LTC1731EMS8-4.1#PBF [Linear]

LTC1731-4.X - Single Cell Lithium-Ion Linear Battery Charger Controllers; Package: MSOP; Pins: 8; Temperature Range: -40°C to 85°C;


型号：	LTC1731EMS8-4.1#PBF
厂家：	Linear
描述：	LTC1731-4.X - Single Cell Lithium-Ion Linear Battery Charger Controllers; Package: MSOP; Pins: 8; Temperature Range: -40°C to 85°C 电池光电二极管控制器
文件：	总8页 (文件大小：150K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

Final Electrical Specifications

LTC1731-4.1

Lithium-Ion Linear

Battery Charger Controller

April 2000

DESCRIPTION

FEATURES

The LTC^®1731-4.1 is a complete constant-current/con-

stant-voltage linear charge controller for lithium-ion bat-

teries. Nickel-cadmium (NiCd) and nickel-metal-hydride

(NiMH) batteries can also be charged with constant

current using external termination. The external sense

resistor sets the charge current with 5% accuracy. An

internal resistor divider and precision reference set the

final float potential with 1% accuracy. The output float

voltage is set internally to 4.1V.

■

Complete Linear Charger Controller for

1-Cell Lithium-Ion Batteries

■

1% Voltage Accuracy

■

Programmable Charge Current

■

C/10 Charge Current Detection Output

■

Programmable Charge Termination Timer

■

Space Saving, Thin 8-Pin MSOP Package

■

Automatic Sleep Mode When Input Supply

is Removed (7µA Battery Drain)

■

Automatic Trickle Charging of Low Voltage Cells

Whentheinputsupplyisremoved,theLTC1731automati-

callyentersalowcurrentsleepmode,droppingthebattery

drain current to 7µA typically. An internal comparator

detects the end-of-charge (C/10) condition while a pro-

grammable timer, using an external capacitor, sets the

total charge time. Fully discharged cells are automatically

trickle charged at 10% of the programmed current until

cell voltage exceeds 2.457V.

■

Programmable for Constant-Current-Only Mode

APPLICATIONS

■

Cellular Phones

■

Handheld Computers

■

Charging Docks and Cradles

Programmable Current Source

■

The LTC1731-4.1 is available in the 8-pin MSOP and SO

packages.

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

TYPICAL APPLICATION

500mA Li-Ion Charger

5V TO 12V

MBRM120T3

SENSE

1µF

SENSE

DRV

0.2Ω

CHARGE

STATUS

Si9430DY

CHRG

LTC1731-4.1

TIMER

BAT

PROG

GND

= 500mA

BAT

TIMER

0.1µF

Li-ION

CELL

PROG

19.6k

10µF

1731 TA01

*SHUTDOWN INVOKED BY FLOATING THE PROG PIN

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.

LTC1731-4.1

ABSOLUTE MAXIMUM RATINGS

W W

U W

(Note 1)

Input Supply Voltage (V_CC) ................................... 13.2V

Input Voltage (SENSE, DRV, BAT,

TIMER, PROG) ....................... –0.3V to (V_CC+ 0.3V)

Output Voltage (CHRG) ......................... –0.3V to 13.2V

Operating Temperature Range (Note 2) .....–40° to 85°C

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

Lead Temperature (Soldering, 10 sec).................. 300°C

W U

PACKAGE/ORDER INFORMATION

ORDER PART

TOP VIEW

NUMBER

TOP VIEW

BAT

CHRG

TIMER

GND

SENSE

BAT

CHRG

TIMER

GND

8 SENSE

7 V

6 DRV

LTC1731ES8-4.1

S8 PART MARKING

173141

LTC1731EMS8-4.1

MS8 PART MARKING

LTJK

DRV

5 PROG

PROG

MS8 PACKAGE

8-LEAD PLASTIC MSOP

S8 PACKAGE

8-LEAD PLASTIC SO

T_JMAX= 150°C, θ_JA= 180°C/W

T_JMAX= 150°C, θ_JA= 125°C/W

Consult factory for Industrial and Military grade parts.

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_CC= 6V unless otherwise noted.

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Input Supply Voltage

Input Supply Current

●

4.5

Charger On, Current Mode

Shutdown Mode

Sleep Mode (Battery Drain Current)

●

µA

Regulated Output Voltage

(5V ≤ V ≤ 12V)

●

4.059

4.1

4.141

BAT

Current Mode Charge Current

PROG

= 19.6k, R

= 97.6k, R

= 0.2Ω

465

415

500

535

585

130

BAT

SENSE

100

Trickle Charge Current

= 2V, R

= 19.6k, I

= (V – V )/0.2Ω

SENSE

●

100

TRIKL

BAT

PROG

TRIKL

Trickle Charge Threshold Voltage

From Low to High

2.35

2.457 2.55

TRIKL

Undervoltage Lockout Voltage

Undervoltage Lockout Hysteresis

4.1

4.5

∆V

200

Manual Shutdown Threshold Voltage

PROG Pin Low to High

PROG Pin High to Low

2.457

2.446

MSD

LTC1731-4.1

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_CC= 6V unless otherwise noted.

SYMBOL PARAMETER CONDITIONS

(V – V ) High to Low

MIN

TYP

MAX

UNITS

Automatic Shutdown Threshold Voltage

100

ASD

BAT

(V – V ) Low to High

BAT

Voltage Mode Disable Threshold Voltage

PROG Pin Current

●

5.6

300

µA

DIS

TIMER

Internal Pull-Up Current, No R

2.5

PROG

PROG Pin Load Regulation

PROG Pin Voltage

PROG Pin Source Current, ∆V

≤ 5mV

PROG

=19.6k

= 1V

2.457

100

0.6

PROG

CHRG

CHRG Pin Weak Pull-Down Current

CHRG Pin Output Low Voltage

End of Charge Indication Current Level

TIMER Accuracy

150

1.2

µA

CHRG

= 5mA

CHRG

= 19.6k, R

= 0.2Ω

SENSE

●

100

C/10

PROG

TIMER

CLAMP

= 0.1µF

= V – V , I = 50µA

DRV DRIVE

TIMER

DRV Pin Clamp Voltage

6.5

CLAMP

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

of a device may be impaired.

Note 2: The LTC1731-4.1 is guaranteed to meet performance

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

operating temperature range are assured by design, characterization and

correlation with statistical process controls. Guaranteed I grade parts are

available, consult factory.

PIN FUNCTIONS

GND (Pin 4): Ground.

BAT (Pin 1): Battery Sense Input. A bypass capacitor of at

least 10µF is required to keep the loop stable when the

battery is not connected. A precision internal resistor

dividersetsthefinalfloatpotentialonthispin. Theresistor

divider is disconnected in sleep mode.

PROG (Pin 5): Charge Current Program and Shutdown

Input Pin. The charge current is programmed by connect-

ing a resistor, R_PROGto ground. The charge current is I_BAT

= (V_PROG• 800Ω)/(R_PROG• R_SENSE). The IC can be forced

into shutdown by floating the PROG pin and allowing the

internal 2.5µA current source to pull the pin above the

2.457V shutdown threshold voltage.

CHRG (Pin 2): 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 for at least 0.32

seconds, the N-channel MOSFET turns off and a 100µA

current source is connected from the CHRG pin to GND.

When the timer runs out or the input supply is removed,

the current source will be disconnected and the CHRG pin

is forced into a high impedance state.

DRV (Pin 6): Drive Output Pin for the P-Channel MOSFET

or PNP Transistor. The impedance is high at this pin,

therefore, a high gain PNP pass transistor should be used.

The DRV pin is internally clamped to 6.5V below V_CC.

_CC(Pin 7): Positive Input Supply Voltage. When V_BATis

within 54mV of V_CC, the LTC1731 is forced into sleep

mode, dropping I_CCto 7µA. V_CCranges from 4.5V to 12V

(LTC1731-4.1). Bypass this pin with a 1µF capacitor.

TIMER (Pin 3): Timer Capacitor and Constant-Voltage

Mode Disable Input Pin. The timer period is set by placing

a capacitor, C_TIMER, to GND. The timer period is t_TIMER

SENSE (Pin 8): Current Sense Input. A sense resistor,

R_SENSE, must be connected from V_CCto the SENSE pin.

This resistor is chosen using the following equation:

(C_TIMER• 3 hours)/(0.1µF). When the TIMER pin is

connected to V_CC, the constant-voltage mode is disabled

and the charger will operate in constant-current mode

only. Short the TIMER pin to GND to disable the internal

timer function.

R_SENSE= (V_PROG• 800Ω)/(R_PROG• I_BAT

)

LTC1731-4.1

BLOCK DIAGRA

SENSE

–

800Ω

80Ω

–

54mV

CHRG

–

C/10 STOP C/10

LOGIC

720Ω

DRV

BAT

100µA

–

SHDN

SLP

LBO

TIMER

OSCILLATOR

COUNTER

REF

–

2.5µA

REF

2.457V

CHARGE

PROG

GND

1731 BD

BATTERY CURRENT I

= (2.457V • 800Ω)/(R

• R

)

SENSE

BAT

PROG

OPERATIO

The LTC1731 is a linear battery charger controller. The

charge current is programmed by the combination of a

program resistor (R_PROG) from the PROG pin to ground

and a sense resistor (R_SENSE) between the V_CCand SENSE

pins. R_PROGsets a program current through an internal

trimmed 800Ω resistor setting up a voltage drop from V_CC

to the input of the current amplifier (CA). The current

amplifierservosthegateoftheexternalP-channelMOSFET

to force the same voltage drop across R_SENSEwhich sets

the charge current. When the potential at the BAT pin

approaches the preset float voltage, the voltage amplifier

(VA) will start sinking current which reduces the voltage

drop across R_SENSE, thus reducing the charge current.

Charging begins when the potential at V_CCpin rises above

the UVLO level and a program resistor is connected from

the PROG pin to ground. At the beginning of the charge

cycle, if the cell voltage is below 2.457V, the charger goes

intotricklechargemode. Thetricklechargecurrentis10%

ofthefull-scalecurrent. Ifthecellvoltagestayslowforone

quarter of the total charge time, the charge sequence will

be terminated immediately.

The charger goes into the fast charge constant-current

mode after the voltage on the BAT pin rises above 2.457V.

In constant-current mode, the charge current is set by the

combination of R_SENSEand R_PROG

LTC1731-4.1

OPERATIO

When the battery approaches the final float voltage, the

charge current will begin to decrease. When the current float potential, the internal 2.457V reference, voltage

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

comparatorwillturnoffthepull-downN-channelMOSFET

at the CHRG pin and connect a weak current source to LTC1731 can be turned into a current source by pulling

ground to indicate an end-of-charge (C/10) condition.

For batteries like lithium-ion that require accurate final

amplifier and the resistor divider provide regulation with

±1% (max) accuracy. For NiMH and NiCd batteries, the

the TIMER pin to V_CC. When in the constant-current only

mode, the voltage amplifier, timer and the trickle charge

function are all disabled.

An external capacitor on the TIMER pin sets the total

charge time. After a time-out occurs, the charging will be

terminated immediately and the CHRG pin is forced to a

high impedance state. To restart the charge cycle, simply

remove the input voltage and reapply it, or float the PROG reduces the current drain on the battery and increases the

pin momentarily.

When the input voltage is not present, the charger goes

into a sleep mode, dropping I_CCto 7µA. This greatly

standbytime.Thechargercanbeshutdownbyfloatingthe

PROG pin. An internal current source will pull it high and

clamp at 3.5V.

W U U

APPLICATIONS INFORMATION

Charge Termination

Shutdown

The charger is off when any of the following conditions

exist: the voltage at the V_CCpin is below 4.1V, the voltage

at the V_CCpin is higher than 4.1V but is less than 54mV

above V_BAT, or the PROG pin is floating. The DRV pin will

be pulled to V_CCand the internal resistor divider is discon-

nected to reduce the current drain on the battery.

TheLTC1731canbeforcedintoshutdownbyfloatingthe

PROGpinthusallowingtheinternal2.5µAcurrentsource

to pull the pin above the 2.457V shutdown threshold

voltage. The DRV pin will then be pulled up to V_CCand

turn off the external P-channel MOSFET. The internal

timer is reset in the shutdown mode.

Undervoltage Lockout (UVLO)

Programming Charge Current

Aninternalundervoltagelockoutcircuitmonitorstheinput

voltageandkeepsthechargerinshutdownmodeuntilV_CC

rises above 4.1V. To prevent oscillation around

V_CC= 4.1V, the UVLO circuit has built-in hysteresis.

The formula for the battery charge current (see Block

Diagram) is:

I_BAT= (I_PROG)(800Ω/R_SENSE

)

= (2.457V/R_PROG)(800Ω/R_SENSE

)

Trickle Charge and Defective Battery Detection

where R_PROGis the total resistance from the PROG pin to

ground.

At the beginning of the charging sequence, if the battery

voltage is low (below 2.457V) the charger goes into trickle

mode. The charge current is dropped to 10% of the full-

scale current. If the low cell voltage persists for one

quarterofthetotalchargingtime,thebatteryisconsidered

defective, the charging will be terminated and the CHRG

pin output is forced to a high impedance state.

For example, if 0.5A charge current is needed, select a

value for R_SENSEthat will drop 100mV at the maximum

chargecurrent.R_SENSE=0.1V/0.5A=0.2Ω,thencalculate:

R_PROG= (2.457V/500mA)(800Ω/0.2Ω) = 19.656k

For best stability over temperature and time, 1% resistors

are recommended. The closest 1% resistor value is 19.6k.

LTC1731-4.1

W U U

APPLICATIONS INFORMATION

Programming the Timer

and a 100µA current source is connected to the CHRG pin.

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

current source will pull the pin low through the 100k

resistor. When the internal timer has expired, the CHRG

pin will change to high impedance state and the 100k

resistor will then pull the pin high to indicate the charging

has stopped.

The programmable timer is used to terminate the charge.

The length of the timer is programmed by an external

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

Time = (3 Hours)(C_TIMER/0.1µF)

The timer starts when the input voltage greater than 4.1V

isappliedandtheprogramresistorisconnectedtoground.

After a time-out occurs, the CHRG output will turn into a

high impedance state to indicate that the charging has

stopped. Connecting the TIMER pin to V_CCdisables the

timer and also puts the charger into a constant-current

mode. To only disable the timer function, short the TIMER

pin to GND.

End of Charge (C/10)

TheLTC1731includesacomparatortomonitorthecharge

current to detect an end-of-charge condition. When the

battery current falls below 10% of full scale, the compara-

tor trips and turns off the N-channel MOSFET at the CHRG

pin and switches in a 100µA current source to ground.

After an internal time delay of at least 300ms, this state is

then latched. This delay will help prevent false triggering

due to transient currents. The end-of-charge comparator

is disabled in trickle charge mode.

CHRG Status Output Pin

Whenthechargecyclestarts, theCHRGpinispulleddown

to ground by an internal N-channel MOSFET that can drive

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

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

and a weak 100µA current source to ground is connected

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

into a high impedance state. By using two different value

pull-upresistors,amicroprocessorcandetectthreestates

from this pin (charging, C/10 and stop charging). See

Figure 1.

Gate Drive

Typically the LTC1731 controls an external P-channel

MOSFET to supply current to the battery. The DRV pin is

internally clamped to 6.5V below V_CC. This feature allows

low voltage P-channel MOSFETs with gate to source

breakdown voltage rated at 8V to be used.

An external PNP transistor can also be used as the pass

transistor instead of the P-channel MOSFET. Due to the

low current gain of the current amplifier (CA), a high gain

Darlington PNP transistor is required to avoid excessive

charge current error. The gain of the current amplifier is

around 0.6µA/mV. For every 1µA of base current, a 1.6mV

µPROCESSOR

100k

LTC1731-4.1

CHRG

OUT

of gain error shows up at the inputs of CA. With R_PROG

19.6k (100mV across R_SENSE), it represents 1.67% of

error in charging current.

1731 F01

Figure 1. Microprocessor Interface

Constant-Current Only Mode

When the LTC1731 is in charge mode, the CHRG pin is

pulled down by an 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 a 1k pull-up

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

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

The LTC1731 can be used as a programmable current

source by forcing the TIMER pin to V_CC. This is particu-

larly useful for charging NiMH or NiCd batteries. In the

constant-current only mode, the timer and voltage ampli-

fier are both disabled. An external termination method is

required to properly terminate the charge.

LTC1731-4.1

W U U

APPLICATIONS INFORMATION

Stability

When a PNP transistor is chosen as the pass transistor, a

1000pFcapacitorisrequiredfromtheDRVpintoV_CC.This

capacitor is needed to help stablize the voltage loop. A

10µF capacitor at the BAT pin is also recommended when

a battery is not present.

The charger is stable without any compensation when a

P-channel MOSFET is used as the pass transistor.

However, a 10µF capacitor is recommended at the BAT

pin to keep the ripple voltage low when the battery is

disconnected.

PACKAGE DESCRIPTION ^{Dimensions in inches (millimeters) unless otherwise noted.}

MS8 Package

8-Lead Plastic MSOP

(LTC DWG # 05-08-1660)

0.118 ± 0.004*

(3.00 ± 0.102)

0.040 ± 0.006

(1.02 ± 0.15)

0.034 ± 0.004

(0.86 ± 0.102)

0.007

(0.18)

0° – 6° TYP

0.118 ± 0.004**

(3.00 ± 0.102)

SEATING

PLANE

0.193 ± 0.006

(4.90 ± 0.15)

0.012

(0.30)

REF

0.021 ± 0.006

(0.53 ± 0.015)

0.006 ± 0.004

(0.15 ± 0.102)

0.0256

(0.65)

BSC

MSOP (MS8) 1098

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

PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

S8 Package

8-Lead Plastic Small Outline (Narrow 0.150)

(LTC DWG # 05-08-1610)

0.189 – 0.197*

(4.801 – 5.004)

0.010 – 0.020

(0.254 – 0.508)

× 45°

0.053 – 0.069

(1.346 – 1.752)

0.004 – 0.010

(0.101 – 0.254)

0.008 – 0.010

(0.203 – 0.254)

0°– 8° TYP

0.150 – 0.157**

(3.810 – 3.988)

0.228 – 0.244

(5.791 – 6.197)

0.016 – 0.050

(0.406 – 1.270)

0.050

(1.270)

BSC

0.014 – 0.019

(0.355 – 0.483)

TYP

*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

SO8 1298

**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD

FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

LTC1731-4.1

TYPICAL APPLICATIONS

Linear Charger Using a PNP Transistor

5V TO 12V

MBRM120T3

1nF

10k

SENSE

0.2Ω

1µF

ZTX749

SENSE

DRV

LTC1731-4.1

TIMER

BAT

PROG

GND

2N5087

CHRG

= 500mA

BAT

TIMER

0.1µF

10µF

Li-ION

CELL

PROG

19.6k

1731 TA02

1.5A Single-Cell Battery Charger

= 5V ~ 6V

MBRS130LT3

22µF

CER

0.082Ω

1/4W

0.47µF

1µF

CER

LED

Si2305DS

4.7Ω

CHRG

LTC1731-4.1

DRV

SENSE

MBRS130LT3

TIMER

BAT

22µF

CDRH6D38-220NC

GND

PROG

0.1µF

TPS2829DBVR

AVX0603ZC104KATIA

18.2k

1-CELL

Li-Ion

BATTERY

–

100µF

1731 TA03

RELATED PARTS

PART NUMBER

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LT1512

DESCRIPTION

COMMENTS

500kHz Constant-Voltage/Constant-Current Battery Charger Most Compact, Up to 1.5A, Charges NiCd, NiMH, Li-Ion Cells

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V Can Be Higher or Lower Than Battery Voltage, 1.5A Switch

LT1571

Battery Charger with Preset Voltage and Termination Flag

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LT1620

Precise Output Current Programming, Up to 32V V , Up to 10A I

OUT

LTC1729

Time or Charge Current Termination, Automatic Charger/Battery

Detection, Status Output, Preconditioning, 8-Lead MSOP

LTC1731-4.2

Li-Ion Linear Battery Charge Controller

Fast Charge 4.2V Li-Ion Batteries with Constant-Voltage/Constant-

Current Linear Charger

173141i LT/TP 0400 4K • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

●

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

LTC1731EMS8-4.1#PBF [Linear]

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