Datasheet

ManualsBrandsLinear Technology ManualsBattery Charger ICsBattery Charg. IC 4.5...6.5 V TSOT-23-5

LTC4054-4.2/LTC4054X-4.2

405442xf

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

Standalone Linear

Li-Ion Battery Charger with

Thermal Regulation in ThinSOT

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

■

Programmable Charge Current Up to 800mA

■

No MOSFET, Sense Resistor or Blocking

Diode Required

■

Complete Linear Charger in ThinSOT

Package for

Single Cell Lithium-Ion Batteries

■

Constant-Current/Constant-Voltage Operation with

Thermal Regulation* to Maximize Charge Rate

Without Risk of Overheating

■

Charges Single Cell Li-Ion Batteries Directly

from USB Port

■

Preset 4.2V Charge Voltage with ±1% Accuracy

■

Charge Current Monitor Output for Gas

Gauging*

■

Automatic Recharge

■

Charge Status Output Pin

■

C/10 Charge Termination

■

25µA Supply Current in Shutdown

■

2.9V Trickle Charge Threshold (LTC4054)

■

Available Without Trickle Charge (LTC4054X)

■

Soft-Start Limits Inrush Current

■

Available in 5-Lead SOT-23 Package

■

Cellular Telephones, PDAs, MP3 Players

■

Charging Docks and Cradles

■

Bluetooth Applications

ThinSOT is a trademark of Linear Technology Corporation.

*U.S.Patent No. 6,522,118

The LTC

4054 is a complete constant-current/constant-

voltage linear charger for single cell lithium-ion batteries.

Its ThinSOT package and low external component count

make the LTC4054 ideally suited for portable applications.

Furthermore, the LTC4054 is specifically designed to work

within USB power specifications.

No external sense resistor is needed, and no blocking

diode is required due to the internal MOSFET architecture.

Thermal feedback regulates the charge current to limit the

die temperature during high power operation or high

ambient temperature. The charge voltage is fixed at 4.2V,

and the charge current can be programmed externally with

a single resistor. The LTC4054 automatically terminates

the charge cycle when the charge current drops to 1/10th

the programmed value after the final float voltage is

reached.

When the input supply (wall adapter or USB supply) is

removed, the LTC4054 automatically enters a low current

state, dropping the battery drain current to less than 2µA.

The LTC4054 can be put into shutdown mode, reducing

the supply current to 25µA.

Other features include charge current monitor, undervoltage

lockout, automatic recharge and a status pin to indicate

charge termination and the presence of an input voltage.

600mA Single Cell Li-Ion Charger

1.65k

4.2V

Li-Ion

BATTERY

405442 TA01a

LTC4054-4.2

1µF

4.5V TO 6.5V

BAT

PROG

GND

600mA

Complete Charge Cycle (750mAh Battery)

TIME (HOURS)

CHARGE CURRENT (mA)

1.5

405442 TAO1b

0.5 1.0 2.0

700

600

500

400

300

200

100

4.75

4.50

4.25

4.00

3.75

3.50

3.25

3.00

0.25 0.75 1.25 1.75

CONSTANT

POWER

CONSTANT

VOLTAGE

CONSTANT

CURRENT

CHARGE

TERMINATED

BATTERY VOLTAGE (V)

= 5V

= 130°C/W

PROG

= 1.65k

= 25°C

Summary of content (16 pages)

PAGE 1
LTC4054-4.2/LTC4054X-4.
PAGE 2
LTC4054-4.2/LTC4054X-4.2 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) Input Supply Voltage (VCC) ....................... –0.3V to 10V PROG ............................................. – 0.3V to VCC + 0.3V BAT .............................................................. –0.3V to 7V CHRG ........................................................ –0.3V to 10V BAT Short-Circuit Duration .......................... Continuous BAT Pin Current ....................................
PAGE 3
LTC4054-4.2/LTC4054X-4.2 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted.
PAGE 4
LTC4054-4.2/LTC4054X-4.2 U W TYPICAL PERFOR A CE CHARACTERISTICS PROG Pin Pull-Up Current vs Temperature and Supply Voltage 3.7 PROG Pin Current vs PROG Pin Voltage (Clamp Current) PROG Pin Current vs PROG Pin Voltage (Pull-Up Current) VBAT = 4.3V VPROG = 0V 3.5 VCC = 4.2V 3.5 0 3.0 –50 –100 2.5 3.1 VCC = 6.5V 2.9 IPROG (µA) IPROG (µA) IPROG (µA) 3.3 2.0 1.5 1.0 2.7 0.5 2.5 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 2.2 2.1 2.3 2.4 2.5 –400 2.0 2.6 2.5 3.0 4.210 5.
PAGE 5
LTC4054-4.2/LTC4054X-4.2 U W TYPICAL PERFOR A CE CHARACTERISTICS CHRG Pin Current vs Temperature (Weak Pull-Down State) 28 25 Trickle Charge Current vs Supply Voltage Trickle Charge Current vs Temperature 50 VCC = 5V VBAT = 4.3V VCHRG = 5V 50 RPROG = 2k RPROG = 2k 40 40 19 ITRIKL (mA) ITRIKL (mA) ICHRG (µA) 23 30 VCC = 5V VBAT = 2.5V 20 30 VBAT = 2.
PAGE 6
LTC4054-4.2/LTC4054X-4.2 U U U PI FU CTIO S CHRG (Pin 1): Open-Drain Charge Status Output. When the battery is charging, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed, a weak pull-down of approximately 20µA is connected to the CHRG pin, indicating an “AC present” condition. When the LTC4054 detects an undervoltage lockout condition, CHRG is forced high impedance. PROG (Pin 5): Charge Current Program, Charge Current Monitor and Shutdown Pin.
PAGE 7
LTC4054-4.2/LTC4054X-4.2 W BLOCK DIAGRA 4 VCC 120°C 1× TA 1000× TDIE BAT – + 5µA 3 MA R1 + VA CA – R2 – + – SHDN REF 1.21V C1 + R3 1V R4 + 0.1V C2 CHRG 1 R5 – STANDBY 3µA TRICKLE CHARGE DISABLED ON LTC4054X + TO BAT – 2.
PAGE 8
LTC4054-4.2/LTC4054X-4.2 U OPERATIO The LTC4054 is a single cell lithium-ion battery charger using a constant-current/constant-voltage algorithm. It can deliver up to 800mA of charge current (using a good thermal PCB layout) with a final float voltage accuracy of ±1%. The LTC4054 includes an internal P-channel power MOSFET and thermal regulation circuitry. No blocking diode or external current sense resistor is required; thus, the basic charger circuit requires only two external components.
PAGE 9
LTC4054-4.2/LTC4054X-4.2 U OPERATIO lockout conditions. A weak pull-down indicates that VCC meets the UVLO conditions and the LTC4054 is ready to charge. High impedance indicates that the LTC4054 is in undervoltage lockout mode: either VCC is less than 100mV above the BAT pin voltage or insufficient voltage is applied to the VCC pin. A microprocessor can be used to distinguish between these three states—this method is discussed in the Applications Information section.
PAGE 10
LTC4054-4.2/LTC4054X-4.2 U W U U APPLICATIO S I FOR ATIO Stability Considerations CHARGE CURRENT MONITOR CIRCUITRY 10k PROG The constant-voltage mode feedback loop is stable without an output capacitor provided a battery is connected to the charger output. With no battery present, an output capacitor is recommended to reduce ripple voltage. When using high value, low ESR ceramic capacitors, it is recommended to add a 1Ω resistor in series with the capacitor.
PAGE 11
LTC4054-4.2/LTC4054X-4.2 U W U U APPLICATIO S I FOR ATIO The LTC4054 can be used above 45°C ambient, but the charge current will be reduced from 400mA. The approximate current at a given ambient temperature can be approximated by: IBAT = 120°C – TA (VCC – VBAT ) • θJA Using the previous example with an ambient temperature of 60°C, the charge current will be reduced to approximately: IBAT 60°C = = 5V – 3.75V • 150°C /W 187.
PAGE 12
LTC4054-4.2/LTC4054X-4.2 U W U U APPLICATIO S I FOR ATIO enough to put the LTC4054 into dropout. Figure 4 shows how this circuit can result in dropout as RCC becomes large. VS RCC This technique works best when RCC values are minimized to keep component size small and avoid dropout. Remember to choose a resistor with adequate power handling capability. VCC BAT 1µF LTC4054-4.
PAGE 13
LTC4054-4.2/LTC4054X-4.2 U W U U APPLICATIO S I FOR ATIO CHRG Status Output Pin The CHRG pin can provide an indication that the input voltage is greater than the undervoltage lockout threshold level. A weak pull-down current of approximately 20µA indicates that sufficient voltage is applied to VCC to begin charging. When a discharged battery is connected to the charger, the constant current portion of the charge cycle begins and the CHRG pin pulls to ground.
PAGE 14
LTC4054-4.2/LTC4054X-4.2 U W U U APPLICATIO S I FOR ATIO USB and Wall Adapter Power The LTC4054 allows charging from both a wall adapter and a USB port. Figure 7 shows an example of how to combine wall adapter 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 a Schottky diode, D1, is used to prevent USB power loss through the 1k pull-down resistor.
PAGE 15
LTC4054-4.2/LTC4054X-4.2 U PACKAGE DESCRIPTIO S5 Package 5-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1635) 0.62 MAX 0.95 REF 2.90 BSC (NOTE 4) 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.30 – 0.45 TYP 5 PLCS (NOTE 3) 0.95 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3.
PAGE 16
LTC4054-4.2/LTC4054X-4.2 U TYPICAL APPLICATIO S USB/Wall Adapter Power Li-Ion Charger 5V WALL ADAPTER BAT VCC 1µF 1k VIN = 5V IBAT 3 + LTC4054-4.2 4 USB POWER Full Featured Single Cell Li-Ion Charger Li-Ion CELL 4 2.5k 5 PROG GND 2 10k VCC 330Ω 100mA/ 500mA 3 LTC4054-4.2 1 µC BAT 1µF 500mA CHRG 405442 TA05 GND 2 PROG 5 + 2k SHDN 800mA Li-Ion Charger with External Power Dissipation 405442 TA02 VIN = 5V Basic Li-Ion Charger with Reverse Polarity Input Protection 0.