MCP16251/2 Data Sheet

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

 2013 - 2016 Microchip Technology Inc.

DS20005173B-page  1

MCP16251/2

Features

• Up to 96% Typical Efficiency

• 650 mA Typical Peak Input Current Limit:

- I

OUT 

> 100 mA @ 3.3V V

OUT

, 1.2V V

IN

- I

OUT 

> 250 mA @ 3.3V V

OUT

, 2.4V V

IN

- I

OUT 

> 225 mA @ 5.0V V

OUT

, 3.3V V

IN

• Low Device Quiescent Current:

- Output Quiescent Current: < 4 µA typical, 

device is not switching (V

OUT 

> V

IN

excluding feedback divider current)

- Input Sleep Current: 1 µA

- No Load Input Current: 14 µA typical

• Shutdown Current: 0.6 µA typical

• Low Start-Up Voltage: 0.82V, 1 mA load

• Low Operating Input Voltage: down to 0.35V

• Adjustable Output Voltage Range: 1.8V to 5.5V

• Maximum Input Voltage 

 V

OUT

 < 5.5V

• Automatic PFM/PWM Operation:

- PWM Operation: 500 kHz

- PFM Output Ripple: 150 mV typical

• Feedback Voltage: 1.23V

• Internal Synchronous Rectifier

• Internal Compensation

• Inrush Current Limiting and Internal Soft Start 

(1.5 ms typical)

• Selectable, Logic Controlled, Shutdown States:

- True Load Disconnect Option (MCP16251)

- Input-to-Output Bypass Option (MCP16252)

•  Anti-Ringing Control

• Overtemperature Protection

• Available Packages:

- SOT-23, 6-Lead

- TDFN, 2 x 3 x 0.8 mm, 8-Lead 

Package Types

Applications

• One, Two and Three-Cell Alkaline and NiMH/NiCd 

Portable Products

• Solar Cell Applications

• Personal Care and Medical Products

• Bias for Status LEDs

• Smartphones, MP3 Players, Digital Cameras

• Remote Controllers, Portable Instruments

• Wireless Sensors

• Bluetooth Headsets

• +3.3V to +5.0V Distributed Power Supply

General Description

The MCP16251/2 is a compact, high-efficiency, fixed 
frequency, synchronous step-up DC-DC converter. 
This family of devices provides an easy-to-use power 
supply solution for applications powered by either 
one-cell, two-cell or three-cell alkaline, NiCd, NiMH, 
one-cell Li-Ion or Li-Polymer batteries.

Low-voltage technology allows the regulator to start-up 
without high inrush current or output voltage overshoot 
from a low-voltage input. High efficiency is 
accomplished by integrating the low-resistance 
N-Channel boost switch and synchronous P-Channel 
switch. All compensation and protection circuitry are 
integrated to minimize external components. 
MCP16251/2 operates and consumes less than 14 µA 
from battery after start-up, while operating at no load 
(V

OUT

 = 3.3V, V

IN

 = 1.5V). The devices provide a true 

disconnect from input to output (MCP16251) or an 
input-to-output bypass (MCP16252), while in shutdown 
(EN = GND). Both shutdown options consume less 
than 0.6 µA from battery.

Output voltage is set by a small external resistor 
divider. Two package options, SOT-23, 6-lead and 
TDFN, 2 x 3 x 0.8 mm, 8-lead are available.

MCP16251/2

2x3x0.8 TDFN*

P

GND

S

GND

EN

V

OUTS

V

OUTP

1

2

3

4

8

7

6

5 SW

V

IN

V

FB

EP

9

4

1

2

3

6 V

IN

V

FB

SW

GND

EN

5 V

OUT

MCP16251/2

6-Lead SOT-23

* Includes Exposed Thermal Pad (EP); see 

Table 3-1

.

Low Quiescent Current, PFM/PWM Synchronous Boost Regulator 

with True Output Disconnect or Input/Output Bypass Option

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

MCP16251/2

DS20005173B-page  2

 2013 - 2016 Microchip Technology Inc.

Typical Application

V

IN

P

GND

V

FB

SW

V

IN

3.0V to 4.2V

V

OUT

5.0V / 200 mA

C

OUT

10 µF

C

IN

4.7 µF

L

4.7 µH

V

OUTS

+

-

3.09 M

1 M

V

OUTP

S

GND

Li

-I

on

EN

V

IN

GND

V

FB

SW

V

IN

0.9V to 1.7V

V

OUT

3.3V / 75 mA

C

OUT

10 µF

C

IN

4.7 µF

L

4.7 µH

V

OUT

+

-

1.69 M

1 M

A

lk

a

lin

e

EN

50

55

60

65

70

75

80

85

90

95

100

0.1

1

10

100

1000

Efficiency

 (%

)

I

OUT

(mA)

V

OUT

= 3.3V

V

IN

= 1.5V

V

IN

= 2.4V

V

IN

= 3.0V

R

TOP

R

BOT

R

TOP

R

BOT

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

 2013 - 2016 Microchip Technology Inc.

DS20005173B-page  3

MCP16251/2

1.0

ELECTRICAL 
CHARACTERISTICS

Absolute Maximum Ratings †

EN, V

FB

, V

IN,

 V

SW

, V

OUT

 - GND ......................... +6.5V

EN, V

FB

.........< maximum V

OUT

 or V

IN

 > (GND - 0.3V)

Output Short-Circuit Current ...................... Continuous
Output Current Bypass Mode........................... 400 mA
Power Dissipation  ............................ Internally Limited
Storage Temperature ......................... -65°C to +150°C
Ambient Temp. with Power Applied...... -40°C to +85°C
Operating Junction Temperature........ -40°C to +125°C
ESD Protection On All Pins:

HBM ............................................................... 4 kV
MM ................................................................ 400V

† 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.

DC CHARACTERISTICS 

Electrical Characteristics: Unless otherwise indicated, V

IN

 = 1.5V, C

OUT

 = C

IN

 = 10 µF, L = 4.7 µH, V

OUT

 = 3.3V, 

I

OUT

 = 0 mA, T

A

 = +25°C. Boldface specifications apply over the T

A

 range of -40°C to +85°C.

Parameters

Sym.

Min.

Typ.

Max.

Units

Conditions

Input Characteristics

Minimum Start-Up Voltage

V

IN

0.82

V

Note 1

Minimum Input Voltage 

After Start-Up

V

IN

0.35

V

Note 1

Output Voltage Adjust 
Range

V

OUT

1.8

5.5

V

V

OUT

 

 V

IN

Note 2

Maximum Output Current

I

OUT

100

150

mA

1.2V V

IN

, 2.0V V

OUT

125

1.5V V

IN

, 3.3V V

OUT

225

3.3V V

IN

, 5.0V V

OUT

Feedback Voltage

V

FB

1.1931

1.23

1.2669

V

Feedback Input 

Bias Current

I

VFB

10

nA

V

OUT 

Quiescent Current

I

QOUT

4.0

8

µA

I

OUT 

= 0 mA, device is not 

switching, EN = V

IN

 = 4.0V, 

V

OUT 

= 5.0V, does not 

include feedback divider 
current (

Note 3

)

V

IN 

Sleep Current

I

QIN

1.0

2.3

µA

I

OUT 

= 0 mA, EN = V

IN

(

Note 3

)(

Note 5

)

No Load Input Current

I

IN0

14

25

µA

I

OUT 

= 0 mA, 

device is switching

Quiescent Current – 

Shutdown

I

QSHDN

0.6

µA

V

OUT

 = EN = GND; 

includes N-Channel and 
P-Channel Switch Leakage

Note 1:

3.3 k

 resistive load, 3.3V

OUT 

(1 mA).

2:

For V

IN

 > V

OUT

, V

OUT

 will not remain in regulation.

3:

I

QOUT

 is measured at V

OUT, 

V

OUT

 is supplied externally for V

OUT 

> V

IN

 (device is not switching), I

QIN 

is 

measured at V

IN

 pin during Sleep period, no load.

4:

220

 resistive load, 3.3V

OUT 

(15 mA).

5:

Determined by characterization, not production tested.

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

MCP16251/2

DS20005173B-page  4

 2013 - 2016 Microchip Technology Inc.

NMOS Switch Leakage

I

NLK

0.15

µA

V

IN 

= V

SW 

= 5V 

V

OUT 

= 5.5V

V

EN 

= V

FB 

= GND

PMOS Switch Leakage

I

PLK

0.15

µA

V

IN 

= V

SW 

= GND 

V

OUT 

= 5.5V

NMOS Switch 

ON Resistance

R

DS(ON)N

0.45

V

IN

 = 3.3V

I

SW

 = 100 mA

PMOS Switch 

ON Resistance

R

DS(ON)P

0.9

V

IN

 = 3.3V

I

SW

 = 100 mA

NMOS Peak 

Switch Current Limit

I

N(MAX)

650

mA

Note 5

V

OUT

 Accuracy

V

OUT

%

-3

+3

%

Includes Line and Load 
Regulation; V

IN 

= 1.5V

Line Regulation

(V

OUT

/V

OUT

)

/

V

IN

-0.4

0.3

0.4

%/V

V

IN 

= 1.5V to 2.8V

I

OUT 

= 50 mA

Load Regulation

V

OUT

/V

OUT

-1.5

0.1

1.5

%

I

OUT 

= 25 mA to 100 mA

V

IN

 = 1.5V

Maximum Duty Cycle

DC

MAX

87

89

91

%

Note 5

Switching Frequency

f

SW

425

500

575

kHz

EN Input Logic High

V

IH

70

% of V

IN

I

OUT 

= 1 mA

EN Input Logic Low

V

IL

20

% of V

IN

I

OUT 

= 1 mA

EN Input Leakage Current

I

ENLK

5.0

nA

V

EN

 = 5V

Soft Start Time

t

SS

1.5

ms

EN Low to High

90% of V

OUT

(

Note 4

)(

Note 5

)

Thermal Shutdown 

Die Temperature

T

SD

160

C

I

OUT 

= 20 mA

V

IN

 > 1.4V

Die Temperature 

Hysteresis

T

SDHYS

20

C

DC CHARACTERISTICS (CONTINUED)

Electrical Characteristics: Unless otherwise indicated, V

IN

 = 1.5V, C

OUT

 = C

IN

 = 10 µF, L = 4.7 µH, V

OUT

 = 3.3V, 

I

OUT

 = 0 mA, T

A

 = +25°C. Boldface specifications apply over the T

A

 range of -40°C to +85°C.

Parameters

Sym.

Min.

Typ.

Max.

Units

Conditions

Note 1:

3.3 k

 resistive load, 3.3V

OUT 

(1 mA).

2:

For V

IN

 > V

OUT

, V

OUT

 will not remain in regulation.

3:

I

QOUT

 is measured at V

OUT, 

V

OUT

 is supplied externally for V

OUT 

> V

IN

 (device is not switching), I

QIN 

is 

measured at V

IN

 pin during Sleep period, no load.

4:

220

 resistive load, 3.3V

OUT 

(15 mA).

5:

Determined by characterization, not production tested.

TEMPERATURE SPECIFICATIONS

Electrical Characteristics: Unless otherwise indicated, V

IN

 = 1.5V, C

OUT

 = C

IN

 = 10 µF, L = 4.7 µH, V

OUT

 = 3.3V, I

OUT

 = 0 mA.

Parameters

Sym.

Min.

Typ.

Max.

Units

Conditions

Temperature Ranges

Operating Temperature Range

T

J

-40

+85

°C

Steady State

Storage Temperature Range

T

A

-65

+150

°C

Maximum Junction Temperature

T

J

+150

°C

Transient

Package Thermal Resistances

Thermal Resistance, SOT-23, 6-LD

JA

190.5

°C/W

EIA/JESD51-3 Standard

Thermal Resistance, TDFN, 2x3x0.8m, 8-LD

JA

52.5

°C/W

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

 2013 - 2016 Microchip Technology Inc.

DS20005173B-page  5

MCP16251/2

2.0

TYPICAL PERFORMANCE CURVES   

Note:  Unless otherwise indicated, V

IN 

= EN = 1.5V, C

OUT 

= C

IN 

= 10 µF, L

 

= 4.7 µH, V

OUT

 = 3.3V, I

LOAD

 = 0 mA, 

T

A

 = +25°C, SOT-23 package.

FIGURE 2-1:

V

OUT

 I

Q

 vs. Ambient 

Temperature.

FIGURE 2-2:

No Load Input Current vs. 

Temperature.

FIGURE 2-3:

No Load Input Current vs. 

V

IN

, after Start-Up.

FIGURE 2-4:

2.0V V

OUT

 Efficiency vs. 

I

OUT

.

FIGURE 2-5:

3.3V V

OUT

 Efficiency vs. 

I

OUT

.

FIGURE 2-6:

5.0V V

OUT

 Efficiency vs. 

I

OUT

.

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.

4

6

8

10

s

cent Current (uA)

V

OUT

= 3.3V

R

TOP

= 1.69 M

ȍ

R

BOT

= 1.0 M

ȍ

0

2

-40

-25

-10

5

20

35

50

65

80

Quie

s

Ambient Temperature (°C)

0

5

10

15

20

25

30

-40 -30 -20 -10 0

10 20 30 40 50 60 70 80

No Load Input Current (µA)

Ambient Temperature (°C)

V

IN

= 3.0V

V

IN

= 1.5V

V

OUT

= 3.3V

R

TOP

= 1.69 M

ȍ

R

BOT

= 1.0 M

ȍ

 

V

IN

= 1.2V

0

5

10

15

20

25

30

35

1

1.5

2

2.5

3

3.5

4

4.5

No Load Input Current (µA)

Input Voltage (V)

R

BOT

= 1.0 M

ȍ

V

OUT

= 3.3V

V

OUT

= 5.0V

V

OUT

= 2.0V

50

55

60

65

70

75

80

85

90

95

100

1

10

100

1000

Efficiency

 (%

)

I

OUT

(mA)

V

OUT

= 2.0V

V

IN

= 0.9V

V

IN

= 1.2V

V

IN

= 1.5V

55

60

65

70

75

80

85

90

95

100

1

10

100

1000

Efficiency

 (%

)

I

OUT

(mA)

V

OUT

= 3.3V

V

IN

= 0.9V

V

IN

= 1.2V

V

IN

= 2.5V

60

65

70

75

80

85

90

95

100

1

10

100

1000

Efficiency

 (%

)

I

OUT

(mA)

V

OUT

= 5.0V

V

IN

= 1.2V

V

IN

= 1.8V

V

IN

= 2.5V

V

IN

= 3.6V

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

MCP16251/2

DS20005173B-page  6

 2013 - 2016 Microchip Technology Inc.

Note:  Unless otherwise indicated, V

IN 

= EN = 1.5V, C

OUT 

= C

IN 

= 10 µF, L

 

= 4.7 µH, V

OUT

 = 3.3V, I

LOAD

 = 0 mA, 

T

A

 = +25°C, SOT-23 package.

FIGURE 2-7:

3.3V V

OUT

 vs. Ambient 

Temperature.

FIGURE 2-8:

3.3V V

OUT

 vs. Ambient 

Temperature.

FIGURE 2-9:

3.3V V

OUT

 vs. V

IN

.

FIGURE 2-10:

Maximum I

OUT

 vs. V

IN

, after 

Start-up, V

OUT

 Maximum 5% below Regulation 

Point.

FIGURE 2-11:

F

OSC

 vs. Ambient 

Temperature.

FIGURE 2-12:

V

IN

 Start-Up vs. 

Temperature into Resistive Load and Constant 
Current.

3 29

3.30

3.31

3.32

3.33

tput V

o

ltage 

(V)

I

LOAD

= 1 mA

I

LOAD

= 10 mA

I

LOAD

= 50 mA

3.27

3.28

3.29

-40

-25

-10

5

20

35

50

65

80

Ou

t

Ambient Temperature (°C)

3.28

3.29

3.30

3.31

3.32

u

tput V

o

ltage 

(V)

V

IN

= 1.2V

V

IN

= 1.5V

V

= 2 4V

3.25

3.26

3.27

-40

-25

-10

5

20

35

50

65

80

O

u

Ambient Temperature (°C)

I

LOAD

= 20 mA

V

IN

= 0.9V

V

IN

= 2.4V

3.26

3.27

3.28

3.29

3.30

3.31

3.32

3.33

1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8

Output V

o

ltage 

(V)

Input Voltage (V)

I

LOAD

= 50 mA

T

A

= +25°C

T

A

= +85°C

T

A

= -40°C

0

50

100

150

200

250

300

350

400

450

500

0.9 1.2 1.5 1.8 2.1 2.4 2.7

3

3.3 3.6 3.9 4.2 4.5

Load Current (mA)

Input Voltage (V)

V

OUT

= 3.3V

V

OUT

= 2.0V

V

OUT

= 5.0V

485

490

495

500

505

510

h

ing Frequency

 (kHz)

470

475

480

-40

-25

-10

5

20

35

50

65

80

Sw

itc

h

Ambient Temperature (°C)

0 8

0.9

1

1.1

1.2

n

put V

o

ltage 

(V)

V

OUT

= 3.3V

---- Electronic Load, CC

Resistive Load

I

LOAD

= 20 mA

0.6

0.7

0.8

-40

-25

-10

5

20

35

50

65

80

In

Ambient Temperature (°C)

I

LOAD

= 1 mA

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

 2013 - 2016 Microchip Technology Inc.

DS20005173B-page  7

MCP16251/2

Note:  Unless otherwise indicated, V

IN 

= EN = 1.5V, C

OUT 

= C

IN 

= 10 µF, L

 

= 4.7 µH, V

OUT

 = 3.3V, I

LOAD

 = 0 mA, 

T

A

 = +25°C, SOT-23 package.

FIGURE 2-13:

1.8V

OUT

 Minimum Start-Up 

and Shutdown V

IN

 into Resistive Load vs. I

OUT

.

FIGURE 2-14:

3.3V

OUT

 Minimum Start-Up 

and Shutdown V

IN

 into Resistive Load vs. I

OUT

.

FIGURE 2-15:

5.0V

OUT

 Minimum Start-Up 

and Shutdown V

IN

 into Resistive Load vs. I

OUT

.

FIGURE 2-16:

N-Channel and P-Channel 

R

DSON

 

vs. the Maximum V

IN

 or V

OUT

.

FIGURE 2-17:

Average of PFM-to-PWM 

Threshold Current vs. V

IN

.

FIGURE 2-18:

MCP16251 3.3V V

OUT

 PFM 

Mode Waveforms.

0.3

0.5

0.7

0.9

1.1

1.3

0

10

20

30

40

50

60

70

80

90

Input V

o

ltage 

(V)

Load Current (mA)

Shutdown

Startup

V

OUT

=1.8V

0.3

0.5

0.7

0.9

1.1

1.3

0

10

20

30

40

50

60

70

80

90

100

Input V

o

ltage 

(V)

Load Current (mA)

Shutdown

Startup

V

OUT

= 3.3V

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

0

10

20

30

40

50

60

70

80

90 100

Input V

o

ltage 

(V)

Load Current (mA)

Shutdown

Startup

V

OUT

= 5.0V

3

4

5

6

7

8

h

 Resistance 

(Ohms)

P - Channel

0

1

2

0.9 1.2 1.5 1.8 2.1 2.4 2.7

3

3.3 3.6 3.9 4.2

Sw

itc

h

> V

IN

or V

OUT

N - Channel

20

25

30

35

40

45

ad Current (mA)

V

OUT

= 5.0V

V

OUT

= 3.3V

V

OUT

= 2.0V

5

10

15

0.8

1.2

1.6

2

2.4

2.8

3.2

3.6

4

4.4

Lo

Input Voltage (V)

V

OUT

 100 mV/div

AC Coupled

I

OUT

= 1 mA

I

L

 100 mA/div

V

SW

 

200 µs/div

2 V/div

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

MCP16251/2

DS20005173B-page  8

 2013 - 2016 Microchip Technology Inc.

Note:  Unless otherwise indicated, V

IN 

= EN = 1.5V, C

OUT 

= C

IN 

= 10 µF, L

 

= 4.7 µH, V

OUT

 = 3.3V, I

LOAD

 = 0 mA, 

T

A

 = +25°C, SOT-23 package.

FIGURE 2-19:

MCP16251 3.3V V

OUT

 

PWM Mode Waveforms.

FIGURE 2-20:

3.3V Start-up after Enable.

FIGURE 2-21:

3.3V Start-Up when 

V

IN

 = V

ENABLE

.

FIGURE 2-22:

MCP16251 3.3V V

OUT

 Load 

Transient Waveforms.

FIGURE 2-23:

3.3V V

OUT

 Line Transient 

Waveforms.

FIGURE 2-24:

MCP16251 3.3V No Load 

V

OUT

 PFM Mode Output Ripple.

V

OUT

 50 mV/div

I

OUT

= 50 mA

I

L

 200 mA/div

V

SW

2 µs/div

2 V/div 

AC Coupled

V

OUT

= 3.3V

V

IN

= 1.5V

I

OUT

= 15 mA

V

OUT

 2 V/div

V

EN

 

400 µs/div

2 V/div 

V

OUT

 2V/div

I

OUT

= 15 mA

I

L

 100 mA/div

400 µs/div

1 V/div

V

IN

 = EN

V

OUT

 100 mV/div

AC Coupled

I

STEP

= 1 mA to 75 mA

I

OUT

 50 mA/div

400 µs/div

PFM Mode

PWM Mode

V

STEP

 from 1V to 2.5V

I

OUT

= 20 mA

V

OUT

 100 mV/div

1 ms/div

AC Coupled

V

IN

1 V/div 

V

OUT

 100 mV/div

AC Coupled

I

OUT

= 0 mA

I

L

 20 mA/div

100 ms/div

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

 2013 - 2016 Microchip Technology Inc.

DS20005173B-page  9

MCP16251/2

3.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in 

Table 3-1

.

3.1

Feedback Voltage Pin (V

FB

)

The V

FB

 pin is used to provide output voltage regulation 

by using a resistor divider. Feedback voltage will 
typically be 1.23V, with the output voltage in regulation.

3.2

Signal Ground Pin (S

GND

)

The signal ground pin is used as a return for the 
integrated V

REF

 and error amplifier. In the 2x3x0.8 

TDFN package, the S

GND

 and power ground (P

GND

pins are connected externally.

3.3

Power Ground Pin (P

GND

)

The power ground pin is used as a return for the 
high-current N-Channel switch. In the 2x3x0.8 TDFN 
package, the P

GND

 and signal ground (S

GND

) pins are 

connected externally.

3.4

Enable Pin (EN)

The EN pin is a logic-level input used to enable or 
disable device switching and lower quiescent current 
while disabled. A logic high (>70%

 

of V

IN

) will enable 

the regulator output. A logic low (<20% of V

IN

) will 

ensure that the regulator is disabled.

3.5

Switch Node Pin (SW)

Connect the inductor from the input voltage to the SW 
pin. The SW pin carries inductor current and can be as 
high as 650 mA typical peak. The integrated 
N-Channel switch drain and integrated P-Channel 
switch source are internally connected at the SW node.

3.6

Output Voltage Power Pin (V

OUTP

)

The output voltage power pin connects the output volt-
age to the switch node. High current flows through the 
integrated P-Channel and out of this pin to the output 
capacitor and output. In the 2x3x0.8 TDFN package, 
V

OUTS

 and V

OUTP

 are connected externally.

3.7

Output Voltage Sense Pin (V

OUTS

)

The output voltage sense pin connects the regulated 
output voltage to the internal bias circuits. In the 
2x3x0.8 TDFN package, V

OUTS

 and V

OUTP

 are 

connected externally.

3.8

Power Supply Input Voltage Pin (V

IN

)

Connect the input voltage source to V

IN

. The input 

source should be decoupled to GND with a 4.7 µF 
minimum capacitor.

3.9

Exposed Thermal Pad (EP)

There is no internal electrical connection between the 
Exposed Thermal Pad (EP) and the P

GND

 and S

GND

pins. They must be connected to the same potential on 
the Printed Circuit Board (PCB).

3.10

Ground Pin (GND)

The ground or return pin is used for circuit ground 
connection. Length of trace from input cap return, 
output cap return and GND pin should be made as 
short as possible to minimize noise on the GND pin. In 
the SOT23-6 package, a single ground pin is used.

3.11

Output Voltage Pin (V

OUT

)

The output voltage pin connects the integrated 
P-Channel MOSFET to the output capacitor. The 
feedback voltage divider is also connected to the V

OUT

pin for voltage regulation.

TABLE 3-1:

PIN FUNCTION TABLE

MCP16251/2 

SOT-23

MCP16251/2 

TDFN 2x3x0.8 

Symbol

Description

4

1

V

FB

Feedback Voltage Pin

2

S

GND

Signal Ground Pin

3

P

GND

Power Ground Pin

3

4

EN

Enable Control Input Pin

1

5

SW

Switch Node, Boost Inductor Input Pin

6

V

OUTP

Output Voltage Power Pin

7

V

OUTS

Output Voltage Sense Pin

6

8

V

IN

Input Voltage Pin

9

EP

Exposed Thermal Pad (EP); must be connected to S

GND

 and P

GND.

2

GND

Ground Pin

5

V

OUT

Output Voltage Pin

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005173B-html.html
background image

MCP16251/2

DS20005173B-page  10

 2013 - 2016 Microchip Technology Inc.

4.0

DETAILED DESCRIPTION

4.1

Device Overview

The MCP16251/2 family of devices is capable of low 
start-up voltage and delivers high efficiency over a wide 
load range for single-cell, two-cell, three-cell alkaline, 
NiMH, NiCd and single-cell Li-Ion battery inputs. A high 
level of integration lowers total system cost, eases 
implementation and reduces board area. The devices 
feature low quiescent current, low start-up voltage, 
adjustable output voltage, PWM/PFM mode operation, 
integrated synchronous switch, internal compensation, 
low noise anti-ring control, inrush current limit and soft 
start. There are two options for the MCP16251/2 family: 
True Output Disconnect and Input-to-Output Bypass 
(see 

Table 4-1

).

4.1.1

PFM/PWM OPERATION

The MCP16251/2 devices use an automatic switchover 
from PWM to PFM mode for light load conditions, to 
maximize efficiency over a wide range of output 
current. During PFM mode, a controlled peak current is 
used to pump the output up to the threshold limit. While 
operating in PFM or PWM mode, the P-Channel switch 
is used as a synchronous rectifier, turning off when the 
inductor current reaches 0 mA to maximize efficiency. 
In PFM mode, a comparator is used to terminate 
switching when the output voltage reaches the upper 
threshold limit. Once switching has terminated, the 
output voltage will decay or coast down. During this 
period, which is called Sleep period, 1 µA is typically 
consumed from the input source, which keeps power 
efficiency high at light load. PWM/PFM mode has 
higher output ripple voltage than PWM mode, and 
variable frequency. The PFM mode frequency is a 
function of input voltage, output voltage and load. While 
in PFM mode, the boost converter periodically pumps 
the output with a fixed switching frequency of 500 kHz. 

Figure 2-17

 represents the load current versus input 

voltage for the PFM-to-PWM threshold. 

4.1.2

TRUE OUTPUT DISCONNECT 
OPTION

The MCP16251 device incorporates a true output 
disconnect feature. With the EN pin pulled low, the 
output of the MCP16251 is isolated or disconnected 
from the input by turning off the integrated P-Channel 
switch and removing the switch bulk diode connection. 
This removes the DC path typical in boost converters, 
which allows the output to be disconnected from the 
input. During this mode, less than 0.6 µA of current is 
consumed from the input (battery). True output discon-
nect does not discharge the output; the output voltage 
is held up by the external C

OUT

 capacitance.

4.1.3

INPUT BYPASS OPTION

The MCP16252 device incorporates the input-to-output 
bypass shutdown option. With the EN input pulled low, 
the output is connected to the input using the internal 
P-Channel MOSFET. In this mode, the current draw 
from the input (battery) is less than 0.6 µA with no load. 
The Input Bypass mode is used when the input voltage 
range is high enough for the load to operate in Standby 
or Low I

Q

 mode. When a higher regulated output 

voltage is necessary to operate the application, the EN 
input is pulled high, enabling the boost converter.

In this mode, the current through the P-Channel 
MOSFET must not be higher than 400 mA.

TABLE 4-1:

PART NUMBER SELECTION

Part 

Number

True Output 

Disconnect

Input-to-Output 

Bypass

MCP16251

MCP16252

Maker
Microchip Technology Inc.
Datasheet PDF Download