LM3622MX-8.2/NOPB - NATIONAL SEMICONDUCTOR

LM3622

LM3622 Lithium-Ion Battery Charger Controller

Literature Number: SNVS043A

LM3622

Lithium-Ion Battery Charger Controller

General Description

The LM3622 is a charge controller for Lithium-Ion batteries.

This monolithic integrated circuit accurately controls an ex-

ternal pass transistor for precision Lithium-Ion battery charg-

ing. The LM3622 provides a constant voltage or constant

current (CVCC) configuration that changes, as necessary, to

optimally charge lithium-ion battery cells. Voltage charging

versions (4.1V, 4.2V, 8.2V, and 8.4V) are available for one or

two cell battery packs and for coke or graphite anode battery

chemistry.

The LM3622 accepts input voltages from 4.5V to 24V. Con-

troller accuracy over temperature is ±30mV/cell for A grade

and ±50mV/cell for the standard grade. No precision exter-

nal resistors are required. Furthermore, the LM3622’s pro-

prietary output voltage sensing circuit drains less than

200nA from the battery when the input source is discon-

nected.

The LM3622 circuitry includes functions for regulating the

charge voltage with a temperature compensated bandgap

reference and regulating the current with an external sense

resistor. The internal bandgap insures excellent controller

performance over the operating temperature and input sup-

ply range.

The LM3622 can sink 15mA minimum at the EXT pin to drive

the base of an external PNP pass transistor. It also has

low-voltage battery threshold circuitry that removes this drive

when the cell voltage drops below a preset limit. The LV

SEL

pin programs this threshold voltage to either 2.7V/cell or

2.15V/cell. The low-voltage detection, which is a user en-

abled feature, provides an output signal that can be used to

enable a "wake up charge" source automatically to precon-

dition a deeply discharged pack.

The LM3622 is available in a standard 8-lead SOIC surface

mount package.

Features

nVersions for charging of 1 cell (4.1V or 4.2V) or 2 cells

(8.2V or 8.4V)

nVersions for coke or graphite anode

nPrecision (±30mV/cell) end-of-charge control

nWide input range: 4.5V-24V

nLow battery drain leakage: 200nA

n15 mA available to drive low cost PNP

Applications

nCellular phone cradle charger

nPDA/Notebook cradle charger

nCamcorder cradle charger

Typical Application

10097401

February 2000

LM3622 Lithium-Ion Battery Charger Controller

Connection Diagram

8-Lead Surface Mount Package

10097402

Refer to the Ordering Information Table in this Datasheet for Specific Part Number

See NS Package M08A

Pin Description

Pin No. Name I/O Description

1LV

SEL

Input Low-voltage detection threshold Select. The threshold is 2.15V/cell when this pin is

pulled low to GND and 2.70V/cell when it is pulled up to V

. The battery voltage is

sensed between CEL and CS pins.

2LV

ENB

Input Low-voltage detection Enable. The low-voltage detection is enabled when this pin is

pulled Low to GND. Pulling this pin HIGH to V

disables the low-voltage detection.

3LVOutput Output of the low-voltage detection. This pin is a NPN open-collector output that goes

to low impedance state when LV

ENB

is pulled LOW and the battery voltage is below

the threshold set by LV

SEL

. LV stays in HIGH impedance state at any battery voltage

when LV

ENB

is pulled HIGH to V

. LV can be used for turning on a low current

source to recondition a deeply depleted battery.

4 GND Ground IC common.

5 CS Input Input for battery charge current and battery negative-terminal voltage sensing. Battery

charging current is sensed through an external resistor, R

, connected between the

battery’s negative terminal and GND. The maximum charge current is regulated to a

value of 100mV/R

6 CEL Input Battery positive-terminal voltage sensing.

7 EXT Output Output of the controller for driving a PNP transistor or P-MOSFET. The controller

modulates the current sinking into this pin to control the regulation of either the charge

current or the battery voltage.

Power Supply IC power supply

LM3622

www.national.com 2

Ordering Information

Voltage Grade Accuracy Order Information Supplied As

4.1V A ±30mV LM3622AM-4.1 95 unit increments in rail

4.1V A ±30mV LM3622AMX-4.1 2500 unit increments in tape and reel

4.1V Standard ±50mV LM3622M-4.1 95 unit increments in rail

4.1V Standard ±50mV LM3622MX-4.1 2500 unit increments in tape and reel

4.2V A ±30mV LM3622AM-4.2 95 unit increments in rail

4.2V A ±30mV LM3622AMX-4.2 2500 unit increments in tape and reel

4.2V Standard ±50mV LM3622M-4.2 95 unit increments in rail

4.2V Standard ±50mV LM3622MX-4.2 2500 unit increments in tape and reel

8.2V A ±60mV LM3622AM-8.2 95 unit increments in rail

8.2V A ±60mV LM3622AMX-8.2 2500 unit increments in tape and reel

8.2V Standard ±100mV LM3622M-8.2 95 unit increments in rail

8.2V Standard ±100mV LM3622MX-8.2 2500 unit increments in tape and reel

8.4V A ±60mV LM3622AM-8.4 95 unit increments in rail

8.4V A ±60mV LM3622AMX-8.4 2500 unit increments in tape and reel

8.4V Standard ±100mV LM3622M-8.4 95 unit increments in rail

8.4V Standard ±100mV LM3622MX-8.4 2500 unit increments in tape and reel

LM3622

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

Supply Voltage (V

) -0.3 to 24V

LV -0.3 to 24V

EXT (Note 2) -0.3 to 24V

SEL

-0.3 to 24V

ENB

-0.3 to 24V

ESD Susceptibility (Note 3) 2500V

Storage Temperature −40˚C to +125˚C

Lead Temp. Soldering

Vapor Phase (60 sec.)

Infrared (15 sec.)

215˚C

220˚C

Power Dissipation (T

= 25˚C)

(Note 4)

Max. Package Dissipation 350mW

Operating Ratings (Note 1)

Supply Voltage (V

) 4.5V to 24V

Ambient Temperature Range −20˚C to 70˚C

Junction Temperature Range −20˚C to 85˚C

Thermal Resistance, θ

SOIC-8 170˚C/W

Electrical Characteristics

LM3622-XX

Unless otherwise specified V

= 5V/Cell T

= 25˚C. Limits with standard typeface apply for T

= 25˚C, and limits in bold-

face type apply over the indicated temperature range.

Symbol Parameter Conditions Min Typ Max Units

Operating power supply range 4.5 24.0 V

Quiescent Current 210 µA

CEL

Regulation Voltage

LM3622A-4.1

LM3622A-8.2

LM3622A-4.2

LM3622A-8.4

LM3622-4.1

LM3622-8.2

LM3622-4.2

LM3622-8.4

= 0˚C to +70˚C

= 4.5V/cell (Note 5) 4.070

8.140

4.170

8.340

4.050

8.100

4.150

8.300

4.100

8.200

4.200

8.400

4.100

8.200

4.200

8.400

4.130

8.260

4.230

8.460

4.150

8.300

4.250

8.500

Long Term Stability (Note 6) 0.02 %

Current limit threshold at CS pin V

CEL

= 4V for LM3622-4.X

CEL

= 8V for LM3622-8.X

90 100 110 mV

CEL

Current in CEL pin V

Supply connected 25 µA

Supply Open 200 nA

LVth Low voltage detect threshold

(between pins CS and GND)

ENB

= 0V and LV

SEL

=0V 2.00 2.15 2.30 V/Cell

ENB

= 0V and LV

SEL

2.55 2.70 2.85 V/Cell

EXT

EXT pin output sink current V

EXT

= 4V for LM3622-4.X

EXT

= 8V for LM3622-8.X

15 25 mA

IN1

SEL

input current LV

SEL

= 5V, LM3622-4.X

SEL

= 10V, LM3622-8.X

50 µA

IN2

ENB

input current LV

ENB

= 5V, LM3622-4.X

ENB

= 10V, LM3622-8.X

50 µA

LV pin leakage current LV = 5V/Cell 250 nA

LV pin saturation voltage I

SINK

= 1mA

= −20˚C to 85˚C

0.25 0.40 V

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: VEXT is not allowed to exceed (VCC+ 0.3V) or damage to the device may occur.

Note 3: Rating is for the human body model, a 100 pF capacitor discharged through a 1.5kΩresistor into each pin.

Note 4: The maximum power dissipation must be de-rated at elevated temperatures and is limited by TJMAX (maximum junction temperature), θJA (junction-to-

ambient thermal resistance) and TA(ambient temperature). The maximum power dissipation at any temperature is: PDissMAX =(T

JMAX −T

A)/θJA up to the value

listed in the Absolute Maximum Ratings.

Note 5: Limits reflect initial accuracy.

LM3622

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Electrical Characteristics (Continued)

Note 6: TJ= 85˚C, 1000 hours. Activation energy of 0.78eV used.

Typical Performance Characteristics

Unless otherwise specified, T

= 25˚C.

Output Voltage Regulation

Vs V

Current Sense Voltage Regulation

Vs V

Current Sense Voltage Regulation

Vs Temperature

10097405 10097408 10097404

Output Drive Current Vs V

Quiescent Current Vs V

10097406 10097407 10097403

LM3622

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Functional Description

The simplified LM3622 block diagram in Figure 1 gives a

general idea of the circuit operation. The controller integrates

the reference, feedback and drive functions on-chip to con-

trol a linear, lithium-ion battery charger in constant voltage

and constant current (CVCC) charge operation. The regu-

lated output voltage is sensed between CEL and CS, and the

battery charge current is sensed across a current-sense

resistor between CS and GND. The EXT pin is designed for

driving a series pass element, which can be a PNP transistor

or a P-MOSFET.

Tying the LV

ENB

pin to ground enables the controller’s low-

voltage detection circuit. When the low-voltage detection

circuit is enabled and a battery voltage below a preset

threshold is detected, the LM3622 will drive the LV pin low

and shut off the current flowing into the EXT pin to suspend

the CVCC charge process. The low-voltage threshold is user

selectable to be either 2.15V/cell or 2.7V/cell by pulling the

SEL

pin to GND or V

respectively. The LV pin is a NPN

open collector output that can be used to turn on a low

current source to wake up charge a deeply depleted battery.

When the low-voltage detection is disabled (LV

ENB

pulled up

to V

), the LM3622 always starts the charge cycle in con-

stant current mode at any battery voltage below the control-

ler’s regulation level, and maintains the LV pin at a high-

impedance state.

Application Information

CEL PIN CURRENT DRAIN

The LM3622 has an internal power down switch in series

with the on-chip resistor divider that is used for sensing the

battery voltage. In the event that the V

supply is removed,

the power down switch will disconnect the resistor divider

from the CS pin, preventing the battery from discharging

through the CEL pin.

EXT PIN

The EXT pin is internally pulled up to V

via a 20µA current

source making it possible to eliminate the external base-

emitter resistor when driving a PNP transistor, or the gate-

source resistor when driving a P-MOSFET. However, the

voltage applied to EXT is not allowed to be higher than (V

+ 0.3V), otherwise the reverse current from EXT pin to V

pin may cause damage to the device.

LV PIN CURRENT RATING

The LV pin is a low power, NPN open collector output that is

rated to sink 10mA maximum. Therefore, the value of the pull

up resistor should be chosen high enough to limit the current

to be less than 10mA.

CS PIN

In normal operation, the current limit threshold voltage for

the CS pin is 100mV typical. In case of a fault condition, the

voltage to this pin should be limited to below 5V.

10097411

FIGURE 1. LM3622 Simplified Block Diagram

LM3622

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Typical Application

The low dropout linear charger shown in Figure 2 provides

constant current and constant voltage charging of 1-cell

lithium-ion battery packs. J1 and J2 are used for selecting

the operation of the low-voltage detection. The LM3622 ini-

tializes the charge cycle based on the battery voltage and

the enable status of the low-voltage detection.

When the low-voltage detection is disabled, the LM3622

starts the charge cycle constant current mode if the battery

voltage is below the controller’s regulation level. In constant

current mode, the LM3622 modulates the base drive of Q2 to

regulate a constant 100mV across the current sense resistor

R1, thus generating charge current of

I-charge = 0.1V/R1

which is equal to 0.5A in this case.

Once the battery voltage reaches the target regulation level

set by the LM3622, Q2 is controlled to regulate the voltage

across the battery, and the constant voltage mode of the

charging cycle starts. Once the charger is in the constant

voltage mode, the charger maintains a regulated voltage

across the battery and the charging current is dependent on

the state of the charge of the battery. As the cell approaches

a fully charged condition, the charge current falls to a very

low value.

When the low-voltage detection is enabled and the initial

battery voltage is below the low-voltage threshold, the

LM3622 turns Q2 off and forces the LV pin low to drive Q1 on

to start a wake up charge phase. Q1 in conjunction with R2

provides a low current source to recondition the battery.

During the wake up charge mode, Q1 is driven into satura-

tion and the wake up charge current is programmed by R2,

I-charge (wake) = (V

–V

1–V

1 – LVth)/R2

where V

is the input supply voltage, V

1 is the collector-

emitter on state voltage of Q1, V

1 is the diode forward

voltage of D1, and LVth is the low-voltage threshold level set

by switch J2.

Once the battery voltage reaches the low-voltage threshold,

the LV pin transitions to a high-impedance state to end the

wake up charge phase, and the EXT pin resumes the base

drive of Q2 to start the constant current mode. The charging

cycle is completed in constant voltage mode when the bat-

tery is fully charged. Figure 3 shows the timing diagram of

the charge cycle with the low-voltage detection enabled.

D1 is a general-purpose silicon diode used for isolating the

battery from the charger circuitry that could discharge the

battery when the input source is removed. Changing D1 to a

Schottky diode will reduce the overall dropout voltage of the

circuit, but the penalty is higher leakage current associated

with Schottky diodes.

10097413

FIGURE 2. Low Dropout, Constant Current/Constant Voltage Li-ion Battery Charger

LM3622

www.national.com7

Timing Diagram

10097412

FIGURE 3. Typical Charge Cycle with Low-Voltage Detection Enabled.

LM3622

www.national.com 8

Physical Dimensions inches (millimeters) unless otherwise noted

SOIC-8 Package

8-Lead Small-Outline Package (M8)

For Ordering, Refer to Ordering Information Table

NS Package Number M08A

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves

the right at any time without notice to change said circuitry and specifications.

For the most current product information visit us at www.national.com.

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WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR

CORPORATION. As used herein:

1. Life support devices or systems are devices or systems

which, (a) are intended for surgical implant into the body, or

(b) support or sustain life, and whose failure to perform when

properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result

in a significant injury to the user.

2. A critical component is any component of a life support

device or system whose failure to perform can be reasonably

expected to cause the failure of the life support device or

system, or to affect its safety or effectiveness.

BANNED SUBSTANCE COMPLIANCE

National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship

Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned

Substances’’ as defined in CSP-9-111S2.

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LM3622 Lithium-Ion Battery Charger Controller

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