MP2635GR_技术文档

MP2635

2A Single Cell Switch Mode Battery Charger

with Power Path Management and Boost OTG

The Future of Analog IC Technology

DESCRIPTION

FEATURES

The MP2635 is a highly-integrated, flexible,

switch-mode battery charge management and

system power path management device for a

single-cell Li-ion and Li-Polymer battery used in

a wide range of portable applications.

•

4.5V-to-6V Operating Input Voltage Range

Power Management Function Integrated

Input-Current Limit and Input-Voltage

Regulation

Up to 2A Programmable Charge Current

Trickle-Charge Function

•

The MP2635 has two operating modes—charge

mode and boost mode—to allow management

of system and battery power based on the state

of the input.

Selectable 3.6V/ 4.2V Charge Voltage with

0.5% Accuracy

•

Negative Temperature Coefficient Pin for

Battery Temperature Monitoring

Programmable Timer Back-Up Protection

Thermal Regulation and Thermal Shutdown

Internal Battery Reverse Leakage Blocking

Reverse Boost Operation Mode for System

Power

Up to 91% 5V Boost Mode Efficiency @ 1A

Programmable Output Current Limit for

Boost Mode

When input power is present, the device

operates in charge mode. It automatically

detects the battery voltage and charges the

battery in the 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.

•

Integrated Short Circuit Protection for Boost

Mode

In the absence of an input source, the MP2635

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 MP2635 also allows an output

short-circuit thanks to an output disconnect

feature, and can auto-recover when the short

circuit fault is removed.

APPLICATIONS

•

Sub-Battery Applications

Power-Bank Applications for Smart-Phone

Tablet and Other Portable Devices

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

status, please visit MPS website under Products, Quality Assurance page.

“MPS” and “The Future of Analog IC Technology” are registered trademarks of

Monolithic Power Systems, Inc.

The MP2635 provides full operating status

indication to distinguish charge mode from

boost mode.

The

MP2635

achieves

low

EMI/EMC

performance with well-controlled switching

edges.

To guarantee safe operation, the MP2635 limits

the die temperature to a preset value 120^oC.

Other safety features include input over-voltage

protection, battery over-voltage protection,

thermal

shutdown,

battery

temperature

monitoring, and a programmable timer to

prevent prolonged charging of a dead battery.

MP2635 Rev. 1.05

6/27/2013

www.MonolithicPower.com

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1

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

TYPICAL APPLICATION

To 5V System

R₁

R₂

R_OLIM

C2

C_SYS

SYS

FB

OLIM

SW

RS1

L1

5V Input

C_IN

I_CHG

V_BATT

I_BATT

C3 C_BATT

VIN

R4

C1

R3

R5

CSP

Battery

REG

BATT

VSYS

PWIN

R6

NTC

VB

Battery Voltage

Program

GND: 3.6V

High/Float: 4.2V

CHG

VCC

ACOK

FREQ

EN

C4

VCC

BOOST

ISET

MODE

ILIM

TMR

AGND

PGND

R_ILIM

C_TMRR_ISET

Table 1: Operation Mode

__________

Power Source

EN

High

Low

X

MODE Operating Mode

ACOK

Charge Mode, Enable Charging

Charge Mode, Disable Charging

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

Low

X

PWIN<0.8V or PWIN >1.15V or

V_IN<V_BATT+300mV

High

Low

Boost Mode

Sleep Mode

V_IN<2V

X

X=Don’t Care.

MP2635 Rev. 1.05

6/27/2013

www.MonolithicPower.com

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2

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

ORDERING INFORMATION

Part Number*

Package

Top Marking

MP2635GR

QFN24 (4×4mm)

M2635E

* For Tape & Reel, add suffix –Z (e.g. MP2635GR–Z);

PACKAGE REFERENCE

TOP VIEW

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⁾

QFN24 (4×4mm)..................... 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

Operating Temperature............. –20°C to +85°C

Recommended Operating Conditions ⁽³⁾

Supply Voltage VIN............................4.5V to 6V

Battery Voltage V_OUT.....................2.5V to 4.35V

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

MP2635 Rev. 1.05

6/27/2013

www.MonolithicPower.com

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3

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

ELECTRICAL CHARACTERISTICS

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

Parameter Symbol Condition

IN to SYS NMOS ON Resistance R_{IN to SYS}

Min

Typ

100

72

Max

Units

mΩ

High-side PMOS ON Resistance

Low-side NMOS ON Resistance

R_{H_DS}

R_{L_DS}

mΩ

70

mΩ

CC Charge Mode/ Boost

Mode

4

A

High-Side PMOS Peak Current

Limit

I_{PEAK_HS}

TC Charge Mode

1.5

4.5

Low-Side NMOS Peak Current

Limit

I_{PEAK_LS}

FREQ = 0

600

1200

2.2

Switching Frequency

f_sw

kHz

FREQ = Float/ High

VCC UVLO

V_{CC_UVLO}

2

2.4

0.85

1.2

V

mV

V

VCC UVLO Hysteresis

PWIN Lower Threshold

Lower Threshold Hysteresis

PWIN Upper Threshold

Upper Threshold Hysteresis

Charge Mode

100

0.8

V_{PWIN_L}

V_{PWIN_H}

0.75

1.1

40

mV

V

1.15

65

mV

EN = 5V, Battery Float

EN = 0

2.5

1.5

mA

Input Quiescent Current

I_IN

R_lLIM= 90.9k

400

720

450

810

2700

3

500

900

3000

Input Current Limit

I_{IN_LIMIT}

mA

R_lLIM= 49.9k

R

_lLIM= 15k

2400

Input Over-Current Threshold

I_IN(OCP)

A

Input Over-Current Blanking

Time⁽⁵⁾

τ_INOCBLK

120

µs

Input Over-Current Recover

Time⁽⁵⁾

τ_INRECVR

100

3.6

ms

V

Connect VB to GND

3.582

4.179

3.39

3.618

4.221

3.49

Terminal Battery Voltage

Recharge Threshold

V_{BATT_FULL}

Leave VB floating or

connect to logic HIGH

4.2

Connect to VB to GND

3.44

4.01

V_RECH

Leave VB floating or

connect to logic HIGH

3.95

4.07

V

Recharge Threshold Hysteresis

Battery Over Voltage Threshold

200

103.3%

1000

2000

230

mV

V_{BATT_FULL}

RS1 = 40mΩ, R_ISET= 69.8k

900

1100

2200

Constant Charge (CC) Current

Trickle Charge Current

I_CC

I_TC

mA

RS1 = 40mΩ, R_ISET= 34.9k 1800

MP2635 Rev. 1.05

6/27/2013

www.MonolithicPower.com

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4

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

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

2.47

2.57

2.67

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

mV

I_CC

V

RS1 = 40mΩ, R_ISET=69.8k

RS1 = 40mΩ, R_ISET=34.9k

2.5%

5%

10% 17.5%

I_BF

10%

1.2

15%

1.22

Input-Voltage-Regulation Reference

Boost Mode

V_REG

1.18

SYS Voltage Range

4.2

6

V

Feedback Voltage

1.18

1.2

1.22

200

Feedback Input Current

V_FB=1V

nA

Threshold over V_SYSto turn

V_SYS(OVP) off the converter during

boost mode

Boost SYS Over-Voltage Protection

Threshold

5.8

6

6.2

V

SYS Over Voltage Protection

Threshold Hysteresis

V

_SYSfalling from V_SYS(OVP)

125

mV

mA

A

Boost Quiescent Current

I_SYS= 0, MODE = 5V

1.4

Programmable Boost Output Current

Limit Accuracy

RS1 = 40mΩ, R_OLIM= 100k

I_OLIM

1

1.2

1.44

Programmable Boost Output

RS1 = 50mΩ, R_OLIM= 63.4k

1.5

A

Current⁽⁵⁾

SYS Over-Current Blanking Time⁽⁵⁾

SYS Over-Current Recover Time⁽⁵⁾

τ_SYSOCBLK

τ_SYSRECVR

120

1

µs

ms

V

During boosting

2.5

2.9

Weak-Battery Threshold

V_BATT(LOW)

Before Boost starts

3.05

30

V

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

13.7

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

MP2635 Rev. 1.05

6/27/2013

www.MonolithicPower.com

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5

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

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

Trickle Charge Time

60

Min

Mode, I_CHG= 1A

Total Charge Time

C_TMR=0.1µF, I_CHG= 1A

360

66%

NTC Low Temp, Rising

Threshold

65%

34%

67%

36%

R

_NTC=NCP18XH103(0ºC)

NTC Low Temp, Rising

Threshold Hysteresis

1%

35%

1%

V_SYS

NTC High Temp, Rising

Threshold

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.

MP2635 Rev. 1.05

6/27/2013

www.MonolithicPower.com

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6

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

TYPICAL CHARACTERISTICS

C_IN=C_BATT=C_SYS=C3=22µF, C1=C2=1µF, L1=4.7µH, RS1=50mΩ, C4=C_TMR=0.1µF, Battery Simulator,

unless otherwise noted.

1.00%

0.00%

2.5

2

2.5

2

-1.00%

-2.00%

-3.00%

-4.00%

-5.00%

1.5

1

1.5

1

0.5

0

0.5

0

40

80

120

160

60

80

100

120

140

4

4.5

5

5.5

6

1200

1000

800

8

7

6

5

4

3

2

V

CC

=SYS

V

=SYS

CC

6

5

4

3

2

600

400

200

0

1

0

1

0

2

4

6

8

10

1

3

5

7

0

0.5

1

1.5

2

2.5

2

6

5

4

3

2

4.5

4

1.5

1

3.5

3

0.5

0

1

0

2.5

30

80

130 180

230

280

0

0.5

1

1.5

1.2 1.22 1.24

1.26 1.28

1.3

MP2635 Rev. 1.05

6/27/2013

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7

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

TYPICAL PERFORMANCE CHARACTERISTICS

For Charge Mode: V_IN=5V, I_CHG=1.5A, L_{IN_LIM}=2.7A, I_SYS=0A

For Boost: BATT=3.7V, SYS_SET=5V, OLIM=1.5A

C_IN=C_BATT=C_SYS=C3=22µF, C1=C2=1µF, L1=4.7µH, RS1=50mΩ, C4=C_TMR=0.1µF, RILIM=15kΩ,

RISET=28kΩ, ROLIM=63.4kΩ, BATT_FULL=4.2V, F_S=1.2MHz, Battery Simulator, unless otherwise

noted.

CHGOK

2V/div.

V

BATT

CHGOK

2V/div.

V

100mV/div.

SW

2V/div.

CHGOK

5V/div.

BATT

200mV/div.

V

BATT

V

1V/div.

IN

V

IN

1V/div.

V

1V/div.

I

CHG

I

L

1A/div.

200mA/div.

V

IN

2V/div.

SW

2V/div.

V

SW

2V/div.

V

BATT

2V/div.

I

L

I

1A/div.

L

1A/div.

100

90

80

70

95

90

85

80

60

50

0

1

2

3

4

5

0

0.5

1

1.5

2

BATTERY VOLTAGE (V)

CHARGE CURRENT (A)

MP2635 Rev. 1.05

6/27/2013

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8

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

For Charge Mode: V_IN=5V, I_CHG=1.5A, L_{IN_LIM}=2.7A, I_SYS=0A

For Boost: BATT=3.7V, SYS_SET=5V, OLIM=1.5A

C_IN=C_BATT=C_SYS=C3=22µF, C1=C2=1µF, L1=4.7µH, RS1=50mΩ, C4=C_TMR=0.1µF, RILIM=15kΩ,

RISET=28kΩ, ROLIM=63.4kΩ, BATT_FULL=4.2V, F_S=1.2MHz, Battery Simulator, unless otherwise

noted.

EN

5V/div.

V

IN

2V/div.

V

SYS

V

SYS

2V/div.

V

SYS

2V/div.

V

BATT

V

BATT

2V/div.

I

L

1A/div.

200mA/div.

V

EN

5V/div.

V

SYS

2V/div.

V

SYS

V

I

SYS

IN

2V/div.

1A/div.

CHG

1A/div.

V

I

BATT

2V/div.

1V/div.

V

I

IN

I

L

SYS

1A/div.

2V/div.

1A/div.

V

SYS

V

SYS

1V/div.

I

BATT

1V/div.

500mA/div.

V

IN

I

V

SYS

IN

1V/div.

BATT

1V/div.

SYS

2A/div.

500mA/div.

1V/div.

BATT

1V/div.

V

IN

1V/div.

I

SYS

2A/div.

V

BATT

2V/div.

MP2635 Rev. 1.05

6/27/2013

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9

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

For Charge Mode: V_IN=5V, I_CHG=1.5A, L_{IN_LIM}=2.7A, I_SYS=0A

For Boost: BATT=3.7V, SYS_SET=5V, OLIM=1.5A

C_IN=C_BATT=C_SYS=C3=22µF, C1=C2=1µF, L1=4.7µH, RS1=50mΩ, C4=C_TMR=0.1µF, RILIM=15kΩ,

RISET=28kΩ, ROLIM=63.4kΩ, BATT_FULL=4.2V, F_S=1.2MHz, Battery Simulator, unless otherwise

noted.

MP2635 Rev. 1.05

6/27/2013

www.MonolithicPower.com

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10

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

For Charge Mode: V_IN=5V, I_CHG=1.5A, L_{IN_LIM}=2.7A, I_SYS=0A

For Boost: BATT=3.7V, SYS_SET=5V, OLIM=1.5A

C_IN=C_BATT=C_SYS=C3=22µF, C1=C2=1µF, L1=4.7µH, RS1=50mΩ, C4=C_TMR=0.1µF, RILIM=15kΩ,

RISET=28kΩ, ROLIM=63.4kΩ, BATT_FULL=4.2V, F_S=1.2MHz, Battery Simulator, unless otherwise

noted.

V

SYS

1V/div.

V

BATT

1V/div.

V

BATT

2V/div.

V

SYS

V

SYS

2V/div.

1V/div.

BOOST

2V/div.

I

L

500mA/div.

100

95

90

85

80

75

70

V

BATT

2V/div.

SYS(AC)

200mV/div.

95

V

SYS(DC)

2V/div.

90

85

I

L

1A/div.

0

0.4

0.8

1.2

1.6

0

0.4

0.8

1.2

1.6

MP2635 Rev. 1.05

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11

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

PIN FUNCTIONS

Pin #

Name Description

Connect to GND to program the operating frequency to 600kHz. Leave floating or connect to

HIGH to program the operating frequency to 1.2MHz.

1

2

3

FREQ

VIN

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

Internal Circuit Power Supply. Bypass to GND with a 100nF ceramic capacitor. This pin

CANNOT carry any load.

VCC

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

charge mode.

4

5

6

ILIM

PWIN AC Input Detect. Detect the presence of valid input power.

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.

TMR

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.

7

8

REG

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

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

supply.

ACOK

9

FB

System voltage feedback input.

10

11

NTC Negative Temperature Coefficient (NTC) Thermistor.

ISET Charge Current Set. Connect an external resistor to GND to program the charge current.

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

program the system current in boost mode.

12

13

14

OLIM

AGND Analog Ground

Programmable Battery-Full Voltage. Connect to GND for 3.6V. Leave floating or connect to

logic HIGH for 4.2V

VB

15

16

BATT Positive Battery Terminal / Battery Charge Current Sense Negative Input.

CSP Battery Charge Current Sense Positive Input.

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

Boost Mode indicator. Logic LOW indicates boost mode in operation. The pin becomes an

open drain when the part operates in charge mode or sleep mode.

17

18

BOOST

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

Charge Completion Indicator. Logic LOW indicates charge mode. The pin becomes an open

drain once the charging has completed or is suspended.

CHG

PGND，

19

Power Ground. Connect the exposed pad and GND pin to the same ground plane.

Exposed

Pad

20

SW

Switch Output Node.

System Output. Please make sure the enough bulk capacitors from SYS to GND. Suggest

21, 22

SYS

4.7μF at least.

__________

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

HIGH (input power is not available).

23

24

MODE

EN

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

__________

when ACOK is low (input power is OK).

MP2635 Rev. 1.05

6/27/2013

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12

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

BLOCK DIAGRAM

Figure 1: Functional Block Diagram in Charge Mode

MP2635 Rev. 1.05

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13

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

SYS

FB

SW

Q1

Q2

HSMOS

VIN

A1

CSP

VCC

LSMOS

Driver

BATT

Charge

Pump

V_BATT

PWM Signal

Integration

ACOK

PGND

FREQ

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

MP2635 Rev. 1.05

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14

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

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

Yes

No

EN High?

Yes

Charger Mode

/CHG Low

Boost Mode

/BOOST Low

Sleep Mode

Figure 3: Mode Selection Flow Chart

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15

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

OPERATION FLOW CHART (continued)

Figure 4: Normal Operation and Fault Protection in Charge Mode

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16

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

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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17

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

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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18

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

START UP TIME FLOW IN CHARGE MODE

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

V_PWIN> 0.8V

0V

&

V_IN

V > V_BATT+ 300mV

IN

5V

0V

EN

Mode

V_CC

V_CCfollowsV

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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19

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

START UP TIME FLOW IN CHARGE MODE

Condition: V_IN= 5V, Mode = 0V, /ACOK and /CHG are always pulled up to an external constant 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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20

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

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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21

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

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

SS

Down

Mode

V_SYS>V_BATT+300mV

0V

V_SYS

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

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22

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

OPERATION

CC>>>CV

Threshold

INTRODUCTION

Constant

Charge

Current

The MP2635 is a highly-integrated, synchronous,

switching charger with bi-directional operation for

a boost function that can step-up the battery

voltage to power the system. Depending on the

VIN value, it operates in one of three modes:

charge mode, boost mode and sleep mode. In

charge mode, the MP2635 supports a precision

Li-ion or Li-polymer charging system for single-

cell applications. In boost mode, MP2635 boosts

the battery voltage to V_SYSto power higher-

voltage systems. In sleep mode, the MP2635

stops charging or boosting and operates at a low

current from the input or the battery to reduce

power consumption when the IC isn’t operating.

The MP2635 monitors VIN to allow smooth

transition between different modes of operation.

I_CHG

V_BAT

TC>>>CC

Threshold

Trickle

Charge

Current

Trickle charge CC charge

CV charge Charge Full

a) Without input current limit

Constant

Charge

Current

CC>>>CV

Threshold

I_CHG

Input

Current

Limit

V_BAT

TC>>>CC

Threshold

Trickle

Charge

Current

Trickle charge CC charge

CV charge Charge Full

CHARGE MODE OPERATION

b) With input current limit

Figure 11: Typical Battery Charge Profile

Auto-Recharge

Charge

ChargeÆCV Charge)

Cycle

(Trickle

ChargeÆCC

In charge mode, the MP2635 has five control

loops to regulate the input current, input voltage,

charge current, charge voltage, and device

junction temperature. It charges the battery in

three phases: trickle current (TC), constant

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

charging, all four loops are active but only one

determines the IC behavior. Figure 11(a) shows

a typical battery charge profile. 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 11(b) shows a typical charge profile when

the input-current-limit loop dominates during the

CC charge mode, and in this case the charge

current exceeds the input current, resulting in

faster charging than a traditional linear solution

that is well-suited for USB applications.

Once the battery charge cycle completes, the

charger remains off. During this process, 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 resets 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 MP2635 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 current source draws a

current from the BATT pin to decrease the

battery voltage and protect the battery.

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23

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

Input Over-Current Protection

Timer Operation in Charge Mode

The MP2635 features input over-current

The MP2635 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.

protection (OCP): when the input current

exceeds 3A, Q2 is controlled linearly to regulate

the current. If the current still exceeds 3A after a

120µs blanking time, Q2 will turn off. A fast off

function turns off Q2 quickly when the input

current exceeds 7A to protect both Q1 and Q2.

If charging remains in TC mode beyond the

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

terminate. The following determines the length of

the trickle-charge period:

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 the input voltage

avoid dropping further.

C_TMR(μF)

0.1μF

1A

τ_{TRICKLE _ TMR}= 60mins×

×

(1)

I_CHG(A)

The maximum total charge time is:

C_TMR(μF)

τ_{TOTAL _ TMR}= 6Hours×

0.1μF

1A

×

(2)

I_CHG(A)

The input voltage can be regulated by a resistor

divider from IN pin to REG pin to AGND

according to the following expression:

Negative Temperature Coefficient (NTC) Input

for Battery Temperature Monitoring

R5

The MP2635 has a built-in NTC resistance

window comparator, which allows the MP2635 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 MP2635

stops charging. The charger will then restart if the

temperature goes back into NTC window range.

(4)

V_REG= V

×

(V)

IN_R

R3+R5

Where the V_REGis the internal voltage reference,

1.2V.

Setting the Charge Current

The external sense resistors, RS1 and R_ISET

program the battery charge current, I_CHG. Select

,

R

_ISETbased on RS1:

70(kΩ)

40(mV)

I_CHG(A)=

×

(5)

R_ISET(kΩ) RS1(mΩ)

Where the 40mV is the charge current limiting

reference.

Input-Current Limiting in Charge Mode

The MP2635 has a dedicated pin that programs

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.

Battery Short Protection

The MP2635 has two current limit thresholds. CC

and CV modes have a peak current limit

threshold of 3.6A, while TC mode has a current

limit threshold of 1.5A. Therefore, the current limit

threshold decreases to 1.5A 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.

Use the following equation to determine the input

current limit threshold,

40.5(kΩ)

R_ILIM(kΩ)

(3)

I_ILIM

=

(A)

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24

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

Thermal Foldback Function

on requirements rather than worst-case

conditions while ensuring safe operation.

Furthermore, the part includes thermal shutdown

protection where the ceases charging if the

junction temperature rises to 150°C.

The MP2635 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 does this function protect against thermal

damage, it can also set the charge current based

Full-Operation Indication

The MP2635 integrates indicators for the

following conditions as shown in Table2.

Table 2: Indicator for Each Operation Mode

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

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

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

Operation

ACOK

CHG

BOOST

In Charging

Low

End of Charge,

charging disabled

NTC Fault, Timer

Out

Charge Mode

Boost Mode

Low

High

Blinking

High

Low

Sleep Mode, VCC absent

High

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MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

Boost Output-Current Limiting

The MP2635 integrates a programmable output

current limit function in boost mode. If the boost

output current exceeds this programmable limit

threshold, 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 1.5A as per the following

equation:

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 MP2635 works in down mode.

In this mode, the synchronous P-MOSFET stops

switching and its gate connects to V_BATTstatically.

The P-MOSFET keeps off as long as the voltage

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 a linear mode

allowing the inductor current to decrease and

flowing into the SYS pin. Once V_SYSexceeds

70(kΩ)× 40(mV)×1.7

R_OLIM(kΩ)×RS1(mΩ)

Where the 40mV is the charge current limiting

reference.

(6)

I_OLIM(A) =

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.

SYS Output Over-Current Protection

The MP2635 integrates three-phase output over-

current protection.

Phase one (boost mode): when the output

current exceeds the output current limit, the

output constant current loop controls the output

current, the output current remains at its limit of

SYS Disconnect and Inrush Limiting

The MP2635 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.

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.

I

_OLIM, and V_SYSdecreases.

Phase two (down mode): when V_SYSdrops below

_BATT+100mV and the output current loop

V

remains in control, the boost converter enters

down mode and shutdown after a 120μs blanking

time.

Phase three (short circuit mode): when V_SYS

drops below 2V, 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.

Thermal Shutdown Protection

Boost Output Voltage

The thermal shutdown protection is also active in

boost mode. Once the junction temperature rises

higher than 150°C, the MP2635 enters thermal

shutdown. It will not resume normal operation

until the junction temperature drops below 120°C

In the boost mode, the MP2635 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. Should output over-voltage occur,

the MP2635 turns off the boost converter. Once

V_SYSdrops to a normal level, the boost converter

restarts again as long as the MODE pin remains

in active status.

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26

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

R6

(11)

V_PWIN= V ×

(V)

APPLICATION INFORMATION

COMPONENT SELECTION

IN

R4 + R6

If the voltage on PWIN is between 0.8V and

1.15V, the MP2635 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

MP2635 works in the boost mode (see Table 1)).

Setting the Charge Current in Charge Mode

In charge mode, both the external sense resistor,

RS1, and the resistor R_ISETconnect to the ISET

pin to set the charge current (I^CHG) of the MP2635

(see the Typical Application circuit).

For a wide operating range, use a maximum

input voltage of 6V as the upper threshold for a

voltage ratio of:

Given I_CHGand RS1, the regulation threshold,

V_IREF, across this resistor is:

V_PWIN

1.15

6

R6

(12)

=

(7)

V_IREF(mV) = RS1(mΩ)×I_CHG(A)

V

R4 + R6

IN

R_ISETsets V_IREFas per the following equation:

With the given R6, R4 is then:

70(kΩ)

R_ISET(kΩ)

V − V_PWIN

IN

(13)

(8)

V_IREF(mV) =

× 40(mV)

R4 =

×R6

V_PWIN

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

is 21.5kꢀ.

So, the R_ISETcan be calculated as:

70(kΩ)

(9)

R_ISET(kΩ) =

× 40(mV)

V_IREF(mV)

Setting the Input Voltage Regulation in

Charge Mode

For example, for I_CHG=2A, and RS1=50mꢀ, thus:

_IREF=100mV, so R_ISET=28kꢀ.

In charge mode, connect a resistor divider from

the IN pin to AGND with tapped to REG pin to

program the input voltage regulation.

R3 + R5

V

Setting the Input Current Limiting in Charge

Mode

(14)

V

= V_REG

×

(V)

IN_R

R5

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:

40.5

With the given R5, R3 is:

V

− V_REG

IN_R

(15)

R3 =

×R5(V)

V_REG

For a preset input voltage regulation value, say

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

R_ILIM

=

(kΩ)

(10)

I_{IN_LIM}(A)

NTC Function in Charge Mode

Where RILIM must exceed 15kꢀ, so that IIN_LIM is in

the range of 0A to 2.7A.

Figure 12 shows that an internal resistor divider

sets the low temperature threshold (V_TL) and high

temperature threshold (V_TH) at 65%·V_SYSand

For most applications, use R_ILIM= 45kꢀ

(I^USB_LIM=900mA) for USB3.0 mode, and use R_LIM

= 81kꢀ (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_TL

(16)

=

= TL = 65%

A resistive voltage divider from the input voltage

to PWIN pin determines the operating mode of

MP2635.

V_SYSR_T1+R_T2//R_{NTC_Cold}

R_T2//R_{NTC_Hot}

V_SYSR_T1+R_T2//R_{NTC_Hot}

V_TH

(17)

=

= TH= 35%

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

the upper bound of its operating temperature

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27

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

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

V_SYS−1.2V

R1= R2×

(V)

(21)

1.2V

The two resistors, R_T1and R_T2, independently

determine the upper and lower temperature limits.

This flexibility allows the MP2635 to operate with

most NTC resistors for different temperature

range requirements. Calculate R_T1and R_T2as

follows:

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

10kꢀ, and R1 is 31.6kꢀ.

Setting the Output Current Limit in Boost

Mode

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:

R_{NTC_Hot}×R_{NTC_Cold}×(TL − TH)

(18)

R_T1

=

TH× TL ×(R_{NTC_Cold}− R_{NTC_Hot}

(TL−TH)×R_{NTC_Cold}×R_{NTC_Hot}

(1−TL)×TH×R_{NTC_Cold}-(1-TH)×TL×R_{NTC_Hot}

)

(19)

R_T2

=

70(kΩ)× 40(mV)×1.7

I_OLIM(A)× RS1(mΩ)

(22)

R_OLIM(kΩ) =

For example, the NCP18XH103 thermistor has

the following electrical characteristic:

Where ROLIM is supposed to be greater than

63.4kꢀ with RS1=50mꢀ, so that I^OLIMcan be

programmed up to 1.5A.

At 0°C, R_{NTC_Cold}= 27.445kꢀ;

At 50°C, R_{NTC_Hot}= 4.1601kꢀ.

Selecting the Inductor

Based on equation (18) and equation (19),

R^T1=6.47kꢀ and RT2 = 21.35kꢀ are suitable for

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

approximate values: e.g., R_T1=6.49kꢀ and

R_T2=21.5kꢀ.

Inductor selection trades off between cost, size,

and efficiency.

A

lower inductance value

corresponds with smaller size, but results in

higher ripple currents, 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.

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= 10kꢀ.

Choose an inductor that does not saturate under

the worst-case load condition.

1. In Charge Mode

When MP2635 works in charge mode (as a

Buck Converter), estimate the required

inductance as:

V − V_BATT

ΔI_{L _MAX}

V_BATT

IN

(23)

L =

×

V × f_S

IN

Figure 12: NTC Function Block

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 inductor ripple current, which is

usually designed at 30% of the CC charge

current.

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.

R1+R2

V_SYS= 1.2V ×

(20)

With a typical 5V input voltage, 30% inductor

current ripple at the corner point between

trickle charge and CC charge (V_BATT=3V), the

inductance is 1.67μH (for a 1.2MHz switching

frequency) and 3.33μH (for a 600kHz

switching frequency).

R2

Where 1.2V is the voltage reference of SYS. With

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

determined by:

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MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

2. In Boost Mode

1. Charge Mode

When the MP2635 is in Boost mode (as a

Boost converter), the required inductance

value is calculated as:

The capacitor C_SYSacts as the input capacitor

of the buck converter in charge mode. The

input current ripple is:

V_BATT×(V_SYS− V_BATT

V_SYS× f_S× ΔI_{L _MAX}

)

V_TC×(V_{IN_MAX}− V_TC)

(24)

L =

(27)

I_{RMS _MAX}= I_{SYS _MAX}

×

V_{IN_MAX}

(25)

(26)

ΔI_{L _MAX}= (30% − 40%)×I_BATT(MAX)

V_SYS×I_SYS

2. Boost Mode

I_BATT(MAX)

=

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× η

Where V_BATTis the minimum battery voltage,

_SWis 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.

f

V_TC×(V_{SYS _MAX}− V_TC)

(28)

I_{RMS _MAX}= I_{SYS _MAX}

×

V_{SYS _MAX}

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 1.8μH (for the 1.2MHz

switching frequency) and 3.6µH (for the

600kHz switching frequency) when the

efficiency is 90%.

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.

For

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

maximum ripple current is 1A. Select the system

capacitors base on the ripple-current temperature

rise not exceeding 10°C. For best results, use

ceramic capacitors with X5R or X7R dielectrics

with low ESR and small temperature coefficients.

For most applications, use a 22µF capacitor.

For best results, use an inductor with an

inductance of 1.8μH (for the 1.2MHz

switching frequency) and 3.6µH (for the

600kHz switching frequency) with a DC

current rating that is at least 30% higher than

the maximum charge current for applications.

For higher efficiency, minimize the inductor’s

DC resistance.

Selecting the Battery Capacitor C_BATT

C_BATTis in parallel with the battery to absorb the

high-frequency switching ripple current.

1. Charge Mode

Selecting the Input Capacitor C_IN

The capacitor C_BATTis the output capacitor of

the buck converter. The output voltage ripple

is then:

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 X5R or X7R dielectrics because

of their low ESR and small temperature

coefficients. For most applications, a 22µF

capacitor will suffice.

ΔV_BATT

1− V_BATT/ V_SYS

(29)

Δr_BATT

=

8×C_BATT× f_S²×L

V_BATT

Selecting the System Capacitor C_SYS

Select C_SYSbased on the demand of the system

current ripple.

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MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

connected to as many coppers planes on the

board as possible. The exposed pad should

2. Boost Mode

connect to as many GND copper planes in the

board as possible. This improves thermal

performance because the board conducts heat

away from the IC.

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 (29)

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). If possible, add vias

inside the exposed pads for the IC. 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.

Both charge mode and boost mode have the

same battery voltage ripple. The capacitor C_BATT

can be calculated as:

1− V_TC/ V_{SYS _MAX}

8× Δr_{BATT _MAX}× f_S²×L

(30)

C_BATT

=

To guarantee the ±0.5% BATT voltage accuracy,

the maximum BATT voltage ripple must not

exceed 0.5% (e.g. 0.1%). The worst case occurs

at the minimum battery voltage of the CC charge

with the maximum input voltage.

4) Place ISET, OLIM and ILIM resistors very

close to their respective IC pins.

For

V

_{SYS_MAX}=6V, V_{CC_MIN}=V_TC=3V, L=3.9µH,

f_S=600kHz or 1.2MHz,

, C is

Δr_{BATT _MAX}= 0.1%

BATT

22µF (for a 600kHz switching frequency) or 10µF

(for a 1.2MHz switching frequency).

A 22µF ceramic with X5R or X7R dielectrics

capacitor in parallel with a 220µF electrolytic

capacitor 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:

Top Layer

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 and the current sense resistor trace.

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.

Bottom Layer

Figure 13: PCB Layout Guide

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

MP2635 Rev. 1.05

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MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

Design Example

Below is a design example following the

application guidelines for the specifications:

Table 3: Design Example

V_IN

V_OUT

f_SW

5V

3.7V

1200kHz

Figure 14 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.

MP2635 Rev. 1.05

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31

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

TYPICAL APPLICATION CIRCUITS

31.6k

63.4k

5.1k

21.5k

15k

Figure 14: The detailed application circuit of MP2635

MP2635 Rev. 1.05

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32

MP2635 – 2A SINGLE CELL SWITCH MODE BATTERY CHARGER

PACKAGE INFORMATION

QFN24 (4x4mm)

3.90

4.10

2.50

2.80

PIN 1 ID

SEE DETAIL A

19

24

PIN 1 ID

MARKING

18

13

1

6

0.50

BSC

3.90

4.10

2.50

2.80

PIN 1 ID

INDEX AREA

0.18

0.30

12

7

0.35

0.45

TOP VIEW

BOTTOM VIEW

PIN 1 ID OPTION A

0.30x45º TYP.

PIN 1 ID OPTION B

R0.25 TYP.

0.80

1.00

0.20 REF

0.00

0.05

DETAIL A

SIDE VIEW

3.90

2.70

NOTE:

1) ALL DIMENSIONS ARE IN MILLIMETERS.

2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.

3) LEAD COPLANARITY SHALL BE0.10 MILLIMETER MAX.

4) DRAWING CONFIRMS TO JEDEC MO-220, VARIATION VGGD.

5) DRAWING IS NOT TO SCALE.

0.70

0.25

0.50

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.

MP2635 Rev. 1.05

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33


型号：	MP2635GR
厂家：	MONOLITHIC POWER SYSTEMS
描述：	2A Single Cell Switch Mode Battery Charger with Power Path Management and Boost OTG 电池
文件：	总33页 (文件大小：1100K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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