LTC4053-4.2_技术文档

LTC4053-4.2

USB Compatible

Lithium-Ion Battery Charger

with Thermal Regulation

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FEATURES

DESCRIPTIO

The LTC^®4053 is a standalone linear charger for lithium-

ionbatteriesthatcanbepowereddirectlyfromaUSBport.

The IC contains an on-chip power MOSFET and eliminates

the need for an external sense resistor and blocking diode.

Thermal regulation automatically adjusts charge current

tolimitdietemperatureduringhighpowerorhighambient

temperature conditions. This feature protects the end

product and the LTC4053 from thermal stress while the IC

charges the battery at maximum rate without interruption.

■

Charges Single-Cell Li-Ion Batteries Directly from

USB Port

■

Thermal Regulation Maximizes Charge Rate

without Risk of Overheating*

■

Programmable Charge Current with ±7% Accuracy

■

Low Dropout Operation

■

No External MOSFET, Sense Resistor or Blocking

Diode Required

■

Programmable Charge Termination Timer

■

Preset Charge Voltage with ±1% Accuracy

The charge current and charge time can be set externally

with a single resistor and capacitor, respectively. When

the input supply (wall adapter or USB supply) is removed,

the LTC4053 automatically enters a low current sleep

mode, dropping the battery drain current to less than 5µA.

■

C/10 Charge Current Detection Output

■

AC Present Logic Output

■

25µA Supply Current in Shutdown Mode

■

Automatic Recharge

■

Charge Current Monitor Useful for Gas Gauging

■

The LTC4053 also includes NTC temperature sensing,

C/10 detection circuitry, AC present logic, low battery

chargeconditioning(tricklecharging)andshutdown(25µA

supply current).

Thermistor Input for Temperature Qualified Charging

Available in 10-pin thermally enhanced MSOP and

low profile (0.75mm) 3mm × 3mm DFN packages

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APPLICATIO S

The LTC4053 is available in 10-pin thermally enhanced

MSOP and low profile (0.75mm) DFN packages.

, LTC and LT are registered trademarks of Linear Technology Corporation.

Protected by U.S. Patents including 6522118, 6700364.

■

Cellular Telephones

■

Handheld Computers

■

Charging Docks and Cradles

MP3 Players

Digital Cameras

■

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TYPICAL APPLICATIO

Charge Current vs Input Voltage

600

USB Powered Standalone Li-Ion Charger

T

= 25°C

PROG

A

R

= 3k

V

= 3.95V

BAT

500

400

300

200

100

0

2

9

SYSTEM

LOAD

USB PORT

4.35V TO 5.5V

V

BAT

CC

+

Li-Ion

V

= 4.05V

BATTERY

BAT

LTC4053-4.2

4

8

SUSPEND

TIMER

SHDN

GND NTC PROG

4.7µF

USB CONTROL

3.74k

V

= 4.15V

4.5

5

6

7

BAT

µC

100mA/

500mA

0.1µF

15k

4.0

5.0

5.5

V

(V)

CC

4053TA01

4053 G04

4053fa

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LTC4053-4.2

W W U W

(Note 1)

ABSOLUTE AXI U RATI GS

Input Supply Voltage (V_CC) ....................................... 7V

BAT........................................................................... 7V

NTC, SHDN, TIMER, PROG............ –0.3V to V_CC+ 0.3V

CHRG, FAULT, ACPR .................................. –0.3V to 7V

BAT Short-Circuit Duration .......................... Continuous

BAT Current (Note 2) ............................................. 1.3A

PROG Current (Note 2) ....................................... 1.3mA

Junction Temperature.......................................... 125°C

Operating Temperature Range (Note 3) ...–40°C to 85°C

Storage Temperature Range

MSE.................................................. –65°C to 150°C

DD .................................................... –65°C to 125°C

Lead Temperature (Soldering, 10 sec)

MSE.................................................................. 300°C

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PACKAGE/ORDER I FOR ATIO

TOP VIEW

ORDER PART

TOP VIEW

CHRG

1

2

3

4

5

10 ACPR

NUMBER

CHRG

1

2

3

4

5

10 ACPR

V

9

8

7

6

BAT

CC

V

9

8

7

6

BAT

CC

11

FAULT

TIMER

GND

SHDN

PROG

NTC

FAULT

TIMER

GND

SHDN

PROG

NTC

LTC4053EDD-4.2

LTC4053EMSE-4.2

MSE EXPOSED PAD PACKAGE

10-LEAD PLASTIC MSOP

DD PACKAGE

DD PART MARKING

LBQC

MSE PART MARKING

LTZT

T_JMAX= 125°C, θ_JA= 40°C/W (NOTE 4)

EXPOSED PAD (PIN 11) IS GND

(MUST BE SOLDERED TO PCB)

10-LEAD (3mm × 3mm) PLASTIC DFN

T_JMAX= 125°C, θ_JA= 40°C/W (NOTE 4)

EXPOSED PAD (PIN 11) IS GND

(MUST BE SOLDERED TO PCB)

Order Options Tape and Reel: Add #TR

Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF

Lead Free Part Marking: http://www.linear.com/leadfree/

Consult LTC Marketing for parts specified with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS

The

●

denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T = 25°C. V = 5V

A

CC

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

V

Supply Voltage

Supply Current

●

4.25

6.5

V

CC

I

Charger On; Current Mode; R

= 30k (Note 5)

●

1

25

2

50

mA

µA

CC

PROG

Shutdown Mode; V

= 0V

or V ≤ 4V

SHDN

Sleep Mode V < V

CC

BAT

CC

V

Regulated Float Voltage

●

4.158

4.2

4.242

V

BAT

I

Battery Pin Current

R

= 3k; Current Mode

= 15k; Current Mode

●

465

93

500

100

±1

535

107

±3

mA

µA

BAT

PROG

Shutdown Mode; V

Sleep Mode V < V

= 0V

SHDN

or V < (V – ∆V )

±1

±3

µA

CC

BAT

CC

UV

I

Trickle Charge Current

V

< 2V; R

= 3k

PROG

●

35

50

2.48

100

4

65

mA

V

TRIKL

BAT

V

Trickle Charge Trip Threshold

Trickle Charge Trip Hysteresis

Rising

TRIKL

∆V

mV

V

TRIKL

UV

V

Undervoltage Lockout Voltage

Undervoltage Lockout Hysteresis

V

Rising

CC

4.25

1.3

UV

CC

∆V

200

mV

V

Manual Shutdown Threshold Voltage

SHDN Pin Voltage

0.6

MSD

ASD

Automatic Shutdown Threshold Voltage (V - V ) High to Low

35

70

mV

CC

BAT

(V - V ) Low to High

CC

BAT

4053fa

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LTC4053-4.2

ELECTRICAL CHARACTERISTICS

The

●

denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T = 25°C. V = 5V

A

CC

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

1.5

MAX

UNITS

V

PROG Pin Voltage

R

= 3k, I

= 500µA

PROG

CHRG

PROG

CHRG

I

CHRG Pin Weak Pulldown Current

CHRG Pin Output Low Voltage

ACPR Pin Output Low Voltage

FAULT Pin Output Low Voltage

End of Charge Indication Current Level

TIMER Accuracy

V

= 1V

15

30

50

0.6

56

µA

V

I

= 5mA

0.35

50

CHRG

ACPR

FAULT

C/10

= 5mA

V

ACPR

V

FAULT

I

t

R

PROG

= 3k

44

mA

%

C

= 0.1µF

10

TIMER

V

Recharge Battery Voltage Threshold

NTC Pin Hot Threshold Voltage

NTC Pin Hot Hysteresis Voltage

NTC Pin Cold Threshold Voltage

NTC Pin Cold Hystersis Voltage

NTC Pin Disable Threshold Voltage

NTC Pin Disable Hystersis Voltage

Battery Voltage Falling

4.035

2.5

V

RECHRG

NTC-HOT

HOT-HYS

NTC-COLD

COLD-HYS

NTC-DIS

DIS-HYS

LIM

V

Falling

Rising

V

NTC

80

mV

V

4.375

80

mV

°C

100

10

T

Junction Temperature in

Constant-Temperature Mode

105

R

ON

Power MOSFET “ON” Resistance

375

mΩ

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

temperature range are assured by design, characterization and correlation

with statistical process controls.

Note 2: The Absolute Maximum BAT Current Rating of 1.3A is guaranteed

by design and current density calculations. The Absolute Maximum PROG

Current Rating is guaranteed to be 1/1000 of BAT current rating by design.

Note 3: The LTC4053E is guaranteed to meet performance specifications

from 0°C to 70°C. Specifications over the –40°C to 85°C operating

Note 4: Failure to solder the exposed backside of the package to the PC

board will result in a thermal resistance much higher than 40°C/W.

Note 5: Supply current includes PROG pin current (approximately 50µA)

but does not include any current delivered to the battery through the BAT

pin (approximately 50mA).

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LTC4053-4.2

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TYPICAL PERFOR A CE CHARACTERISTICS

Battery Regulation Voltage

vs Battery Charge Current

Battery Regulation Voltage

vs Temperature

Battery Regulation Voltage

vs V

CC

4.22

4.21

4.24

4.22

4.20

4.18

4.16

4.14

4.12

4.10

4.08

4.210

4.208

4.206

4.204

4.202

4.200

4.198

4.196

4.194

4.192

4.190

V

T

= 5V

CC

A

R

V

= 5V

PROG

= 10mA

CC

= 25°C

R

= 3k

PROG

I

BAT

4.20

4.19

4.18

4.17

4.16

V

= 5V

PROG

= 10mA

CC

R

= 3k

I

BAT

4.06

0

50 100 150 200 250 300 350 400 450 500

(mA)

–50 –25

0

25

125

50

75 100

4

4.5

5.5

(V)

6

6.5

7

5

I

TEMPERATURE (°C)

V

BAT

CC

4053 G01

4053 G02

4053 G03

Charge Current vs Ambient

Temperature with Thermal

Regulation

Charge Current vs Battery Voltage

Charge Current vs Input Voltage

550

500

450

400

350

300

250

200

150

100

50

600

500

400

300

200

100

0

1000

900

800

700

600

500

400

300

200

100

0

T

= 25°C

PROG

V

T

= 5V

A

CC

= 25°C

R

= 3k

A

V

BAT

= 3.95V

R

= 3k

PROG

V

BAT

= 4.05V

THERMAL CONTROL

LOOP IN OPERATION

V

BAT

= 4.15V

4.5

V

= 5V

CC

= 3.5V

BAT

R

= 1.5k

PROG

0

4.0

5.0

5.5

2

4

4.5

0

1

1.5

2.5

(V)

3

3.5

0.5

–50 –25

25

50

75

100

0

V

(V)

V

BAT

TEMPERATURE (°C)

CC

4053 G04

4053 G05

4053 G06

Undervoltage Lockout Voltage

vs Temperature

Shutdown Supply Current

vs Temperature

Manual Shutdown Threshold

Voltage vs Temperature

4.05

4.04

4.03

4.02

4.01

4.00

3.99

3.98

3.97

3.96

3.95

1.30

1.25

1.20

1.15

1.10

1.05

1.00

0.95

0.90

0.85

0.80

30

25

20

15

V

SHDN

= 0V

V

= 6.5V

= 5.5V

CC

V

= 6V

CC

V

= 5.5V

CC

V

CC

= 4.5V

V

= 5V

CC

10

5

V

= 4.5V

50

CC

0

–50

0

25

50

75 100 125

–25

50

TEMPERATURE (°C)

100 125

–50

0

25

75

125

–50 –25

0

25

75

100

–25

TEMPERATURE (°C)

4053 G07

4053 G08

4053 G09

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LTC4053-4.2

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TYPICAL PERFOR A CE CHARACTERISTICS

PROG Pin Voltage

vs Charge Current

PROG Pin Voltage vs V

PROG Pin Voltage vs Temperature

Constant Current Mode

CC

Constant Current Mode

1.515

1.510

1.505

1.500

1.495

1.490

1.485

1.515

1.510

1.505

1.500

1.495

1.490

1.485

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

V

= 5V

= 4V

PROG

V

T

= 3.5V

= 3k

V

T

= 5V

CC

BAT

R

BAT

CC

A

R

= 25°C

A

= 3k

R

= 3k

PROG

–50

0

25

50

75

100

4

5

5.5

(V)

6

6.5

7

–25

4.5

0

50 100 150 200 250 300 350 400 450 500

CHARGE CURRENT (mA)

4052 G10

TEMPERATURE (°C)

V

CC

4053 G12

4053 G11

Trickle Charge Current

vs Temperature

CHRG Pin Weak Pull-Down

Current vs Temperature

CHRG Pin Output Low Voltage

vs Temperature

35

34

33

32

31

30

29

28

27

26

25

12

11

10

9

0.6

0.5

0.4

0.3

V

BAT

= 5V

< C/10

V

A

R

= 2V

CC

V

CHRG

= 5V

CC

BAT

= 25°C

I

T

I

= 5mA

= 3k

PROG

0.2

0.1

0

8

7

–50

0

25

50

75 100 125

50

75 100 125

–25

–50 –25

0

25

50

TEMPERATURE (°C)

100 125

–50 –25

0

25

75

TEMPERATURE (°C)

LTC1323 • TPC05

4053 G13

4053 G15

Timer Error vs Temperature

Timer Error vs V

CC

5

4

5

4

V

C

= 5V

T

= 25°C

CC

TIMER

A

= 0.1µF

C

= 0.1µF

TIMER

3

2

1

0

–1

–2

–3

–4

–5

–1

–2

–3

–4

–5

–50

0

25

50

75 100 125

4

4.5

5.5

(V)

6

6.5

7

–25

5

TEMPERATURE (°C)

V

CC

LTC1323 • TPC05

4056 G17

4053fa

5

LTC4053-4.2

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PI FU CTIO S

CHRG: Open-Drain Charge Status Output. When the

battery is being charged, the CHRG pin is pulled low by an

internal N-channel MOSFET. When the charge current

drops to 10% of the full-scale current, the N-channel

MOSFET latches off and a 30µA current source is con-

nected from the CHRG pin to ground. The C/10 latch can

be cleared by grounding the SHDN pin, momentarily, or

toggling V_CC. When the timer runs out or the input supply

is removed, the current source is disconnected and the

CHRG pin is forced high impedance.

NTC: Input to the NTC (Negative Temperature Coefficient)

Thermistor Temperature Monitoring Circuit. With an ex-

ternal 10kΩ NTC thermistor to ground and a 1% resistor

to V_CC, this pin can sense the temperature of the battery

pack and stop charging when it is out of range. When the

voltage at this pin drops below (0.5)•(V_CC) at hot tempera-

tures or rises above (0.875)•(V_CC) at cold, charging is

suspended and the internal timer is frozen. The CHRG pin

output status is not affected in this hold state. The FAULT

pin will be pulled to ground, but not latched. When the

temperature returns to an acceptable range, charging will

resume and the FAULT pin will be released. The NTC

feature can be disabled by grounding the NTC pin.

V_CC: Positive Input Supply Voltage. When V_CCis within

35mV of V_BATor less than the undervoltage lockout

threshold, the LTC4053 enters sleep mode, dropping I_BAT

to less than 3µA. V_CCcan range from 4.25V to 6.5V.

Bypass this pin with at least a 4.7µF ceramic capacitor to

ground.

PROG:ChargeCurrentProgramandChargeCurrentMoni-

tor Pin. The charge current is programmed by connecting

a resistor, R_PROGto ground. When in constant-current

mode, the LTC4053 servos the PROG pin voltage to 1.5V.

In all modes the voltage on the PROG pin can be used to

measure the charge current as follows:

FAULT:Open-DrainFaultStatusOutput. TheFAULTopen-

drain logic signal indicates that the charger has timed out

under trickle charge conditions or the NTC comparator is

indicating an out-of-range battery temperature condition.

If V_BATis less that 2.48V, trickle charging begins whereby

the charge current drops to one tenth of its programmed

value and the timer period is reduced by a factor of four.

When one fourth of the timing period has elapsed, if V_BAT

is still less than 2.48V, trickle charging stops and the

FAULT pin latches to ground. The fault can be cleared by

toggling V_CC, momentarily grounding the SHDN pin or

pulling the BAT pin above 2.48V. If the NTC comparator is

indicating an out-of-range battery temperature condition,

the FAULT pin will pull to ground until the temperature

returns to the acceptable range.

I_BAT= (V_PROG/R_PROG) • 1000.

SHDN: Shutdown Input Pin. Pulling the SHDN pin to

ground will put the LTC4053 into standby mode where the

BAT drain current is reduced to less than 3µA, and the

supply current is reduced to less than 25µA. For normal

operation, pull the SHDN pin up to V_CC.

BAT: ChargeCurrentOutput. Abypasscapacitorofatleast

1µF with a 1Ω series resistor is required to keep the loop

stable when the battery is not present. A precision internal

resistordividersetsthefinalfloatpotentialonthispin. The

internal resistor divider is disconnected in sleep and

shutdown mode.

TIMER:TimerCapacitor. Thetimerperiodissetbyplacing

a capacitor, C_TIMER, to ground. The timer period is:

ACPR: Open-Drain Power Supply Status Output. When

V_CCis greater than the undervoltage lockout threshold

and at least 35mV above V_BAT, the ACPR pin will pull to

ground. Otherwise, the pin is high impedance.

Time (Hours) = (C_TIMER• 3 hr)/(0.1µF)

ShorttheTIMERpintogroundtodisabletheinternaltimer

function.

GND:Ground.Theexposedbacksideofthepackageisalso

ground and must be soldered to the PC board for maxi-

mum heat transfer.

4053fa

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LTC4053-4.2

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SI PLIFIED BLOCK DIAGRA

V

CC

2

105°C

–

D1

TA

D2

D3

T

+

DIE

M2

×1

M1

×1000

+

–

MA

BAT

9

30µA

R1

R2

NTC

6

NTC

MP

+

–

VA

CA

+

–

2.485V

REF

HOT COLD DISABLE

1

CHRG

STOP

SHDN

8

SHDN

C/10

R3

R4

R5

30µA

1.5V

LOGIC

10

3

ACPR

0.15V

+

–

C2

C/10

FAULT

CHARGE

COUNTER

OSCILLATOR

4

C3

+

–

2.485V

TO BAT

7

5

4053 BD

PROG

GND

TIMER

R

PROG

C

TIMER

Figure 1

4053fa

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LTC4053-4.2

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OPERATIO

TheLTC4053isalinearbatterychargerdesignedprimarily

for charging single cell lithium-ion batteries. Featuring an

internal P-channel power MOSFET, the charger uses a

constant-current/constant-voltage charge algorithm with

programmable current and a programmable timer for

charge termination. Charge current can be programmed

up to 1.25A with a final float voltage accuracy of ±1%. No

blocking diode or sense resistor is required thus dropping

the external component count to three for the basic

charger circuit. The CHRG, ACPR, and FAULT open-drain

status outputs provide information regarding the status of

the LTC4053 at all times. An NTC thermistor input pro-

vides the option of charge qualification using battery

temperature.

voltage up to a safe level for charging. The charger goes

into the fast charge constant-current mode once the

voltage on the BAT pin rises above 2.48V. In constant-

current mode, the charge current is set by R_PROG

.

When the battery approaches the final float voltage, the

charge current begins to decrease as the LTC4053 enters

the constant-voltage mode. When the current drops to

10% of the full-scale charge current, an internal compara-

tor latches off the MOSFET on the CHRG pin and connects

a weak current source to ground (30µA) to indicate a near

end-of-charge (C/10) condition. The C/10 latch can be

cleared by grounding the SHDN pin momentarily, or

momentarily removing and reapplying V_CC.

An external capacitor on the TIMER pin sets the total

charge time. When this time elapses, the charge cycle

terminates and the CHRG pin assumes a high impedance

state. Torestartthechargecycle, removetheinputvoltage

and reapply it, or momentarily force the SHDN pin to 0V.

ThechargecyclewillalsorestartiftheBATpinvoltagefalls

below the recharge threshold.

An internal thermal limit reduces the programmed charge

current if the die temperature attempts to rise above a

presetvalueofapproximately105°C. Thisfeatureprotects

the LTC4053 from excessive temperature, and allows the

user to push the limits of the power handling capability of

agivencircuitboardwithoutriskofdamagingtheLTC4053

ortheexternalcomponents.AnotherbenefitoftheLTC4053

thermal limit is that charge current can be set according to

typical, not worst-case, ambient temperatures for a given

application with the assurance that the charger will auto-

matically reduce the current in worst-case conditions.

For lithium-ion and similar batteries that require an accu-

rate final float voltage, the internal reference, voltage

amplifier and the resistor divider provide regulation with

±1% (max) accuracy.

When the input voltage is not present, the charger goes

into a sleep mode, dropping battery drain current, I_BAT, to

lessthan5µA.Thisgreatlyreducesthecurrentdrainonthe

batteryandincreasesthestandbytime.Thechargercanbe

shut down (I_CC= 25µA) by forcing the SHDN pin to 0V.

The charge cycle begins when the voltage at the V_CCpin

rises above the UVLO level, a program resistor is con-

nected from the PROG pin to ground, and the SHDN pin is

pulled above the shutdown threshold. At the beginning of

the charge cycle, if the battery voltage is below 2.48V, the

charger goes into trickle charge mode to bring the cell

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LTC4053-4.2

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APPLICATIO S I FOR ATIO

Undervoltage Lockout (UVLO)

For example, if 500mA charge current is required,

calculate:

Aninternalundervoltagelockoutcircuitmonitorstheinput

voltageandkeepsthechargerinshutdownmodeuntilV_CC

risesabovetheundervoltagelockoutthreshold. TheUVLO

circuit has a built-in hysteresis of 150mV. Furthermore, to

protect against reverse current in the power MOSFET, the

UVLO circuit keeps the charger in shutdown mode if V_CC

falls to within 35mV of the battery voltage. If the UVLO

comparator is tripped, the charger will not come out of

shutdown until V_CCrises 70mV above the battery voltage.

R_PROG= 1500V/0.5A = 3kΩ

For best stability over temperature and time, 1% metal-

film resistors are recommended.

If the charger is in constant-temperature or constant-

voltage mode, the battery current can be monitored by

measuring the PROG pin voltage as follows:

I_CHG= (V_PROG/ R_PROG) • 1000

Trickle Charge And Defective Battery Detection

USB and Wall Adapter Power

At the beginning of a charge cycle, if the battery voltage is

low (below 2.48V) the charger goes into trickle charge

reducing the charge current to 10% of the full-scale

current. If the low battery voltage persists for one quarter

of the total charge time, the battery is assumed to be

defective, the charge cycle is terminated, the CHRG pin

output assumes a high impedance state, and the FAULT

pin pulls low. The fault can be cleared by toggling V_CC,

temporarily forcing the SHDN pin to 0V, or temporarily

forcing the BAT pin voltage above 2.48V.

Although the LTC4053 allows charging from a USB port,

a wall adapter can also be used to charge Li-Ion batteries.

Figure2showsanexampleofhowtocombinewalladapter

and USB power inputs. A P-channel MOSFET, MP1, is

used to prevent back conducting into the USB port when

a wall adapter is present and Schottky diode, D1, is used

to prevent USB power loss through the 1k pull-down

resistor.

Typically a wall adapter can supply significantly more

currentthanthe500mA-limitedUSBport.Therefore,anN-

channel MOSFET, MN1 and an extra 3k program resistor

can be used to increase the charge current to 1A when the

wall adapter is present.

Shutdown

The LTC4053 can be shut down (I_CC= 25µA) by pulling the

SHDN pin to 0V. For normal operation, pull the SHDN pin

above the manual shutdown threshold voltage level. Do

not leave this pin open. In shutdown the internal linear

regulator is turned off, and the internal timer is reset.

5V WALL

ADAPTER

I

CHG

LTC4053

1A I

CHG

9

7

SYSTEM

LOAD

D1

2

BAT

USB

POWER

Programming Charge Current

V

CC

MP1

500mA I

CHG

+

PROG

The formula for the battery charge current (see Figure 1)

is:

Li-Ion

BATTERY

3k

1k

3k

MN1

I_CHG= (I_PROG) • 1000

= (1.5V / R_PROG) • 1000 or

R_PROG= 1500V/I_CHG

4053 F02

Figure 2. Combining Wall Adapter and USB Power

where R_PROGis the total resistance from the PROG pin to

ground. Under trickle charge conditions, this current is

reduced to 10% of the full-scale value.

4053fa

9

LTC4053-4.2

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APPLICATIO S I FOR ATIO

Table 1.

FAULT

High

Programming The Timer

CHRG

Description

The programmable timer is used to terminate the charge

cycle. The timer duration is programmed by an external

capacitor at the TIMER pin. The total charge time is:

Low

Charge cycle has started, C/10 has not been

reached and charging is proceeding normally.

Low

Charge cycle has started, C/10 has not been

reached, but the charge current and timer

have been paused due to an NTC out-of-

temperature condition.

Time (Hours) = (3 Hours) • (C_TIMER/0.1µF) or

C_TIMER= 0.1µF • Time (Hours)/3 (Hours)

High

Low

30µA

C/10 has been reached and charging is

The timer starts when an input voltage greater than the

undervoltage lockout threshold level is applied and the

SHDN pin is greater than the manual shutdown threshold

voltage level. After a time-out occurs, the charge current

stops, and the CHRG output assumes a high impedance

state to indicate that the charging has stopped. Connect-

ing the TIMER pin to ground disables the timer function.

pull-down proceeding normally.

30µA

C/10 has been reached but the charge current

pull-down and timer have paused due to an NTC out-of-

temperature condition.

High

Low

High

Normal timeout (charging has terminated).

If FAULT goes low and CHRG goes high

impedance simultaneously, then the LTC4053

has timed out due to a bad cell (V

<2.48V

BAT

Recharge

after one-quarter the programmed charge time).

If CHRG goes high impedance first, then

the LTC4053 has timed out normally (charging

has terminated), but NTC is indicating an out-

of-temperature condition.

After a charge cycle has terminated, if the battery voltage

dropsbelowtherechargethresholdof4.05Vanewcharge

cycle will begin. The recharge circuit integrates the BAT

pin voltage for a few milliseconds to prevent a transient

from restarting the charge cycle.

CHRG Status Output Pin

If the battery voltage remains below 2.48V during trickle

chargefor1/4oftheprogrammedtime, thebatterymaybe

defective and the charge cycle will end. In addition, the

recharge comparator is disabled and a new charge cycle

will not begin unless the input voltage is toggled off-then-

on, the SHDN pin is momentarily pulled to ground, or the

BATpinispulledabovethe2.48Vtricklechargethreshold.

When the charge cycle starts, the CHRG pin is pulled to

ground by an internal N-channel MOSFET capable of

driving an LED. When the charge current drops to 10% of

the full-scale current (C/10), the N-channel MOSFET is

latched off and a weak 30µA current source to ground is

connected to the CHRG pin. After a time-out occurs,

the pin assumes a high impedance state. By using two

different value pull-up resistors a microprocessor can

detect three states from this pin (charging, C/10 and time-

out). See Figure 3.

Open-Drain Status Outputs

The LTC4053 has three open-drain status outputs: ACPR,

CHRG and FAULT. The ACPR pin pulls low when an input

voltage greater than the undervoltage lockout threshold is

applied and becomes high impedance when power (V_IN<

V_UV) is removed. CHRG and FAULT work together to

indicate the status of the charge cycle. Table 1 describes

the status of the charge cycle based on the CHRG and

FAULT outputs.

When the LTC4053 is in charge mode, the CHRG pin is

pulled low by the internal N-channel MOSFET. To detect

this mode, force the digital output pin, OUT, high and

measure the voltage at the CHRG pin. The N-channel

MOSFET will pull the pin low even with the 2k pull-up

resistor. Once the charge current drops to 10% of the

4053fa

10

LTC4053-4.2

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APPLICATIO S I FOR ATIO

U

+

V

CC

V

DD

7/8 V

1/2 V

–

+

CC

8

R

HOT

1%

TOO COLD

TOO HOT

V

CC

400k

LTC4053

CHRG

µPROCESSOR

2k

3

OUT

NTC

IN

R

+

–

NTC

10k

4053 F03

Figure 3. Microprocessor Interface

3/160 V

+

–

full-scale current (C/10), the N-channel MOSFET is turned

off and a 30µA current source is connected to the CHRG

pin. The IN pin will then be pulled high by the 2k pull-up.

By forcing the OUT pin to a high impedance state, the

current source will pull the pin low through the 400k

resistor. When the internal timer has expired, the CHRG

pin will assume a high impedance state and the 400k

resistor will then pull the pin high to indicate that charging

has terminated.

DISABLE NTC

LTC4053

4053 F04

Figure 4

Thermistors

The LTC4053 NTC trip points were designed to work with

thermistors whose resistance-temperature characteris-

tics follow Vishay Dale’s “R-T Curve 2”. The Vishay

NTHS0603N02N1002J is an example of such a ther-

mistor. However, Vishay Dale has many thermistor prod-

uctsthatfollowthe“R-TCurve2”characteristicinavariety

of sizes. Futhermore, any thermistor whose ratio of R_COLD

to R_HOTis about 7.0 will also work (Vishay Dale R-T Curve

2 shows a ratio of R_COLDto R_HOTof 2.816/0.4086 = 6.9).

NTC Thermistor

Thebatterytemperatureismeasuredbyplacinganegative

temperature coefficient (NTC) thermistor close to the

batterypack.TheNTCcircuitryisshowninFigure4.Touse

this feature, connect a 10k NTC thermistor between the

NTCpinandgroundandaresistor(R_HOT)fromtheNTCpin

to V_CC. R_HOTshould be a 1% resistor with a value equal to

the value of the chosen NTC thermistor at 50°C (this value

is 4.1k for a Vishay NTHS0603N02N1002J thermistor).

The LTC4053 goes into hold mode when the resistance of

the NTC thermistor drops below 4.1k which should be

approximately 50°C. The hold mode freezes the timer and

stops the charge cycle until the thermistor indicates a

return to a valid temperature. As the temperature drops,

the resistance of the NTC thermistor rises. The LTC4053

isdesignedtogointoholdmodewhenthevalueoftheNTC

thermistor increases to seven times the value of R_HOT. For

a Vishay NTHS0603N02N1002J thermistor, this value is

28.7k which corresponds to approximately 0°C. The hot

and cold comparators each have approximately 2°C of

hysteresis to prevent oscillation about the trip point. The

NTC function can be disabled by grounding the NTC pin.

NTC Layout Considerations

It is important that the NTC thermistor not be in close

thermal contact with the LTC4053. Because the LTC4053

package can reach temperatures in excess of the 50°C trip

point, the NTC function can cause a hysteretic oscillation

which turns the charge current on and off according to the

package temperature rather than the battery temperature.

This problem can be eliminated by thermally coupling the

NTC thermistor to the battery and not to the LTC4053.

Furthermore, it is essential that the V_CCconnection to

R_HOTis made according to standard Kelvin sense tech-

niques. Since V_CCis a high current path into the LTC4053,

it is essential to minimize voltage drops between the V_CC

input pin and the top of R_HOT

.

4053fa

11

LTC4053-4.2

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APPLICATIO S I FOR ATIO

NTC Trip Point Errors

Constant-Current/Constant-Voltage/

Constant-Temperature

When a 1% resistor is used for R_HOT, the major error in

the 50°C trip point is determined by the tolerance of

the NTC thermistor. A typical 10k NTC thermistor has

The LTC4053 uses a unique architecture to charge a

battery in a constant-current, constant-voltage, constant-

temperature fashion. Figure 1 shows a simplified block

diagram of the LTC4053. Three of the amplifier feedback

loops shown control the constant-current, CA, constant-

voltage, VA, and constant-temperature, TA modes. A

fourth amplifier feedback loop, MA, is used to increase the

output impedance of the current source pair, M1 and M2

(note that M1 is the internal P-channel power MOSFET). It

ensures that the drain current of M1 is exactly 1000 times

greater than the drain current of M2.

a

±10% tolerance. By looking up the temperature

coefficient of the thermistor at 50°C, the tolerance error

can be calculated in degrees centigrade. Consider the

Vishay NTHS0603N02N1002J thermistor which has a

temperature coefficient of –3.3%/°C at 50°C. Dividing

the tolerance by the temperature coefficient, ±10%/

(3.3%/°C) = ±3°C, gives the temperature error of the hot

trip point.

The cold trip point is a little more complicated because its

error depends on the tolerance of the NTC thermistor and

thedegreetowhichtheratioofitsvalueat0°Canditsvalue

at 50°C varies from 7 to 1. Therefore, the cold trip point

error can be calculated using the tolerance, TOL, the

temperature coefficient of the thermistor at 0°C, TC

(in %/°C), the value of the thermistor at 0°C, R_COLD, and

the value of the thermistor at 50°C, R_HOT. The formula is:

Amplifiers CA, TA, and VA are used in three separate

feedback loops to force the charger into constant-current,

temperature, or voltage mode, respectively. Diodes, D1,

D2, and D3 provide priority to whichever loop is trying to

reduce the charge current the most. The outputs of the

other two amplifiers saturate low which effectively re-

moves their loops from the system. When in constant-

current mode, CA servos the voltage at the PROG pin to be

precisely 1.50V (or 0.15V when in trickle-charge mode).

TA limits the die temperature to approximately 105°C

when in constant-temperature mode and the PROG pin

voltage gives an indication of the charge current as dis-

cussed in “Programming Charge Current”. VA servos its

inverting input to precisely 2.485V when in constant-

voltage mode and the internal resistor divider made up of

R1 and R2 ensures that the battery voltage is maintained

at 4.2V. Again, the PROG pin voltage gives an indication of

the charge current.

⎛

⎞

1+ TOL R_COLD

•

– 1 •100

⎜

⎟

7

R_HOT

TC

⎝

⎠

TemperatureError(°C)=

Forexample,theVishayNTHS0603N02N1002Jthermistor

with a tolerance of ±10%, TC of –4.5%/°C, and R_COLD

/

R_HOTof 6.89, has a cold trip point error of:

⎛

⎞

1± 0.10

•6.89 – 1 •100

⎜

⎟

7

⎝

⎠

Temperature Error (°C) =

In typical operation, the charge cycle begins in constant-

current mode with the current delivered to the battery

equal to 1500V/R_PROG. If the power dissipation of the

LTC4053 results in the junction temperature approaching

105°C, the amplifier (TA) will begin decreasing the charge

current to limit the die temperature to approximately

105°C. As the battery voltage rises, the LTC4053 either

returns to constant-current mode or it enters constant-

voltage mode straight from constant-temperature mode.

–4.5

= –1.8°C, +2.5°C

Ifathermistorwithatolerancelessthan±10%isused, the

trip point errors begin to depend on errors other than

thermistor tolerance including the input offset voltage of

theinternalcomparatorsoftheLTC4053andtheeffectsof

internal voltage drops due to high charging currents.

4053fa

12

LTC4053-4.2

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APPLICATIO S I FOR ATIO

U

Regardless of mode, the voltage at the PROG pin is

proportional to the current being delivered to the battery.

Furthermore, the voltage at the PROG pin will change

proportionally with the charge current as discussed in the

Programming Charge Current section.

Power Dissipation

It is important to remember that LTC4053 applications do

notneedtobedesignedforworst-casethermalconditions

since the IC will automatically reduce power dissipation

when the junction temperature reaches approximately

105°C.

The conditions that cause the LTC4053 to reduce charge

current due to the thermal protection feedback can be

approximated by considering the power dissipated in the

IC. For high charge currents, the LTC4053 power dissipa-

tion is approximately:

Board Layout Considerations

P_D= (V_CC– V_BAT) • I_BAT

The ability to deliver maximum charge current under all

conditions require that the exposed metal pad on the

backside of the LTC4053 package be soldered to the PC

board ground. Correctly soldered to a 2500mm²double-

sided 1oz. copper board the LTC4053 has a thermal

resistance of approximately 40°C/W. Failure to make

thermal contact between the exposed pad on the backside

of the package and the copper board will result in thermal

resistances far greater than 40°C/W. As an example, a

correctly soldered LTC4053 can deliver over 1250mA to a

battery from a 5V supply at room temperature. Without a

backside thermal connection, this number could drop to

less than 500mA.

where P_Dis the power dissipated, V_CCis the input supply

voltage, V_BATis the battery voltage, and I_BATis the battery

charge current. It is not necessary to perform any worst-

case power dissipation scenarios because the LTC4053

will automatically reduce the charge current to maintain

the die temperature at approximately 105°C. However, the

approximate ambient temperature at which the thermal

feedback begins to protect the IC is:

T_A= 105°C – P_Dθ_JA

T_A= 105°C – (V_CC– V_BAT) • I_BAT• θ_JA

Example: Consider an LTC4053 operating from a 5V wall

adapter providing 1.2A to a 3.75V Li-Ion battery. The

ambient temperature above which the LTC4053 will begin

to reduce the 1.2A charge current is approximately:

V_CCBypass Capacitor

Many types of capacitors can be used for input bypassing.

However, caution must be exercised when using multi-

layer ceramic capacitors. Because of the self resonant and

high Q characteristics of some types of ceramic capaci-

tors, high voltage transients can be generated under some

start-up conditions, such as connecting the charger input

to a hot power source. For more information refer to

Application Note 88.

T_A= 105°C – (5V – 3.75V) • 1.2A • 40°C/W

T_A= 105°C – 1.5W • 40°C/W = 105°C – 60°C = 45°C

The LTC4053 can be used above 45°C, but the charge

current will be reduced below 1.2A. The approximate

charge current at a given ambient temperature can be

approximated by:

105°C – T_A

(V_CC– V_BAT)•θ_JA

Stability

I_BAT

=

The constant-voltage mode feedback loop is stable

without any compensation provided that a battery is

connected. However, a 1µF capacitor with a 1Ω series

resistor to GND is recommended at the BAT pin to keep

ripple voltage low when the battery is disconnected.

Consider the above example with an ambient temperature

of 55°C. The charge current will be reduced to approxi-

mately:

105°C – 55°C

(5V – 3.75V)•40°C / W 50°C /A

50°C

In the constant-current mode it is the PROG pin that is in

the feedback loop and not the battery. The constant-

I_BAT

=

= 1A

current mode stability is affected by the impedance at the

4053fa

13

LTC4053-4.2

W U U

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APPLICATIO S I FOR ATIO

PROG pin. With no additional capacitance on the PROG

pin, stability is acceptable with program resistor values as

high as 50k. However, additional capacitance on this node

reduces the maximum allowed program resistor. The pole

frequency at the PROG pin should be kept above 500kHz.

Therefore, if the PROG pin is loaded with a capacitance, C,

the following equation should be used to calculate the

Average, rather than instantaneous, battery current may

beofinteresttotheuser.Forexample,ifaswitchingpower

supply operating in low-current mode is connected in

parallel with the battery the average current being pulled

out of the BAT pin is typically of more interest than the

instantaneous current pulses. In such a case, a simple RC

filter can be used on the PROG pin to measure the average

battery current as shown in Figure 5. A 10k resistor is

added between the PROG pin and the filter capacitor and

monitoring circuit to ensure stability.

maximum resistance value for R_PROG

:

R_PROG< 1/(6.283 • 5 × 10⁵• C)

LTC4053

PROG

CHARGE

10k

7

CURRENT

MONITOR

CIRCUITRY

R

PROG

C

FILTER

GND

5

4053 F05

Figure 5. Isolating Capacitive Load on PROG Pin and Filtering

U

PACKAGE DESCRIPTIO

DD Package

10-Lead Plastic DFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1698)

R = 0.115

TYP

6

0.38 ± 0.10

10

0.675 ±0.05

3.50 ±0.05

2.15 ±0.05 (2 SIDES)

1.65 ±0.05

3.00 ±0.10

(4 SIDES)

1.65 ± 0.10

(2 SIDES)

PIN 1

TOP MARK

(SEE NOTE 6)

PACKAGE

OUTLINE

(DD10) DFN 1103

5

1

0.25 ± 0.05

0.50 BSC

0.75 ±0.05

0.200 REF

0.25 ± 0.05

0.50

BSC

2.38 ±0.10

(2 SIDES)

2.38 ±0.05

(2 SIDES)

0.00 – 0.05

BOTTOM VIEW—EXPOSED PAD

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

NOTE:

1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).

CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT

2. DRAWING NOT TO SCALE

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE

TOP AND BOTTOM OF PACKAGE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4053fa

14

LTC4053-4.2

U

PACKAGE DESCRIPTIO

MSE Package

10-Lead Plastic MSOP

(Reference LTC DWG # 05-08-1663)

BOTTOM VIEW OF

EXPOSED PAD OPTION

2.06 ± 0.102

(.081 ± .004)

1.83 ± 0.102

(.072 ± .004)

2.794 ± 0.102

(.110 ± .004)

0.889 ± 0.127

(.035 ± .005)

1

5.23

(.206)

MIN

2.083 ± 0.102 3.2 – 3.45

(.082 ± .004) (.126 – .136)

10

0.50

(.0197)

BSC

0.305 ± 0.038

(.0120 ± .0015)

TYP

3.00 ± 0.102

(.118 ± .004)

(NOTE 3)

0.497 ± 0.076

(.0196 ± .003)

REF

10 9

8

7 6

RECOMMENDED SOLDER PAD LAYOUT

3.00 ± 0.102

(.118 ± .004)

NOTE 4

4.90 ± 0.15

(1.93 ± .006)

DETAIL “A”

0.254

(.010)

0° – 6° TYP

1

2

3

4 5

GAUGE PLANE

0.53 ± 0.01

(.021 ± .006)

0.86

(.034)

REF

1.10

(.043)

MAX

DETAIL “A”

0.18

(.007)

SEATING

PLANE

0.17 – 0.27

(.007 – .011)

TYP

0.13 ± 0.076

(.005 ± .003)

MSOP (MSE) 0802

0.50

(.0197)

BSC

NOTE:

1. DIMENSIONS IN MILLIMETER/(INCH)

2. DRAWING NOT TO SCALE

3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.

MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX

4053fa

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.

15

LTC4053-4.2

U

TYPICAL APPLICATIO S

USB/Wall Adapter Power Li-Ion Battery Charger

5V WALL

ADAPTER

I

LTC4053-4.2

BAT

9

+

Li-Ion

CELL

2

1µF

1Ω

USB

POWER

V

CC

4.7µF

4

8

SUSPEND

TIMER

SHDN

1k

GND NTC PROG

µC

5

6

7

3.74k

100mA/

500mA

0.1µF

15k

4053 F06

Li-Ion Battery Charger with Reverse Polarity Input Protection

Full Featured Single Cell Li-Ion Charger

V

= 5V

IN

I

= 1A

BAT

LTC4053-4.2

9

5V WALL

ADAPTER

2

8

1k

V

BAT

CC

8

2

1k

1-CELL

Li-Ion

+

SHDN

V

CC

SHDN

10

3

4k

BATTERY

ACPR

1%

4.7µF

1

6

4

7

CHRG

LTC4053-4.2

FAULT

TIMER

GND

PROG

4.7µF

I

= 500mA

BAT

NTC

6

9

1.5k

1%

NTC

BAT

5

0.1µF

1µF

7

TIMER

GND

PROG

R

Li-Ion

CELL

4053 F07

NTC

10k

3k

1%

1Ω

5

0.1µF

4053 F08

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4053fa

LT/LT 0705 REV A • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

16

●

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LTC4053-4.2
厂家：	Linear
描述：	USB Compatible Lithium-Ion Battery Charger with Thermal Regulation USB兼容锂离子电池充电器与热调节电池
文件：	总16页 (文件大小：196K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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