MCP16312 [MICROCHIP]

The MCP16311 is a compact, high-efficiency, fixed frequency PWM/PFM, synchronous step-down DC-DC c;
MCP16312
型号: MCP16312
厂家: MICROCHIP    MICROCHIP
描述:

The MCP16311 is a compact, high-efficiency, fixed frequency PWM/PFM, synchronous step-down DC-DC c

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MCP16311/2  
30V Input, 1A Output, High-Efficiency,  
Integrated Synchronous Switch Step-Down Regulator  
Features  
General Description  
• Up to 95% Efficiency  
The MCP16311/2 is a compact, high-efficiency, fixed  
frequency, synchronous step-down DC-DC converter in  
an 8-pin MSOP, or 2 x 3 TDFN package that operates  
from input voltage sources up to 30V. Integrated  
features include a high-side and a low-side switch, fixed  
frequency peak current mode control, internal  
compensation, peak current limit and overtemperature  
protection. The MCP16311/2 provides all the active  
functions for local DC-DC conversion, with fast transient  
response and accurate regulation.  
• Input Voltage Range: 4.4V to 30V  
• 1A Output Current Capability  
• Output Voltage Range: 2.0V to 24V  
• Qualification: AEC-Q100 Rev. G, Grade 1 (-40°C  
to 125°C)  
• Integrated N-Channel High-Side and Low-Side  
Switches:  
- 170 m, Low Side  
- 300 m, High Side  
• Stable Reference Voltage: 0.8V  
High converter efficiency is achieved by integrating the  
current-limited, low-resistance, high-speed high-side  
and low-side switches and associated drive circuitry.  
The MCP16311 is capable of running in PWM/PFM  
mode. It switches in PFM mode for light load  
conditions and for large buck conversion ratios. This  
results in a higher efficiency over all load ranges. The  
MCP16312 runs in PWM-only mode, and is  
recommended for noise-sensitive applications.  
• Automatic Pulse Frequency Modulation/Pulse-  
Width Modulation (PFM/PWM) Operation  
(MCP16311):  
- PFM Operation Disabled (MCP16312)  
- PWM Operation: 500 kHz  
• Low Device Shutdown Current: 3 µA typical  
• Low Device Quiescent Current:  
- 44 µA (non-switching, PFM Mode)  
• Internal Compensation  
The MCP16311/2 can supply up to 1A of continuous  
current while regulating the output voltage from 2V to  
12V. An integrated, high-performance peak current  
mode architecture keeps the output voltage tightly  
regulated, even during input voltage steps and output  
current transient conditions common in power systems.  
• Internal Soft-Start: 300 µs (EN low-to-high)  
• Peak Current Mode Control  
• Cycle-by-Cycle Peak Current Limit  
• Undervoltage Lockout (UVLO):  
- 4.1V typical to start  
The EN input is used to turn the device on and off.  
While off, only a few micro amps of current are  
consumed from the input.  
- 3.6V typical to stop  
• Overtemperature Protection  
• Thermal Shutdown:  
Output voltage is set with an external resistor divider.  
The MCP16311/2 is offered in small MSOP-8 and 2 x 3  
TDFN surface mount packages.  
- +150°C  
- +25°C Hysteresis  
Package Type  
Applications  
• PIC®/dsPIC® Microcontroller Bias Supply  
• 24V Industrial Input DC-DC Conversion  
• General Purpose DC-DC Conversion  
• Local Point of Load Regulation  
• Automotive Battery Regulation  
• Set-Top Boxes  
• Cable Modems  
• Wall Transformer Regulation  
• Laptop Computers  
MCP16311/2  
2x3 TDFN*  
MCP16311/2  
MSOP  
VFB  
AGND  
1
8 AGND  
VFB  
VCC  
1
2
8
7
6
5
BOOST  
VCC  
EN  
BOOST  
SW  
2
3
4
7
6
5
EP  
9
EN 3  
VIN  
4
SW  
PGND  
VIN  
PGND  
* Includes Exposed Thermal Pad (EP); see Table 3-1.  
• Networking Systems  
• AC-DC Digital Control Bias  
• Distributed Power Supplies  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 1  
MCP16311/2  
Typical Applications  
CBOOST  
100 nF  
L1  
15 µH  
VOUT  
3.3V @ 1A  
VIN  
4.5V to 30V  
BOOST  
VIN  
SW  
VFB  
COUT  
2 x 10 µF  
CIN  
2 x 10 µF  
EN  
31.6 k  
VCC  
GND  
10 k  
CVCC  
1 µF  
CBOOST  
100 nF  
L1  
22 µH  
VOUT  
5V, @ 1A  
Vin  
6V to 30V  
BOOST  
VIN  
SW  
VFB  
COUT  
2 x 10 µF  
CIN  
2 x 10 µF  
EN  
52.3 k  
10 k  
VCC  
GND  
CVCC  
1 µF  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
V
OUT= 5V  
V
OUT = 3.3V  
VIN = 12V  
PWM ONLY  
PWM/PFM  
1
10  
100  
1000  
IOUT (mA)  
DS20005255B-page 2  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
† 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.  
1.0  
ELECTRICAL  
CHARACTERISTICS  
Absolute Maximum Ratings †  
V
SW ............................................................... -0.5V to 32V  
IN,  
BOOST – GND ................................................... -0.5V to 38V  
BOOST – SW Voltage........................................ -0.5V to 6.0V  
V
Voltage........................................................ -0.5V to 6.0V  
FB  
EN Voltage ............................................. -0.5V to (V + 0.3V)  
IN  
Output Short-Circuit Current .................................Continuous  
Power Dissipation .......................................Internally Limited  
Storage Temperature ....................................-65°C to +150°C  
Ambient Temperature with Power Applied ....-40°C to +125°C  
Operating Junction Temperature...................-40°C to +150°C  
ESD Protection on All Pins:  
HBM.....................................................................1 kV  
MM......................................................................200V  
DC CHARACTERISTICS  
Electrical Characteristics: Unless otherwise indicated, TA = +25°C, VIN = VEN = 7V, VBOOST - VSW = 5.0V,  
OUT = 5.0V, IOUT = 100 mA, L = 22 µH, COUT = CIN = 2 x 10 µF X7R Ceramic Capacitors.  
Boldface specifications apply over the TA range of -40°C to +125°C.  
V
Parameters  
Sym.  
Min.  
Typ.  
Max.  
Units  
Conditions  
VIN Supply Voltage  
Input Voltage  
VIN  
IQ  
4.4  
30  
60  
V
Note 1  
Quiescent Current  
44  
µA  
Nonswitching,  
VFB = 0.9V  
Quiescent Current -  
PFM Mode  
IQ_PFM  
IQ_PWM  
IQ_SHDN  
85  
3.8  
3
8
µA  
mA  
µA  
Switching,  
IOUT = 0 (MCP16311)  
Quiescent Current -  
PWM Mode  
Switching,  
I
OUT = 0 (MCP16312)  
Quiescent Current -  
Shutdown  
9
VOUT = EN = 0V  
VIN Undervoltage Lockout  
Undervoltage Lockout Start  
Undervoltage Lockout Stop  
UVLOSTRT  
UVLOSTOP  
UVLOHYS  
3.18  
0.2  
4.1  
3.6  
0.5  
4.4  
1
V
V
V
VIN Rising  
VIN Falling  
Undervoltage Lockout  
Hysteresis  
Output Characteristics  
Feedback Voltage  
VFB  
0.784  
2.0  
0.800  
0.816  
24  
V
V
IOUT = 5 mA  
Output Voltage  
Adjust Range  
VOUT  
Note 2, Note 3  
Feedback Voltage  
Line Regulation  
VFB/VFB)/VIN -0.15  
VFB / VFB  
0.01  
0.25  
0.15  
%/V  
%
VIN = 7V to 30V,  
IOUT = 50 mA  
Feedback Voltage  
Load Regulation  
IOUT = 5 mA to 1A,  
MCP16312  
Note 1: The input voltage should be greater than the output voltage plus headroom voltage; higher load currents  
increase the input voltage necessary for regulation. See characterization graphs for typical input-to-output  
operating voltage range.  
2: For VIN < VOUT, VOUT will not remain in regulation; for output voltages above 12V, the maximum current  
will be limited to under 1A.  
3: Determined by characterization, not production tested.  
4: This is ensured by design.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 3  
MCP16311/2  
DC CHARACTERISTICS (CONTINUED)  
Electrical Characteristics: Unless otherwise indicated, TA = +25°C, VIN = VEN = 7V, VBOOST - VSW = 5.0V,  
VOUT = 5.0V, IOUT = 100 mA, L = 22 µH, COUT = CIN = 2 x 10 µF X7R Ceramic Capacitors.  
Boldface specifications apply over the TA range of -40°C to +125°C.  
Parameters  
Feedback Input  
Sym.  
Min.  
Typ.  
Max.  
250  
Units  
Conditions  
IFB  
10  
nA  
Bias Current  
Output Current  
IOUT  
1
A
Notes 1 to 3, Figure 2-7  
Switching Characteristics  
Switching Frequency  
Maximum Duty Cycle  
Minimum Duty Cycle  
fSW  
425  
85  
500  
94  
2
575  
kHz  
%
DCMAX  
DCMIN  
RDS(ON)  
Note 3  
Note 4  
%
High-Side NMOS Switch-On  
Resistance  
0.3  
VBOOST – VSW = 5V,  
Note 3  
Buck NMOS Switch  
Current Limit  
I(MAX)  
1.8  
A
VBOOST – VSW = 5V,  
Note 3  
Synchronous NMOS Switch-  
On Resistance  
RDS(ON)  
0.17  
Note 3  
EN Input Characteristics  
EN Input Logic High  
EN Input Logic Low  
EN Input Leakage Current  
Soft-Start Time  
VIH  
VIL  
1.85  
0.4  
1
V
V
IENLK  
tSS  
0.1  
300  
µA  
µs  
VEN = 5V  
EN Low-to-High,  
90% of VOUT  
Thermal Characteristics  
Thermal Shutdown  
Die Temperature  
TSD  
150  
25  
°C  
°C  
Note 3  
Note 3  
Die Temperature Hysteresis  
TSDHYS  
Note 1: The input voltage should be greater than the output voltage plus headroom voltage; higher load currents  
increase the input voltage necessary for regulation. See characterization graphs for typical input-to-output  
operating voltage range.  
2: For VIN < VOUT, VOUT will not remain in regulation; for output voltages above 12V, the maximum current  
will be limited to under 1A.  
3: Determined by characterization, not production tested.  
4: This is ensured by design.  
TEMPERATURE CHARACTERISTICS  
Electrical Specifications: Unless otherwise indicated, TA = +25°C, VIN = VEN = 7V, VBOOST - VSW = 5.0V,  
VOUT = 5.0V.  
Parameters  
Temperature Ranges  
Sym.  
Min.  
Typ.  
Max.  
Units  
Conditions  
Operating Junction Temperature Range  
Storage Temperature Range  
TJ  
TA  
TJ  
-40  
-65  
+125  
+150  
+150  
°C  
°C  
°C  
Steady State  
Transient  
Maximum Junction Temperature  
Package Thermal Resistances  
Thermal Resistance, 8L-MSOP  
Thermal Resistance, 8L-2x3 TDFN  
JA  
JA  
211  
°C/W EIA/JESD51-3 Standard  
°C/W EIA/JESD51-3 Standard  
52.5  
DS20005255B-page 4  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
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.  
Note: Unless otherwise indicated, VIN = EN = 7V, COUT = CIN = 2 x 10 µF, L = 22 µH, VOUT = 5.0V, ILOAD = 100 mA,  
TA = +25°C, 8L-MSOP package.  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
80  
60  
40  
20  
0
VIN = 6V  
VIN = 12V  
IOUT = 800 mA  
IOUT = 10 mA  
VIN = 24V  
VIN = 30V  
IOUT = 200 mA  
PWM/PFM  
PWM ONLY  
PWM/PFM option  
25 30  
1
10  
100  
1000  
5
10  
15  
20  
VIN (V)  
IOUT (mA)  
FIGURE 2-1:  
IOUT  
3.3V VOUT Efficiency vs.  
FIGURE 2-4:  
3.3V VOUT Efficiency vs.VIN.  
.
100  
80  
60  
40  
20  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
IOUT = 800 mA  
VIN = 12V  
VIN = 24V  
VIN = 30V  
IOUT = 200 mA  
IOUT = 10 mA  
PWM/PFM  
PWM ONLY  
PWM/PFM option  
1
10  
100  
1000  
6
10  
14  
18  
22  
26  
30  
VIN (V)  
IOUT (mA)  
FIGURE 2-2:  
IOUT  
5.0V VOUT Efficiency vs.  
FIGURE 2-5:  
5.0V VOUT Efficiency vs.VIN.  
.
100  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
VIN = 15V  
IOUT = 800 mA  
IOUT = 200 mA  
80  
60  
40  
20  
0
VIN = 30V  
IOUT = 10 mA  
VIN = 24V  
PWM/PFM  
PWM ONLY  
PWM/PFM option  
12 14 16 18 20 22 24 26 28 30  
VIN (V)  
1
10  
100  
1000  
IOUT (mA)  
FIGURE 2-3:  
IOUT  
12.0V VOUT Efficiency vs.  
FIGURE 2-6:  
VIN.  
12.0V VOUT Efficiency vs.  
.
2013-2014 Microchip Technology Inc.  
DS20005255B-page 5  
MCP16311/2  
Note: Unless otherwise indicated, VIN = EN = 7V, COUT = CIN = 2 x 10 µF, L = 22 µH, VOUT = 5.0V, ILOAD = 100 mA,  
TA = +25°C, 8L-MSOP package.  
1600  
1400  
1200  
1000  
800  
600  
400  
200  
0
5
4.6  
4.2  
3.8  
3.4  
3
VOUT = 3.3V  
VOUT = 12V  
VOUT = 5V  
UVLO START  
UVLO STOP  
-40 -25 -10  
5
20 35 50 65 80 95 110 125  
Temperature (°C)  
0
5
10  
15  
20  
25  
30  
VIN (V)  
FIGURE 2-7:  
Max IOUT vs.VIN.  
FIGURE 2-10:  
Undervoltage Lockout vs.  
Temperature.  
1.4  
1.3  
1.2  
1.1  
1
0.8  
0.798  
0.796  
0.794  
0.792  
0.79  
VIN = 12V  
VOUT = 3.3V  
IOUT = 200 mA  
VIN =7V  
VOUT = 3.3V  
IOUT = 100 mA  
HIGH  
LOW  
0.9  
-40 -25 -10  
5
20 35 50 65 80 95 110 125  
Temperature (°C)  
-40 -25 -10  
5
20 35 50 65 80 95 110 125  
Temperature (°C)  
FIGURE 2-8:  
VFB vs. Temperature;  
FIGURE 2-11:  
Enable Threshold Voltage  
VOUT = 3.3V.  
vs. Temperature.  
0.5  
0.45  
0.4  
5.03  
VIN = 12V  
VOUT = 5V  
5.02  
IOUT = 100 mA  
0.35  
0.3  
0.25  
0.2  
0.15  
0.1  
0.05  
0
High Side  
5.01  
5
Low Side  
4.99  
4.98  
4.97  
VIN = 12V  
VOUT = 5V  
IOUT = 500 mA  
-40 -25 -10  
5
20 35 50 65 80 95 110 125  
Temperature (°C)  
-40 -25 -10  
5
20 35 50 65 80 95 110 125  
Temperature (°C)  
FIGURE 2-9:  
Switch RDSON vs.  
FIGURE 2-12:  
VOUT vs. Temperature.  
Temperature.  
DS20005255B-page 6  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
Note: Unless otherwise indicated, VIN = EN = 7V, COUT = CIN = 2 x 10 µF, L = 22 µH, VOUT = 5.0V, ILOAD = 100 mA,  
TA = +25°C, 8L-MSOP package.  
60  
40  
20  
0
1.8  
1.6  
1.4  
1.2  
1
VIN = 12V  
VOUT = 5V  
VOUT = 3.3V  
Non-Swithcing  
Shutdown  
-40 -25 -10  
5
20 35 50 65 80 95 110 125  
Temperature (°C)  
5
10  
15  
VIN (V)  
20  
25  
30  
FIGURE 2-13:  
Input Quiescent Current vs.  
FIGURE 2-16:  
PWM No Load Input Current  
Temperature.  
vs.VIN, MCP16312.  
50  
40  
30  
20  
10  
0
150  
125  
100  
75  
Non-Switching  
VOUT = 3.3V  
VOUT = 3.3V  
VOUT = 5V  
50  
Shutdown  
25  
VOUT = 12V  
0
5
10  
15  
20  
25  
30  
5
10  
15  
20  
25  
30  
Input Voltage (°C)  
VIN (V)  
FIGURE 2-14:  
Input Quiescent Current vs.  
FIGURE 2-17:  
PFM/PWM IOUT Threshold  
Input Voltage.  
vs. VIN.  
50  
40  
30  
20  
10  
0
120  
100  
80  
VOUT = 3.3V  
VOUT = 3.3V  
VOUT = 5V  
60  
VOUT = 12V  
40  
5
5
10  
15  
20  
25  
30  
10  
15  
20  
25  
30  
VIN (V)  
Input Voltage (V)  
FIGURE 2-15:  
PFM No Load Input Current  
FIGURE 2-18:  
Skipping/PWM IOUT  
vs. Input Voltage, MCP16311.  
Threshold vs. Input Voltage.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 7  
MCP16311/2  
Note: Unless otherwise indicated, VIN = EN = 7V, COUT = CIN = 2 x 10 µF, L = 22 µH, VOUT = 5.0V, ILOAD = 100 mA,  
TA = +25°C, 8L-MSOP package.  
4.5  
VOUT = 3.3V  
To Start  
VOUT  
4
2 V/div  
VIN  
5 V/div  
To Stop  
3.5  
0
200  
400  
600  
800  
1000  
Output Current (mA)  
200 µs/div  
FIGURE 2-19:  
Typical Minimum Input  
FIGURE 2-22:  
Start-Up From VIN.  
Voltage vs. Output Current.  
525  
VOUT  
2 V/div  
500  
475  
450  
IL  
500 mA/div  
VIN = 12V  
IOUT  
VOUT = 3.3V  
IOUT = 200 mA  
2 A/div  
-40 -25 -10  
5
20 35 50 65 80 95 110 125  
Temperature (°C)  
10 µs/div  
FIGURE 2-20:  
Switching Frequency vs.  
FIGURE 2-23:  
Short-Circuit Response.  
Temperature.  
Load Step from  
100 mA to 800 mA  
IOUT  
VOUT  
2 V/div  
500 mA/div  
EN  
2 V/div  
VOUT  
100 mV/div  
AC Coupled  
80 µs/div  
200 µs/div  
FIGURE 2-21:  
Start-Up From Enable.  
FIGURE 2-24:  
Load Transient Response.  
DS20005255B-page 8  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
Note: Unless otherwise indicated, VIN = EN = 7V, COUT = CIN = 2 x 10 µF, L = 22 µH, VOUT = 5.0V, ILOAD = 100 mA,  
TA = +25°C, 8L-MSOP package.  
V
IN = 12V  
VOUT  
50 mV/div  
AC Coupled  
VOUT = 5V  
IOUT = 800 mA  
IL  
200 mA/div  
SW  
10 V/div  
VIN Step from 7V to 12V  
VIN  
5 V/div  
VOUT  
50 mV/div  
400 µs/div  
AC Coupled  
2 µs/div  
FIGURE 2-25:  
Line Transient Response.  
FIGURE 2-28:  
Heavy Load Switching  
Waveforms.  
VIN = 24V  
VOUT  
100 mV/div  
AC Coupled  
IOUT = 25 mA  
SW  
10 V/div  
VIN = 12V  
V
OUT = 5V  
Load Current  
50 mA/div  
SW  
5 V/div  
IL  
200 mA/div  
VOUT  
100 mV/div  
AC Coupled  
20 µs/div  
400 µs/div  
PFM to PWM Transition;  
Load Step from 5 mA to 100 mA.  
FIGURE 2-26:  
Waveforms.  
PFM Light Load Switching  
FIGURE 2-29:  
VIN = 24V  
IOUT = 15 mA  
SW  
10 V/div  
IL  
100 mA/div  
VOUT  
10 mV/div  
AC Coupled  
1 µs/div  
PWM Light Load Switching  
FIGURE 2-27:  
Waveforms.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 9  
MCP16311/2  
NOTES:  
DS20005255B-page 10  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
3.0 PIN DESCRIPTIONS  
The descriptions of the pins are listed in Table 3-1.  
TABLE 3-1:  
PIN FUNCTION TABLE  
MCP16311/2 MCP16311/2  
Symbol  
Description  
2 x 3 TDFN  
MSOP  
1
1
VFB  
Output Voltage Feedback pin. Connect VFB to an external resistor  
divider to set the output voltage.  
2
3
2
3
VCC  
EN  
Internal Regulator Output pin. Bypass Capacitor is required on this  
pin to provide high peak current for gate drive.  
Enable pin. Logic high enables the operation. Do not allow this pin to  
float.  
4
5
6
4
5
6
VIN  
PGND  
SW  
Input Supply Voltage pin for power and internal biasing.  
Power Ground pin  
Output Switch Node pin, connects to the inductor and the bootstrap  
capacitor.  
7
7
BOOST  
Boost Voltage pin that supplies the driver used to control the high-  
side NMOS switch. A bootstrap capacitor is connected between the  
BOOST and SW pins.  
8
9
8
AGND  
EP  
Signal Ground pin  
Exposed thermal pad  
3.1  
Feedback Voltage Pin (V  
)
3.5  
Analog Ground Pin (A  
)
GND  
FB  
The VFB pin is used to provide output voltage regulation  
by using a resistor divider. The VFB voltage will be  
0.800V typical with the output voltage in regulation.  
This ground is used by most internal circuits, such as  
the analog reference, control loop and other circuits.  
3.6  
Power Ground Pin (P  
)
GND  
3.2  
Internal Bias Pin (V  
)
CC  
This is a separate ground connection used for the low-  
side synchronous switch.The length of the trace from  
the input cap return, output cap return and GND pin  
should be made as short as possible to minimize the  
noise in the system. The power ground and the analog  
ground should be connected in a single point.  
The VCC internal bias is derived from the input voltage  
VIN. VCC is set to 5.0V typical. The VCC is used to pro-  
vide a stable low bias voltage for the upper and lower  
gate drive circuits. This output should be decoupled to  
AGND with a 1 µF capacitor, X7R. This capacitor should  
be connected as close as possible to the VCC and  
3.7  
Switch Node Pin (SW)  
AGND pin.  
The switch node pin is connected internally to the low-  
side and high-side switch, and externally to the SW  
node, consisting of the inductor and boost capacitor.  
The SW node can rise very fast as a result of the  
internal switch turning on.  
3.3  
Enable Pin (EN)  
The EN pin is a logic-level input used to enable or  
disable the device and lower the quiescent current  
while disabled. A logic high (> 1.3V) will enable the reg-  
ulator output. A logic low (< 1V) will ensure that the reg-  
ulator is disabled.  
3.8  
Boost Pin (BOOST)  
The high side of the floating supply used to turn the  
integrated N-Channel high-side MOSFET on and off is  
connected to the boost pin.  
3.4  
Power Supply Input Voltage Pin  
(V )  
IN  
Connect the input voltage source to VIN. The input  
source should be decoupled to GND with  
a
3.9  
Exposed Thermal Pad Pin (EP)  
4.7 µF-20 µF capacitor, depending on the impedance  
of the source and output current. The input capacitor  
provides current for the switch node and a stable volt-  
age source for the internal device power. This capacitor  
should be connected as close as possible to the VIN  
and GND pins. For light-load applications, a 2.2 µF  
X7R or X5R ceramic capacitor can be used.  
There is an internal electrical connection between the  
EP and the PGND and AGND pins.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 11  
MCP16311/2  
NOTES:  
DS20005255B-page 12  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
4.1.3  
INTERNAL REFERENCE VOLTAGE  
4.0  
4.1  
DETAILED DESCRIPTION  
Device Overview  
(VFB  
)
An integrated precise 0.8V reference combined with an  
external resistor divider sets the desired converter  
output voltage. The resistor divider range can vary  
without affecting the control system gain. High-value  
resistors consume less current, but are more  
susceptible to noise. Consult typical applications for the  
recommended resistors value.  
The MCP16311/2 is a high input voltage step-down  
regulator, capable of supplying 1A typical to a regulated  
output voltage from 2.0V to 12V. Internally, the trimmed  
500 kHz oscillator provides a fixed frequency, while the  
peak current mode control architecture varies the duty  
cycle for output voltage regulation. An internal floating  
driver is used to turn the high-side integrated  
N-Channel MOSFET on and off. The power for this  
driver is derived from an external boost capacitor  
whose energy is replenished when the low-side N-  
Channel MOSFET is turned on.  
4.1.4  
INTERNAL BIAS REGULATOR (VCC)  
An internal Low Dropout Voltage Regulator (LDO) is  
used to supply 5.0V to all the internal circuits. The LDO  
regulates the input voltage (VIN) and can supply  
enough current (up to 50 mA) to sustain the drivers and  
internal bias circuitry. The VCC pin must be decoupled  
to ground with a 1 µF capacitor. In the event of a  
thermal shut down, the LDO will shut down. There is a  
short-circuit protection for the VCC pin, with a threshold  
set at 150 mA.  
4.1.1  
PWM/PFM MODE OPTION  
The MCP16311 selects the best operating switching  
mode (PFM or PWM) for high efficiency across a wide  
range of load currents. Switching to PFM mode at light-  
load currents results in a low quiescent current. During  
the sleep period (between two packets of switching  
cycles), the MCP16311 draws 44 µA (typical) from the  
supply line. The switching pulse packets represent a  
small percentage of the total running cycle, and the  
overall average current drawn from power line is small.  
In PFM switching mode, during sleep periods, the VCC  
regulator enters Low Quiescent Current mode to avoid  
unnecessary power dissipation.  
Avoid driving any external load using the VCC pin.  
4.1.5  
INTERNAL COMPENSATION  
The disadvantages of PWM/PFM mode are higher  
output ripple voltage and variable PFM mode frequency.  
The PFM mode threshold is a function of the input  
voltage, output voltage and load (see Figure 2-17).  
All control system components necessary for stable  
operation over the entire device operating range are  
integrated, including the error amplifier and inductor  
current slope compensation. To add the proper amount  
of slope compensation, the inductor value changes  
along with the output voltage (see Table 5-1).  
4.1.2  
PWM-ONLY MODE OPTION  
In the MCP16312 devices, the PFM mode is disabled  
and the part runs only in PWM over the entire load  
range. During normal operation, the MCP16312  
continues to operate at a constant 500 kHz switching  
frequency, keeping the output ripple voltage lower than  
in PFM mode. At lighter loads, the MCP16312 devices  
begin to skip pulses. Figure 2-18 represents the input  
voltage versus load current for the pulse skipping  
threshold in PWM-only mode.  
4.1.6  
EXTERNAL COMPONENTS  
External components consist of:  
• Input capacitor  
• Output filter (inductor and capacitor)  
• Boost capacitor  
• Resistor divider  
Because the MCP16312 has very low output voltage  
ripple, it is recommended for noise-sensitive applications.  
The selection of the external inductor, output capacitor  
and input capacitor is dependent upon the output volt-  
age and the maximum output current.  
TABLE 4-1:  
Part Number  
PART NUMBER SELECTION  
4.1.7  
ENABLE INPUT  
PWM/PFM  
PWM  
The enable input (EN) is used to disable the device. If  
disabled, the device consumes a minimum current from  
the input. Once enabled, the internal soft start controls  
the output voltage rate of rise, preventing high-inrush  
current and output voltage overshoot.  
MCP16311  
MCP16312  
X
X
There is no internal pull-up or pull-down resistor. To  
enable the converter, the EN pin must be pulled high.  
To disable the converter, the EN pin must be pulled low.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 13  
MCP16311/2  
4.1.8  
SOFT START  
The internal reference voltage rate of rise is controlled  
during start-up, minimizing the output voltage  
overshoot and the inrush current.  
4.1.9  
UNDERVOLTAGE LOCKOUT  
An integrated Undervoltage Lockout (UVLO) prevents  
the converter from starting until the input voltage is high  
enough for normal operation. The converter will  
typically start at 4.1V and operate down to 3.6V.  
Hysteresis is added to prevent starting and stopping  
during start-up as a result of loading the input voltage  
source.  
4.1.10  
OVERTEMPERATURE  
PROTECTION  
Overtemperature protection limits the silicon die  
temperature to +150°C by turning the converter off. The  
normal switching resumes at +125°C.  
VCC  
VCC  
VREG  
VIN  
CVCC  
BG  
CIN  
REF  
BOOST  
VOUT  
OTEMP  
SS  
VREF  
CBOOST  
500 kHz OSC  
VOUT  
RTOP  
S
HS  
Drive  
+
SW  
Amp  
-
-
FB  
PWM  
Latch  
Comp  
+
COUT  
RBOT  
R
UVLO  
RCOMP  
CCOMP  
Overtemp  
CS  
VREF  
PFM  
RSENSE  
PFM  
CTR  
+
VCC  
+
LS  
Drive  
Slope  
Comp  
VREF  
+
-
EN  
SHDN all blocks  
AGND  
PGND  
FIGURE 4-1:  
MCP16311/2 Block Diagram.  
DS20005255B-page 14  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
4.2  
Functional Description  
L
VOUT  
4.2.1  
STEP-DOWN OR BUCK  
CONVERTER  
S1  
IL  
The MCP16311/2 is a synchronous step-down or buck  
converter capable of stepping input voltages ranging  
COUT  
VIN  
S2  
from 4.4V to 30V down to 2.0V to 24V for VIN > VOUT  
.
The integrated high-side switch is used to chop or  
modulate the input voltage using a controlled duty  
cycle. The integrated low-side switch is used to  
freewheel current when the high-side switch is turned  
off. High efficiency is achieved by using low-resistance  
switches and low equivalent series resistance (ESR)  
inductors and capacitors. When the high-side switch is  
IL  
IOUT  
turned on, a DC voltage is applied to the inductor (VIN  
VOUT), resulting in a positive linear ramp of inductor  
current. When the high-side switch turns off and the  
low-side switch turns on, the applied inductor voltage is  
equal to –VOUT, resulting in a negative linear ramp of  
inductor current. In order to ensure there is no shoot-  
through current, a dead time where both switches are  
off is implemented between the high-side switch  
turning off and the low-side switch turning on, and the  
low-side switch turning off and the high-side switch  
turning on.  
VIN  
SW  
VOUT  
S1 ON  
S
2 ON  
Continuous Inductor Current Mode  
For steady-state, continuous inductor current  
operation, the positive inductor current ramp must  
equal the negative current ramp in magnitude. While  
operating in steady state, the switch duty cycle must be  
equal to the relationship of VOUT/VIN for constant  
output voltage regulation, under the condition that the  
inductor current is continuous or never reaches zero.  
For discontinuous inductor current operation, the  
steady-state duty cycle will be less than VOUT/VIN to  
maintain voltage regulation. When the inductor current  
reaches zero, the low-side switch is turned off so that  
current does not flow in the reverse direction, keeping  
the efficiency high. The average of the chopped input  
voltage or SW node voltage is equal to the output  
voltage, while the average inductor current is equal to  
the output current.  
IL  
IOUT  
VIN  
SW  
S2 Both  
S
1 ON  
ON OFF  
Discontinuous Inductor Current Mode  
FIGURE 4-2:  
Converter.  
Synchronous Step-Down  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 15  
MCP16311/2  
When working close to the boundary conduction  
threshold, a jitter on the SW node may occur, reflecting  
in the output voltage. Although the low-frequency  
output component is very small, it may be desirable to  
completely eliminate this component. To achieve this,  
an RC Snubber between the SW node and GND is  
used.  
4.2.2  
PEAK CURRENT MODE CONTROL  
The MCP16311/2 integrates a peak current mode  
control architecture, resulting in superior AC regulation  
while minimizing the number and size of voltage loop  
compensation components for integration. Peak  
current mode control takes a small portion of the  
inductor current, replicates it, and compares this  
replicated current sense signal with the error voltage. In  
practice, the inductor current and the internal switch  
current are equal during the switch-on time. By adding  
this peak current sense to the system control, the step-  
down power train system can be approximated by a  
first order system rather than a second order system.  
This reduces the system complexity and increases its  
dynamic performance.  
Typical values for the snubber are: 680 pF and 430.  
Using such a snubber completely eliminates the jitter  
on the SW node, but slightly decreases the overall  
efficiency of the converter.  
4.2.4  
PFM MODE OPERATION  
The MCP16311 devices are capable of automatic  
operation in normal PWM or PFM mode to maintain  
high efficiency at all loads. In PFM mode, the output  
ripple has a variable frequency component that  
changes with the input voltage and output current. With  
no load, the quiescent current drawn from the output is  
very low.  
For Pulse-Width Modulation (PWM) duty cycles that  
exceed 50%, the control system can become bimodal,  
where a wide pulse followed by a short pulse repeats  
instead of the desired fixed pulse width. To prevent this  
mode of operation, an internal compensating ramp is  
summed into the current sense signal.  
There are two comparators that decide when device  
starts switching in PFM mode. One of the comparators  
is monitoring the output voltage and has a reference of  
810 mV with 10 mV hysteresis. If the load current is  
low, the output rises and triggers the comparator, which  
will put the logic control of the drivers and other block  
circuitry (including the internal regulator VCC) in Sleep  
mode to minimize the power consumption during the  
switching cycle’s off period. When the output voltage  
drops below its nominal value, PFM operation pulses  
one or several times to bring the output back into  
regulation (Figure 2-26). The second comparator fixes  
the minimum duty cycle for PFM mode. Minimum duty  
cycle in PFM mode depends on the sensed peak  
current and input voltage. As a result, the PFM-to-PWM  
mode threshold depends on load current and value of  
the input voltage (Figure 2-17). If the output load  
current rises above the upper threshold, the  
MCP16311 transitions smoothly into PWM mode.  
4.2.3  
PULSE-WIDTH MODULATION  
The internal oscillator periodically starts the switching  
period, which in the MCP16311/2’s case occurs every  
2 µs or 500 kHz. With the high-side integrated  
N-Channel MOSFET turned on, the inductor current  
ramps up until the sum of the current sense and slope  
compensation ramp exceeds the integrated error  
amplifier output. Once this occurs, the high-side switch  
turns off and the low-side switch turns on. The error  
amplifier output slews up or down to increase or  
decrease the inductor peak current feeding into the  
output LC filter. If the regulated output voltage is lower  
than its target, the inverting error amplifier output rises.  
This results in an increase in the inductor current to  
correct for errors in the output voltage. The fixed  
frequency duty cycle is terminated when the sensed  
inductor peak current, summed with the internal slope  
compensation, exceeds the output voltage of the error  
amplifier. The PWM latch is set by turning off the high-  
side internal switch and preventing it from turning on  
until the beginning of the next cycle.  
The MCP16312 devices will operate in PWM-only  
mode even during periods of light load operation. By  
operating in PWM-only mode, the output ripple remains  
low and the frequency is constant (Figure 2-28).  
Operating in fixed PWM mode results in lower  
efficiency during light-load operation (when compared  
to PFM mode (MCP16311)).  
DS20005255B-page 16  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
4.2.5  
HIGH-SIDE DRIVE  
The MCP16311/2 features an integrated high-side  
N-Channel MOSFET for high-efficiency step-down  
power conversion. An N-Channel MOSFET is used for  
its low resistance and size (instead of a P-Channel  
MOSFET). The N-Channel MOSFET gate must be  
driven above its source to fully turn on the device, result-  
ing in a gate-drive voltage above the input to turn on the  
high-side N-Channel. The high-side N-channel source  
is connected to the inductor and boost cap or switch  
node. When the high-side switch is off and the low-side  
switch is on, the inductor current flows through the low-  
side switch, providing a path to recharge the boost cap  
from the boost voltage source. The voltage for the boost  
cap is supplied from the internal regulator (VCC). An  
internal boost blocking diode is used to prevent current  
flow from the boost cap back into the regulator during  
the internal switch-on time. If the boost voltage  
decreases significantly, the low side will be forced low  
for 90 ns in order to charge the boost capacitor.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 17  
MCP16311/2  
NOTES:  
DS20005255B-page 18  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
5.3  
General Design Equations  
5.0  
5.1  
APPLICATION INFORMATION  
Typical Applications  
The step-down converter duty cycle can be estimated  
using Equation 5-2 while operating in Continuous  
Inductor Current mode. This equation accounts for the  
forward drop of the two internal N-Channel MOSFETS.  
As load current increases, the voltage drop in both  
internal switches will increase, requiring a larger PWM  
duty cycle to maintain the output voltage regulation.  
Switch voltage drop is estimated by multiplying the  
The MCP16311/2 synchronous step-down converter  
operates over a wide input range, up to 30V maximum.  
Typical applications include generating a bias or VDD  
voltage for PIC® microcontrollers, digital control system  
bias supply for AC-DC converters and 12V industrial  
input and similar applications.  
switch current times the switch resistance or RDSON  
.
5.2  
Adjustable Output Voltage  
Calculations  
EQUATION 5-2:  
CONTINUOUS INDUCTOR  
CURRENT DUTY CYCLE  
To calculate the resistor divider values for the  
MCP16311/2 adjustable version, use Equation 5-1.  
RTOP is connected to VOUT, RBOT is connected to  
AGND, and both are connected to the VFB input pin.  
VOUT + ILSW RDSONL  
D = ------------------------------------------------------------  
VIN IHSW RDSONH  
EQUATION 5-1:  
RESISTOR DIVIDER  
CALCULATION  
The MCP16311/2 device features an integrated slope  
compensation to prevent bimodal operation of the  
PWM duty cycle. Internally, half of the inductor current  
down slope is summed with the internal current sense  
signal. For the proper amount of slope compensation,  
it is recommended to keep the inductor down-slope  
VOUT  
RTOP = RBOT ------------ 1  
VFB  
current constant by varying the inductance with VOUT  
,
where K = 0.22 V/µH.  
EXAMPLE 5-1:  
3.3V RESISTOR DIVIDER  
EQUATION 5-3:  
VOUT = 3.3V  
VFB = 0.8V  
RBOT = 10 k  
K = VOUT L  
RTOP = 31.25 k(standard value = 31.6 k)  
VOUT = 3.328V (using standard value)  
For example, for VOUT = 3.3V, an inductance of 15 µH  
is recommended.  
EXAMPLE 5-2:  
5.0V RESISTOR DIVIDER  
TABLE 5-1:  
RECOMMENDED INDUCTOR  
VALUES  
VOUT = 5.0V  
VFB = 0.8V  
VOUT  
K
LSTANDARD  
RBOT = 10 k  
2.0V  
3.3V  
5.0V  
12V  
15V  
24V  
0.20  
0.22  
0.23  
0.21  
0.22  
0.24  
10 µH  
15 µH  
22 µH  
56 µH  
68 µH  
100 µH  
RTOP = 52.5 k(standard value = 52.3 k)  
VOUT = 4.984V (using standard values)  
EXAMPLE 5-3:  
12.0V RESISTOR DIVIDER  
VOUT = 12.0V  
VFB = 0.8V  
RBOT = 10 k  
RTOP = 140 k(standard value = 140 k)  
The error amplifier is internally compensated to ensure  
loop stability. External resistor dividers, inductance and  
output capacitance all have an impact on the control  
system and should be selected carefully and evaluated  
for stability. A 10 kbottom resistor is recommended as a  
good trade-off for quiescent current and noise immunity.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 19  
MCP16311/2  
5.4  
Input Capacitor Selection  
5.6  
Inductor Selection  
The step-down converter input capacitor must filter the  
high-input ripple current that results from pulsing or  
chopping the input voltage. The MCP16311/2 input  
voltage pin is used to supply voltage for the power train  
and as a source for internal bias. A low equivalent  
The MCP16311/2 is designed to be used with small  
surface-mount inductors. Several specifications should  
be considered prior to selecting an inductor. To  
optimize system performance, low DCR inductors  
should be used.  
series resistance (ESR), preferably  
capacitor, is recommended. The  
a
ceramic  
necessary  
To optimize system performance, the inductance value  
is determined by the output voltage (Table 5-1) so the  
inductor ripple current is somewhat constant over the  
output voltage range.  
capacitance is dependent upon the maximum load  
current and source impedance. Three capacitor  
parameters to keep in mind are the voltage rating,  
equivalent series resistance and the temperature  
rating. For wide temperature range applications, a  
multi-layer X7R dielectric is recommended, while for  
EQUATION 5-4:  
INDUCTOR RIPPLE  
CURRENT  
applications with limited temperature range,  
a
VIN VOUT  
= --------------------------- tON  
multi-layer X5R dielectric is acceptable. Typically, input  
capacitance between 10 µF and 20 µF is sufficient for  
most applications. For applications with 100 mA to  
200 mA load, a 4.7 µF to 2.2 µF X7R capacitor can be  
used, depending on the input source and its  
impedance. In case of an application with high  
variations of the input voltage, a higher capacitor value  
is recommended. The input capacitor voltage rating  
must be VIN plus margin.  
IL  
L
EXAMPLE 5-4:  
VIN = 12V  
VOUT = 3.3V  
IOUT = 800 mA  
Table 5-2 contains the recommended range for the  
input capacitor value.  
EQUATION 5-5:  
INDUCTOR PEAK  
CURRENT  
IL  
2
5.5  
Output Capacitor Selection  
ILPK = -------- + I OUT  
The output capacitor provides a stable output voltage  
during sudden load transients and reduces the output  
voltage ripple. As with the input capacitor, X5R and  
X7R ceramic capacitors are well suited for this  
application. For typical applications, the output  
capacitance can be as low as 10 µF ceramic and as  
high as 100 µF electrolytic. In a typical application, a  
20 µF output capacitance usage will result in a 10 mV  
output ripple.  
Where:  
Inductor ripple current  
Inductor peak current  
=
=
319 mA  
960 mA  
For this example, an inductor with a current saturation  
rating of minimum 960 mA is recommended. Low DCR  
inductors result in higher system efficiency. A trade-off  
between size, cost and efficiency is made to achieve  
the desired results.  
The amount and type of output capacitance and  
equivalent series resistance will have a significant  
effect on the output ripple voltage and system stability.  
The range of the output capacitance is limited due to  
the integrated compensation of the MCP16311/2. See  
Table 5-2 for the recommended output capacitor range.  
TABLE 5-3:  
MCP16311/2 RECOMMENDED  
3.3V VOUT INDUCTORS  
Size  
WxLxH  
(mm)  
Part Number  
The output voltage capacitor rating should be a  
minimum of VOUT plus margin.  
Coilcraft  
XAL4040  
LPS6235  
MSS6132  
XAL6060  
MSS7341  
TABLE 5-2:  
Parameter  
CAPACITOR VALUE RANGE  
15 0.109 2.8  
4.0x4.0x2.1  
Min.  
Max.  
15 0.125 2.00 6.0x6.0x3.5  
15 0.135 1.56 6.1x6.1x3.2  
15 0.057 1.78 6.36x6.5x6.1  
15 0.057 1.78 7.3x7.3x4.1  
CIN  
2.2 µF  
20 µF  
None  
None  
COUT  
DS20005255B-page 20  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
Another important aspect when creating such an  
application is the value of the inductor. The value of the  
inductor needs to follow Equation 5-3 or, as a guideline,  
Table 5-1, where the output voltage is approximated as  
the sum of the forward voltages of the LEDs and a 0.8V  
headroom for the sense resistor. A typical application is  
shown in Figure 5-3.  
TABLE 5-3:  
Part Number  
MCP16311/2 RECOMMENDED  
3.3V VOUT INDUCTORS  
Size  
WxLxH  
(mm)  
Wurth Elektronik®  
74408943150  
744062150  
744778115  
7447779115  
Coiltronics®  
SD25  
The following equations are used to determine the  
value and the losses for the sense resistor:  
15 0.118 1.7  
15 0.085 1.1  
4.8x4.8x3.8  
6.8x6.8x2.3  
15  
15  
0.1  
1.75 7.3x7.3x3.2  
2.2 7.3x7.3x4.5  
EQUATION 5-6:  
0.07  
VFB  
RB = -----------  
ILED  
15 0.095 1.08 5.2x5.2x2.5  
14.1 0.103 1.1 6.0x6.0x3.0  
PLOSSES = VFB ILED  
SD6030  
TDK - EPC®  
Where:  
B82462G4153M 15 0.097 1.05 6.0x6.0x3.0  
B82462A4153K 15 0.21 1.5 6.0x6.0x3.0  
VFB = Feedback Voltage  
EXAMPLE 5-5:  
5.7  
Boost Capacitor  
ILED = 400 mA  
The boost capacitor is used to supply current for the  
internal high-side drive circuitry that is above the input  
voltage. The boost capacitor must store enough energy to  
completely drive the high-side switch on and off. A 100 nF  
X5R or X7R capacitor is recommended for all  
applications. The boost capacitor maximum voltage is 5V.  
VFB = 0.8V  
VF = 1 x 3.2V (one white LED is used)  
RB = 2  
PLOSSES = 0.32 W (sense resistor losses)  
L = 22 µH  
5.8  
V
Capacitor  
cc  
5.10 Thermal Calculations  
The VCC internal bias regulates at 5V. The VCC pin is  
current limited to 50 mA and protected from a short-  
circuit condition at 150 mA load. The VCC regulator  
must sustain all load and line transients because it  
supplies the internal drivers for power switches. For  
stability reasons, the VCC capacitor must be at least  
1 µF X7R ceramic for extended temperature range, or  
X5R for limited temperature range.  
The MCP16311/2 is available in MSOP-8 and DFN-8  
packages. By calculating the power dissipation and  
applying the package thermal resistance (θJA), the  
junction temperature is estimated. The maximum  
continuous junction temperature rating for the  
MCP16311/2 is +125°C.  
To quickly estimate the internal power dissipation for  
the switching step-down regulator, an empirical  
calculation using measured efficiency can be used.  
Given the measured efficiency, the internal power  
dissipation is estimated in Equation 5-7. This power  
dissipation includes all internal and external  
component losses. For a quick internal estimate,  
subtract the estimated inductor DCR loss from the PDIS  
calculation in Equation 5-7.  
5.9  
MCP16312 – LED Constant  
Current Driver  
MCP16312 can be used to drive an LED or a string of  
LEDs. The process of transforming the MCP16312  
from a constant voltage source into a constant current  
source is simple. It implies that the sensing/feedback  
for the current is on the low side by adding a resistor in  
series with the string of LEDs.  
EQUATION 5-7:  
TOTAL POWER  
When using the MCP16312 as an LED driver, care must  
be taken when selecting the sense resistor. Due to the  
high feedback voltage of 0.8V, there will be significant  
losses on the sense resistor, so a larger package with  
better power dissipation must be selected.  
DISSIPATION ESTIMATE  
VOUT IOUT  
PDIS = ------------------------------ VOUT IOUT  
Efficiency  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 21  
MCP16311/2  
The difference between the first term, input power, and  
the second term, power delivered, is the total system  
power dissipation. The inductor losses are estimated  
by PL = IOUT2 x LDCR  
.
EXAMPLE 5-6:  
POWER DISSIPATION –  
MCP16311/2 MSOP  
PACKAGE  
VIN  
VOUT  
IOUT  
=
=
=
=
=
=
=
12V  
5.0V  
0.8A  
Efficiency  
92.5%  
324 mW  
0.15   
96 mW  
Total System Dissipation  
LDCR  
PL  
MCP16311/2 internal power dissipation estimate:  
P
DIS – PL  
=
=
=
228 mW  
211°C/W  
+48.1°C  
JA  
Estimated Junction  
Temperature Rise  
EXAMPLE 5-7:  
POWER DISSIPATION –  
MCP16311/2 DFN  
PACKAGE  
VIN  
VOUT  
IOUT  
=
=
=
=
=
=
=
12V  
3.3V  
0.8A  
Efficiency  
90%  
Total System Dissipation  
293 mW  
0.15   
96 mW  
LDCR  
PL  
MCP16311 internal power dissipation estimate:  
PDIS – PL  
=
=
=
197 mW  
68°C/W  
+13.4°C  
JA  
Estimated Junction  
Temperature Rise  
DS20005255B-page 22  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
supplying high-frequency switch current, the input  
capacitor also provides a stable voltage source for the  
internal MCP16311/2 circuitry. Unstable PWM opera-  
tion can result if there are excessive transients or ring-  
ing on the VIN pin of the MCP16311/2 device. In  
Figure 5-1, the input capacitors are placed close to the  
VIN pins. A ground plane on the bottom of the board  
provides a low-resistive and low-inductive path for the  
return current. The next priority in placement is the  
freewheeling current loop formed by output capacitors  
and inductance (L1), while strategically placing the out-  
put capacitor ground return close to the input capacitor  
ground return. Then, CBOOST should be placed  
between the boost pin and the switch node pin. This  
leaves space close to the MCP16311/2 VFB pin to place  
RTOP and RBOT. The feedback loop must be routed  
away from the switch node, so noise is not coupled into  
the high-impedance VFB input.  
5.11 Printed Circuit Board (PCB)  
Layout Information  
Good PCB layout techniques are important to any  
switching circuitry, and switching power supplies are no  
different. When wiring the switching high-current paths,  
short and wide traces should be used. Therefore, it is  
important that the input and output capacitors be  
placed as close as possible to the MCP16311/2 to  
minimize the loop area.  
The feedback resistors and feedback signal should be  
routed away from the switching node and the switching  
current loop. When possible, ground planes and traces  
should be used to help shield the feedback signal and  
minimize noise and magnetic interference.  
A good MCP16311/2 layout starts with the placement of  
the input capacitor, which supplies current to the input  
of the circuit when the switch is turned on. In addition to  
Component  
Value  
CIN  
COUT  
L1  
2 x 10 µF  
2 x 10 µF  
22 µH  
RT  
52.3 k  
10 k  
RB  
REN  
1 M  
CVCC  
CBOOST  
1 µF  
0.1 µF  
CBOOST  
VOUT  
VIN  
12V  
L1  
5V @ 1A  
BOOST  
SW  
VFB  
COUT  
VIN  
CIN  
RT  
EN  
VCC  
REN  
GND  
CVCC  
RB  
FIGURE 5-1:  
MSOP-8 Recommended Layout, 5V Output Design.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 23  
MCP16311/2  
Component  
Value  
CIN  
COUT  
L1  
2 x 10 µF  
2 x 10 µF  
15 µH  
RT  
31.2 k  
10 k  
RB  
REN  
1 M  
CVCC  
CBOOST  
1 µF  
0.1 µF  
CBOOST  
VOUT  
VIN  
12V  
L1  
3.3V @ 1A  
BOOST  
SW  
VFB  
COUT  
VIN  
CIN  
RT  
EN  
REN  
CVCC  
VCC  
GND  
RB  
FIGURE 5-2:  
DFN Recommended Layout, 3.3V Output Design.  
DS20005255B-page 24  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
CBOOST  
I
LED = 400 mA  
L1  
VIN  
12V  
BOOST  
SW  
VFB  
COUT  
VIN  
LED  
CIN  
EN  
REN  
VCC  
VFB  
GND  
RB = -----------  
RB  
CVCC  
ILED  
Component  
Value  
CIN  
COUT  
L1  
2 x 10 µF  
2 x 10 µF  
15 µH  
RB  
2  
REN  
1 M  
CVCC  
CBOOST  
LED  
1 µF  
0.1 µF  
1 x White LED  
FIGURE 5-3:  
MCP16312 - Typical LED Driver Application: 400 mA Output.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 25  
MCP16311/2  
NOTES:  
DS20005255B-page 26  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
6.0  
6.1  
PACKAGING INFORMATION  
Package Marking Information  
8-Lead MSOP (3x3 mm)  
Example  
16311E  
309256  
8-Lead TDFN (2x3)  
Example  
Part Number  
Code  
MCP16311T-E/MNY  
MCP16312T-E/MNY  
ABM  
ABU  
ABM  
309  
25  
Legend: XX...X Customer-specific information  
Y
Year code (last digit of calendar year)  
YY  
WW  
NNN  
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.  
e3  
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.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 27  
MCP16311/2  
Note: For the most current package drawings, please see the Microchip Packaging Specification located at  
http://www.microchip.com/packaging  
DS20005255B-page 28  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
Note: For the most current package drawings, please see the Microchip Packaging Specification located at  
http://www.microchip.com/packaging  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 29  
MCP16311/2  
Note: For the most current package drawings, please see the Microchip Packaging Specification located at  
http://www.microchip.com/packaging  
DS20005255B-page 30  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
Note: For the most current package drawings, please see the Microchip Packaging Specification located at  
http://www.microchip.com/packaging  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 31  
MCP16311/2  
Note: For the most current package drawings, please see the Microchip Packaging Specification located at  
http://www.microchip.com/packaging  
DS20005255B-page 32  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
ꢀꢁꢂꢃꢄꢅꢆꢇꢈꢄꢉꢊꢋꢌꢆꢍꢎꢄꢈꢆꢏꢈꢄꢊꢐꢆꢑꢒꢆꢂꢃꢄꢅꢆꢇꢄꢌꢓꢄꢔꢃꢆꢕꢖꢑꢗꢆꢘꢆꢙꢚꢛꢚꢜꢝꢞꢟꢆꢠꢠꢆꢡꢒꢅꢢꢆꢣꢤꢍꢏꢑꢥ  
ꢑꢒꢊꢃꢦ ꢀꢁꢂꢃꢄꢅꢆꢃ!ꢁ"ꢄꢃꢇ#ꢂꢂꢆꢈꢄꢃꢉꢊꢇ$ꢊꢋꢆꢃ%ꢂꢊ&ꢌꢈꢋ"'ꢃꢉꢍꢆꢊ"ꢆꢃ"ꢆꢆꢃꢄꢅꢆꢃꢎꢌꢇꢂꢁꢇꢅꢌꢉꢃ(ꢊꢇ$ꢊꢋꢌꢈꢋꢃꢏꢉꢆꢇꢌ)ꢌꢇꢊꢄꢌꢁꢈꢃꢍꢁꢇꢊꢄꢆ%ꢃꢊꢄꢃ  
ꢅꢄꢄꢉ*++&&&ꢐ!ꢌꢇꢂꢁꢇꢅꢌꢉꢐꢇꢁ!+ꢉꢊꢇ$ꢊꢋꢌꢈꢋ  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 33  
MCP16311/2  
NOTES:  
DS20005255B-page 34  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
APPENDIX A: REVISION HISTORY  
Revision B (November 2014)  
The following is the list of modifications:  
1. Added AEC-Q100 qualification information.  
2. Updated the Typical Applications section.  
3. Updated the DC Characteristics table.  
4. Updated Section 4.2.2 “Peak Current Mode  
Control”.  
5. Updated the standard values in Example 5-1.  
6. Added a 24V option in Table 5-1.  
Revision A (December 2013)  
• Original Release of this Document.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 35  
MCP16311/2  
NOTES:  
DS20005255B-page 36  
2013-2014 Microchip Technology Inc.  
MCP16311/2  
PRODUCT IDENTIFICATION SYSTEM  
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.  
PART NO.  
Device  
X
/XX  
Examples:  
a) MCP16311-E/MS:  
Extended Temperature,  
8LD MSOP package  
Temperature  
Range  
Package  
b) MCP16311T-E/MS: Tape and Reel,  
Extended Temperature,  
8LD MSOP package  
c) MCP16311T-E/MNY: Tape and Reel,  
Device:  
MCP16311:  
High-Efficiency, PFM/PWM Integrated  
Synchronous Switch Step-Down Regulator  
(MSOP only)  
Extended Temperature,  
8LD2 x 3TDFNpackage  
MCP16311T: High-Efficiency, PFM/PWM Integrated  
Synchronous Switch Step-Down Regulator  
(Tape and Reel) (MSOP and TDFN)  
MCP16312:  
High-Efficiency, PFM Integrated Synchronous  
Switch Step-Down Regulator  
(MSOP only)  
a) MCP16312-E/MS:  
Extended Temperature,  
8LD MSOP package  
b) MCP16312T-E/MS: Tape and Reel,  
Extended Temperature,  
8LD MSOP package  
c) MCP16312T-E/MNY: Tape and Reel,  
MCP16312T: High-Efficiency, PWM Integrated Synchronous  
Switch Step-Down Regulator (Tape and Reel)  
(MSOP and TDFN)  
Extended Temperature,  
8LD 2 x 3 TDFN package  
Temperature  
Range:  
E
=
-40°C to +125°C (Extended)  
Package:  
MNY*  
MS  
=
=
Plastic Micro Small Outline Package  
Plastic Dual Flat, No Lead Package -  
2 x 3 x 0.75 mm Body  
*Y  
= Nickel palladium gold manufacturing designator.  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 37  
MCP16311/2  
NOTES:  
DS20005255B-page 38  
2013-2014 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.  
Trademarks  
The Microchip name and logo, the Microchip logo, dsPIC,  
FlashFlex, flexPWR, JukeBlox, KEELOQ, KEELOQ logo, Kleer,  
LANCheck, MediaLB, MOST, MOST logo, MPLAB,  
32  
OptoLyzer, PIC, PICSTART, PIC 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.  
The Embedded Control Solutions Company and mTouch are  
registered trademarks of Microchip Technology Incorporated  
in the U.S.A.  
Analog-for-the-Digital Age, BodyCom, chipKIT, chipKIT logo,  
CodeGuard, dsPICDEM, dsPICDEM.net, ECAN, In-Circuit  
Serial Programming, ICSP, Inter-Chip Connectivity, KleerNet,  
KleerNet logo, MiWi, MPASM, MPF, MPLAB Certified logo,  
MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code  
Generation, PICDEM, PICDEM.net, PICkit, PICtail,  
RightTouch logo, REAL ICE, SQI, Serial Quad I/O, 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.  
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.  
© 2013-2014, Microchip Technology Incorporated, Printed in  
the U.S.A., All Rights Reserved.  
ISBN: 978-1-63276-806-3  
QUALITY MANAGEMENT SYSTEM  
CERTIFIED BY DNV  
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.  
== ISO/TS 16949 ==  
2013-2014 Microchip Technology Inc.  
DS20005255B-page 39  
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  
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Suites 3707-14, 37th Floor  
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Tel: 852-2943-5100  
Fax: 852-2401-3431  
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Tel: 91-80-3090-4444  
Fax: 91-80-3090-4123  
Austria - Wels  
Tel: 43-7242-2244-39  
Fax: 43-7242-2244-393  
Denmark - Copenhagen  
Tel: 45-4450-2828  
Fax: 45-4485-2829  
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Tel: 91-11-4160-8631  
Fax: 91-11-4160-8632  
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Web Address:  
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Fax: 678-957-1455  
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Tel: 86-10-8569-7000  
Fax: 86-10-8528-2104  
Germany - Munich  
Tel: 49-89-627-144-0  
Fax: 49-89-627-144-44  
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Tel: 81-3-6880- 3770  
Fax: 81-3-6880-3771  
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Tel: 86-28-8665-5511  
Fax: 86-28-8665-7889  
Austin, TX  
Tel: 512-257-3370  
Germany - Pforzheim  
Tel: 49-7231-424750  
Korea - Daegu  
Tel: 82-53-744-4301  
Fax: 82-53-744-4302  
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  
Korea - Seoul  
Tel: 82-2-554-7200  
Fax: 82-2-558-5932 or  
82-2-558-5934  
China - Hangzhou  
Tel: 86-571-8792-8115  
Fax: 86-571-8792-8116  
Italy - Venice  
Tel: 39-049-7625286  
Chicago  
Itasca, IL  
Tel: 630-285-0071  
Fax: 630-285-0075  
Netherlands - Drunen  
Tel: 31-416-690399  
Fax: 31-416-690340  
Malaysia - Kuala Lumpur  
Tel: 60-3-6201-9857  
Fax: 60-3-6201-9859  
China - Hong Kong SAR  
Tel: 852-2943-5100  
Fax: 852-2401-3431  
Cleveland  
Independence, OH  
Tel: 216-447-0464  
Fax: 216-447-0643  
Poland - Warsaw  
Tel: 48-22-3325737  
Malaysia - Penang  
Tel: 60-4-227-8870  
Fax: 60-4-227-4068  
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Tel: 86-25-8473-2460  
Fax: 86-25-8473-2470  
Spain - Madrid  
Tel: 34-91-708-08-90  
Fax: 34-91-708-08-91  
Dallas  
Addison, TX  
Tel: 972-818-7423  
Fax: 972-818-2924  
Philippines - Manila  
Tel: 63-2-634-9065  
Fax: 63-2-634-9069  
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Tel: 86-532-8502-7355  
Fax: 86-532-8502-7205  
Sweden - Stockholm  
Tel: 46-8-5090-4654  
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Tel: 65-6334-8870  
Fax: 65-6334-8850  
Detroit  
Novi, MI  
Tel: 248-848-4000  
China - Shanghai  
Tel: 86-21-5407-5533  
Fax: 86-21-5407-5066  
UK - Wokingham  
Tel: 44-118-921-5800  
Fax: 44-118-921-5820  
Taiwan - Hsin Chu  
Tel: 886-3-5778-366  
Fax: 886-3-5770-955  
Houston, TX  
Tel: 281-894-5983  
China - Shenyang  
Tel: 86-24-2334-2829  
Fax: 86-24-2334-2393  
Indianapolis  
Noblesville, IN  
Tel: 317-773-8323  
Fax: 317-773-5453  
Taiwan - Kaohsiung  
Tel: 886-7-213-7830  
China - Shenzhen  
Tel: 86-755-8864-2200  
Fax: 86-755-8203-1760  
Taiwan - Taipei  
Tel: 886-2-2508-8600  
Fax: 886-2-2508-0102  
Los Angeles  
China - Wuhan  
Tel: 86-27-5980-5300  
Fax: 86-27-5980-5118  
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Tel: 949-462-9523  
Fax: 949-462-9608  
Thailand - Bangkok  
Tel: 66-2-694-1351  
Fax: 66-2-694-1350  
China - Xian  
Tel: 86-29-8833-7252  
Fax: 86-29-8833-7256  
New York, NY  
Tel: 631-435-6000  
San Jose, CA  
Tel: 408-735-9110  
China - Xiamen  
Tel: 86-592-2388138  
Fax: 86-592-2388130  
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China - Zhuhai  
Tel: 86-756-3210040  
Fax: 86-756-3210049  
03/25/14  
DS20005255B-page 40  
2013-2014 Microchip Technology Inc.  

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