated by:  
The resistance of the copper wire, DCR, increases with  
the temperature. The value of the winding resistance  
used should be at the operating temperature.  
EQUATION 5-8:  
EQUATION 5-4:  
DCRHT= DCR20C 1 + 0.0042  TH T20C  
VOUT  VINMAXVOUT  
L = -------------------------------------------------------------------  
V
INMAX ILPPfSW  
Where:  
Where:  
fSW  
IL(PP)  
TH  
Temperature of wire under full load  
Ambient temperature  
T20C  
Switching Frequency  
DCR(20C)  
Room temperature winding resistance  
(usually specified by the manufacturer)  
The peak-to-peak inductor current  
ripple; typically 20% of the maximum  
output current  
5.4  
Output Capacitor Selection  
In continuous conduction mode, the peak inductor  
current is equal to the average output current plus one  
half of the peak-to-peak inductor current ripple.  
The type of the output capacitor is usually determined  
by its equivalent series resistance (ESR). Voltage and  
RMS current capability are also important factors in  
selecting an output capacitor. Recommended capacitor  
types are ceramic, tantalum, low-ESR aluminum  
electrolytic, OS-CON and POSCAP. For high ESR  
electrolytic capacitors, ESR is the main cause of the  
output ripple. The output capacitor ESR also affects the  
control loop from a stability point of view. For a low ESR  
ceramic output capacitor, ripple is dominated by the  
reactive impedance. The maximum value of ESR is  
calculated by Equation 5-9.  
EQUATION 5-5:  
ILPK= IOUT + 0.5  ILPP  
The RMS inductor current is used to calculate the I2R  
losses in the inductor.  
EQUATION 5-6:  
2
ILPP  
2
EQUATION 5-9:  
ILRMS  
=
IOUTMAX+ --------------------  
I2  
VOUTPP  
---------------------------  
ESRC  
OUT  
ILPP  
Maximizing efficiency requires the proper selection of  
core material and minimizing the winding resistance.  
The high frequency operation of the MIC28513  
requires the use of ferrite materials for all but the most  
cost sensitive applications. Lower cost iron powder  
cores may be used but the increase in core loss will  
reduce the efficiency of the power supply. This is  
especially noticeable at low output power. The winding  
resistance decreases efficiency at the higher output  
current levels.  
Where:  
VOUT(PP) Peak-to-Peak Output Voltage Ripple  
IL(PP) Peak-to-Peak Inductor Current Ripple  
The total output ripple is a combination of the ESR and  
output capacitance. The total ripple is calculated by  
Equation 5-10.  
EQUATION 5-10:  
The winding resistance must be minimized although  
this usually comes at the expense of a larger inductor.  
The power dissipated in the inductor is equal to the sum  
of the core and copper losses. At higher output loads,  
the core losses are usually insignificant and can be  
ignored. At lower output currents, the core losses can  
be a significant contributor. Core loss information is  
usually available from the magnetics vendor. Copper  
loss in the inductor is calculated by Equation 5-7:  
VOUTPP  
=
2  ILPP  
+ ILPPESRCOUT2  
-------------------------------------  
COUT fSW 8  
Where:  
D
Duty Cycle  
COUT  
fSW  
Output Capacitance Value  
Switching Frequency  
DS20005522A-page 22  
2016 Microchip Technology Inc.  
MIC28513  
As described in the Theory of Operation subsection of  
the Functional Description, the MIC28513 requires at  
least 20 mV peak-to-peak ripple at the FB pin for the gM  
amplifier and the error comparator to operate properly.  
Also, the ripple on FB pin should be in phase with the  
inductor current. Therefore, the output voltage ripple  
caused by the output capacitors value should be much  
smaller than the ripple caused by the output capacitor  
ESR. If low-ESR capacitors, such as ceramic  
capacitors, are selected as the output capacitors, a  
ripple injection method should be applied to provide the  
enough feedback voltage ripple. Refer to the Ripple  
Injection subsection for details.  
EQUATION 5-14:  
CINRMSIOUTMAXD  1 – D  
I
The power dissipated in the input capacitor is:  
EQUATION 5-15:  
PDISSCIN= ICINRMS2 ESRCIN  
5.6  
Ripple Injection  
The voltage rating of the capacitor should be twice the  
output voltage for a tantalum and 20% greater for  
aluminum electrolytic or OS-CON. The output capacitor  
RMS current is calculated in Equation 5-11.  
The VFB ripple required for proper operation of the  
MIC28513’s gM amplifier and error comparator is  
20 mV to 100 mV. However, the output voltage ripple is  
generally designed as 1% to 2% of the output voltage.  
If the feedback voltage ripple is so small that the gM  
amplifier and error comparator can’t sense it, then the  
MIC28513 will lose control and the output voltage is not  
regulated. In order to have some amount of VFB ripple,  
a ripple injection method is applied for low output  
voltage ripple applications.  
EQUATION 5-11:  
ILPP  
IC  
= ------------------  
12  
OUTRMS  
The power dissipated in the output capacitor is:  
EQUATION 5-12:  
The applications are divided into three situations  
according to the amount of the feedback voltage ripple:  
• Enough ripple at the feedback voltage due to the  
large ESR of the output capacitors (Figure 5-4).  
The converter is stable without any ripple  
injection.  
PDISSCOUT= ICOUTRMS2 ESRCOUT  
5.5  
Input Capacitor Selection  
L
SW  
The input capacitor for the power stage input VIN  
should be selected for ripple current rating and voltage  
rating. Tantalum input capacitors may fail when  
subjected to high inrush currents, caused by turning the  
input supply on. A tantalum input capacitor’s voltage  
rating should be at least two times the maximum input  
voltage to maximize reliability. Aluminum electrolytic,  
OS-CON, and multilayer polymer film capacitors can  
handle the higher inrush currents without voltage  
de-rating. The input voltage ripple will primarily depend  
on the input capacitor’s ESR. The peak input current is  
equal to the peak inductor current, so:  
COUT  
R1  
MIC28513  
FB  
R2  
ESR  
FIGURE 5-4:  
Enough Ripple at FB.  
The feedback voltage ripple is:  
EQUATION 5-16:  
R2  
R1 + R2  
-------------------  
VFBPP  
Where:  
IL(PP)  
=
ESR  
 ILPP  
COUT  
EQUATION 5-13:  
VIN = ILPKESRCIN  
Peak-to-Peak Value of the Inductor  
Current Ripple  
The input capacitor must be rated for the input current  
ripple. The RMS value of input capacitor current is  
determined at the maximum output current. Assuming  
the peak-to-peak inductor current ripple is low:  
• Inadequate ripple at the feedback voltage due to  
the small ESR of the output capacitors.  
The output voltage ripple is fed into the FB pin  
through a feed-forward capacitor, CFF in this  
situation, as shown in Figure 5-5. The typical CFF  
value is selected by using Equation 5-17.  
2016 Microchip Technology Inc.  
DS20005522A-page 23  
MIC28513  
In Equation 5-19 and Equation 5-20, it is assumed that  
the time constant associated with CFF must be much  
greater than the switching period:  
EQUATION 5-17:  
10  
fSW  
-------  
R1 CFF  
EQUATION 5-21:  
With the feed-forward capacitor, the feedback  
voltage ripple is very close to the output voltage  
ripple.  
1
T
---------------- = -- « 1  
fSW    
If the voltage divider resistors R1 and R2 are in the kꢀ  
range, a CFF of 1 nF to 100 nF can easily satisfy the  
large time constant requirements. Also, a 100 nF  
injection capacitor CINJ is used in order to be  
EQUATION 5-18:  
VFBPPESR  ILPP  
considered as short for  
frequencies.  
a wide range of the  
L
SW  
The process of sizing the ripple injection resistor and  
capacitors is as follows.  
COUT  
MIC28513  
R1  
R2  
FB  
CFF  
• Select CFF to feed all output ripples into the  
feedback pin and make sure the large time  
constant assumption is satisfied. Typical choice of  
CFF is 1 nF to 100 nF if R1 and R2 are in the kꢀ  
range.  
ESR  
FIGURE 5-5:  
Inadequate Ripple at FB.  
• Select RINJ according to the expected feedback  
voltage ripple using Equation 5-22:  
• Virtually no ripple at the FB pin voltage due to the  
very low ESR of the output capacitors.  
In this situation, the output voltage ripple is less than  
20 mV. Therefore, additional ripple is injected into  
the FB pin from the switching node SW via a resistor  
RINJ and a capacitor CINJ, as shown in Figure 5-6.  
EQUATION 5-22:  
VFBPP  
fSW    
D  1 – D  
----------------------- ----------------------------  
Kdiv  
=
VIN  
L
The value of RINJ is calculated using Equation 5-23.  
SW  
CINJ  
COUT  
ESR  
MIC28513  
R1  
R2  
RINJ  
CFF  
EQUATION 5-23:  
FB  
1
Kdiv  
RINJ = R1//R2  ---------- – 1  
• Select CINJ as 100 nF, which could be considered  
as short for a wide range of the frequencies.  
FIGURE 5-6:  
Invisible Ripple at FB.  
The injected ripple is calculated via:  
EQUATION 5-19:  
VFBPP= VIN Kdiv D  1 – D   
Where:  
1
----------------  
fSW    
VIN  
D
Power stage input voltage  
Duty cycle  
fSW  
τ
Switching frequency  
(R1//R2//RINJ) x CFF  
EQUATION 5-20:  
R1//R2  
Kdiv = ----------------------------------  
RINJ + R1//R2  
DS20005522A-page 24  
2016 Microchip Technology Inc.  
MIC28513  
operating voltage must be derated by 50%.  
6.0  
PCB LAYOUT GUIDELINES  
• In “Hot-Plug” applications, a Tantalum or  
Electrolytic bypass capacitor must be used to limit  
the overvoltage spike seen on the input supply  
with power is suddenly applied.  
PCB Layout is critical to achieve reliable, stable and  
efficient performance. A ground plane is required to  
control EMI and minimize the inductance in power,  
signal and return paths.  
Figure 6-1 is optimized from a small form-factor point of  
view and shows the top and bottom layers of a  
four-layer PCB. It is recommended to use Mid-Layer 1  
as a continuous ground plane.  
6.3  
SW Node  
• Do not route any digital lines underneath or close  
to the SW node.  
• Keep the switch node (SW) away from the  
feedback (FB) pin.  
6.4  
Output Capacitor  
• Use a copper island to connect the output  
capacitor ground terminal to the input capacitor  
ground terminal.  
• Phase margin will change as the output capacitor  
value and ESR changes. Contact the factory if the  
output capacitor is different from what is shown in  
the BOM.  
• The feedback trace should be separate from the  
power trace and connected as close as possible  
to the output capacitor. Sensing a long  
high-current load trace can degrade the DC load  
regulation.  
FIGURE 6-1:  
Four-Layer Board.  
Top and Bottom Layers of a  
The following guidelines should be followed to ensure  
proper operation of the MIC28513 converter.  
6.5  
Thermal Measurements  
Measuring the IC’s case temperature is recommended  
to ensure it is within its operating limits. Although this  
might seem like a very elementary task, it is easy to get  
erroneous results. The most common mistake is to use  
the standard thermal couple that comes with a thermal  
meter. This thermal couple wire gauge is large, typically  
22 gauge, and behaves like a heatsink, resulting in a  
lower case measurement.  
6.1  
IC  
• The analog ground pin (AGND) must be  
connected directly to the ground planes. Do not  
route the AGND pin to the PGND pin on the top  
layer.  
• Place the IC close to the point-of-load (POL).  
• Use copper planes to route the input and output  
power lines.  
Two methods of temperature measurement are using a  
smaller thermal couple wire or an infrared  
thermometer. If a thermal couple wire is used, it must  
be constructed of 36 gauge wire or higher then (smaller  
wire size) to minimize the wire heat-sinking effect. In  
addition, the thermal couple tip must be covered in  
either thermal grease or thermal glue to make sure that  
the thermal couple junction is making good contact with  
the case of the IC. Omega brand thermal couple  
(5SC-TT-K-36-36) is adequate for most applications.  
• Analog and power grounds should be kept  
separate and connected at only one location.  
6.2  
Input Capacitor  
• Place the input capacitors on the same side of the  
board and as close to the PVIN and PGND pins as  
possible.  
• Place several vias to the ground plane close to  
the input capacitor ground terminal.  
Wherever possible, an infrared thermometer is  
recommended. The measurement spot size of most  
infrared thermometers is too large for an accurate  
reading on a small form factor ICs. However, a IR  
thermometer from Optris has a 1 mm spot size, which  
makes it a good choice for measuring the hottest point  
on the case. An optional stand makes it easy to hold the  
beam on the IC for long periods of time.  
• Use either X7R or X5R dielectric input capacitors.  
Do not use Y5V or Z5U type capacitors.  
• Do not replace the ceramic input capacitor with  
any other type of capacitor. Any type of capacitor  
can be placed in parallel with the input capacitor.  
• If a Tantalum input capacitor is placed in parallel  
with the input capacitor, it must be recommended  
for switching regulator applications and the  
For more information about the Evaluation board layout, please contact Microchip sales.  
2016 Microchip Technology Inc.  
DS20005522A-page 25  
MIC28513  
7.0  
PACKAGING INFORMATION  
24-Lead FQFN 3 mm x 4 mm Package Outline and Recommended Land Pattern  
Note:  
For the most current package drawings, please see the Microchip Packaging Specification located at  
http://www.microchip.com/packaging  
DS20005522A-page 26  
2016 Microchip Technology Inc.  
MIC28513  
Note:  
For the most current package drawings, please see the Microchip Packaging Specification located at  
http://www.microchip.com/packaging  
2016 Microchip Technology Inc.  
DS20005522A-page 27  
MIC28513  
NOTES:  
DS20005522A-page 28  
2016 Microchip Technology Inc.  
MIC28513  
APPENDIX A: REVISION HISTORY  
Revision A (May 2016)  
• Converted Micrel document MIC28513 to Micro-  
chip data sheet template DS20005522A.  
• Minor text changes throughout.  
2015 Microchip Technology Inc.  
DS20005522A-page 29  
MIC28513  
NOTES:  
DS20005522A-page 30  
2015 Microchip Technology Inc.  
MIC28513  
PRODUCT IDENTIFICATION SYSTEM  
To order or obtain information, e.g., on pricing or delivery, contact your local Microchip representative or sales office.  
Examples:  
XX  
PART NO.  
Device  
X
X
a)  
MIC28513-1YFL:  
45V, 4A Synchronous Buck  
Regulator, HyperLight  
Load, –40°C to +125°C  
Junction Temperature  
Range, 24LD FQFN  
45V, 4A Synchronous Buck  
Regulator, Hyper Speed  
Control, –40°C to +125°C  
Junction  
Package  
Temperature  
Architecture  
Device:  
MIC28513:  
45V, 4A Synchronous Buck Regulator  
b)  
MIC28513-2YFL:  
Architecture:  
1
2
=
=
HyperLight Load  
Hyper Speed Control  
Temperature Range,  
24LD FQFN  
Temperature:  
Package:  
Y
=
=
–40°C to +125°C  
Note 1: FQFN is a lead-free package. Pb-Free lead  
finish is Matte Tin.  
FL  
24-Pin 3 mm x 4 mm FQFN; Note 1  
2015 Microchip Technology Inc.  
DS20005522A-page 31  
MIC28513  
NOTES:  
DS20005522A-page 32  
2015 Microchip Technology Inc.  
Note the following details of the code protection feature on Microchip devices:  
Microchip products meet the specification contained in their particular Microchip Data Sheet.  
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the  
intended manner and under normal conditions.  
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our  
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data  
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.  
Microchip is willing to work with the customer who is concerned about the integrity of their code.  
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not  
mean that we are guaranteeing the product as “unbreakable.”  
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our  
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts  
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.  
Information contained in this publication regarding device  
applications and the like is provided only for your convenience  
and may be superseded by updates. It is your responsibility to  
ensure that your application meets with your specifications.  
MICROCHIP MAKES NO REPRESENTATIONS OR  
WARRANTIES OF ANY KIND WHETHER EXPRESS OR  
IMPLIED, WRITTEN OR ORAL, STATUTORY OR  
OTHERWISE, RELATED TO THE INFORMATION,  
INCLUDING BUT NOT LIMITED TO ITS CONDITION,  
QUALITY, PERFORMANCE, MERCHANTABILITY OR  
FITNESS FOR PURPOSE. Microchip disclaims all liability  
arising from this information and its use. Use of Microchip  
devices in life support and/or safety applications is entirely at  
the buyer’s risk, and the buyer agrees to defend, indemnify and  
hold harmless Microchip from any and all damages, claims,  
suits, or expenses resulting from such use. No licenses are  
conveyed, implicitly or otherwise, under any Microchip  
intellectual property rights unless otherwise stated.  
Trademarks  
The Microchip name and logo, the Microchip logo, AnyRate,  
dsPIC, FlashFlex, flexPWR, Heldo, JukeBlox, KeeLoq,  
KeeLoq logo, Kleer, LANCheck, LINK MD, MediaLB, MOST,  
MOST logo, MPLAB, OptoLyzer, PIC, PICSTART, PIC32 logo,  
RightTouch, SpyNIC, SST, SST Logo, SuperFlash and UNI/O  
are registered trademarks of Microchip Technology  
Incorporated in the U.S.A. and other countries.  
ClockWorks, The Embedded Control Solutions Company,  
ETHERSYNCH, Hyper Speed Control, HyperLight Load,  
IntelliMOS, mTouch, Precision Edge, and QUIET-WIRE are  
registered trademarks of Microchip Technology Incorporated  
in the U.S.A.  
Analog-for-the-Digital Age, Any Capacitor, AnyIn, AnyOut,  
BodyCom, chipKIT, chipKIT logo, CodeGuard, dsPICDEM,  
dsPICDEM.net, Dynamic Average Matching, DAM, ECAN,  
EtherGREEN, In-Circuit Serial Programming, ICSP, Inter-Chip  
Connectivity, JitterBlocker, KleerNet, KleerNet logo, MiWi,  
motorBench, MPASM, MPF, MPLAB Certified logo, MPLIB,  
MPLINK, MultiTRAK, NetDetach, Omniscient Code  
Generation, PICDEM, PICDEM.net, PICkit, PICtail,  
PureSilicon, RightTouch logo, REAL ICE, Ripple Blocker,  
Serial Quad I/O, SQI, SuperSwitcher, SuperSwitcher II, Total  
Endurance, TSHARC, USBCheck, VariSense, ViewSpan,  
WiperLock, Wireless DNA, and ZENA are trademarks of  
Microchip Technology Incorporated in the U.S.A. and other  
countries.  
SQTP is a service mark of Microchip Technology Incorporated  
in the U.S.A.  
Microchip received ISO/TS-16949:2009 certification for its worldwide  
headquarters, design and wafer fabrication facilities in Chandler and  
Tempe, Arizona; Gresham, Oregon and design centers in California  
and India. The Company’s quality system processes and procedures  
are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping  
devices, Serial EEPROMs, microperipherals, nonvolatile memory and  
analog products. In addition, Microchip’s quality system for the design  
and manufacture of development systems is ISO 9001:2000 certified.  
Silicon Storage Technology is a registered trademark of  
Microchip Technology Inc. in other countries.  
GestIC is a registered trademarks of Microchip Technology  
Germany II GmbH & Co. KG, a subsidiary of Microchip  
Technology Inc., in other countries.  
All other trademarks mentioned herein are property of their  
respective companies.  
QUALITYMANAGEMENTꢀꢀSYSTEMꢀ  
CERTIFIEDBYDNVꢀ  
© 2016, Microchip Technology Incorporated, Printed in the  
U.S.A., All Rights Reserved.  
ISBN: 978-1-5224-0542-9  
== ISO/TS16949==ꢀ  
2016 Microchip Technology Inc.  
DS20005522A-page 33  
Worldwide Sales and Service  
AMERICAS  
ASIA/PACIFIC  
ASIA/PACIFIC  
EUROPE  
Corporate Office  
2355 West Chandler Blvd.  
Chandler, AZ 85224-6199  
Tel: 480-792-7200  
Fax: 480-792-7277  
Technical Support:  
http://www.microchip.com/  
support  
Asia Pacific Office  
China - Xiamen  
Tel: 86-592-2388138  
Fax: 86-592-2388130  
Austria - Wels  
Tel: 43-7242-2244-39  
Fax: 43-7242-2244-393  
Suites 3707-14, 37th Floor  
Tower 6, The Gateway  
Harbour City, Kowloon  
China - Zhuhai  
Tel: 86-756-3210040  
Fax: 86-756-3210049  
Denmark - Copenhagen  
Tel: 45-4450-2828  
Fax: 45-4485-2829  
Hong Kong  
Tel: 852-2943-5100  
Fax: 852-2401-3431  
India - Bangalore  
Tel: 91-80-3090-4444  
Fax: 91-80-3090-4123  
France - Paris  
Tel: 33-1-69-53-63-20  
Fax: 33-1-69-30-90-79  
Australia - Sydney  
Tel: 61-2-9868-6733  
Fax: 61-2-9868-6755  
Web Address:  
www.microchip.com  
India - New Delhi  
Tel: 91-11-4160-8631  
Fax: 91-11-4160-8632  
Germany - Dusseldorf  
Tel: 49-2129-3766400  
Atlanta  
Duluth, GA  
Tel: 678-957-9614  
Fax: 678-957-1455  
China - Beijing  
Tel: 86-10-8569-7000  
Fax: 86-10-8528-2104  
Germany - Karlsruhe  
Tel: 49-721-625370  
India - Pune  
Tel: 91-20-3019-1500  
China - Chengdu  
Tel: 86-28-8665-5511  
Fax: 86-28-8665-7889  
Germany - Munich  
Tel: 49-89-627-144-0  
Fax: 49-89-627-144-44  
Austin, TX  
Tel: 512-257-3370  
Japan - Osaka  
Tel: 81-6-6152-7160  
Fax: 81-6-6152-9310  
Boston  
China - Chongqing  
Tel: 86-23-8980-9588  
Fax: 86-23-8980-9500  
Italy - Milan  
Tel: 39-0331-742611  
Fax: 39-0331-466781  
Westborough, MA  
Tel: 774-760-0087  
Fax: 774-760-0088  
Japan - Tokyo  
Tel: 81-3-6880- 3770  
Fax: 81-3-6880-3771  
China - Dongguan  
Tel: 86-769-8702-9880  
Italy - Venice  
Tel: 39-049-7625286  
Chicago  
Itasca, IL  
Tel: 630-285-0071  
Fax: 630-285-0075  
Korea - Daegu  
Tel: 82-53-744-4301  
Fax: 82-53-744-4302  
China - Hangzhou  
Tel: 86-571-8792-8115  
Fax: 86-571-8792-8116  
Netherlands - Drunen  
Tel: 31-416-690399  
Fax: 31-416-690340  
Korea - Seoul  
Cleveland  
Tel: 82-2-554-7200  
Fax: 82-2-558-5932 or  
82-2-558-5934  
China - Hong Kong SAR  
Tel: 852-2943-5100  
Fax: 852-2401-3431  
Poland - Warsaw  
Tel: 48-22-3325737  
Independence, OH  
Tel: 216-447-0464  
Fax: 216-447-0643  
Spain - Madrid  
Tel: 34-91-708-08-90  
Fax: 34-91-708-08-91  
China - Nanjing  
Tel: 86-25-8473-2460  
Fax: 86-25-8473-2470  
Malaysia - Kuala Lumpur  
Tel: 60-3-6201-9857  
Fax: 60-3-6201-9859  
Dallas  
Addison, TX  
Tel: 972-818-7423  
Fax: 972-818-2924  
Sweden - Stockholm  
Tel: 46-8-5090-4654  
China - Qingdao  
Tel: 86-532-8502-7355  
Fax: 86-532-8502-7205  
Malaysia - Penang  
Tel: 60-4-227-8870  
Fax: 60-4-227-4068  
Detroit  
Novi, MI  
UK - Wokingham  
Tel: 44-118-921-5800  
China - Shanghai  
Tel: 86-21-5407-5533  
Fax: 86-21-5407-5066  
Philippines - Manila  
Tel: 63-2-634-9065  
Fax: 63-2-634-9069  
Tel: 248-848-4000  
Fax: 44-118-921-5820  
Houston, TX  
Tel: 281-894-5983  
China - Shenyang  
Tel: 86-24-2334-2829  
Fax: 86-24-2334-2393  
Singapore  
Tel: 65-6334-8870  
Fax: 65-6334-8850  
Indianapolis  
Noblesville, IN  
Tel: 317-773-8323  
Fax: 317-773-5453  
China - Shenzhen  
Tel: 86-755-8864-2200  
Fax: 86-755-8203-1760  
Taiwan - Hsin Chu  
Tel: 886-3-5778-366  
Fax: 886-3-5770-955  
Los Angeles  
Mission Viejo, CA  
Tel: 949-462-9523  
Fax: 949-462-9608  
China - Wuhan  
Tel: 86-27-5980-5300  
Fax: 86-27-5980-5118  
Taiwan - Kaohsiung  
Tel: 886-7-213-7828  
Taiwan - Taipei  
Tel: 886-2-2508-8600  
Fax: 886-2-2508-0102  
New York, NY  
Tel: 631-435-6000  
China - Xian  
Tel: 86-29-8833-7252  
Fax: 86-29-8833-7256  
San Jose, CA  
Tel: 408-735-9110  
Thailand - Bangkok  
Tel: 66-2-694-1351  
Fax: 66-2-694-1350  
Canada - Toronto  
Tel: 905-673-0699  
Fax: 905-673-6509  
07/14/15  
DS20005522A-page 34  
2015 Microchip Technology Inc.  

相关型号:

SI9130DB

5- and 3.3-V Step-Down Synchronous Converters

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9135LG-T1

SMBus Multi-Output Power-Supply Controller

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9135LG-T1-E3

SMBus Multi-Output Power-Supply Controller

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9135_11

SMBus Multi-Output Power-Supply Controller

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9136_11

Multi-Output Power-Supply Controller

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9130CG-T1-E3

Pin-Programmable Dual Controller - Portable PCs

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9130LG-T1-E3

Pin-Programmable Dual Controller - Portable PCs

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9130_11

Pin-Programmable Dual Controller - Portable PCs

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9137

Multi-Output, Sequence Selectable Power-Supply Controller for Mobile Applications

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9137DB

Multi-Output, Sequence Selectable Power-Supply Controller for Mobile Applications

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9137LG

Multi-Output, Sequence Selectable Power-Supply Controller for Mobile Applications

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY

SI9122E

500-kHz Half-Bridge DC/DC Controller with Integrated Secondary Synchronous Rectification Drivers

Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY