MIC2127 [MICROCHIP]

The MIC2127A is a constant-frequency synchronous buck controllers featuring a unique adaptive ON-t;
MIC2127
型号: MIC2127
厂家: MICROCHIP    MICROCHIP
描述:

The MIC2127A is a constant-frequency synchronous buck controllers featuring a unique adaptive ON-t

文件: 总38页 (文件大小:827K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
MIC2127A  
75V, Synchronous Buck Controller Featuring Adaptive  
On-Time Control  
Features  
General Description  
• Hyper Speed Control® Architecture Enables:  
The MIC2127A is a constant-frequency synchronous  
buck controller featuring a unique adaptive on-time  
control architecture. The MIC2127A operates over an  
input voltage range from 4.5V-75V. The output voltage  
is adjustable down to 0.6V with an accuracy of ±1%.  
The device operates with programmable switching  
frequency from 270 kHz-800 kHz.  
- High Input to Output Voltage Conversion  
Ratio Capability  
- Any Capacitor™ Stable  
- Ultra-Fast Load Transient Response  
• Wide 4.5V-75V Input Voltage Range  
• Adjustable Output Voltage from 0.6V to 30V  
The MIC2127A features a MODE pin that allows the  
user to select either Continuous Conduction mode or  
Hyper Light Load (HLL) mode under light loads. An  
auxiliary bootstrap LDO improves the system efficiency  
by supplying the MIC2127A internal circuit bias power  
and gate drivers from the output of the converter. A  
logic level enable (EN) signal can be used to enable or  
disable the controller. The MIC2127A can start-up  
monotonically into a prebiased output. The MIC2127A  
features an open drain power good signal (PG) that  
signals when the output is in regulation and can be  
used for simple power supply sequencing.  
• 270 kHz-800 kHz Programmable Switching Fre-  
quency  
• Built-In 5V Regulator for Single-Supply Operation  
• Auxiliary Bootstrap LDO for Improving System  
Efficiency  
• Internal Bootstrap Diode  
• Selectable Light Load Operating Mode  
• Enable Input and Power Good Output  
• Programmable Current Limit  
• Hiccup Mode Short-Circuit Protection  
The MIC2127A offers a full suite of protection features  
to ensure protection of the IC during Fault conditions.  
These include undervoltage lockout to ensure proper  
operation under power-sag conditions, “hiccup” mode  
short-circuit protection, internal soft start of 5 ms to  
reduce inrush current during start-up and thermal shut-  
down.  
• Soft Start, Internal Compensation and Thermal  
Shutdown  
• Supports Safe Start-Up into a Prebiased Output  
Applications  
• Networking/Telecom Equipment  
• Base Station, Servers  
The MIC2127A is available in a 16-pin 3 mm x 3 mm  
VQFN package, with an operating junction temperature  
range from –40°C to +125°C.  
• Distributed Power Systems  
• Industrial Power Supplies  
Typical Application  
VIN  
PVDD  
VIN  
4.5V* to 75V  
4.7 μF  
0.1 μF  
0.1 μF  
2.2 μFX3  
Q1  
DH  
10Ÿ  
BST  
L1  
10 μH  
VDD  
VOUT  
5V@5A  
4.7 μF  
SW  
ILIM  
C1  
+
330 μF  
MIC2127A  
47 μF  
1.3 kŸ  
0.1 μF  
PG  
EN  
Q2  
DL  
7.5 kŸ  
4.7 nF  
VIN  
36 kŸ  
VDD  
MODE  
FB  
1 kŸ  
100 kŸ  
60 kŸ  
EXTVDD  
VOUT  
FREQ  
VIN  
1 μF  
AGND  
PGND  
Q1,Q3: SiR878ADP  
L1: SRP1265A-100M, Bourns  
C1: 10SVP330M  
*Output voltage follows input voltage when the input is below the target output voltage  
2016 Microchip Technology Inc.  
DS20005676B-page 1  
MIC2127A  
Package Types  
MIC2127A  
3 x 3 VQFN*  
(Top View)  
13  
16 15 14  
PG  
ILIM  
1
2
3
4
MODE  
FREQ  
EN  
12  
11  
EP  
SW  
10  
9
BST  
EXTVDD  
5
6
7
8
* Includes Exposed Thermal Pad (EP); see Table 3-1.  
Functional Block Diagram  
PVDD  
VIN  
VDD  
EXTVDD  
EN  
9
8
10  
16  
15  
LINEAR  
REGULATOR  
LINEAR  
REGULATOR  
UVLO  
4
5
3
BST  
DH  
THERMAL  
SHUTDOWN  
12  
11  
MODE  
FREQ  
Control  
Logic  
TON  
ESTIMATION  
Zero Crossing  
Detection (ZCD) and  
Negative Current Limit  
SW  
DL  
COMPENSATION  
gm  
PVDD  
13  
FB  
7
Soft  
Start  
CURRENT  
LIMIT  
DETECTION  
VREF  
0.6V  
100 µA  
2
6
ILIM  
PG  
1
VREF  
FB  
0.9  
PGND  
14  
AGND  
DS20005676B-page 2  
2016 Microchip Technology Inc.  
MIC2127A  
1.0  
ELECTRICAL CHARACTERISTICS  
Absolute Maximum Ratings †  
VIN, FREQ, ILIM, SW to PGND.................................................................................................................... –0.3V to +76V  
VDD, PVDD, FB, PG, MODE to AGND ........................................................................................................... –0.3V to +6V  
EXTVDD to AGND...................................................................................................................................... –0.3V to +16V  
BST to SW .................................................................................................................................................. –0.3V to +6V  
BST to AGND ............................................................................................................................................. –0.3V to +82V  
EN to AGND ...................................................................................................................................... –0.3V to (VIN +0.3V)  
DH, DL to AGND ............................................................................................................................. –0.3V to (VDD +0.3V)  
PGND to AGND .......................................................................................................................................... –0.3V to +0.3V  
Junction Temperature .......................................................................................................................................... +150°C  
Storage Temperature (TS)..................................................................................................................... –65°C to +150°C  
Lead Temperature (soldering, 10s)........................................................................................................................ 260°C  
ESD Rating(1)......................................................................................................................................................... 1000V  
† Notice: Stresses above those listed under “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.  
Note 1: Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5 kin series with  
100 pF.  
(1)  
Operating Ratings  
Supply Voltage (VIN) ..................................................................................................................................... 4.5V to 75V  
SW, FREQ, ILIM, EN........................................................................................................................................... 0V to VIN  
Junction Temperature (TJ) .................................................................................................................... –40°C to +125°C  
Package Thermal Resistance (3 mm × 3 mm VQFN 16LD)  
Junction to Ambient (JA).................................................................................................................................. 50.8°C/W  
Junction to Case (JC)....................................................................................................................................... 25.3°C/W  
Note 1: The device is not ensured to function outside the operating range.  
2016 Microchip Technology Inc.  
DS20005676B-page 3  
MIC2127A  
ELECTRICAL CHARACTERISTICS (Note 1)  
Electrical Specifications: unless otherwise specified, VIN = 12V, VOUT = 1.2V; VBST – VSW = 5V, TA = +25°C.  
Boldface values indicate –40°C TJ +125°C (Note 2).  
Parameter  
Symbol  
Min.  
Typ.  
Max. Units  
Test Conditions  
Power Supply Input  
Input Voltage Range  
VVIN  
4.5  
5.5  
V
PVDD and VDD shorted to VIN  
(VPVDD = VVIN = VVDD  
)
5.5  
75  
Quiescent Supply Current  
IQ  
1.4  
1.8  
mA  
µA  
VFB = 1.5V, MODE = VDD  
no switching  
,
300  
600  
VFB = 1.5V, MODE = AGND  
,
no switching  
Shutdown Supply Current  
IVIN(SHDN)  
0.1  
30  
5
µA  
µA  
EN = Low  
60  
EN = Low, VIN = VDD = 5.5V  
PVDD,VDD and EXTVDD  
PVDD Output Voltage  
VPVDD  
4.8  
5.1  
5.4  
V
VVIN = 7V to 75V,  
IPVDD = 10 mA  
VDD UVLO Threshold  
VVDD_UVLO_Rise  
VVDD_UVLO_Hys  
VEXTVDD_Rise  
VEXTVDD_Hys  
3.7  
4.2  
600  
4.6  
4.5  
V
VDD rising  
VDD UVLO Hysteresis  
EXTVDD Bypass Threshold  
EXTVDD Bypass Hysteresis  
EXTVDD Dropout Voltage  
Reference  
mV  
V
VDD falling  
4.4  
4.85  
EXTVDD rising  
200  
250  
mV  
mV  
VEXTVDD = 5V, IPVDD = 25 mA  
Feedback Reference Voltage  
VREF  
IFB  
0.597  
0.594  
0.6  
0.6  
50  
0.603  
0.606  
500  
V
V
TJ = 25°C  
–40°C TJ 125°C  
VFB = 0.6V  
FB Bias Current (Note 3)  
nA  
Enable Control  
EN Logic Level High  
EN Logic Level Low  
EN Hysteresis  
VEN_H  
VEN_L  
VEN_Hys  
IEN  
1.6  
0.6  
V
V
100  
6
mV  
µA  
EN Bias Current  
ON Timer  
30  
VEN = 12V  
Switching Frequency  
f0  
800  
270  
kHz VFREQ = VVIN, VVIN = 12V  
230  
300  
VFREQ = 33% of VVIN  
,
VVIN = 12V  
Maximum Duty Cycle  
Minimum Duty Cycle  
Minimum ON Time  
Minimum OFF Time  
MODE  
DMAX  
DMIN  
85  
0
%
%
VFREQ = VVIN = 12V  
VFB > 0.6V  
tON(MIN)  
tOFF(MIN)  
80  
230  
ns  
ns  
150  
350  
MODE Logic High Level  
VMODE_H  
VMODE_L  
1.6  
70  
0.6  
V
V
MODE Logic Low Level  
MODE Hysteresis  
VMODE_Hys  
mV  
Note 1: Specification for packaged product only.  
2: The application is fully functional at low VDD (supply of the control section) if the external MOSFETs have  
low voltage VTH  
3: Design specification.  
.
DS20005676B-page 4  
2016 Microchip Technology Inc.  
MIC2127A  
ELECTRICAL CHARACTERISTICS (Note 1)  
Electrical Specifications: unless otherwise specified, VIN = 12V, VOUT = 1.2V; VBST – VSW = 5V, TA = +25°C.  
Boldface values indicate –40°C TJ +125°C (Note 2).  
Parameter  
Current Limit  
Symbol  
Min.  
Typ.  
Max. Units  
Test Conditions  
Current-Limit Comparator  
Offset  
VOFFSET  
ICL  
–15  
0
15  
mV  
VFB = 0.59V  
VFB = 0.59V  
I
I
LIM Source Current  
90  
100  
0.3  
48  
110  
µA  
µA/°C  
mV  
LIM Source Current Tempco  
Negative Current Limit  
Comparator Threshold  
Zero Crossing Detection Comparator  
Zero Crossing Detection  
Comparator Threshold  
–24  
–8  
8
mV  
FET Drivers  
DH On-Resistance, High  
State  
RDH(PULL-UP)  
RDH(PULL_DOWN)  
RDL(PULL-UP)  
2
2
3
4
DH On-Resistance, Low  
State  
DL On-Resistance, High  
State  
2
4
DL On-Resistance, Low State RDL(PULL_DOWN)  
0.36  
0.8  
SW, VIN and BST Leakage  
BST Leakage  
30  
50  
50  
µA  
µA  
µA  
VIN Leakage  
SW Leakage  
Power Good (PG)  
PG Threshold Voltage  
PG Hysteresis  
VPG_Rise  
VPG_Hys  
85  
6
95  
%VOUT VFB rising  
%VOUT VFB falling  
PG Delay Time  
PG_R_DLY  
VOL_PG  
150  
140  
µs  
VFB rising  
PG Low Voltage  
Thermal Protection  
Overtemperature Shutdown  
200  
mV  
VFB < 90% × VNOM, IPG = 1 mA  
TSHDN  
150  
15  
°C  
°C  
Junction temperature rising  
Overtemperature Shutdown  
Hysteresis  
TSHDN_Hys  
Note 1: Specification for packaged product only.  
2: The application is fully functional at low VDD (supply of the control section) if the external MOSFETs have  
low voltage VTH  
.
3: Design specification.  
TEMPERATURE SPECIFICATIONS  
Electrical Specifications: unless otherwise specified, VIN = 12V, VOUT = 1.2V; VBST – VSW = 5V, TA = +25°C.  
Parameters  
Temperature Ranges  
Sym.  
Min. Typ.  
Max.  
Units  
Conditions  
Storage Temperature  
TS  
TJ  
–65  
–40  
+150  
+150  
°C  
°C  
Junction Temperature  
Package Thermal Resistances  
Thermal Resistance,  
16 Lead,  
3 x 3 mm VQFN  
Junction to Ambient  
Junction to Case  
JA  
JC  
50.8  
25.3  
°C/W  
°C/W  
2016 Microchip Technology Inc.  
DS20005676B-page 5  
MIC2127A  
2.0  
TYPICAL CHARACTERISTIC 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.  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
25  
20  
15  
10  
5
1.8  
1.6  
1.4  
1.2  
1
0.8  
0.6  
0.4  
0.2  
0
VOUT = 5V  
IOUT = 0A  
EXTVDD = GND  
FSW = 300 kHz  
VEN = VVIN  
VEXTVDD = VOUT  
VVIN = 48V  
IOUT = 0A  
FSW = 300 kHz  
VEN = VIN  
HLL Mode  
0
-50  
-25  
0
25  
50  
75  
100  
6
12 18 24 30 36 42 48 54 60 66 72 78  
Input Voltage (V)  
Temperature (°C)  
FIGURE 2-1:  
Input Supply Current vs.  
FIGURE 2-4:  
Input Supply Current vs.  
Input Voltage.  
Temperature (HLL Mode).  
30  
25  
20  
15  
600  
VVIN = 48V, with resistor divider  
between VIN and AGND at FREQ pin  
500  
400  
300  
200  
100  
0
(100 kŸ and 60 kŸ)  
EXTVDD = GND  
VEXTVDD = VOUT  
EN = GND  
10  
VVIN = 48V  
IOUT = 0A  
5
FSW = 300 kHz  
0
-50  
-25  
0
25  
50  
75  
100  
6
18  
30  
42  
54  
66  
78  
Input Voltage (V)  
Temperature (°C)  
FIGURE 2-2:  
Input Supply Current vs.  
FIGURE 2-5:  
Input Shutdown Current vs.  
Temperature.  
Input Voltage.  
0.7  
0.6  
0.5  
0.4  
0.3  
350  
VVIN = 48V, with resistor divider between VIN  
340  
330  
320  
310  
300  
290  
280  
270  
260  
250  
and AGND at FREQ pin  
(100 kŸ and 60 kŸ)  
EN = GND  
VOUT =5V  
0.2  
IOUT =0A  
FSW =300 kHz  
0.1  
0
VEN =VVIN  
HLL Mode  
6
12 18 24 30 36 42 48 54 60 66 72 78  
Input Voltage (V)  
-50  
-25  
0
25  
50  
75  
100  
Temperature (°C)  
FIGURE 2-3:  
Input Supply Current vs.  
FIGURE 2-6:  
Input Shutdown Current vs.  
Input Voltage (HLL Mode).  
Temperature.  
DS20005676B-page 6  
2016 Microchip Technology Inc.  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
4.5  
4.3  
4.1  
3.9  
3.7  
3.5  
3.3  
3.1  
5.4  
5.3  
5.2  
5.1  
5
IPVDD = 10 mA  
V
EN = VVIN  
VVDD rising  
EXTVDD = GND  
VDD falling  
100  
4.9  
4.8  
IVDD = 0 mA  
EXTVDD = GND  
6
12 18 24 30 36 42 48 54 60 66 72 78  
Input Voltage (V)  
-50  
-25  
0
25  
50  
75  
125  
Temperature (°C)  
FIGURE 2-7:  
PVDD Line Regulation.  
FIGURE 2-10:  
V
DD UVLO Threshold vs.  
Temperature.  
4.8  
4.7  
4.6  
4.5  
4.4  
4.3  
4.2  
5.4  
VVIN = 48V  
I
PVDD = 10 mA  
5.3  
5.2  
5.1  
5
VEN = VVIN  
VEXTVDD rising  
VEXTVDD = 12V  
EXTVDD = GND  
VEXTVDD falling  
4.9  
4.8  
VEXTVDD = 5V  
-50  
-25  
0
25  
50  
75  
100  
-50  
-25  
0
25  
50  
75  
100  
125  
Temperature (°C)  
Temperature (°C)  
FIGURE 2-8:  
Temperature.  
PVDD Voltage vs.  
FIGURE 2-11:  
Temperature.  
EXTVDD Threshold vs.  
5.2  
5
1.6  
1.4  
1.2  
1.0  
0.8  
0.6  
VEXTVDD = 12V  
EXTVDD = GND  
4.8  
4.6  
4.4  
4.2  
VEN rising  
VEXTVDD = 5V  
VEN falling  
VVIN = 48V  
VEN = VVIN  
4
0
10  
20  
30  
40  
50  
60  
-50  
-25  
0
25  
50  
75  
100  
125  
IPVDD (mA)  
Temperature (°C)  
FIGURE 2-9:  
PVDD Load Regulation.  
FIGURE 2-12:  
Enable Threshold vs.  
Temperature.  
2016 Microchip Technology Inc.  
DS20005676B-page 7  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
140  
5.6  
VVIN = 12V  
130  
120  
110  
100  
90  
VEN = 5V  
5.4  
5.2  
5.0  
4.8  
4.6  
4.4  
4.2  
4.0  
80  
70  
-50  
-25  
0
25  
50  
75  
100  
125  
-50  
-25  
0
25  
50  
75  
100  
125  
Temperature (°C)  
Temperature (°C)  
FIGURE 2-13:  
Enable Bias Current vs.  
FIGURE 2-16:  
ILIM Source Current vs.  
Temperature.  
Temperature.  
320  
310  
300  
290  
280  
270  
260  
250  
1.4  
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
0.0  
IOUT = 5A  
IOUT = 0A  
VOUT = 5V  
SW_SETPONIT = 300 kHz  
EXTVDD = VOUT  
VEN = VVIN  
240  
230  
220  
F
V
-50  
-25  
0
25  
50  
75  
100  
125  
6
12 18 24 30 36 42 48 54 60 66 72 78  
Input Voltage (V)  
Temperature (°C)  
FIGURE 2-14:  
Switching Frequency vs.  
FIGURE 2-17:  
Current Limit Comparator  
Input Voltage.  
Offset vs Temperature.  
606.0  
604.0  
602.0  
600.0  
598.0  
596.0  
594.0  
310  
305  
300  
TA = 25°C  
TA = -40°C  
TA = 85°C  
295  
290  
285  
280  
275  
270  
265  
VVIN = 48V  
OUT = 5V  
SW_SETPONIT = 300 kHz  
V
F
VEXTVDD = VOUT  
VEN = VVIN  
3.5  
0
0.5  
1
1.5  
2
2.5  
3
4
4.5  
5
-50  
-25  
0
25  
50  
75  
100  
125  
Load Current (A)  
Temperature (°C)  
FIGURE 2-15:  
Switching Frequency vs.  
FIGURE 2-18:  
Feedback Voltage vs.  
Load Current.  
Temperature.  
DS20005676B-page 8  
2016 Microchip Technology Inc.  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
VOUT = 1.0V  
VOUT =1.0V
VOUT = 1.2V  
VOUT = 1.2V  
V=1.5V  
VOUT = 1.5V  
OUT  
VOUT = 1.8V  
VOUT = 1.8V  
VOUT = 2.5V  
VOUT = 2.5V  
V
= 3.3V  
OUT
VOUT = 3.3V  
VOUT = 5V  
VOUT = 5V  
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
Output Current (A)  
Output Current (A)  
FIGURE 2-19:  
Efficiency vs. Output  
FIGURE 2-22:  
Efficiency vs. Output  
Current (Input Voltage = 12V, CCM Mode).  
Current (Input Voltage = 48V, CCM Mode).  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
VOUT = 1.0V  
VOUT = 1.2V  
V=1.5V  
OUT  
V
= 1.2V  
VOUT = 1.0V  
OUUT .
VOUT = 1.8V  
V
= 1.8V  
VOUT = 2.5V  
V=1.5V  
OUT  
OUT  
V
= 3.3V  
OUT  
V
= 3.3V  
VOUT = 2.5V  
OUT  
VOUT = 5V  
VOUT = 5V  
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
Output Current (A)  
Output Current (A)  
FIGURE 2-20:  
Efficiency vs. Output  
FIGURE 2-23:  
Efficiency vs. Output  
Current (Input Voltage = 24V, CCM Mode).  
Current (Input Voltage = 60V, CCM Mode).  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
100%  
90%  
80%  
70%  
VOUT =1.0V
60%  
VOUT =1.2V
50%  
VOUT =1.5V
40%  
V
= 1.2V  
VOUT = 1.0V  
2
VOUT =1.8V
30%  
OUT  
V
= 1.5V  
V
= 1.8V  
VOUT = 2.5V  
OUT  
OUT  
20%  
10%  
0%  
V
= 3.3V  
VOUT = 2.5V  
VOUT = 3.3V  
OUT  
V
= 5V  
V
= 5V  
OUT
OUT  
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
Output Current (A)  
Output Current (A)  
FIGURE 2-21:  
Efficiency vs. Output  
FIGURE 2-24:  
Efficiency vs. Output  
Current (Input Voltage = 36V, CCM Mode).  
Current (Input Voltage = 75V, CCM Mode).  
2016 Microchip Technology Inc.  
DS20005676B-page 9  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
V=5V
VOUT = 3.3V  
OUT  
VOUT = 5V  
VOUT = 3.3V  
V=2.5V
OUT  
V
= 2.5V  
OUT
V
= 1.8V  
OUT  
V
= 1.8V  
OUT
V
= 1.5V  
OUT  
V
= 1.5V  
OUT
VOUT =1.2V
V
= 1.2V  
OUT  
VOUT = 1.0V  
VOUT = 1.0V  
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
Load Current (A)  
Load Current (A)  
FIGURE 2-25:  
Efficiency vs. Output  
FIGURE 2-28:  
Efficiency vs. Output  
Current (Input Voltage = 12V, HLL Mode).  
Current (Input Voltage = 48V, HLL Mode).  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
VOUT = 5V  
V=5V
OUT  
VOUT = 3.3V  
VOUT = 3.3V  
VOUT = 2.5V  
VOUT = 2.5V  
VOUT = 1.8V  
V=1.8V  
OUT  
V
= 1.5V  
V=1.5V  
OUT  
OUT  
V
= 1.2V  
VOUT = 1.2V  
VOUT = 1.0V  
VOUT=1.2V  
OUT  
V
= 1.0V  
OUT  
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
Load Current (A)  
Load Current (A)  
FIGURE 2-26:  
Efficiency vs. Output  
FIGURE 2-29:  
Efficiency vs. Output  
Current (Input Voltage = 24V, HLL Mode).  
Current (Input Voltage = 60V, HLL Mode).  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
100%  
90%  
80%  
70%  
60%  
50%  
40%  
30%  
20%  
10%  
0%  
VOUT = 5V  
VOUT = 3.3V  
VOUT = 2.5V  
= 1.8V  
V
OUT  
V
= 3.3V  
VOUT = 2.5V  
OUT  
VOUT = 5V  
V
= 1.5V  
OUT  
V=1.8V  
VOUT = 1.2V  
OUT  
V
= 1.2V  
OUT  
V=1.5V  
VOUT = 1.0V  
VOUT=1.0V  
OUT  
V
= 1.0V  
OUT  
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
0
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
Load Current (A)  
Load Current (A)  
FIGURE 2-27:  
Current (Input Voltage = 36V, HLL Mode).  
Efficiency vs. Output  
FIGURE 2-30:  
Current (Input Voltage = 75V, HLL Mode).  
Efficiency vs. Output  
DS20005676B-page 10  
2016 Microchip Technology Inc.  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
VVIN  
20V/div  
VVIN  
20V/div  
VSW  
VSW  
20V/div  
20V/div  
VVIN = 0V to 48V  
VOUT = 5V  
IOUT = 5A  
VVIN = 0V to 48V  
VOUT = 5V  
IOUT = 0.1A  
VOUT  
2V/div  
VOUT  
2V/div  
IL  
5A/div  
IL  
2A/div  
10 ms/div  
10 ms/div  
FIGURE 2-31:  
Power-Up.  
FIGURE 2-34:  
Power-Up at Light Load in  
HLL Mode (IOUT = 0.1A).  
VVIN  
20V/div  
VVIN = 48V to 0V  
VVIN = 48V  
VOUT = 5V  
IOUT = 5A  
V
OUT = 5V  
IOUT = 5A  
VEN  
2V/div  
VSW  
20V/div  
VOUT  
2V/div  
VOUT  
2V/div  
IL  
5A/div  
IL  
5A/div  
VPG  
5V/div  
10 ms/div  
4 ms/div  
FIGURE 2-32:  
Power-Down.  
FIGURE 2-35:  
Enable Turn-On/Turn-Off.  
VVIN  
20V/div  
VEN  
2V/div  
VVIN = 48V  
VOUT = 5V  
IOUT = 5A  
VSW  
20V/div  
VVIN = 0V to 48V  
V
OUT = 5V  
VOUT  
2V/div  
IOUT = 0.1A  
VOUT  
2V/div  
IL  
5A/div  
I
VPG  
L
5V/div  
2 ms/div  
10 ms/div  
2A/div  
FIGURE 2-36:  
Enable Turn-On Delay.  
FIGURE 2-33:  
Power-Up at Light Load in  
CCM Mode (IOUT = 0.1A).  
2016 Microchip Technology Inc.  
DS20005676B-page 11  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
VEN  
2V/div  
VVIN = 48V  
OUT = 5V  
IOUT = 5A  
V
VEN  
2V/div  
VOUT  
2V/div  
VOUT  
2V/div  
VVIN = 48V  
VOUT = 5V  
IOUT = 0A  
V
OUT_PREBIAS = 2.5V  
IL  
5A/div  
VSW  
50V/div  
VPG  
5V/div  
IL  
2A/div  
2 ms/div  
4 ms/div  
FIGURE 2-37:  
Enable Turn-Off Delay.  
FIGURE 2-40:  
Enable Turn-On with  
Prebiased Output (CCM Mode).  
VVIN = 48V  
VOUT = 5V  
IOUT = 0.2A  
VEN  
2V/div  
VEN  
2V/div  
VOUT  
2V/div  
VVIN = 48V  
VOUT = 5V  
IOUT = 0A  
VOUT  
2V/div  
VOUT_PREBIAS = 2.5V  
VSW  
50V/div  
IL  
2A/div  
IL  
2A/div  
VPG  
5V/div  
10 ms/div  
4 ms/div  
FIGURE 2-38:  
Enable Turn-On/Turn-Off at  
FIGURE 2-41:  
Enable Turn-On with  
Light Load in CCM Mode.  
Prebiased Output (HLL Mode).  
VVIN = 48V  
VVIN = 48V  
V
OUT = 5V  
V
OUT = 5V  
IOUT = 0.2A  
IOUT = 0A  
VEN  
2V/div  
VEN  
1V/div  
VOUT  
2V/div  
VOUT  
2V/div  
IL  
2A/div  
VSW  
50V/div  
VPG  
5V/div  
4 ms/div  
10 ms/div  
FIGURE 2-39:  
Enable Turn-On/Turn-Off at  
FIGURE 2-42:  
Enable Thresholds.  
Light Load in HLL Mode.  
DS20005676B-page 12  
2016 Microchip Technology Inc.  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
VVIN = Rising  
VVDD  
1V/div  
VOUT = 5V  
IOUT = 0A  
VVIN = 0V to 48V  
VOUT = 5V  
VVIN  
20V/div  
Load = Short  
ILIM = 1.3 k  
R
VOUT  
500 mV/div  
VOUT  
2V/div  
IL  
5A/div  
VSW  
5V/div  
4 ms/div  
10 ms/div  
FIGURE 2-43:  
VDD UVLO Threshold-  
FIGURE 2-46:  
Power-Up into Output Short.  
Rising.  
VVIN = 48V  
VVDD  
1V/div  
V
OUT = 5V  
VVIN = Falling  
VOUT = 5V  
IOUT = 0A  
RILIM = 1.3 k  
VOUT  
2V/div  
VOUT  
2V/div  
VSW  
5V/div  
IOUT  
5A/div  
2 ms/div  
100 ms/div  
FIGURE 2-47:  
Threshold.  
Output Current Limit  
FIGURE 2-44:  
Falling.  
V
DD UVLO Threshold-  
VVIN = 48V  
VOUT = 5V  
Load = Short  
VOUT  
2V/div  
R
ILIM = 1.3 k  
VEN  
2V/div  
VVIN = 48V  
VOUT = 5V  
Load = Short  
RILIM = 1.3 k  
VOUT  
500 mV/div  
IL  
5A/div  
IL  
5A/div  
4 ms/div  
2 ms/div  
FIGURE 2-45:  
Enable into Output Short.  
FIGURE 2-48:  
Output Short Circuit.  
2016 Microchip Technology Inc.  
DS20005676B-page 13  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
VVIN = 48V  
VOUT = 5V  
Load = Short  
VOUT  
2V/div  
R
ILIM = 1.3 k  
VOUT  
100 mV/div  
AC coupled  
VVIN = 48V  
VOUT = 5V  
IOUT = 0A to 2.5A  
IL  
5A/div  
IOUT  
2A/div  
4 ms/div  
100 µs/div  
FIGURE 2-49:  
Recovery from Output Short  
FIGURE 2-52:  
Load Transient Response  
Circuit.  
(CCM Mode).  
VOUT  
200 mV/div  
AC coupled  
VOUT  
100 mV/div  
AC coupled  
VVIN = 48V  
VOUT = 5V  
VVIN = 48V  
VOUT = 5V  
IOUT = 0A to 2.5A  
I
OUT = 0A to 5A  
IOUT  
IOUT  
2A/div  
2A/div  
2 ms/div  
100 µs/div  
FIGURE 2-50:  
Load Transient Response  
FIGURE 2-53:  
Load Transient Response  
(CCM Mode).  
(HLL Mode).  
VOUT  
100 mV/div  
AC coupled  
VOUT  
200 mV/div  
AC coupled  
VVIN = 48V  
VVIN = 48V  
VOUT = 5V  
V
OUT = 5V  
IOUT = 2.5A to 5A  
I
OUT = 0A to 5A  
IOUT  
IOUT  
2A/div  
2A/div  
100 µs/div  
2 ms/div  
FIGURE 2-51:  
Load Transient Response  
FIGURE 2-54:  
Load Transient Response  
(HLL Mode).  
(HLL Mode).  
DS20005676B-page 14  
2016 Microchip Technology Inc.  
MIC2127A  
Note: Unless otherwise indicated, VVIN = 12V, fSW = 300 kHz, RILIM = 1.3 k, L = 10 µH, VEXTVDD = VOUT, TA = +25°C  
(refer to the Typical Application circuit).  
VVIN = 48V  
VOUT = 5V  
IOUT = 0A  
VVIN = 48V  
OUT = 5V  
IOUT = 5A  
V
VOUT  
VOUT  
50 mV/div  
AC coupled  
50 mV/div  
AC coupled  
VSW  
50V/div  
IL  
2A/div  
IL  
5A/div  
VSW  
50 V/div  
2 µs/div  
2 µs/div  
FIGURE 2-55:  
Switching Waveform at No  
FIGURE 2-57:  
Switching Waveform at Full  
Load (CCM Mode).  
Load.  
VVIN = 48V  
V
OUT = 5V  
IOUT = 0A  
VOUT  
50 mV/div  
AC coupled  
IL  
2A/div  
VSW  
50V/div  
10 µs/div  
FIGURE 2-56:  
Switching Waveform at No  
Load (HLL Mode).  
2016 Microchip Technology Inc.  
DS20005676B-page 15  
MIC2127A  
3.0  
PIN DESCRIPTION  
The descriptions of the pins are listed in Table 3-1.  
TABLE 3-1:  
MIC2127A  
PIN FUNCTION TABLE  
Symbol  
Pin Function  
1
2
PG  
ILIM  
Open-drain Power Good Output Pin  
Current Limit Setting Resistor Connection Pin  
Switch Pin and Current Sense Input for negative current limit  
Bootstrap Capacitor Connection Pin  
High-side N-MOSFET Gate Driver Output  
Power Ground  
3
SW  
4
BST  
DH  
5
6
PGND  
DL  
7
Low-side N-MOSFET Gate Driver Output  
Internal Low Dropout Regulators Output of the MIC2127A  
Supply Input for the internal low voltage LDO  
Enable Input  
8
PVDD  
EXTVDD  
EN  
9
10  
11  
12  
13  
14  
15  
16  
17  
FREQ  
MODE  
FB  
Switching Frequency Programming Input  
Light Load Mode Selection Input  
Feedback Input  
AGND  
VDD  
Analog Ground  
Supply Input for the MIC2127A internal analog circuits  
Supply Input for the internal high-voltage LDO  
Exposed Pad  
VIN  
EP  
3.1  
Power Good Output Pin (PG)  
3.5  
High-Side N-MOSFET Gate Driver  
Output Pin (DH)  
Connect PG to VDD through a pull-up resistor. PG is low  
when the FB voltage is 10% below the 0.6V reference  
voltage.  
High-side N-MOSFET gate driver Output. Connect DH  
to the gate of external high-side N-MOSFET.  
3.2  
Current Limit Pin (I  
)
LIM  
3.6  
Power Ground Pin (P  
)
GND  
Connect a resistor from ILIM to SW to set the current  
limit. Refer to Section 4.3 “Current Limit (ILIM)” for  
more details.  
PGND provides the return path for the internal low-side  
N-MOSFET gate driver output and also acts as  
reference for the current limit comparator. Connect  
PGND to the external low-side N-MOSFET source  
terminal and to the return terminal of PVDD bypass  
capacitor.  
3.3  
Switch Pin (SW)  
The SW pin provides the return path for the high-side  
N-MOSFET gate driver when High-Side MOSFET  
Gate Drive (DH) is low and is also used to sense  
low-side MOSFET current by monitoring the SW node  
voltage for negative current limit function.  
3.7  
Low-Side N-MOSFET Gate Driver  
Output Pin (DL)  
Low-side N-MOSFET gate driver output. Connect to  
the gate terminal of the external low-side N-MOSFET.  
Connect SW to the pin where the high-side MOSFET  
source and the low-side MOSFET drain terminal are  
connected together.  
3.8  
Internal Low Dropout Regulators  
Output Pin (P  
)
VDD  
3.4  
Bootstrap Capacitor Pin (BST)  
Combined output of the two internal LDOs (one LDO  
powered by VIN and the other LDO powered by  
EXTVDD). PVDD is the supply for the low-side  
MOSFET driver and for the floating high-side MOSFET  
driver. Connect a minimum of 4.7 µF low ESR ceramic  
BST capacitor acts as supply for the high-side  
N-MOSFET driver. Connect a minimum of 0.1 µF low  
ESR ceramic capacitor between BST and SW. Refer to  
Section 4.5 “High-Side MOSFET Gate Drive (DH)”  
for more details.  
capacitor from PVDD to PGND  
.
DS20005676B-page 16  
2016 Microchip Technology Inc.  
MIC2127A  
3.9  
EXTVDD  
3.13 Feedback Input Pin (FB)  
Supply to the internal low voltage LDO. Connect  
EXTVDD to the output of the buck converter if it is  
between 4.7V to 14V to improve system efficiency.  
Bypass EXTVDD with a minimum of 1 µF low ESR  
ceramic capacitor.  
FB is input to the transconductance amplifier of the  
control loop. The control loop regulates the FB voltage  
to 0.6V. Connect the FB node to the mid-point of the  
resistor divider between output and AGND  
.
3.14 Analog Ground Pin (A  
)
GND  
3.10 Enable Input Pin (EN)  
AGND is the reference to the analog control circuits  
inside the MIC2127A. Connect AGND to PGND at one  
point on the PCB.  
EN is a logic input. Connect to logic high to enable the  
converter, and connect to logic low to disable the  
converter.  
3.15 Bias Voltage Pin (V  
)
DD  
3.11 Switching Frequency  
Supply for the MIC2127A internal analog circuits. Con-  
nect VDD to PVDD of the MIC2127A through a low-pass  
filter. Connect a minimum of 4.7 µF low ESR ceramic  
capacitor from VDD to AGND for decoupling.  
Programming Input Pin (FREQ)  
Switching Frequency Programming Input. Connect to  
mid-point of the resistor divider formed between VIN  
and AGND to set the switching frequency of the con-  
verter. Tie FREQ to VIN to set the switching frequency  
to 800 kHz. Refer to Section 5.1 “Setting the Switch-  
ing Frequency” for more details.  
3.16 Input Voltage Pin (V )  
IN  
Supply Input to the internal high-voltage LDO. Connect  
to the main power source and bypass to PGND with a  
minimum of 0.1 µF low ESR ceramic capacitor.  
3.12 Light Load Mode Selection Input  
Pin (MODE)  
3.17 Exposed Pad (EP)  
Light Load Mode Selection Input. Connect MODE pin  
to VDD to select Continuous Conduction mode under  
light loads, or connect to AGND to select Hyper Light  
Load (HLL) mode of operation under light loads. Refer  
to Section 4.2 “Light Load Operating Mode  
(MODE)” for further details.  
Connect to the AGND copper plane to improve thermal  
performance of the MIC2127A.  
2016 Microchip Technology Inc.  
DS20005676B-page 17  
MIC2127A  
The maximum duty cycle can be calculated using  
Equation 4-2:  
4.0  
FUNCTIONAL DESCRIPTION  
The MIC2127A is an adaptive on-time synchronous  
buck controller, designed to cover a wide range of input  
voltage applications ranging from 4.5V-5V. An adaptive  
on-time control scheme is employed to get a fast  
transient response and to obtain high-voltage  
conversion ratios at constant switching frequency.  
Overcurrent protection is implemented by sensing  
low-side MOSFET's RDS(ON), which eliminates lossy  
current sense resistor. The device features internal  
soft-start, enable input, UVLO, power good output  
(PG), secondary bootstrap LDO and thermal shutdown.  
EQUATION 4-2:  
tSW tOFFMIN  
230 ns  
tSW  
DMAX = --------------------------------------- = 1 ---------------  
tSW  
Where:  
t
=
Switching period, equal to 1/f  
SW  
SW  
It is not recommended to use the MIC2127A with an  
OFF time close to tOFF(MIN) during steady-state  
operation.  
4.1  
Theory of Operation  
The adaptive on-time control scheme results in a  
constant switching frequency over the wide range of  
input voltage and load current. The actual ON time and  
resulting switching frequency varies with the different  
rising and falling times of the external MOSFETs. The  
minimum controllable ON time (tON(MIN)) results in a  
lower switching frequency than the target switching  
frequency in high VIN to VOUT ratio applications.  
The MIC2127A is an adaptive on-time synchronous  
buck controller that operates based on ripple at the  
feedback node. The output voltage is sensed by the  
MIC2127A feedback pin (FB) and is compared to a  
0.6V reference voltage (VREF  
) at the low-gain  
transconductance error amplifier (gM), as shown in the  
Functional Block Diagram. Figure 4-1 shows the  
MIC2127A control loop timing during steady-state  
operation.  
Equation 4-3 shows the output-to-input voltage ratio,  
below which the MIC2127A lowers the switching  
frequency in order to regulate the output to set value.  
The error amplifier behaves as the short circuit for the  
ripple voltage frequency on the FB pin, which causes  
the error amplifier output voltage ripple to follow the  
feedback voltage ripple. When the transconductance  
error amplifier output (VgM) is below the reference  
voltage of the comparator, which is same as the error  
amplifier reference (VREF), the comparator triggers and  
generates an on-time event. The on-time period is  
predetermined by the fixed tON estimator circuitry,  
which is given by Equation 4-1:  
EQUATION 4-3:  
VOUT  
------------- tON(MIN) fSW  
VIN  
Where:  
V
V
f
=
=
=
=
Output voltage  
OUT  
IN  
Input voltage  
Switching frequency  
EQUATION 4-1:  
SW  
t
Minimum controllable ON time (80 ns typ.)  
ON(MIN)  
VOUT  
tONESTIMATED= --------------------------  
VVIN fSW  
Where:  
V
V
=
=
=
Output voltage  
OUT  
VIN  
Power stage input voltage  
Switching frequency  
f
SW  
At the end of the ON time, 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 of the  
high-side MOSFET depends on the feedback voltage.  
When the feedback voltage decreases, the output of  
the gM amplifier (VgM) also decreases. When the output  
of the gM amplifier (VgM) is below the reference voltage  
of the comparator (which is same as the error amplifier  
reference (VREF)), the OFF time ends and ON time is  
triggered. If the OFF time determined by the feedback  
voltage is less than the minimum OFF time (tOFF(MIN)  
)
of the MIC2127A, which is about 230 ns (typical), the  
MIC2127A control logic applies the tOFF(MIN), instead.  
DS20005676B-page 18  
2016 Microchip Technology Inc.  
MIC2127A  
Full Load  
ǻIL  
IL  
IL  
No Load  
ǻVOUT  
VOUT  
ǻVOUT = ESR*ǻIL  
VOUT  
ǻVFB  
VREF  
VFB  
ǻVFB = ǻVOUT *(VREF/VOUT  
)
ǻVFB  
VREF  
VREF  
VgM  
VFB  
MIC2127A Triggers ON-Time event if  
the error amplifier output (VgM) is below VREF  
VDH  
VREF  
VgM  
Estimated ON-Time  
FIGURE 4-1:  
MIC2127A Control Loop  
Timing.  
Figure 4-2 shows operation of the MIC2127A during  
load transient. The output voltage drops due to a  
sudden increase in load, which results in the error  
amplifier output (VgM) falling below VREF. This causes  
the comparator to trigger an on-time event. At the end  
of the ON time, a minimum OFF time tOFF(MIN) is  
generated to charge the bootstrap capacitor. The next  
ON time is triggered immediately after the tOFF(MIN) if  
the error amplifier output voltage (VgM) is still below  
VREF due to the low feedback voltage. This operation  
results in higher switching frequency during load  
transients. The switching frequency returns to the  
nominal set frequency once the output stabilizes at new  
load current level. The output recovery time is fast and  
the output voltage deviation is small in the MIC2127A  
converter due to the varying duty cycle and switching  
frequency.  
VDH  
toff(MIN)  
FIGURE 4-2:  
Response.  
MIC2127A Load Transient  
Unlike true current-mode control, the MIC2127A uses  
the output voltage ripple to trigger an on-time event. In  
order to meet the stability requirements, the MIC2127A  
feedback voltage ripple should be in phase with the  
inductor current ripple and large enough to be sensed  
by the internal error amplifier. The recommended  
feedback voltage ripple is approximately 20 mV-  
100 mV over the full input voltage range. If a low-ESR  
output capacitor is selected, then the feedback voltage  
ripple may be too small to be sensed by the internal  
error amplifier. Also, the output voltage ripple and the  
feedback voltage ripple are not necessarily in phase  
with the inductor current ripple if the ESR of the output  
capacitor is very low. For these applications, ripple  
injection is required to ensure proper operation. Refer  
to Section 5.7 “Ripple Injection” for details about the  
ripple injection technique.  
2016 Microchip Technology Inc.  
DS20005676B-page 19  
MIC2127A  
4.2  
Light Load Operating Mode  
(MODE)  
4.3  
Current Limit (I  
)
LIM  
The MIC2127A uses the low-side MOSFET RDS(ON) to  
sense inductor current. In each switching cycle of the  
MIC2127A converter, the inductor current is sensed by  
monitoring the voltage across the low-side MOSFET  
during the OFF period of the switching cycle, during  
which low-side MOSFET is ON. An internal current  
source of 100 µA generates a voltage across the  
external current limit, setting resistor RCL as shown in  
Figure 4-4.  
MIC2127A features a MODE pin that allows the user to  
select either Continuous Conduction mode or Hyper  
Light Load (HLL) mode under light loads. HLL mode  
increases the system efficiency at light loads by  
reducing the switching frequency. Continuous  
Conduction mode keeps the switching frequency  
almost constant over the load current range.  
Figure 4-3 shows the control loop timing in HLL mode.  
The MIC2127A has a zero crossing comparator  
(ZC Detection) that monitors the inductor current by  
sensing the voltage drop across the low-side MOSFET  
during its ON time. The zero crossing comparator  
triggers whenever the low-side MOSFET current goes  
negative and turns off the low-side MOSFET. The  
switching instant of the high-side MOSFET depends on  
the error amplifier output, which is same as the  
comparator inverting input (see the Functional Block  
Diagram). If the error amplifier output is higher than the  
comparator reference, then the MIC2127A enters into  
Sleep mode. During Sleep mode, both the high-side  
and low-side MOSFETs are kept off and the efficiency  
is optimized by shutting down all the nonessential  
circuits inside the MIC2127A. The load current is  
supplied by the output capacitor during Sleep mode.  
The control circuitry wakes up when the error amplifier  
output falls below the comparator reference and a tON  
pulse is triggered.  
VIN  
DH  
MIC2127A  
L1  
SW  
Control  
Logic  
RCL  
DL  
PGND  
CURRENT  
LIMIT  
DETECTION  
ICL  
ILIM  
FIGURE 4-4:  
MIC2127A Current Limiting  
Circuit.  
The ILIM pin voltage (VILIM) is the difference of the  
voltage across the low-side MOSFET and the voltage  
across the resistor (VCL). The sensed voltage VILIM is  
compared with the power ground (PGND) after a  
blanking time of 150 ns.  
Low side MOSFET current crosses 0A and the comparator inverting input, VgM, is higher than its reference.  
This condition triggers the HLL mode  
The comparator inverting input, VgM, is lower than its reference. The  
MIC2127A comes out of HLL mode  
IL  
0A  
If the absolute value of the voltage drop across the  
low-side MOSFET is greater than the absolute value of  
the voltage across the current setting resistor (VCL), the  
MIC2127A triggers the current limit event. Consecutive  
eight-current limit events trigger the Hiccup mode.  
Once the controller enters into Hiccup mode, it initiates  
a soft-start sequence after a hiccup timeout of 4 ms  
(typical). Both the high-side and low-side MOSFETs  
are turned off during hiccup timeout. The hiccup  
sequence, including the soft start, reduces the stress  
on the switching FETs and protects the load and supply  
from severe short conditions.  
VREF  
VFB  
VREF  
VgM  
ZCD  
The current limit can be programmed by using the  
following Equation 4-4.  
VDH  
VDL  
FIGURE 4-3:  
MIC2127A Control Loop  
Timing (HLL Mode).  
The typical no-load supply current during HLL mode is  
only about 300 µA, allowing the MIC2127A to achieve  
high efficiency at light load operation.  
DS20005676B-page 20  
2016 Microchip Technology Inc.  
MIC2127A  
bootstrap diode between the PVDD and BST pins. This  
circuit supplies energy to the high-side drive circuit. A  
low ESR ceramic capacitor should be connected  
between BST and SW pins (refer to the Typical  
Application circuit).The capacitor between BST and  
SW pins, CBST, is charged while the low-side MOSFET  
is on. When the high-side MOSFET driver is turned on,  
energy from CBST is used to turn the MOSFET on. A  
minimum of 0.1 µF low ESR ceramic capacitor is  
recommended between BST and SW pins. The  
required value of CBST can be calculated using the  
following Equation 4-6:  
EQUATION 4-4:  
ILPP  
ICLIM + --------------- RDSON+ VOFFSET  
2
RCL = --------------------------------------------------------------------------------------------------  
ICL  
Where:  
I
=
=
=
=
=
Load current limit  
CLIM  
R
On-resistance of low-side power MOSFET  
Inductor peak-to-peak ripple current  
Current-limit comparator offset (15 mV max.)  
Current-limit source current (100 µA typ)  
DS (ON)  
IL  
PP  
V
OFFSET  
I
CL  
EQUATION 4-6:  
Since MOSFET RDS(ON) varies from 30%-40% with  
temperature, it is recommended to consider the  
RDS(ON) variation while calculating RCL in the above  
equation, to avoid false current limiting due to  
increased MOSFET junction temperature rise. Also  
connect the SW pin directly to the drain of the low-side  
QG_HS  
CBST = ---------------  
VBST  
Where:  
Q
=
=
High-side MOSFET total gate charge  
Drop across the C  
G_HS  
V  
,
BST  
MOSFET to accurately sense the MOSFETs RDS(ON)  
.
BST  
generally 50 mV to 100 mV  
To improve the current limit variation, the MIC2127A  
adjusts the internal source current of the current limit  
(ICL) at a rate of 0.3 µA/°C when the MIC2127A  
junction temperature changes to compensate the  
RDS(ON) variation of external low-side MOSFET. The  
effectiveness of this method depends on the thermal  
gradient between the MIC2127A and the external  
low-side MOSFET. The lower the thermal gradient, the  
better the current limit variation.  
A small resistor in series with CBST can be used to slow  
down the turn-on time of the high-side N-channel  
MOSFET.  
4.6  
Low-Side MOSFET Gate Drive (DL)  
The MIC2127A's low-side drive circuit is designed to  
switch an N-Channel external MOSFET. The internal  
low-side MOSFET driver is powered by PVDD. Connect  
a minimum of 4.7 µF low-ESR ceramic capacitor to  
supply the transient gate current of the external  
MOSFET.  
A small capacitor (CCL) can be connected from the ILIM  
pin to PGND to filter the switch node ringing during the  
OFF time, allowing a better current sensing. The time  
constant of RCL and CCL should be less than the  
minimum OFF time.  
4.7  
Auxiliary Bootstrap LDO  
(EXTVDD)  
4.4  
Negative Current Limit  
The MIC2127A features an auxiliary bootstrap LDO  
that improves the system efficiency by supplying the  
MIC2127A internal circuit bias power and gate drivers  
from the converter output voltage. This LDO is enabled  
when the voltage on the EXTVDD pin is above 4.6V  
(typical) and, at the same time, the main LDO that  
operates from VIN is disabled to reduce power  
consumption.  
The MIC2127A implements negative current limit by  
sensing the SW voltage when the low-side FET is ON.  
If the SW node voltage exceeds 48 mV typical, the  
device turns off the low-side FET for 500 ns. Negative  
current limit value is shown in Equation 4-5.  
EQUATION 4-5:  
48mV  
INLIM = --------------------  
RDSON  
Where:  
I
=
=
Negative current limit  
NLIM  
R
On-resistance of low-side power MOSFET  
DS (ON)  
4.5  
High-Side MOSFET Gate Drive  
(DH)  
The MIC2127A's high-side drive circuit is designed to  
switch an N-Channel external MOSFET. The  
MIC2127A Functional Block diagram shows  
a
2016 Microchip Technology Inc.  
DS20005676B-page 21  
MIC2127A  
5.2  
Output Voltage Setting  
5.0  
5.1  
APPLICATIONS INFORMATION  
The output voltage can be adjusted using a resistor  
divider from output to AGND whose mid-point is  
connected to the FB pin, as shown the Figure 5-3.  
Setting the Switching Frequency  
The MIC2127A is an adjustable-frequency, synchro-  
nous buck controller, featuring a unique adaptive  
on-time control architecture. The switching frequency  
can be adjusted between 270 kHz-800 kHz by chang-  
ing the resistor divider network between VIN and AGND  
pins consisting of R1 and R2, as shown in Figure 5-1.  
MIC2127A  
VOUT  
MIC2127A  
R1  
VIN  
COMPENSATION  
VIN  
16  
11  
4.5V to 75V  
FB  
13  
gm  
R1  
R2  
SOFT-  
START  
R2  
FREQ  
Comparator  
VREF  
0.6V  
AGND  
14  
FIGURE 5-3:  
Output Voltage Adjustment.  
The output voltage can be calculated using  
Equation 5-2.  
FIGURE 5-1:  
Adjustment.  
Switching Frequency  
Equation 5-1 shows the estimated switching frequency.  
EQUATION 5-2:  
R1  
EQUATION 5-1:  
VOUT = VREF 1 + -----  
R2  
R2  
Where:  
fSW_ADJ = fO ------------------  
R1 + R2  
V
= 0.6V  
REF  
fO is the switching frequency when R1 is 100 kand R2  
being open; fO is typically 800 kHz. For more precise  
setting, it is recommended to use Figure 5-2.  
The maximum output voltage that can be programmed  
using the MIC2127A is limited to 30V, if not limited by  
the maximum duty cycle (see Equation 4-2).  
A typical value of R1 is less than 30 k. If R1 is too  
large, it may allow noise to be introduced into the  
voltage feedback loop. It also increases the offset  
between the set output voltage and actual output  
voltage because of the error amplifier bias current. 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 5-3.  
800  
VOUT = 5V  
R
1 = 100 kŸ  
700  
600  
500  
400  
300  
200  
IOUT = 5A  
VIN = 48V  
VIN = 75V  
VIN = 24V  
EQUATION 5-3:  
50  
500  
R2 (kŸ)  
5000  
R1  
R2 = ----------------------  
VOUT  
------------- 1  
VREF  
FIGURE 5-2:  
Switching Frequency vs. R2.  
DS20005676B-page 22  
2016 Microchip Technology Inc.  
MIC2127A  
EQUATION 5-5:  
IRMSHS= ILOAD  
5.3  
MOSFET Selection  
Important parameters for MOSFET selection are:  
D
• Voltage rating  
• On-resistance  
Total gate charge  
ILOAD is the load current and D is the operating duty  
cycle, given by Equation 5-6.  
The voltage rating for the high-side and low-side  
MOSFETs is essentially equal to the power stage input  
voltage VIN. A safety factor of 30% should be added to  
the VIN(MAX) while selecting the voltage rating of the  
MOSFETs to account for voltage spikes due to circuit  
parasitic elements.  
EQUATION 5-6:  
VOUT  
D = -------------  
VIN  
5.3.1  
HIGH-SIDE MOSFET POWER  
LOSSES  
EQUATION 5-7:  
The total power loss in the high-side MOSFET  
(PHSFET) is the sum of the power losses because of  
conduction (PCONDUCTION), switching (PSW), reverse  
recovery charge of low-side MOSFET body diode  
(PQrr) and MOSFET's output capacitance discharge, as  
calculated in the Equation 5-4.  
Q
SWHS RDHPULL_UP+ RHSGATE  
tR = -----------------------------------------------------------------------------------------------------  
DD VTH  
V
EQUATION 5-8:  
Q
SWHS RDHPULL_DOWN+ RHSGATE  
tF = -------------------------------------------------------------------------------------------------------------  
VTH  
EQUATION 5-4:  
Where:  
PHSFET = PCONDUCTIONHS+ PSWHS+ PQrr + PCOSS  
R
= High-side gate driver pull-up  
resistance  
DH(PULL-UP)  
DH(PULL-DOWN)  
HS(GATE)  
PCONDUCTIONHS= IRMSHS2 RDSON_HS  
R
= High-side gate driver pull-down  
resistance  
PSWHS= 0.5 VIN ILOAD tR + tFfSW  
PQrr = VIN Qrr fSW  
R
V
= High-side MOSFET gate resistance  
= Gate to Source threshold voltage of  
the high-side MOSFET  
TH  
1
PCOSS = -- COSSHS+ COSSHSVIN2 fSW  
Q
= Switching gate charge of the  
high-side MOSFET which can be  
approximated by Equation 5-9.  
SW(HS)  
2
Where:  
R
=
=
=
=
=
On-resistance of the high-side MOSFET  
Operating input voltage  
DS(ON_HS)  
V
IN  
EQUATION 5-9:  
I
f
Load current  
LOAD  
SW  
QGSHS  
Operating switching frequency  
QSWHS= -------------------- + Q GDHS  
2
Q
Reverse recovery charge of low-side  
MOSFET body diode or of external  
diode across low-side MOSFET  
rr  
Where:  
Q
= High-side MOSFET gate to source  
charge  
GS(HS)  
C
C
=
=
=
Effective high-side MOSFET output  
capacitance  
OSS(HS)  
OSS(LS)  
Q
)
= High-side MOSFET gate to drain charge  
GD(HS  
Effective low-side MOSFET output  
capacitance  
IRMS(HS)  
RMS current of the high-side MOSFET  
which can be calculated using  
Equation 5-5.  
=
The high-side MOSFET turn-on and  
turn-off transition times which can be  
approximated by Equation 5-7 and  
Equation 5-8  
tR, F  
t
2016 Microchip Technology Inc.  
DS20005676B-page 23  
MIC2127A  
5.3.2  
LOW-SIDE MOSFET POWER  
LOSSES  
The total power loss in the low-side MOSFET (PLSFET  
EQUATION 5-12:  
VOUT  VIN VOUT  
L = -----------------------------------------------------  
)
VIN fSW 0.3 IFL  
is the sum of the power losses because of conduction  
(PCONDUCTION(LS)) and body diode conduction during  
the dead time (PDT), as calculated in Equation 5-10.  
Where:  
V
= Input voltage  
IN  
f
I
= Switching frequency  
= Full load current  
= Output voltage  
SW  
FL  
EQUATION 5-10:  
V
PLSFET = PCONDUCTIONLS+ PDT  
OUT  
PCONDUCTIONLS= IRMSLS2 RDSON_LS  
For a selected Inductor, the peak-to-peak inductor  
current ripple can be calculated using Equation 5-13.  
PDT = 2 VF ILOAD tDT fSW  
EQUATION 5-13:  
Where:  
VOUT  VIN VOUT  
R
V
= On-resistance of the low-side MOSFET  
DS(ON_LS)  
IL_PP = -----------------------------------------------------  
VIN fSW L  
= Low-side MOSFET body diode forward  
voltage drop  
F
t
f
I
= Dead time which is approximately 20 ns  
= Switching Frequency  
DT  
The peak inductor current is equal to the load current  
plus one half of the peak-to-peak inductor current ripple  
which is shown in Equation 5-14.  
SW  
= RMS current of the low-side MOSFET  
which can be calculated using  
Equation 5-11  
RMS(LS)  
EQUATION 5-14:  
IL_PP  
EQUATION 5-11:  
IRMSLS= ILOAD  
IL_PK = ILOAD + ----------------  
2
1 – D  
The RMS and saturation current ratings of the selected  
inductor should be at least equal to the RMS current  
and saturation current calculated in Equation 5-15 and  
Equation 5-16.  
Where:  
ILOAD = load current  
D
= operating duty cycle  
EQUATION 5-15:  
5.4  
Inductor Selection  
IL_PP2  
IL_RMS  
=
ILOAD(MAX)2 + -----------------------  
Inductance value, saturation 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.  
12  
Where:  
I
= Maximum load current  
LOAD(MAX)  
The lower the inductance value, the higher the  
peak-to-peak ripple current through the inductor, which  
increases the core losses in the inductor. Higher  
inductor ripple current also requires more output  
capacitance to smooth out the ripple current. The  
greater the inductance value, the lower the  
peak-to-peak ripple current, which results in a larger  
and more expensive inductor.  
EQUATION 5-16:  
RCL ICL+ 15mV  
IL_SAT = -------------------------------------------------  
RDS(ON)  
Where:  
R
= Current limit resistor  
CL  
I
= Current-Limit Source Current  
(100 µA typical)  
CL  
A good compromise between size, loss and cost is to  
set the inductor ripple current to be equal to 30% of the  
maximum output current.  
R
= On-resistance of low-side power MOSFET  
DS (ON)  
The inductance value is calculated by Equation 5-12.  
DS20005676B-page 24  
2016 Microchip Technology Inc.  
MIC2127A  
Maximizing efficiency requires the proper selection of  
core material and minimizing the winding resistance.  
Use of ferrite materials is recommended in the higher  
switching frequency applications. Lower-cost iron  
powder cores may be used, but the increase in core  
loss reduces 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. 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 magnetic’s vendor.  
EQUATION 5-19:  
IL_PP  
COUT = -------------------------------------------------  
8 fSW VOUT_PP  
Where:  
C
= Output capacitance value  
= Switching frequency  
OUT  
f
SW  
V  
= Steady state output voltage ripple  
OUT_PP  
As described in Section 4.1 “Theory of Operation”,  
the MIC2127A requires at least 20 mV peak-to-peak  
ripple at the FB pin to ensure that the gM amplifier and  
the comparator behave properly. Also, the output  
voltage ripple should be in phase with the inductor  
current. Therefore, the output voltage ripple caused by  
the output capacitor’s 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  
circuit should be used to provide enough  
feedback-voltage ripple. Refer to the Section 5.7  
“Ripple Injection” for details.  
The amount of copper loss in the inductor is calculated  
by Equation 5-17.  
EQUATION 5-17:  
PINDUCTORCU= IL_RMS2 RDCR  
The voltage rating of the capacitor should be twice the  
output voltage for tantalum and 20% greater for alumi-  
num electrolytic, ceramic or OS-CON. The output  
capacitor RMS current is calculated in Equation 5-20.  
5.5  
Output Capacitor Selection  
The main parameters for selecting the output capacitor  
are capacitance value, voltage rating and RMS current  
rating. The type of the output capacitor is usually  
determined by its equivalent series resistance (ESR).  
Recommended capacitor types are ceramic, tantalum,  
low-ESR aluminum electrolytic, OS-CON and  
POSCAP. The output capacitor ESR also affects the  
control loop from a stability point of view. The maximum  
value of ESR can be calculated using Equation 5-18.  
EQUATION 5-20:  
IL_PP  
IC_OUT(RMS) = ----------------  
12  
The power dissipated in the output capacitor is shown  
in Equation 5-21.  
EQUATION 5-21:  
EQUATION 5-18:  
PDIS(C_OUT) = IC_OUT(RMS)2 ESRC_OUT  
VOUT_PP  
ESR -------------------------  
IL_PP  
Where:  
V  
I  
= Peak-to-peak output voltage ripple  
= Peak-to-peak inductor current ripple  
OUT_PP  
L_PP  
The required output capacitance to meet steady state  
output voltage ripple can be calculated using  
Equation 5-19.  
2016 Microchip Technology Inc.  
DS20005676B-page 25  
MIC2127A  
The applications are divided into three situations  
according to the amount of the feedback voltage ripple:  
5.6  
Input Capacitor Selection  
The input capacitor reduces peak current drawn from  
the power supply and reduces noise and voltage ripple  
on the input. The input voltage ripple depends on the  
input capacitance and ESR. The input capacitance and  
ESR values can be calculated using Equation 5-22.  
1. Enough ripple at the feedback due to the large  
ESR of the output capacitor (Figure 5-4). The  
converter is stable without any additional ripple  
injection at the FB node. The feedback voltage  
ripple is given by Equation 5-25.  
EQUATION 5-22:  
EQUATION 5-25:  
ILOAD D  1 – D  
R2  
CIN = ------------------------------------------------  
  fSW VIN_C  
VFBPP= ------------------ ESR IL_PP  
R2 + R1  
VIN_ESR  
ESRC_IN = -----------------------  
IL_PP is the peak-to-peak value of the inductor current  
ripple.  
IL_PK  
Where:  
I
I
= Load Current  
LOAD  
L_PK  
= Peak Inductor Current  
L
SW  
V  
V  
η
= Input ripple due to capacitance  
= Input ripple due to input capacitor ESR  
= Power conversion efficiency  
INC  
R1  
COUT  
INESR  
MIC2127A  
FB  
ESR  
R2  
The input capacitor should be rated for ripple current  
rating and voltage rating. The RMS value of input  
capacitor current is determined at the maximum output  
current. The RMS current rating of the input capacitor  
should be greater than or equal to the input capacitor  
RMS current calculated using Equation 5-23.  
FIGURE 5-4:  
Enough Ripple at FB.  
2. Inadequate ripple at the feedback voltage due to  
the small ESR of the output capacitor.  
EQUATION 5-23:  
The output voltage ripple can be fed into the FB pin  
through a feed forward capacitor, CFF in this case, as  
shown in Figure 5-5. The typical CFF value is between  
1 nF-100 nF. With the feed forward capacitor, the feed-  
back voltage ripple is very close to the output voltage  
ripple, which is shown in Equation 5-26.  
IC_IN(RMS) = ILOAD(MAX)  
D  1 – D  
The power dissipated in the input capacitor is  
calculated using Equation 5-24.  
EQUATION 5-26:  
EQUATION 5-24:  
VFBPP= ESR IL_PP  
PDISS(C_IN) = IC_IN(RMS)2 ESRC_IN  
5.7  
Ripple Injection  
L
SW  
The minimum recommended ripple at the FB pin for  
proper operation of the MIC2127A error amplifier and  
comparator is 20 mV. However, the output voltage  
ripple is generally designed as 1%-2% of the output  
voltage. For low output voltages, such as a 1V, the  
output voltage ripple is only 10 mV-20 mV, and the  
feedback voltage ripple is less than 20 mV. If the  
feedback voltage ripple is so small that the gM amplifier  
and comparator cannot sense it, then the MIC2127A  
loses control and the output voltage is not regulated. In  
order to have sufficient VFB ripple, the ripple injection  
method should be applied for low output voltage ripple  
applications.  
R1  
R2  
CFF  
COUT  
ESR  
MIC2127A  
FB  
FIGURE 5-5:  
Inadequate Ripple at FB.  
3. Virtually no ripple at the FB pin voltage due to  
the very-low ESR of the output capacitors.  
DS20005676B-page 26  
2016 Microchip Technology Inc.  
MIC2127A  
In this case, additional ripple can be injected into the  
FB pin from the switching node SW, via a resistor RINJ  
and a capacitor CINJ, as shown in Figure 5-6.  
5.8  
Power Dissipation in MIC2127A  
The MIC2127A features two Low Dropout Regulators  
(LDOs) to supply power at the PVDD pin from either VIN  
or EXTVDD depending on the voltage at the EXTVDD  
pin. PVDD powers MOSFET drivers and VDD pin, which  
is recommended to connect to PVDD through a low  
pass filter, powers the internal circuitry. In the  
applications where the output voltage is 5V and above  
(up to 14V), it is recommended to connect EXTVDD to  
the output to reduce the power dissipation in the  
MIC2127A, to reduce the MIC2127A junction  
temperature and to improve the system efficiency.  
L
SW  
RINJ  
R1  
R2  
CFF  
COUT  
ESR  
CINJ  
MIC2127A  
FB  
The power dissipation in the MIC2127A depends on  
the internal LDO being in use, on the gate charge of the  
external MOSFETs and on the switching frequency.  
The power dissipation and the junction temperature of  
the MIC2127A can be estimated using Equations 5-30,  
5-31 and 5-32.  
FIGURE 5-6:  
Invisible Ripple at FB.  
The injected ripple at the FB pin in this case is given by  
the Equation 5-27.  
EQUATION 5-27:  
Power dissipation in the MIC2127A when EXTVDD is  
not used.  
VOUT  1 – D  
VFBPP= ------------------------------------------  
CFF RINJ fSW  
EQUATION 5-30:  
In Equation 5-27, it is assumed that the time constant  
associated with the CFF meets the criterion shown in  
Equation 5-28.  
PIC = VIN  ISW + IQ  
Power dissipation in the MIC2127A when EXTVDD is  
used.  
EQUATION 5-28:  
  TSW  
EQUATION 5-31:  
= CFF  R1 R2 RINJ  
PIC = VEXTVDD  ISW + IQ  
ISW = QG fSW  
QG = QG_HS + QG_LS  
The process of sizing the ripple injection resistor and  
capacitors is:  
1. Select CINJ in the range of 47 nF-100 nF, which  
can be considered as short for a wide range of  
the frequencies.  
Where:  
2. Select CFF in the range of 0.47 nF-10 nF, if R1  
I
I
= Switching current into the V pin  
SW  
Q
IN  
and R2 are in krange.  
= Quiescent current  
3. Select RINJ according to Equation 5-29.  
Q
= Total gate charge of the external MOS-  
FETs which is sum of the gate charge of  
G
high-side MOSFET (Q  
)
and the  
EQUATION 5-29:  
G_HS  
low-side MOSFET (Q  
) at 5V gate to  
G_LS  
source voltage. Gate charge information  
can be obtained from the MOSFETs  
datasheet.  
VOUT  1 D  
RINJ = -------------------------------------------------------  
CFF fSW VFBPP  
Where:  
V
= Voltage at the EXTVDD pin  
EXTVDD  
V
= Output voltage  
= Duty cycle  
OUT  
(4.6 V  
14 V typ.)  
EXTVDD  
D
f
= Switching frequency  
The junction temperature of the MIC2127A can be  
estimated using Equation 5-32.  
SW  
V (pp) = Feedback Ripple  
FB  
Once all the ripple injection component values are cal-  
culated, ensure that the criterion shown in  
Equation 5-28 is met.  
2016 Microchip Technology Inc.  
DS20005676B-page 27  
MIC2127A  
EQUATION 5-32:  
EQUATION 5-33:  
·
PIC = 48V 10 mA + 1.5mA  
TJ = PIC JA+ TA  
PIC = 0.552W  
Where:  
TJ = 0.552W 50.8C W + 85C  
TJ = 113C  
T
= Junction temperature  
= Power dissipation  
J
P
IC  
θ
= Junction Ambient Thermal resistance  
(50.8°C/W)  
JA  
When the 5V output is used as the input to the  
EXTVDD pin, the MIC2127A junction temperature  
reduces from +113°C to +88°C, as calculated in  
Equation 5-34.  
The maximum recommended operating junction  
temperature for the MIC2127A is +125°C.  
Using the output voltage of the same switching  
regulator, when it is between 4.6V (typ.) to 14V, as the  
voltage at the EXTVDD pin significantly reduces the  
power dissipation inside the MIC2127A. This reduces  
the junction temperature rise as illustrated in  
Equation 5-34.  
EQUATION 5-34:  
PIC = 5V 10 mA +1.5 mA  
PIC = 0.058W  
TJ = 0.058W 50.8C W + 85C  
TJ = 88C  
For the typical case of VVIN = 48V, VOUT = 5V,  
maximum ambient temperature of +85°C and 10 mA of  
ISW, the MIC2127A junction temperature when the  
EXTVDD is not used is given by Equation 5-33.  
DS20005676B-page 28  
2016 Microchip Technology Inc.  
MIC2127A  
6.4  
Output Capacitor  
6.0  
PCB LAYOUT GUIDELINES  
• Use a copper plane to connect the output  
capacitor ground terminal to the input capacitor  
ground terminal.  
PCB layout is critical to achieve reliable, stable and  
efficient performance. The following guidelines should  
be followed to ensure proper operation of the  
MIC2127A converter.  
• The feedback trace should be separate from the  
power trace and connected as closely as possible  
to the output capacitor. Sensing a long  
high-current load trace can degrade the DC load  
regulation.  
6.1  
IC  
• The ceramic bypass capacitors, which are con-  
nected to the VDD and PVDD pins, must be located  
right at the IC. Use wide traces to connect to the  
VDD, PVDD and AGND, and PGND pins respectively.  
6.5  
MOSFETs  
• MOSFET gate drive traces must be short and  
wide. The ground plane should be the connection  
• The signal ground pin (AGND) must be connected  
directly to the ground planes.  
between the MOSFET source and PGND  
.
• Place the IC close to the point-of-load (POL).  
• Chose a low-side MOSFET with a high CGS/CGD  
ratio and a low internal gate resistance to  
minimize the effect of dv/dt inducted turn-on.  
• Signal and power grounds should be kept  
separate and connected at only one location.  
• Use a 4.5V VGS rated MOSFET. Its higher gate  
threshold voltage is more immune to glitches than  
a 2.5V or 3.3V rated MOSFET.  
6.2  
Input Capacitor  
• Place the input ceramic capacitors as closely as  
possible to the MOSFETs.  
• Place several vias to the ground plane closely to  
the input capacitor ground terminal.  
6.3  
Inductor  
• Keep the inductor connection to the switch node  
(SW) short.  
• Do not route any digital lines underneath or close  
to the inductor.  
• Keep the switch node (SW) away from the  
feedback (FB) pin.  
• The SW pin should be connected directly to the  
drain of the low-side MOSFET to accurately  
sense the voltage across the low-side MOSFET.  
2016 Microchip Technology Inc.  
DS20005676B-page 29  
MIC2127A  
7.0  
7.1  
PACKAGING INFORMATION  
Package Marking Information  
16-Pin QFN (3 x 3 mm)  
Example  
Legend: XX...X Product code or customer-specific information  
Y
YY  
WW  
NNN  
Year code (last digit of calendar year)  
Year code (last 2 digits of calendar year)  
Week code (week of January 1 is week ‘01’)  
Alphanumeric traceability code  
Pb-free JEDEC® designator for Matte Tin (Sn)  
e
3
*
This package is Pb-free. The Pb-free JEDEC designator (  
can be found on the outer packaging for this package.  
e
3
)
, , Pin one index is identified by a dot, delta up, or delta down (triangle  
mark).  
Note: In the event the full Microchip part number cannot be marked on one line, it will  
be carried over to the next line, thus limiting the number of available  
characters for customer-specific information. Package may or may not include  
the corporate logo.  
Underbar (_) and/or Overbar () symbol may not be to scale.  
DS20005676B-page 30  
2016 Microchip Technology Inc.  
MIC2127A  
Note: For the most current package drawings, please see the Microchip Packaging Specification located at  
http://www.microchip.com/packaging.  
2016 Microchip Technology Inc.  
DS20005676B-page 31  
MIC2127A  
NOTES:  
DS20005676B-page 32  
2016 Microchip Technology Inc.  
MIC2127A  
APPENDIX A: REVISION HISTORY  
Revision B (December 2016)  
• Minor editorial corrections.  
• Updated Product Identification System page.  
Revision A (December 2016)  
• Original Release of this Document.  
2016 Microchip Technology Inc.  
DS20005676B-page 33  
MIC2127A  
NOTES:  
DS20005676B-page 34  
2016 Microchip Technology Inc.  
MIC2127A  
PRODUCT IDENTIFICATION SYSTEM  
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.  
X
XX  
XX  
PART NO.  
Device  
Examples:  
a) MIC2127AYML-TR: 75V, Synchronous Buck  
Controller Featuring  
Temperature  
Package Code Media Type  
Adaptive On-Time Control,  
–40°C to +125°C junction  
temperature range, 16-LD  
VQFN package, 5000/reel  
Device:  
MIC2127A: 75V, Synchronous Buck Controller Featuring  
Adaptive On-Time Control  
b) MIC2127AYML-T5: 75V, Synchronous Buck  
Controller Featuring  
Temperature:  
Y
= Industrial Temperature Grade  
Adaptive On-Time Control,  
–40°C to +125°C junction  
(-40°C to +125°C)  
temperature range, 16-LD  
VQFN package, 500/reel  
Package:  
ML  
=
16 Lead, 3x3 mm VQFN  
TR  
T5  
=
=
5000/reel  
500/reel  
Media Type:  
2016 Microchip Technology Inc.  
DS20005676B-page 35  
MIC2127A  
NOTES:  
DS20005676B-page 36  
2016 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, AVR,  
AVR logo, AVR Freaks, BeaconThings, BitCloud, CryptoMemory,  
CryptoRF, dsPIC, FlashFlex, flexPWR, Heldo, JukeBlox, KEELOQ,  
KEELOQ logo, Kleer, LANCheck, LINK MD, maXStylus,  
maXTouch, MediaLB, megaAVR, MOST, MOST logo, MPLAB,  
OptoLyzer, PIC, picoPower, PICSTART, PIC32 logo, Prochip  
Designer, QTouch, RightTouch, SAM-BA, SpyNIC, SST, SST  
Logo, SuperFlash, tinyAVR, UNI/O, and XMEGA 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.  
Adjacent Key Suppression, AKS, Analog-for-the-Digital Age, Any  
Capacitor, AnyIn, AnyOut, BodyCom, chipKIT, chipKIT logo,  
CodeGuard, CryptoAuthentication, CryptoCompanion,  
CryptoController, dsPICDEM, dsPICDEM.net, Dynamic Average  
Matching, DAM, ECAN, EtherGREEN, In-Circuit Serial  
Programming, ICSP, Inter-Chip Connectivity, JitterBlocker,  
KleerNet, KleerNet logo, Mindi, MiWi, motorBench, MPASM, MPF,  
MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach,  
Omniscient Code Generation, PICDEM, PICDEM.net, PICkit,  
PICtail, PureSilicon, QMatrix, RightTouch logo, REAL ICE, Ripple  
Blocker, SAM-ICE, Serial Quad I/O, SMART-I.S., 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 trademark 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.  
QUALITY MANAGEMENT SYSTEM  
CERTIFIED BY DNV  
© 2016, Microchip Technology Incorporated, All Rights Reserved.  
ISBN: 978-1-5224-1227-4  
== ISO/TS 16949 ==  
2016 Microchip Technology Inc.  
DS20005676B-page 37  
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  
Finland - Espoo  
Tel: 358-9-4520-820  
Australia - Sydney  
Tel: 61-2-9868-6733  
Fax: 61-2-9868-6755  
Web Address:  
www.microchip.com  
France - Paris  
Tel: 33-1-69-53-63-20  
Fax: 33-1-69-30-90-79  
India - New Delhi  
Tel: 91-11-4160-8631  
Fax: 91-11-4160-8632  
Atlanta  
Duluth, GA  
Tel: 678-957-9614  
Fax: 678-957-1455  
China - Beijing  
Tel: 86-10-8569-7000  
Fax: 86-10-8528-2104  
France - Saint Cloud  
Tel: 33-1-30-60-70-00  
India - Pune  
Tel: 91-20-3019-1500  
China - Chengdu  
Tel: 86-28-8665-5511  
Fax: 86-28-8665-7889  
Germany - Garching  
Tel: 49-8931-9700  
Germany - Haan  
Austin, TX  
Tel: 512-257-3370  
Japan - Osaka  
Tel: 81-6-6152-7160  
Fax: 81-6-6152-9310  
Boston  
Tel: 49-2129-3766400  
China - Chongqing  
Tel: 86-23-8980-9588  
Fax: 86-23-8980-9500  
Westborough, MA  
Tel: 774-760-0087  
Fax: 774-760-0088  
Japan - Tokyo  
Tel: 81-3-6880- 3770  
Fax: 81-3-6880-3771  
Germany - Heilbronn  
Tel: 49-7131-67-3636  
China - Dongguan  
Tel: 86-769-8702-9880  
Germany - Karlsruhe  
Tel: 49-721-625370  
Chicago  
Itasca, IL  
Tel: 630-285-0071  
Fax: 630-285-0075  
Korea - Daegu  
Tel: 82-53-744-4301  
Fax: 82-53-744-4302  
China - Guangzhou  
Tel: 86-20-8755-8029  
Germany - Munich  
Tel: 49-89-627-144-0  
Fax: 49-89-627-144-44  
China - Hangzhou  
Tel: 86-571-8792-8115  
Fax: 86-571-8792-8116  
Korea - Seoul  
Dallas  
Addison, TX  
Tel: 972-818-7423  
Fax: 972-818-2924  
Tel: 82-2-554-7200  
Fax: 82-2-558-5932 or  
82-2-558-5934  
Germany - Rosenheim  
Tel: 49-8031-354-560  
China - Hong Kong SAR  
Tel: 852-2943-5100  
Fax: 852-2401-3431  
Israel - Ra’anana  
Tel: 972-9-744-7705  
Malaysia - Kuala Lumpur  
Tel: 60-3-6201-9857  
Fax: 60-3-6201-9859  
Detroit  
Novi, MI  
Tel: 248-848-4000  
Italy - Milan  
Tel: 39-0331-742611  
Fax: 39-0331-466781  
China - Nanjing  
Tel: 86-25-8473-2460  
Fax: 86-25-8473-2470  
Malaysia - Penang  
Tel: 60-4-227-8870  
Fax: 60-4-227-4068  
Houston, TX  
Tel: 281-894-5983  
Italy - Padova  
Tel: 39-049-7625286  
China - Qingdao  
Tel: 86-532-8502-7355  
Fax: 86-532-8502-7205  
Indianapolis  
Noblesville, IN  
Tel: 317-773-8323  
Fax: 317-773-5453  
Tel: 317-536-2380  
Philippines - Manila  
Tel: 63-2-634-9065  
Fax: 63-2-634-9069  
Netherlands - Drunen  
Tel: 31-416-690399  
Fax: 31-416-690340  
China - Shanghai  
Tel: 86-21-3326-8000  
Fax: 86-21-3326-8021  
Singapore  
Tel: 65-6334-8870  
Fax: 65-6334-8850  
Norway - Trondheim  
Tel: 47-7289-7561  
Los Angeles  
China - Shenyang  
Tel: 86-24-2334-2829  
Fax: 86-24-2334-2393  
Mission Viejo, CA  
Tel: 949-462-9523  
Fax: 949-462-9608  
Tel: 951-273-7800  
Poland - Warsaw  
Tel: 48-22-3325737  
Taiwan - Hsin Chu  
Tel: 886-3-5778-366  
Fax: 886-3-5770-955  
Romania - Bucharest  
Tel: 40-21-407-87-50  
China - Shenzhen  
Tel: 86-755-8864-2200  
Fax: 86-755-8203-1760  
Taiwan - Kaohsiung  
Tel: 886-7-213-7830  
Raleigh, NC  
Tel: 919-844-7510  
Spain - Madrid  
Tel: 34-91-708-08-90  
Fax: 34-91-708-08-91  
China - Wuhan  
Tel: 86-27-5980-5300  
Fax: 86-27-5980-5118  
Taiwan - Taipei  
Tel: 886-2-2508-8600  
Fax: 886-2-2508-0102  
New York, NY  
Tel: 631-435-6000  
Sweden - Gothenberg  
Tel: 46-31-704-60-40  
San Jose, CA  
Tel: 408-735-9110  
Tel: 408-436-4270  
China - Xian  
Tel: 86-29-8833-7252  
Fax: 86-29-8833-7256  
Thailand - Bangkok  
Tel: 66-2-694-1351  
Fax: 66-2-694-1350  
Sweden - Stockholm  
Tel: 46-8-5090-4654  
Canada - Toronto  
Tel: 905-695-1980  
Fax: 905-695-2078  
UK - Wokingham  
Tel: 44-118-921-5800  
Fax: 44-118-921-5820  
DS20005676B-page 38  
2016 Microchip Technology Inc.  
11/07/16  

相关型号:

MIC2127A

75V, Synchronous Buck Controller Featuring Adaptive On-Time Control
MICROCHIP

MIC2127AYML-T5

75V, SYNCHRONOUS BUCK CONTROLLER
MICROCHIP

MIC2127AYML-TR

75V SYNCHRONOUS BUCK CONTROLLER
MICROCHIP

MIC2128YML

SWITCHING CONTROLLER
MICROCHIP

MIC2128YML-T5

75V, SYNCHRONOUS BUCK CONTROLLER
MICROCHIP

MIC2128YML-TR

75V, SYNCHRONOUS BUCK CONTROLLER
MICROCHIP

MIC2128YML-TRVAO

Switching Regulator/Controller
MICROCHIP

MIC2128YML-TS

Switching Controller
MICROCHIP

MIC2130

High Voltage Synchronous Buck Control IC with Low EMI Option
MICREL

MIC2130-1YML

High Voltage Synchronous Buck Control IC with Low EMI Option
MICREL

MIC2130-1YML-TR

SWITCHING CONTROLLER, 170kHz SWITCHING FREQ-MAX, QCC16
MICROCHIP

MIC2130-1YTSE

High Voltage Synchronous Buck Control IC with Low EMI Option
MICREL