LINEAR TECHNOLOGY LTC4006 Technical data

FEATURES

■

Complete Charger Controller for 2-, 3- or 4-Cell
Lithium-Ion Batteries

■

High Conversion Efficiency: Up to 96%

■

Output Currents Exceeding 4A

■

±0.8% Accurate Preset Voltages: 8.4V, 12.6V, 16.8V

■

Built-In Charge Termination with Automatic Restart

■

AC Adapter Current Limiting Maximizes Charge Rate*

■

Automatic Conditioning of Deeply Discharged
Batteries

■

Thermistor Input for Temperature Qualified Charging

■

Wide Input Voltage Range: 6V to 28V

■

0.5V Dropout Voltage; Maximum Duty Cycle: 98%

■

Programmable Charge Current: ±4% Accuracy

■

Indicator Outputs for Charging, C/10 Current
Detection and AC Adapter Present

■

Charging Current Monitor Output

■

16-Pin Narrow SSOP Package

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APPLICATIO S

■

Notebook Computers

■

Portable Instruments

■

Battery-Backup Systems

■

Standalone Li-Ion Chargers

LTC4006

4A, High Efficiency,

Standalone Li-Ion

Battery Charger

U

DESCRIPTIO

The LTC®4006 is a complete constant-current/constant­voltage charger controller for 2-, 3- or 4-cell lithium bat­teries in a small package using few external components.
The PWM controller is a synchronous, quasi-constant fre­quency, constant off-time architecture that will not gener­ate audible noise even when using ceramic capacitors.

The LTC4006 is available in 8.4V, 12.6V and 16.8V versions
with ±0.8% voltage accuracy. Charging current is program-
mable with a single sense resistor to ±4% typical accuracy.
Charging current can be monitored as a representative
voltage at the I
resistor, sets the total charge time or is reset to 25% of total
charge time after C/10 charging current is reached. Charg­ing automatically resumes when the cell voltage falls below

3.9V/cell.

Fully discharged cells are automatically trickle charged at
10% of the programmed current until the cell voltage ex­ceeds 2.5V/cell. Charging terminates if the low-battery
condition persists for more than 25% of the total charge
time.

The LTC4006 includes a thermistor sensor input that
suspends charging if an unsafe temperature condition is
detected and automatically resumes charging when the
battery temperature returns to within safe limits.

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 5723970.

pin. A timer, programmed by an external

MON

TYPICAL APPLICATIO

DCIN

0V TO 28V

3A

V

LOGIC

CHG

ACP

CHARGING

CURRENT MONITOR

THERMISTOR

10k

NTC

0.47µF

U

32.4k

0.0047µF

309k

TIMING

RESISTOR

(~2 HOURS)

100k

0.1µF

0.12µF

4A Li-Ion Battery Charger

INPUT SWITCH

T

LTC4006

INFET

CLP

CLN

TGATE

BGATE

PGND

CSP

BAT

DCIN

CHG

ACP/SHDN

I

MON

NTC

R

I

TH

6k

GND

5k

15nF

0.033Ω

20µF
10µH

TO SYSTEM LOAD

0.025Ω

4006 TA01

BATTERY

20µF

4006fa

1

LTC4006

WW

W

ABSOLUTE MAXIMUM RATINGS

U

U

W

PACKAGE/ORDER INFORMATION

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(Note 1)

Voltage from DCIN, CLP, CLN, TGATE, INFET,

ACP/SHDN, CHG to GND ....................... +32V to –0.3V

Voltage from CLP to CLN..................................... ±0.3V

CSP, BAT to GND................................... +28V to –0.3V

to GND ................................................. +7V to –0.3V

R

T

NTC ........................................................ +10V to –0.3V

Operating Ambient Temperature Range

(Note 4) ............................................. –40°C to 85°C

DCIN

CHG

ACP/SHDN

GND

NTC

I

I

MON

Operating Junction Temperature ......... –40°C to 125°C

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

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

ELECTRICAL CHARACTERISTICS

temperature range (Note 4), otherwise specifications are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

DCIN Operating Range 628V

I

DCIN

V

TOL

I

TOL

T

TOL

Shutdown

UVLO Undervoltage Lockout Threshold DCIN Rising, V

Current Sense Amplifier, CA1

CMSL CA1/I1 Input Common Mode Low
CMSH CA1/I1 Input Common Mode High

DCIN Operating Current Sum of Current from CLP, CLN, DCIN 3 5 mA

Voltage Accuracy (Note 2)

Current Accuracy (Note 3) V

Termination Timer Accuracy RRT = 270k

Battery Leakage Current DCIN = 0V 20 35 µA

Shutdown Threshold at ACP/SHDN
DCIN Current in Shutdown V

Input Bias Current Into BAT Pin 11.67 µA

The ● denotes specifications which apply over the full operating

= 25°C. V

A

LTC4006-6 8.333 8.4 8.467 V
LTC4006-6
LTC4006-2 12.499 12.6 12.700 V
LTC4006-2
LTC4006-4 16.665 16.8 16.935 V
LTC4006-4

– V

CSP

= 11.5V (LTC4006-2)

V

BAT

V

= 7.6V (LTC4006-6)

BAT

= 12V (LTC4006-4)

V

BAT

V

< 6V, V

BAT

6V ≤ V

BAT

– V

V

CSP

DCIN = 0V
DCIN = 20V, V

= 0V, Sum of Current from CLP, 2 3 mA

SHDN

CLN, DCIN

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.

Target = 100mV – 4 4 %

BAT

– V

CSP

≤ V

LOBAT

Target = 10mV

BAT

SHDN

BAT

T

= 20V, V

DCIN

Target = 10mV –60 60 %

BAT

,–4040%

= 0V, V

= 0V

TOP VIEW

1

2

3

4

R

T

5

6

7

TH

8

GN PACKAGE

16-LEAD PLASTIC SSOP

= 125°C, θJA = 110°C/W

JMAX

= 12V unless otherwise noted.

BAT

= 12V

BAT

ORDER PART

INFET

16

BGATE

15

PGND

14

TGATE

13

CLN

12

CLP

11

BAT

10

CSP

9

NUMBER

LTC4006EGN-2
LTC4006EGN-4
LTC4006EGN-6

GN PART MARKING

40062
40064
40066

●

8.316 8.4 8.484 V

●

12.474 12.6 12.726 V

●

16.632 16.8 16.968 V

●

–5 5 %

●

–15 15 %

●

●

–10 0 10 µA

●

4.2 4.7 5.5 V

●

1 2.5 V

●

0V

●

25 45 µA

V

– 0.2 V

CLN

4006fa

2

LTC4006

ELECTRICAL CHARACTERISTICS

temperature range (Note 4), otherwise specifications are at T

The ● denotes specifications which apply over the full operating

= 25°C. V

A

DCIN

= 20V, V

= 12V unless otherwise noted.

BAT

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Current Comparators I

I

TMAX

I

TREV

Maximum Current Sense Threshold (V

Reverse Current Threshold (V

CMP

and I

REV

CSP

– V

)V

CSP

BAT

– V

)–30mV

BAT

ITH

= 2.5V

●

140 165 200 mV

Current Sense Amplifier, CA2

Transconductance 1 mmho

Source Current Measured at ITH, V

Sink Current Measured at ITH, V

= 1.4V – 40 µA

ITH

= 1.4V 40 µA

ITH

Current Limit Amplifier

Transconductance 1.5 mmho

V

I

CLP

CLP

Current Limit Threshold

●

93 100 107 mV

CLP Input Bias Current 100 nA

Voltage Error Amplifier, EA

Transconductance 1 mmho

Sink Current Measured at ITH, V

OVSD Overvoltage Shutdown Threshold as a Percent

= 1.4V 36 µA

ITH

●

102 107 110 %

of Programmed Charger Voltage

Input P-Channel FET Driver (INFET)

DCIN Detection Threshold (V

Forward Regulation Voltage (V

Reverse Voltage Turn-Off Voltage (V

INFET “On” Clamping Voltage (V

INFET “Off” Clamping Voltage (V

DCIN

DCIN

– V

) DCIN Voltage Ramping Up

DCIN

DCIN

– V

DCIN

CLN

– V

– V

CLN

)

– V

INFET

INFET

from V

CLN

) DCIN Voltage Ramping Down

CLN

)I

)I

= 1µA

INFET

= –25µA 0.25 V

INFET

– 0.1V

●

0 0.17 0.25 V

●

●

–60 –25 mV

●

5 5.8 6.5 V

25 50 mV

Thermistor

NTCVR Reference Voltage During Sample Time 4.5 V

High Threshold V

NTC

Rising

●

NTCVR NTCVR NTCVR V

• 0.48 • 0.5 • 0.52

Low Threshold V

NTC

Falling

●

NTCVR NTCVR NTCVR V

• 0.115 • 0.125 • 0.135

Thermistor Disable Current V

≤ 10V 10 µA

NTC

Indicator Outputs (ACP/SHDN, CHG)

C10TOL C/10 Indicator Accuracy Voltage Falling at PROG

LBTOL LOBAT Threshold Accuracy LTC4006-6

LTC4006-2
LTC4006-4

RESTART Threshold Accuracy LTC4006-6

LTC4006-2
LTC4006-4

V

OL

V

OH

I

PO

Low Logic Level of ACP/SHDN, CHG IOL = 100µA

High Logic Level of ACP/SHDN IOH = –1µA

Pull-Up Current on ACP/SHDN V = 0V –10 µA

IC10 C/10 Indicator Sink Current from CHG VOH = 3V

I

OFF

Off State Leakage Current of CHG VOH = 3V –1 1 µA

●

0.375 0.400 0.425 V

●

4.70 4.93 5.14 V

●

7.27 7.5 7.71 V

●

9.70 10 10.28 V

●

7.5 7.8 7.96 V

●

11.35 11.7 11.94 V

●

15.15 15.6 15.92 V

●

●

2.7 V

●

15 25 38 µA

0.5 V

Timer Defeat Threshold at CHG 1 V

4006fa

3

LTC4006

ELECTRICAL CHARACTERISTICS

temperature range (Note 4), otherwise specifications are at T

The ● denotes specifications which apply over the full operating

= 25°C. V

A

DCIN

= 20V, V

= 12V unless otherwise noted.

BAT

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Oscillator

f

f

DC

OSC

MIN

MAX

Regulator Switching Frequency 255 300 345 kHz
Regulator Switching Frequency in Drop Out Duty Cycle ≥ 98% 20 25 kHz

Regulator Maximum Duty Cycle V

CSP

= V

BAT

98 99 %

Gate Drivers (TGATE, BGATE)

V

High (V

TGATE

V

High C

BGATE

V

Low (V

TGATE

V

Low I

BGATE

CLN

CLN

– V

– V

)I

TGATE

)C

TGATE

= –1mA 50 mV

TGATE

= 3000pF 4.5 5.6 10 V

LOAD

= 3000pF 4.5 5.6 10 V

LOAD

= 1mA 50 mV

BGATE

TGATE Transition Time
TGTR TGATE Rise Time C
TGTF TGATE Fall Time C

= 3000pF, 10% to 90% 50 110 ns

LOAD

= 3000pF, 10% to 90% 50 100 ns

LOAD

BGATE Transition Time
BGTR BGATE Rise Time C
BGTF BGATE Fall Time C

V

at Shutdown (V

TGATE

V

at Shutdown I

BGATE

CLN

– V

)I

TGATE

Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.

Note 2: See Test Circuit

= 3000pF, 10% to 90% 40 90 ns

LOAD

= 3000pF, 10% to 90% 40 80 ns

LOAD

= –1µA, DCIN = 0V, CLN = 12V 100 mV

TGATE

= 1µA, DCIN = 0V, CLN = 12V 100 mV

BGATE

Note 3: Does not include tolerance of current sense resistor.
Note 4: The LTC4006E 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.

UW

TYPICAL PERFOR A CE CHARACTERISTICS

INFET Response Time to
Reverse Current

= 0

V

gs

= 0V

V

s

Id (REVERSE) OF
PFET (5A/DIV)

I

= 0A

d

TEST PERFORMED ON DEMOBOARD

= 15VDC

V

IN

CHARGER = ON

= <10mA

I

CHARGE

Vgs OF PFET (2V/DIV)

Vs OF PFET (5V/DIV)

1.25µs/DIV

LTC4006-2
INFET = 1/2 Si4925DY

4006 G01

V

vs I

OUT

OUT

0

–0.5

–1.0

–1.5

–2.0

–2.5

–3.0

–3.5

–4.0

OUTPUT VOLTAGE ERROR (%)

DCIN = 20V

–4.5

–5.0

= 12.6V

V

BAT

0 0.5 1.0 2.0 3.0 4.01.5 2.5 3.5 4.5

OUTPUT CURRENT (A)

4006 G02

PWM Frequency vs Duty Cycle

350

300

250

200

150

100

PWM FREQUENCY (kHz)

50

PROGRAMMED CURRENT = 10%

DCIN = 15V
DCIN = 20V

0

0 0.1 0.2 0.4 0.6 0.90.80.3 0.5 0.7 1.0

DCIN = 24V

DUTY CYCLE (V

OUT/VIN

)

4006 G03

4006fa

4

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LTC4006

Disconnect/Reconnect Battery
(Load Dump)

3A STEP

V

FLOAT

1V/(DIV)

LOAD

STATE

LOAD CURRENT = 1A, 2A, 3A
DCIN = 20V
LTC4006-2

1A STEP

DISCONNECT

Efficiency at 19VDC V

100

LTC4006-4

95

90

1A STEP

3A STEP

RECONNECT

LTC4006-2

Battery Leakage Current vs
Battery Voltage

40

VDCIN = 0V

35

30

25

20

15

10

BATTERY LEAKAGE CURRENT (µA)

5

0

0 5 10 15 20 25 30

4006 G04

BATTERY VOLTAGE (V)

4006 G05

LTC4006-2 Efficiency with

IN

15VDC V

100

95

90

IN

85

EFFICIENCY (%)

80

75

U

1.000.50 1.50 2.00 2.50 3.00
CHARGING CURRENT (A)

4006 G07

UU

PI FU CTIO S

DCIN (Pin 1): External DC Power Source Input. Bypass
this pin with at least 0.01µF. See Applications Information
section.

CHG (Pin 2): Open-Drain Charge Status Output. When the
battery is being charged, the CHG pin is pulled low by an
internal N-channel MOSFET. When the charge current
drops below 10% of programmed current, the N-channel
MOSFET turns off and a 25µA current source is connected
from the CHG pin to GND. When the timer runs out or the
input supply is removed, the current source will be discon-

85

EFFICIENCY (%)

80

75

1.000.50 1.50 2.00 2.50 3.00
CHARGING CURRENT (A)

4006 G08

nected and the CHG pin is forced into a high impedance
state. A pull-up resistor is required. The timer function is
defeated by forcing this pin below 1V (or connecting it to
GND).

ACP/SHDN (Pin 3): Open-Drain Output used to indicate if
the AC adapter voltage is adequate for charging. Active
high digital output. Internal 10µA pull-up to 3.5V. The
charger can also be inhibited by pulling this pin below 1V.
Reset the charger by pulsing the pin low for a minimum of

0.1µs.

4006fa

5

LTC4006

U

UU

PI FU CTIO S

(Pin 4): Timer Resistor. The timer period is set by

R

T

placing a resistor, R

The timer period is t

If this resistor is not present, the charger will not start.

GND (Pin 5): Ground for low power circuitry.

NTC (Pin 6): A thermistor network is connected from NTC

to GND. This pin determines if the battery temperature is
safe for charging. The charger and timer are suspended if
the thermistor indicates a temperature that is unsafe for
charging. The thermistor function may be disabled with a
300k to 500k resistor from DCIN to NTC.

I

(Pin 7): Control Signal of the Inner Loop of the Current

TH

Mode PWM. Higher I
charging currrent in normal operation. A 6.04k resistor, in
series with a capacitor of at least 0.1µF to GND, provides
loop compensation. Typical full-scale output current is
40µA. Nominal voltage range for this pin is 0V to 3V.

I

(Pin 8): Current Monitoring Output. The voltage at

MON

this pin provides a linear indication of charging current.
Peak current is equivalent to 1.19V. Zero current is ap­proximately 0.309V. A capacitor from I
required to filter higher frequency components. If V

2.5V/cell, then V(I
depleted battery. Any current sourced or sinked from this
pin directly affects the charging current accuracy. If this
pin is to be monitored, a high impedance input buffer
should be used.

, to GND.

RT

= (1hour • RRT/154k)

TIMER

voltage corresponds to higher

TH

to ground is

MON

) = 1.19V when conditioning a

MON

BAT

<

CSP (Pin 9): Current Amplifier CA1 Input. This pin and the
BAT pin measure the voltage across the sense resistor,
R

, to provide the instantaneous current signals re-

SENSE

quired for both peak and average current mode operation.

BAT (Pin 10): Battery Sense Input and the Negative
Reference for the Current Sense Resistor. A precision
internal resistor divider sets the final float potential on this
pin. The resistor divider is disconnected during shutdown.

CLP (Pin 11): Positive Input to the Supply Current Limiting
Amplifier, CL1. The threshold is set at 100mV above the
voltage at the CLN pin. When used to limit supply current,
a filter is needed to filter out the switching noise. If no
current limit function is desired, connect this pin to CLN.

CLN (Pin 12): Negative Reference for the Input Current
Limit Amplifier, CL1. This pin also serves as the power
supply for the IC. A 10µF to 22µF bypass capacitor should
be connected as close as possible to this pin.

TGATE (Pin 13): Drives the top external P-channel MOSFET
of the battery charger buck converter.

PGND (Pin 14): High Current Ground Return for the BGATE
Driver.

BGATE (Pin 15): Drives the bottom external N-channel
MOSFET of the battery charger buck converter.

INFET (Pin 16): Drives the Gate of the External Input PFET.

TEST CIRCUIT

6

35mV

+

–

LTC4006

I

7

4006 TC

TH

0.6V

4006fa

11.67µA

+

–

3k

BAT

10

V

+

REF

EA

–

CSP

9

LT1055