MP2637GR_技术文档

MP2637

2.5A Single Cell Switch Mode Battery Charger

with Power Path Management (PPM)

and 2.4A Boost Current with Trickle Timer

DESCRIPTION

FEATURES



Up to 16V Sustainable Input Voltage

4.5V-to-6V Operating Input Voltage Range

Power Management function, Integrated

The MP2637 is a highly-integrated, flexible,

switch-mode battery charger with system power

path management, designed for single-cell Li-

ion or Li-Polymer batteries used in a wide range

of applications.

Input-Current

Regulation

Limit,

Input

Voltage



Up to 2.5A Programmable Charge Current

Trickle-Charge Function

Selectable 4.2V/ 4.35V Charge Voltage with

0.5% Accuracy

The MP2637 can operate in both charge mode

and boost mode to allow full system and battery

power management.

When input power is present, the device

operates in charge mode. It automatically

detects the battery voltage and charges the

battery in three phases: trickle current, constant

current and constant voltage. Other features

include charge termination and auto-recharge.

This device also integrates both input current

limit and input voltage regulation in order to

manage input power and meet the priority of the

system power demand.



Negative Temperature Coefficient Pin for

Battery Temperature Monitoring

Programmable Timer Back-Up Protection

Thermal Regulation and Thermal Shutdown

Internal Battery Reverse Leakage Blocking

Integrated Over Voltage Protection and

Over Current Protection for Pass-Through

Path

Reverse Boost Operation Mode for System

Power

Up to 2.4A Programmable Output Current

Limit for Boost Mode



In the absence of an input source, the MP2637

switches to boost mode through the MODE pin

to power the SYS pins from the battery. The

OLIM pin programs the output current limit in

boost mode. The MP2637 also allows for output

short circuit protection to completely disconnect

the battery from the load in the event of a short

circuit fault. Normal operation will recover as

soon as the short circuit fault is removed. The

MP2637 provides full operating status indication

to distinguish charge mode from boost mode.

Integrated Short Circuit Protection and

Output Over Voltage Protection for Boost

Mode

APPLICATIONS



Sub-Battery Applications

Power-Bank Applications for Smart-Phone

Tablet and Other Portable Devices

All MPS parts are lead-free, halogen free, and adhere to the RoHS directive. For

MPS green status, please visit MPS website under Quality Assurance.

To guarantee safe operation, the MP2637 limits

the die temperature to a preset value of 120^oC.

Other safety features include input over-voltage

protection, battery over-voltage protection,

“MPS” and “The Future of Analog IC Technology” are Registered Trademarks

of Monolithic Power Systems, Inc.

thermal

shutdown,

battery

temperature

monitoring, and a programmable timer to

prevent prolonged charging of a dead battery.

MP2637 Rev. 1.04

8/3/2017

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1

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

TYPICAL APPLICATION

To 5V System

C2

R₁

R₂

R_OLIM*

C_SYS

*

SYS

Q1

FB

OLIM

SW

RS1

L1*

5V Input

I_CHG

V_BATT

I_BATT

VIN

Q2

Q3

R4

R6

R3

R5

C_BATT

CSP

Battery

C_IN

REG

Q4

BATT

VSYS

PWIN

NTC

VB

Battery Voltage

Program

GND: 4.35V

High/Float: 4.2V

MP2637

CHG

VCC

ACOK

C4*

EN

VCC

BOOST

ISET

MODE

ILIM

TMR

AGND

PGND

R_ILIM

C_TMRR_ISET

*Note:

1. R_OLIMCANNOT be lower than 47.5kΩ. R_OLIMis for the boost output current loop setting, and please refer to

the APPLICATION INFORMATION section for details.

2. C_SYSshould be put as close to the SYS pin and PGND as possible. At least 22μF is recommended, and

C_SYS+C2 should not be less than 44μF, the ceramic is preferred and E-cap is not recommended.

3. VCC cap should not exceed 100nF. Recommend 47nF or 100nF.

4. Inductor should not exceed 2.2μH. Recommend 1.5μH or 2.2μH.

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

Table 1: Operation Mode

Power Source

__________

Operating

MODE

EN

Q1,Q2

Q3

Q4

ACOK

Mode

VIN

PWIN

Only Pass

Through Mode

Low

On

Off

V_IN> V_BATT+300mV 0.8V<PWIN<1.15V

X

Low

High

Charging Mode

SW

PWIN<0.8V or

PWIN >1.15V

X

Boost Discharge

Mode

High

X

High

Off

SW

V_IN<V_BATT+300mV

X

PWIN<0.8V or

PWIN >1.15V

SYS Force-off

Mode

X

Low

X

High

Off

V_IN<2V

X

Sleep Mode

X=Don’t Care.

On = Fully Turn On

Off = Fully Off

SW = Switching

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

ORDERING INFORMATION

Part Number*

Package

Top Marking

MP2637GR

QFN-24 (4mm×4mm)

See Below

* For Tape & Reel, add suffix –Z (e.g. MP2637GR–Z);

TOP MARKING

MPS: MPS prefix;

Y: year code;

WW: week code:

MP2637: first six digits of the part number;

LLLLLL: lot number;

PACKAGE REFERENCE

TOP View

24

23

22

21

20

19

18

EN

1

2

3

4

5

6

PGND

____

CHG

17

16

15

14

13

VB

______

BOOST

VCC

ILIM

PWIN

CSP

BATT

AGND

TMR

7

8

9

10

11

12

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

ABSOLUTE MAXIMUM RATINGS ⁽¹⁾

VIN.................................................–0.3V to 20V

SYS...............................................–0.3V to 6.5V

SW…………….. .................................................

–0.3V (-2V for <20ns) to 6.5V (8.5V for <20ns)

Thermal Resistance ⁽⁴⁾

QFN-24 (4mm×4mm) ............. 42........9 ... °C/W

θ_JA

θ_JC

Notes:

1) Exceeding these ratings may damage the device.

2) The maximum allowable power dissipation is a function of the

maximum junction temperature T_J(MAX), the junction-to-

ambient thermal resistance θ_JA, and the ambient temperature

T_A. The maximum allowable continuous power dissipation at

any ambient temperature is calculated by P_D(MAX) = (T_J

(MAX)-T_A)/θ_JA. Exceeding the maximum allowable power

dissipation will cause excessive die temperature, and the

regulator will go into thermal shutdown. Internal thermal

shutdown circuitry protects the device from permanent

damage.

BATT.............................................–0.3V to 6.5V

----------------- ------------- ---------------------

ACOK, CHG, BOOST ...................–0.3V to 6.5V

All Other Pins................................–0.3V to 6.5V

Junction Temperature...............................150°C

Lead Temperature ....................................260°C

(2)

Continuous Power Dissipation (T_A= +25°C)

3) The device is not guaranteed to function outside of its

operating conditions.

4) Measured on JESD51-7, 4-layer PCB.

........................................................... 2.97W

Junction Temperature...............................150°C

Storage Temperature.............. –65°C to +150°C

Recommended Operating Conditions ⁽³⁾

Supply Voltage V_VIN............................4.5V to 6V

Battery Voltage V_BATT....................2.5V to 4.35V

Operating Junction Temp. (T_J).−40°C to +125°C

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

ELECTRICAL CHARACTERISTICS

V_IN= 5.0V, T_A= 25°C, unless otherwise noted.

Parameter

Symbol Condition

R_{IN to SYS}VCC=5V,

Min

Typ

65

Max Units

IN to SYS NMOS ON Resistance

High-side PMOS ON Resistance

Low-side NMOS ON Resistance

mΩ

R_{H_DS}

R_{L_DS}

VCC=5V,

30

CC Charge Mode/ Boost

Mode

6.5

A

High-Side PMOS Peak Current

Limit

I_{PEAK_HS}

TC Charge Mode

3.2

6.3

600

2.2

100

0.8

50

A

Low-Side NMOS Peak Current Limit I_{PEAK_LS}

Switching Frequency*

VCC UVLO

f_sw

490

2

700

2.4

kHz

V

V_{CC_UVLO}

VCC UVLO Hysteresis

PWIN Lower Threshold

Lower Threshold Hysteresis

PWIN Upper Threshold

Upper Threshold Hysteresis

Charge Mode

mV

V

V_{PWIN_L}

V_{PWIN_H}

0.75

1.1

0.85

1.2

mV

V

1.15

50

mV

EN = 5V, Battery Float

EN = 0

2.5

1.5

mA

Input Quiescent Current

I_IN

R_lLIM= 100k

R_lLIM= 56k

400

720

450

810

2700

4.2

500

900

3000

Input Current Limit

I_{IN_LIMIT}

mA

R_lLIM= 16.5k

2400

Input Over-Current Threshold

I_IN(OCP)

τ_INOCBLK

τ_INRECVR

A

Input Over-Current Blanking Time⁽⁵⁾

Input Over-Current Recover Time⁽⁵⁾

120

100

4.35

µs

ms

Connect VB to GND

4.328

4.179

4.09

4.372

4.221

4.21

Terminal Battery Voltage

Recharge Threshold

V_{BATT_FULL}

Leave VB floating or

connect to logic HIGH

4.2

4.15

V

Connect to VB to GND

V_RECH

Leave VB floating or

connect to logic HIGH

3.95

4.01

4.07

V

Recharge Threshold Hysteresis

Battery Over Voltage Threshold

200

mV

As percentage of the

V_{BATT_FULL}

V_{BATT_}

FULL

103.3%

RS1 = 20mΩ, R_ISET= 120k

850

1000

1987

2525

250

1150

2250

2825

Constant Charge (CC) Current

I_CC

I_TC

RS1 = 20mΩ, R_ISET= 60.4k 1725

RS1 = 20mΩ, R_ISET= 47.5k 2225

125

mA

Trickle Charge Current

* Reserve 1200kHz Option

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

ELECTRICAL CHARACTERISTICS (continued)

V_IN= 5.0V, T_A= 25°C, unless otherwise noted.

Parameter

Symbol Condition

Min

Typ

Max Units

Connect to VB to GND

3.0

3.1

3.2

Trickle Charge Voltage Threshold

V_{BATT_TC}

V

Leave VB floating or

connect to high logic

2.9

3

3.1

Trickle Charge Hysteresis

Termination Charge Current

200

10%

mV

RS1 = 20mΩ, R_ISET=60.4k

RS1 = 20mΩ, R_ISET=47.5k

2.5%

17.5%

I_CC

I_BF

Input-Voltage-Regulation

Reference

V_REG

1.18

1.2

1.22

V

Boost Mode

SYS Voltage Range

Feedback Voltage

Feedback Input Current

4.2

6

V

1.18

1.2

1.22

200

V_FB=1V

nA

Threshold over V_SYSto turn

off the converter during

boost mode

Boost SYS Over-Voltage

Protection Threshold

V_SYS(OVP

)

5.6

5.75

125

5.9

V

SYS Over Voltage Protection

Threshold Hysteresis

V_SYSfalling from V_SYS(OVP)

mV

mA

Boost Quiescent Current

I_SYS= 0, MODE = 5V

1.4

RS1 = 20mΩ, R_OLIM

57.6k

=

1.875

2.1

2.083

2.290

Programmable Boost Output

Current Limit Accuracy

I_OLIM

A

RS1 = 20mΩ, R_OLIM= 51k

SYS Over-Current Blanking

Time⁽⁵⁾

τ_SYSOCBLK

τ_SYSRECVR

V_BATT(LOW)

120

1

µs

SYS Over-Current Recover

Time⁽⁵⁾

ms

During boosting

2.5

2.9

V

Weak-Battery Threshold

Before Boost starts

3.05

30

Sleep Mode

V_BATT= 4.2V, SYS Float,

V_IN= 0V, MODE = 0V

Battery Leakage Current

I_LEAKAGE

15

μA

Indication and Logic

-------------

----------------

-------------------

ACOK, CHG, BOOST pin output

low voltage

Sinking 1.5mA

400

1

mV

-------------

----------------

-------------------

ACOK, CHG, BOOST pin leakage

current

Connected to 5V

μA

NTC and Time-out Fault Blinking

Frequency⁽⁵⁾

C_TMR= 0.1μF, I_CHG= 1A

12.5

Hz

EN Input Logic Low Voltage

EN Input High Voltage

0.4

V

1.4

Mode Input Logic Low Voltage

Mode Input Logic High Voltage

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

ELECTRICAL CHARACTERISTICS (continued)

V_IN= 5.0V, T_A= 25°C, unless otherwise noted.

Parameter

Protection

Symbol Condition

Min

Typ

Max

Units

C_TMR=0.1µF, remains in TC

Mode, I_TC= 100mA test

mode

Trickle Charge Time

26

Min

Total Charge Time

C_TMR=0.1µF, I_CHG= 1A

336

NTC Low Temp, Rising Threshold

65.6% 66.6% 67.6%

R_NTC=NCP18XH103(0ºC)

NTC Low Temp, Rising Threshold

Hysteresis

1%

V_SYS

NTC High Temp, Rising

Threshold

34%

35%

1%

36%

R_NTC=NCP18XH103(50ºC)

Charge Mode

NTC High Temp, Rising

Threshold Hysteresis

Charging Current Foldback

120

150

°C

Threshold⁽⁵⁾

Thermal Shutdown Threshold⁽⁵⁾

Notes:

5) Guaranteed by design.

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

TYPICAL CHARACTERISTICS

C_IN= C_BATT= C_SYS= C2 = 22µF, L1 = 2.2µH, RS1 = 20mΩ, C4 = C_TMR= 0.1µF, Battery Simulator,

unless otherwise noted.

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

TYPICAL CHARACTERISTICS (continued)

C_IN= C_BATT= C_SYS= C2 = 22µF, L1 = 2.2µH, RS1 = 20mΩ, C4 = C_TMR= 0.1µF, Battery Simulator,

unless otherwise noted.

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

TYPICAL PERFORMANCE CHARACTERISTICS

For Charge Mode: V_IN= 5V, I_CHG= 2.5A, L_{IN_LIM}= 2.7A, I_SYS= 0A

For Boost Mode:

V_BATT= 3.7V, V_{SYS_SET}= 5V, I_OLIM= 2.1A

C_IN= C_BATT= C_SYS= C2 = 22µF, L1 = 2.2µH, RS1 = 20mΩ, C4 = C_TMR= 0.1µF, Battery Simulator,

unless otherwise noted.

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

For Charge Mode: V_IN= 5V, I_CHG= 2.5A, L_{IN_LIM}= 2.7A, I_SYS= 0A

For Boost Mode:

V_BATT= 3.7V, V_{SYS_SET}= 5V, I_OLIM= 2.1A

C_IN= C_BATT= C_SYS= C2 = 22µF, L1 = 2.2µH, RS1 = 20mΩ, C4 = C_TMR= 0.1µF, Battery Simulator,

unless otherwise noted.

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

For Charge Mode: V_IN= 5V, I_CHG= 2.5A, L_{IN_LIM}= 2.7A, I_SYS= 0A

For Boost Mode:

V_BATT= 3.7V, V_{SYS_SET}= 5V, I_OLIM= 2.1A

C_IN= C_BATT= C_SYS= C2 = 22µF, L1 = 2.2µH, RS1 = 20mΩ, C4 = C_TMR= 0.1µF, Battery Simulator,

unless otherwise noted.

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

For Charge Mode: V_IN= 5V, I_CHG= 2.5A, L_{IN_LIM}= 2.7A, I_SYS= 0A

For Boost Mode:

V_BATT= 3.7V, V_{SYS_SET}= 5V, I_OLIM= 2.1A

C_IN= C_BATT= C_SYS= C2 = 22µF, L1 = 2.2µH, RS1 = 20mΩ, C4 = C_TMR= 0.1µF, Battery Simulator,

unless otherwise noted.

MP2637 Rev. 1.04

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

PIN FUCTIONS

Pin #

Name

Description

1, 23, 24

PGND

------------

Power Ground.

Charge Completion Indicator. Logic LOW indicates charge mode. This is an open drain

pin during charge complete or suspended

Boost Mode indicator. Logic LOW indicates boost mode in operation. This is an open

drain pin during charge mode or sleep mode operation.

2

3

CHG

-------------------

BOOST

4

5

6

CSP

BATT

AGND

Battery Charge Current Sense Positive Input.

Positive Battery Terminal / Battery Charge Current Sense Negative Input.

Analog Ground

Programmable Output-Current Limit for boost mode. Connect an external resistor to GND

to program the system current in boost mode. The R_OLIMCANNOT be lower than 47.5kΩ.

Programmable Charge Current Pin. Connect an external resistor to GND to program the

charge current.

7

8

OLIM

ISET

9

10

NTC

FB

Negative Temperature Coefficient (NTC) Thermistor.

System voltage feedback input.

----------------

Valid Input Supply Indicator. Logic LOW on this pin indicates the presence of a valid

power supply.

11

12

ACOK

Input Voltage Feedback for input voltage regulation loop. Connect to tap of an external

resistor divider from VIN to GND to program the input voltage regulation. Once the voltage

at REG pin drops to the inner threshold, the charge current is reduced to maintain the

input voltage at the regulation value.

REG

Oscillator Period Timer. Connect a timing capacitor between this pin and GND to set the

oscillator period. Short to GND to disable the Timer function.

Input pin to detect the presence of valid input power. Pulling this pin to GND will turn off

the IN-to-SYS pass through MOSFET

Input Current Set. Connect to GND with an external resistor to program input current limit

in charge mode.

Internal Circuit Power Supply. Bypass this pin to GND with a ceramic capacitor not higher

than 100nF. This pin CANNOT carry external load higher than 5mA.

Programmable Battery-Full Voltage. Leave floating or connect to logic HIGH for 4.2V,

while connect to GND for 4.35V.

13

14

15

16

17

TMR

PWIN

ILIM

VCC

VB

Charge Control Input. Logic HIGH enables charging. Logic LOW disables charging. Active

__________

18

19

EN

only when ACOK is low (input power is OK).

Mode Select. Logic HIGH→boost mode. Logic LOW→sleep mode. Active only when

__________

MODE

ACOK is HIGH (input power is not available).

Adapter Input. Place a bypass capacitor close to this pin to prevent large input voltage

spikes.

System Output. A minimum of 22uF ceramic cap is required to be placed as close as

possible to the SYS and PGND pins. Total capacitance should not be lower than 44uF

Switch Output Node. It is recommended not to place Via's on the SW plane during PCB

layout

20

21

22

VIN

SYS

SW

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

BLOCK DIAGRAM

SYS

FB

SW

Q1

Q2

HSMOS

VIN

Buffer

Current

Sense

LSMOS

A1

CSP

VCC

Driver

BATT

K1*I_CHG

V_BATT

PWM Signal

Charge

Pump

PGND

ACOK

V_BATT

PWIN

0.8V

Mode Control

PWM Controller

1.15V

VCC

Control Logic&

Mode Selection

BATT+

300mV

NTC

T_Ref

MODE

EN

GMT

T_J

VB

V_{BATT_Ref}

ACOK

Thermal

Shutdown

GMV

V_BATT

CHG

REG

BOOST

GMINV

Indication&

Timer

MIN

V_{REG_Ref}

GMI

I_{CHG_Ref}

K1*I_CHG

ISET

ILIM

I_{IN_Ref}

Current Setting

GMINI

TMR

K2*I_IN

OLIM

AGND

Figure 1: Functional Block Diagram in Charge Mode

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

SYS

FB

SW

Q1

Q2

HSMOS

VIN

A1

CSP

VCC

LSMOS

Driver

BATT

Charge

Pump

V_BATT

PWM Signal

Integration

ACOK

PGND

To Current

Setting

V_BATT

PWIN

0.8V

Mode Control

PWM Controller

1.15V

VCC

Control Logic&

Mode Selection

BATT+

300mV

NTC

MODE

EN

VB

V_{SYS_Ref}

ACOK

CHG

Thermal

Shutdown

GMV

V_FB

REG

BOOST

Indication&

Timer

ISET

ILIM

I_{OLIM_Ref}

Current Setting

GMINI

TMR

K3*I_SYS

OLIM

AGND

Figure 2: Functional Block Diagram in Boost Mode

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

OPERATION FLOW CHART

POR

Yes

V_CC<V_{CC_UVLO}

No

V_{PWIN_L}<V_PWIN<V_{PWIN_H}

&V_IN>V_BATT+300mV

Yes

No

/ACOK is Low, System

Powered By IN

MODE High?

No

EN High?

Yes

No

Charge Mode

/CHG Low

Boost Mode

/BOOST Low

Sleep Mode

Figure 3: Mode Selection Flow Chart

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

OPERATION FLOW CHART (continued)

Normal Operation

Charge Mode

/CHG Low

Charge Mode?

V_BATT>V_{BATT_FULL}

V_{BATT_TC}<V_BATT<V_{BATT_FULL}

V_BATT<V_{BATT_TC}

C.V.C

C.C.C

T.C.C

No

I_CHG<I_BF

Battery Full

V_BATT>V_{BATT_FULL}

V_BATT>V_{BATT_TC}

Yes

Charger “Off”,

/CHG is high

Yes

No

V_BATT< V_RECH

?

No

Timer Out ?

Yes

NTC Fault?

T_J≥120^oC?

Yes

Charge

Termination, /CHG

is high

Charge Suspend,

/CHG is high

Decrease I_CHGto

maintain T_Jat 120^oC

No

Reset

Timer?

NTC OK?

T_J≥150^oC?

Yes

Charge Recovery,

Return to Normal

Operation

Thermal

Shutdown, /CHG is

high

No

T_J≤120^oC?

Yes

Fault Protection

Figure 4: Normal Operation and Fault Protection in Charge Mode

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19

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

OPERATION FLOW CHART (continued)

Power Path Management

SYS Output

Current Increase

V_PWINtouch the V_REG

?

I_INhit the I_{IN_LIMIT}?

No

Yes

Charge Current

Decrease

I_CHG=0?

Yes

No

I_IN>7A?

No

Normal Operation

I_INexceeds I

?

IN(OCP)

No

Yes

Regulate the I at

IN

I_IN(OCP)

No

Yes

T_INOCBLKreaches?

Yes

IN to SYS MOSFET

turns Off

No

T_INRECVRreaches?

Figure 5: Power-path Management in Charge Mode

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20

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

OPERATION FLOW CHART (continued)

Boost Mode

Normal Boost

/BOOST Low

Operation

No

I_SYS> I_OLIM

?

V_BATT>2.9V?

Yes

Output current loop

works, V_SYSdecreases

No

Mode High?

Yes

V_SYS< V_BATT

?

Yes

Normal Boost

Operation

V_SYS< 2V?

Yes

No

Yes

No

V_BATT<2.5V?

Yes

Down mode

No

I_Lhits the

current limit

T_SYSBLKReaches?

Yes

Boost Turns Off

Yes

Boost Shutdown

No

T_SYSRECVR

Reaches?

Figure 6: Operation Flow Chart in Boost Mode

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21

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

START UP TIME FLOW IN CHARGE MODE

Condition: EN = 5V, Mode = 0V, /ACOK and /CHG are always pulled up to an external 5V.

V_PWIN> 0.8V

0V

&

V_IN

V_IN> V_BATT+ 300mV

5V

0V

EN

Mode

V_CC

V_CCfollows V_IN

2.2V

Band

Gap

0V

5V

ACOK

0V

V_SYS> V_BATT+ 50mV

V_SYS

5V

0V

CHG

SS

400μs

150μs

Force

Charge

I_CC

10%I_CC

Charge

Current

0A

I_BF

Comparator

V_{BATT_FULL}

Battery

Voltage

Auto-recharge threshold

Assume v_BATT> V_{BATT_TC}

Auto-

recharge

Figure 7: Input Power Start-Up Time Flow in Charge Mode

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22

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

START UP TIME FLOW IN CHARGE MODE

Condition: EN = 5V, Mode = 0V, /ACOK and /CHG are always pulled up to an external 5V.

0V

V_IN

5V

0V

EN

0V

Mode

V_CC

2.2V

Band

Gap

0V

5V

ACOK

0V

V_SYS

5V

0V

CHG

SS

400μs

150μs

Force

Charge

I_CC

10%I_CC

0A

Charge

Current

I_BF

Comparator

V_{BATT_FULL}

Battery

Voltage

Assume v_BATT> V_{BATT_TC}

Auto-

recharge

Figure 8: EN Start-Up Time Flow in Charge Mode

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23

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

START UP TIME FLOW IN BOOST MODE

Condition: V_IN= 0V, Mode = 5V, /Boost is always pulled up to an external constant 5V.

2.5V

2.9V

0V

V_CCfollows V_SYS

V_BATT

V_CCfollows

V_BATT

2.2V

V_CC

MODE

Band

Gap

5V

0V

BOOST

1.2ms

Boost

SS

Down

Mode

V_SYS>V_BATT+300mV

0V

V_SYS

Figure 9: Battery Power Start-Up Time Flow in Boost Mode

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

START UP TIME FLOW IN BOOST MODE

Condition: V_IN= 0V, /Boost is always pulled up to an external constant 5V.

V_BATT

2.9V

V_CCfollows V_SYS

V_CCfollows V_BATT

2.2V

V_CC

5V

0V

MODE

5V

Band

Gap

0V

5V

0V

BOOST

1.2ms

Boost

Down

Mode

SS

V_SYS>V_BATT+300mV

0V

V_SYS

Figure 10: Mode Start-Up Time Flow in Boost Mode

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25

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

OPERATION

INTRODUCTION

The MP2637 is a highly-integrated, flexible,

switch-mode battery charger with system power

path management, designed for single-cell Li-ion

or Li-Polymer batteries used in a wide range of

applications. Depending on the status of the

Input, the MP2637 can operate in three different

modes: Charge Mode; Boost Mode; Sleep Mode.

In charge mode the MP2637 can work with a

single cell Li-ion or Li-polymer battery. In boost

mode the MP2637 boosts the battery voltage to

V_{SYS_SET}to power higher voltage system rails. In

sleep mode both charging and boost operations

are disabled and the device enters a power

saving mode to help reduce the overall power

consumption. The MP2637 monitors V_INto allow

smooth transition between different modes of

operation.

CHARGE MODE OPERATION

Charge

Cycle

(Trickle

ChargeCC

ChargeCV Charge)

In charge mode, the MP2637 has five control

loops to regulate the input current, input voltage,

charge current, charge voltage, and device

junction temperature. The MP2637 charges the

battery in three phases: trickle current (TC),

constant current (CC), and constant voltage (CV).

While charge operation is enabled, all five loops

are active but only one determines the IC

behavior. A typical battery charge profile is

depicted in Figure11 (a). The charger stays in TC

charge mode until the battery voltage reaches a

TC-to-CC threshold. Otherwise the charger

enters CC charge mode. When the battery

voltage rises to the CV-mode threshold, the

charger operates in constant voltage mode.

Figure (b) shows a typical charge profile when

the input-current-limit loop dominates during the

CC charge mode, and in this case the charger

maximizes the charging current due to the

switching-mode charging solution, resulting in

faster charging than a traditional linear solution.

Figure 11: Typical Battery Charge Profile

Auto-recharge

Once the battery charge cycle is completed, the

charger remains off. During this time, the system

load may consume battery power, or the battery

may self discharge. To ensure the battery will not

go into depletion,

a

new charge cycle

automatically begins when the battery voltage

falls below the auto-recharge threshold and the

input power is present. The timer is reset when

the auto-recharge cycle begins.

During the off state after the battery is fully

charged, if the input power re-starts or the EN

signal refreshes, the charge cycle will start and

the timer will reset no matter what the battery

voltage is.

Battery Over-Voltage Protection

The MP2637 has battery over-voltage protection.

If the battery voltage exceeds the battery over-

voltage threshold, (103.3% of the battery-full

voltage), charging is disabled. Under this

condition, an internal 5kΩ dummy load draws a

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26

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

current from the BATT pin to decrease the

battery voltage and protect the battery.

Input Voltage Regulation in Charge Mode

In charge mode, if the input power source is not

sufficient to support both the charge current and

system load current, the input voltage will

decrease. As the input voltage approaches the

programmed input voltage regulation value,

charge current is reduced to allow priority of

system power and maintain proper regulation of

the input voltage.

Timer Operation in Charge Mode

The MP2637 uses an internal timer to terminate

the charging. The timer remains active during the

charging process. An external capacitor between

TMR and GND programs the charge cycle

duration.

If charging remains in TC mode beyond the

trickle-charge time, τ_{TRICKLE_TMR}, charging will

terminate. The following equation determines the

length of the trickle-charge period:

The input voltage can be regulated by a resistor

divider from IN pin to REG pin to AGND

according to the following equation:

R5

4.510⁴1.6(V)C_TMR(F)

1.25I_TC(A)RS1(m) 2(A)

(4)

V_REG V_{IN_R}

(V)

(1)

_{TC_ TMR}



(s)

R3 R5

where the V_REGis the internal voltage reference,

1.2V, and the V_{IN_R}is the desired regulation

voltage.

The maximum total charge time is:

3.410⁶1.6(V)C_TMR(F)

1.25I_CHG(A)RS1(m) 2(A)

Negative Temperature Coefficient (NTC) Input

for Battery Temperature Monitoring

(2)

_{TOTAL _ TMR}



(s)

Integrated Over Current Protection and Over

Voltage Protection for Pass-through Path

The MP2637 has an integrated IN to SYS pass-

through path to allow direct connection of the

input voltage to the system even if charging is

disabled. Based on the above, the MP2637

continuously monitors both input current and

voltage. In the event of an OCP or OVP charge

current will be reduced to ensure priority of the

system power requirements.

The MP2637 has a built-in NTC resistance

window comparator, which allows the MP2637 to

monitor the battery temperature via the battery-

integrated thermistor. Connect an appropriate

resistor from V_SYSto the NTC pin and connect the

thermistor from the NTC pin to GND. The resistor

divider determines the NTC voltage depending

on the battery temperature. If the NTC voltage

falls outside of the NTC window, the MP2637

stops charging. The charger will then restart if the

temperature goes back into NTC window range.

Please refer to Application Information section for

the appropriate resistance selection.

In addition, the MP2637 also features input over

current and voltage protection for the IN to SYS

pass-through path.

Input over-current protection (OCP):

When the total input current exceeds 4.2A, Q2

(Fig 12) is controlled linearly to regulate the

current. If the current continues to exceeds 4.2A

after a 120µs blanking time, Q2 will be turn off. In

the event of input current exceeding 7A Q2 will

be turned off almost instantaneously and without

any blanking time, this to protect both Q1 and Q2.

Input Current Limiting in Charge Mode

The MP2637 has a dedicated pin used to

program the input current limit. The current at

ILIM is a fraction of the input current; the voltage

at ILIM indicates the average input current of the

switching regulator as determined by the resistor

value between ILIM and GND. As the input

current approaches the programmed input

current limit, charge current is reduced to allow

priority to system power.

Input over-voltage protection (OVP):

The MP2637 uses the PWIN pin to sense the

status of input voltage. When the voltage at the

PWIN pin is lower than 0.8V or higher than 1.15V,

an invalid input power source is detected by the

MP2637. At this time the IN to SYS pass-through

path will be turned off. An OVP threshold can be

programmed via PWIN pin to prevent an over

Use the following equation to determine the input

current limit threshold.

45(k)

R_ILIM(k)

(3)

I



(A)

ILIM

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

voltage event happening at SYS side when

junction temperature rises to 150°C.

plugging in a wrong adapter.

Non-sync Operation Mode

During charging mode, the MP2637 continuously

monitors the total input current flowing from IN

pin to SYS pin. When the input current is lower

than 170mA, the low side switch operates as a

non-synchronous MOSFET.

SYS

Q1

Q2

IN

Constant-Off-Time Control for Large Duty

Charging Operation

The MP2637 has a built-in 600kHz frequency

oscillator for the switching frequency. Unlike a

traditional fixed frequency, the MP2637 features

a constant off time control to support constant-

current charge even when the input voltage is

very close to battery voltage. As shown in the

Figure 13, the MP2637 continuously compares

the high-side FET sense current with comp level,

if the sense current doesn’t reach the comp level

within the original switching period, the next clock

will be delayed until the sense current reaches

the comp level. As a result the duty cycle is able

to be extended as large as possible.

Charge

Pump

Figure12: Integrated Pass-through Path

Charge Current Setting

The external sense resistors, RS1 and R_ISET

program the battery charge current, I_CHG. Select

R_ISETbased on RS1:

,

2400

I_CHG(A) 

(5)

R_ISET(k)RS1(m)

Battery Short Protection

The MP2637 has two current limit thresholds. CC

and CV modes have a peak current limit

threshold of 6.5A, while TC mode has a current

limit threshold of 3.2A. Therefore, the current limit

threshold decreases to 3.2A when the battery

voltage drops below the TC threshold. Moreover,

the switching frequency also decreases when the

BATT voltage drops to 40% of the charge-full

voltage.

Full Operation Indication

The MP2637 integrates indicators for the

following conditions as shown in Table2.

The blinking frequency is:

1(A)

0.8C_TMR(F)

F



(6)

Blinking

Table 2: Indicator for Each Operation Mode

----------------

------------

-------------------

Thermal Foldback Function

Operation

ACOK

CHG

BOOST

The MP2637 implements thermal protection to

prevent thermal damage to the IC and the

surrounding components. An internal thermal

sense and feedback loop automatically

decreases the programmed charge current when

the die temperature reaches 120°C. This function

is called the charge-current-thermal foldback. Not

only this function protects against thermal

damage, it can also set the charge current based

on requirements rather than worst-case

conditions while ensuring safe operation.

Furthermore, the part includes thermal shutdown

protection where the ceases charging if the

In Charging

Low

End of Charge,

Charging

disabled,

Battery OVP

NTC Fault,

Timer Out

Charge

Mode

Low

High

Blinking

Boost Mode

Sleep Mode

High

Low

High

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

Comp

Slope Compensation

HS Sense Current

Constant Off Time

HS Signal

600kHz

Lower the Fsw to support larger Duty

Figure 13: Constant-Off-Time Operation Profile

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

boost converter restarts again as long as the

MODE pin remains in active status.

BOOST MODE OPERATION

Low-Voltage Start-Up

The minimum battery voltage required to start up

the circuit in boost mode is 2.9V. Initially, when

V_SYS< V_BATT, the MP2637 works in down mode.

In this mode, the synchronous P-MOSFET stops

switching and its gate connects to V_BATTstatically.

The P-MOSFET stays off as long as the voltage

Boost Output Current Limiting

The MP2637 integrates a programmable output

current limit function in boost mode. If the boost

output current exceeds this programmable limit,

the output current will be limited at this level and

the SYS voltage will start to drop down. The

OLIM pin programs the current limit threshold up

to 2.4A as per the following equation:

across the parasitic C_DS(V_SW) is lower than V_BATT

.

When the voltage across C_DSexceeds V_BATT, the

synchronous P-MOSFET enters linear mode

allowing the inductor current to decrease and

flowing into the SYS pin. Once V_SYSexceeds

V_BATT, the P-MOSFET gate is released and

normal closed-loop PWM operation is initiated. In

boost mode, the battery voltage can drop to as

low as 2.5V without affecting circuit operation.

2400

I_OLIM(A) 

(7)

R_OLIM(k)RS1(m)

SYS Output Over Current Protection

The MP2637 integrates three-phase output over-

current protection.

Phase one (boost mode output current limit):

when the output current exceeds the

programmed output current limit, the output

constant current loop controls the output current,

the output current remains at its limit of I_OLIM, and

V_SYSdecreases.

SYS Disconnect and Inrush Limiting

The MP2637 allows for true output disconnect by

eliminating body diode conduction of the internal

P-MOSFET rectifier. V_SYScan go to 0V during

shutdown, drawing no current from the input

source. It also allows for inrush current limiting at

start-up, minimizing surge currents from the input

supply. To optimize the benefits of output

disconnect, avoid connecting an external

Schottky diode between the SW and SYS pins.

Phase two (down mode): when V_SYSdrops below

V_BATT+100mV and the output current loop

remains in control, the boost converter enters

down mode and shutdown after a 120μs blanking

time.

Board layout is extremely critical to minimize

voltage overshoot at the SW pin due to stray

inductance. Keep the output filter capacitor as

close as possible to the SYS pin and use very

low ESR/ESL ceramic capacitors tied to a good

ground plane.

Phase three (short circuit mode): when V_SYS

drops below 3.75V (will be 2V during boost soft

start), the boost converter shuts down

immediately once the inductor current hits the

fold-back peak current limit of the low side N-

MOSFET. The boost converter can also recover

automatically after a 1ms deglitch period.

Boost Output Voltage Setting

In boost mode, the MP2637 programs the output

voltage via the external resistor divider at FB pin,

and provides built-in output over-voltage

protection (OVP) to protect the device and other

components against damage when V_SYSgoes

beyond 6V. Once the output over voltage occurs,

the MP2637 turns off the boost converter. When

the voltage on V_SYSdrops to a normal level, the

Thermal Shutdown Protection

The thermal shutdown protection is also active in

boost mode. Once the junction temperature rises

higher than 150°C, the MP2637 enters thermal

shutdown. It will not resume normal operation

until the junction temperature drops below 120°C

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

APPLICATION INFORMATION

COMPONENT SELECTION

With the given R6, R4 is then:

Setting the Charge Current in Charge Mode

V  V

IN

^PWINR6

(12)

R4 

V_PWIN

In charge mode, both the external sense resistor,

RS1, and the resistor R_ISETconnect to the ISET

pin to set the charge current (ICHG) of the MP2637

(see the Typical Application circuit).

For a typical application, start with R6=5.1kΩ, R4

is 21.5kΩ.

Setting the Input Voltage Regulation in

Charge Mode

In charge mode, connect a resistor divider from

the IN pin to AGND with tapped to REG pin to

program the input voltage regulation.

Given ICHG and RS1, RISET can be calculated as:

2400

R_ISET(k) 

(8)

I_CHG(A)RS1(m)

For example, for ICHG=2.5A, and RS1=20mΩ,

thus: RISET=48kΩ.

R3 R5

(13)

V

 V_REG



(V)

Setting the Input Current Limiting in Charge

Mode

IN_R

R5

With the given R5, R3 is:

_{IN_R} V

In charge mode, connect a resistor from the ILIM

pin to AGND to program the input current limit.

The relationship between the input current limit

and setting resistor is as following:

45

V

^REGR5(V)

(14)

R3 

V_REG

For a preset input voltage regulation value, say

4.75V, start with R5=5.1kΩ, R3 is 15kΩ.

R_ILIM



(k)

(9)

I_{IN_LIM}(A)

NTC Function in Charge Mode

where RILIM must exceed 16.5kΩ, so that IIN_LIM is

in the range of 0A to 2.7A.

Figure 14 shows that an internal resistor divider

sets the low temperature threshold (V_TL) and high

temperature threshold (V_TH) at 66.6%·V_SYSand

For most applications, use R_ILIM= 50kΩ

(IUSB_LIM=900mA) for USB3.0 mode, and use R_ILIM

= 90kΩ (I_{USB_LIM}=500mA) for USB2.0 mode.

35%·V_SYS

,

respectively. For

a

given NTC

thermistor, select an appropriate R_T1and R_T2to

set the NTC window.

Setting the Input Voltage Range for Different

Operation Modes

R_T2//R_{NTC_Cold}

V_SYSR_T1R_T2//R_{NTC_Cold}

V_TL

(15)



 TL  66.6%

TH  35%

A resistive voltage divider from the input to PWIN

pin determines the operating mode of MP2637.

R_T2//R_{NTC_Hot}

V_SYSR_T1R_T2//R_{NTC_Hot}

V_TH

(16)



R6

(10)

V_PWIN V 

(V)

IN

R4 R6

Where R_{NTC_Hot}is the value of the NTC resistor at

the upper bound of its operating temperature

range, and R_{NTC_Cold}is its lower bound.

If the voltage on PWIN is between 0.8V and

1.15V, the MP2637 works in the charge mode.

While the voltage on the PWIN pin is not in the

range of 0.8V to 1.15V and VIN > 2V, the

MP2637 works in the boost mode (see Table 1)).

The two resistors, R_T1and R_T2, independently

determine the upper and lower temperature limits.

This flexibility allows the MP2637 to operate with

most NTC resistors for different temperature

range requirements. Calculate R_T1and R_T2as

follows:

For a wide operating range, use a maximum

input voltage of 6V as the upper threshold for a

voltage ratio of:

V_PWIN1.15

R6

(11)



V

6

R4 R6

IN

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31

MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

R_{NTC_Hot}R_{NTC_Cold}(TL  TH)

Setting the Output Current Limit in Boost

Mode

(17)

(18)

R_T1

R_T2



THTL(R_{NTC_Cold}R_{NTC_Hot}

)

In boost mode, connect a resistor from the OLIM

pin to AGND to program the output current limit.

The relationship between the output current limit

and setting resistor is as follows:

2400

(TL  TH)R_{NTC_Cold}R_{NTC_Hot}

(1 TL)THR_{NTC_Cold}-(1-TH)TLR_{NTC_Hot}

For example, the NCP18XH103 thermistor has

the following electrical characteristic:

I_OLIM(A) 

(21)

R_OLIM(k)RS1(m)

At 0°C, R_{NTC_Cold}= 27.445kΩ;

At 50°C, R_{NTC_Hot}= 4.1601kΩ.

The output current limit of the boost can be

programmed up to 2.1A (min). Considering 10%

output current limit accuracy, typical 2.3A output

current limit is required. According to the above

equation, given 20mΩ sense resistor, 52k R_OLIM

will get 2.3A output current limit.

Based on equation (17) and equation (18),

RT1=6.65kΩ and RT2 = 25.63kΩ are suitable for

an NTC window between 0°C and 50°C. Chose

approximate values: e.g., R_T1=6.65kΩ and

R_T2=25.5kΩ.

For safety operation, R_OLIMCANNOT be lower

than 47.5kΩ

If no external NTC is available, connect R_T1and

R_T2to keep the voltage on the NTC pin within the

valid NTC window: e.g., R_T1= R_T2= 10kΩ.

Selecting the Inductor

Inductor selection trades off between cost, size,

and efficiency.

A

lower inductance value

SYS

corresponds with smaller size, but results in

higher current ripple, higher magnetic hysteretic

losses, and higher output capacitances. However,

a higher inductance value benefits from lower

ripple current and smaller output filter capacitors,

but results in higher inductor DC resistance (DCR)

loss.

Low Temp Threshold

R_T1

V_TL

NTC

R_NTC

R_T2

High Temp Threshold

V_TH

Choose an inductor that does not saturate under

the worst-case load condition.

Figure 14: NTC Function Block

For convenience, an NTC thermistor design

spreadsheet is also provided, please inquire if

necessary.

1. In Charge Mode

When MP2637 works in charge mode (as a Buck

Converter), estimate the required inductance as:

Setting the System Voltage in Boost Mode

In the boost mode, the system voltage can be

regulated to the value customer required

between 4.2V to 6V by the resistor divider at FB

pin as R1 and R2 in the typical application circuit.

V  V_BATT

I_{L _MAX}

V_BATT

IN

(22)

L 



V  f_SW

IN

where V_IN, V_BATT, and f_Sare the typical input

voltage, the CC charge threshold, and the

switching frequency, respectively. ΔI_{L_MAX}is the

maximum peak-to-peak inductor current, which is

usually designed at 30%-40% of the CC charge

current.

R1R2

V_SYS 1.2V

(19)

R2

where 1.2V is the voltage reference of SYS. With

a typical value for R2, 10kΩ, R1 can be

determined by:

With a typical 5V input voltage, 35% inductor

current ripple at the corner point between trickle

charge and CC charge (V_BATT=3V, Ichg=2.5A),

the inductance 2.2μH.

V_SYS1.2V

R1 R2

(V)

(20)

1.2V

2. In Boost Mode

For example, for a 5V system voltage, R2 is

10kΩ, and R1 is 31.6kΩ.

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

2. Boost Mode

When the MP2637 is in Boost mode (as a Boost

converter), the required inductance value is

calculated as:

The capacitor, C_SYS, is the output capacitor of

boost converter. C_SYSkeeps the system voltage

ripple small and ensures feedback loop stability.

The system current ripple is given by:

V_BATT(V_SYS V_BATT

V_SYS f_SW I_{L _MAX}

)

(23)

L 

V_TC(V_{SYS _MAX} V_TC)

(27)

I_{RMS _MAX} I_{SYS _MAX}



(24)

I_{L _MAX} (30% 40%)I_BATT(MAX)

V_{SYS _MAX}

V_SYSI_SYS

V_BATT

(25)

Since the input voltage is passes to the system

directly, V_{IN_MAX}=V_{SYS_MAX}, both charge mode and

boost mode have the same system current ripple.

I_BATT(MAX)



Where V_BATTis the minimum battery voltage, f_SW

is the switching frequency, and ∆I_{L_MAX}is the

peak-to-peak inductor ripple current, which is

approximately 30% of the maximum battery

current I_BATT(MAX), I_SYS(MAX)is the system current

and η is the efficiency.

For I_{CC_MAX}=2A, V_TC=3V, V_{IN_MAX}=6V, the

maximum ripple current is 1.25A. Select the

system capacitors base on the ripple-current

temperature rise not exceeding 10°C. For best

results, use ceramic capacitors with X7R

dielectrics with low ESR and small temperature

coefficients. For most applications, use three

22µF capacitors.

In the worst case where the battery voltage is 3V,

a 30% inductor current ripple, and a typical

system voltage (V_SYS=5V), the inductance is

1.5µH when the efficiency is 90%.

Selecting the Battery Capacitor C_BATT

C_BATTis in parallel with the battery to absorb the

high-frequency switching ripple current.

For best results, use an inductor with an

inductance of 2.2uH with a DC current rating that

is not lower than the peak current of MOSFET.

For higher efficiency, minimize the inductor’s DC

resistance.

1. Charge Mode

The capacitor C_BATTis the output capacitor of the

buck converter. The output voltage ripple is then:

Selecting the Input Capacitor C_IN

The input capacitor C_INreduces both the surge

current drawn from the input and the switching

noise from the device. The input capacitor

impedance at the switching frequency should be

less than the input source impedance to prevent

high-frequency-switching current from passing to

the input. For best results, use ceramic

capacitors with X7R dielectrics because of their

low ESR and small temperature coefficients. For

most applications, a 22µF capacitor will suffice.

V_BATT

V_BATT

1 V_BATT/ V_SYS

(28)

r_BATT



8C_BATT f_SW²L

2. Boost Mode

The capacitor C_BATTis the input capacitor of the

boost converter. The input voltage ripple is the

same as the output voltage ripple from equation

(28)

Both charge mode and boost mode have the

same battery voltage ripple. The capacitor C_BATT

can be calculated as:

Selecting the System Capacitor C_SYS

Select C_SYSbased on the demand of the system

current ripple.

1 V_TC/ V_{SYS _MAX}

8 r_{BATT _MAX} f_SW²L

(29)

C_BATT



1. Charge Mode

The capacitor C_SYSacts as the input capacitor of

the buck converter in charge mode. The input

current ripple is:

To guarantee the ±0.5% BATT voltage accuracy,

the maximum BATT voltage ripple must not

exceed 0.5% (e.g. 0.2%). The worst case occurs

at the minimum battery voltage of the CC charge

with the maximum input voltage.

V_TC(V_{IN_MAX} V_TC)

(26)

I_{RMS _MAX} I_{SYS _MAX}



V

IN_MAX

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

For V_{SYS_MAX}=6V, V_{CC_MIN}=V_TC=3V, L=2.2µH,

f_SW=600kHz, , C_BATTis 39µF .

r_{BATT _ MAX} 0.2%

Two pieces of 22µF ceramic with X7R dielectrics

capacitor in parallel will suffice.

PCB Layout Guide

PCB layout is very important to meet specified

noise, efficiency and stability requirements. The

following design considerations can improve

circuit performance:

1) Route the power stage adjacent to their

grounds. Aim to minimize the high-side switching

node (SW, inductor) trace lengths in the high-

current paths.

Top Layer

Keep the switching node short and away from all

small control signals, especially the feedback

network.

Place the input capacitor as close as possible to

the VIN and PGND pins. The local power input

capacitors, connected from the SYS to PGND,

must be placed as close as possible to the IC.

Place the output inductor close to the IC and

connect the output capacitor between the

inductor and PGND of the IC.

2) For high-current applications, the power pads

for IN, SYS, SW, BATT and PGND should be

connected to as many coppers planes on the

board as possible. This improves thermal

performance because the board conducts heat

away from the IC.

Bottom Layer

Figure 15: PCB Layout Example – board size is

22x25mm

Design Example

Below is a design example following the

application guidelines for the specifications:

3) The PCB should have a ground plane

connected directly to the return of all components

through vias (e.g., two vias per capacitor for

power-stage capacitors, one via per capacitor for

small-signal components). A star ground design

approach is typically used to keep circuit block

currents isolated (power-signal/control-signal),

which reduces noise-coupling and ground-

bounce issues. A single ground plane for this

design gives good results.

Table 3: Design Example

V_IN

5V/500mA for USB,

5V/3A for Adapter

3.7V / 2.5A

Charge

Discharge

f_SW

5V / 2.1A

600kHz

Figure 16 shows the detailed application

schematic. The Typical Performance

Characteristics section shows the typical

performance and circuit waveforms. For more

possible applications of this device, please refer

to the related Evaluation Board datasheets.

4) Place ISET, OLIM and ILIM resistors very

close to their respective IC pins.

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

TYPICAL APPLICATION CIRCUITS

Figure 16: Typical Application Circuit of MP2637 with USB connectors

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MP2637 –2.5A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 2.4A BOOST

PACKAGE INFORMATION

QFN-24 (4mmx4mm)

PIN 1 ID

MARKING

PIN 1 ID

INDEX AREA

TOP VIEW

BOTTOM VIEW

SIDE VIEW

NOTE:

1) ALL DIMENSIONS ARE IN MILLIMETERS.

2) EXPOSED PADDLE SIZE DOES NOT INCLUDE

MOLD FLASH.

3) LEAD COPLANARITY SHALL BE 0.10

MILLIMETERS MAX.

4) JEDEC REFERENCE IS MO-220.

5) DRAWING IS NOT TO SCALE.

RECOMMENDED LAND PATTERN

NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third

party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not

assume any legal responsibility for any said applications.

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36


型号：	MP2637GR
厂家：	MONOLITHIC POWER SYSTEMS
描述：	2.5A Single Cell Switch Mode Battery Charger with Power Path Management (PPM) and 2.4A Boost Current with Trickle Timer 电池
文件：	总36页 (文件大小：1862K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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