1

LT1510/LT1510-5

Constant-Voltage/

Constant-Current Battery Charger

Figure 2. Charging Lithium Batteries (Efficiency at 1.3A > 87%)

* NiCd and NiMH batteries require charge termination circuitry (not shown in Figure 1).

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

plest, most efficient solution to fast-charge modern re-

chargeable batteries including lithium-ion (Li-Ion), nickel-

metal-hydride (NiMH)* and nickel-cadmium (NiCd)* that

require constant-current and/or constant-voltage charg-

ing. The internal switch is capable of delivering 1.5A DC

current (2A peak current). The 0.1

Ω onboard current

sense resistor makes the charging current programming

very simple. One resistor (or a programming current from

a DAC) is required to set the full charging current (1.5A) to

within 5% accuracy. The LT1510 with 0.5% reference

voltage accuracy meets the critical constant-voltage charg-

ing requirement for lithium cells.

The LT1510 can charge batteries ranging from 2V to 20V.

Ground sensing of current is not required and the battery’s

negative terminal can be tied directly to ground. A saturat-

ing switch running at 200kHz (500kHz for LT1510-5) gives

high charging efficiency and small inductor size. A block-

ing diode is not required between the chip and the battery

because the chip goes into sleep mode and drains only 3

µA

when the wall adaptor is unplugged. Soft start and shutdown

features are also provided. The LT1510 is available in a 16-pin

fused lead power SO package with a thermal resistance of

50

°C/W, an 8-pin SO and a 16-pin PDIP.

FEATURES

s

Charges NiCd, NiMH and Lithium-Ion Batteries ––

Charging Current

s

High Efficiency Current Mode PWM with 1.5A

Internal Switch and Sense Resistor

s

3% Typical Charging Current Accuracy

s

Precision 0.5% Voltage Reference for Voltage

Mode Charging or Overvoltage Protection

s

Current Sensing Can Be at Either Terminal of

the Battery

s

Low Reverse Battery Drain Current: 3

µA

s

Charging Current Soft Start

s

Shutdown Control

s

500kHz Version Uses Small Inductor

With switching frequency as high as 500kHz, The LT

current mode PWM battery charger is the smallest, sim-

s

Chargers for NiCd, NiMH and Lithium Batteries

s

Step-Down Switching Regulator with Precision

Adjustable Current Limit

Figure 1. 500kHz Smallest Li-Ion Cell Phone Charger (0.8A)

SW

BOOST

GND

SENSE

PROG

BAT

6.19k

8.2V TO 20V

+

R3

70.6k

0.25%

R4

100k

0.25%

2N7002

NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED

TOKIN OR MARCON CERAMIC SURFACE MOUNT

COILTRONICS TP3-100, 10

µH, 2.2mm HEIGHT (0.8A CHARGING CURRENT)

COILTRONICS TP1 SERIES, 10

µH, 1.8mm HEIGHT (<0.5A CHARGING CURRENT)

PANASONIC EEFCD1B220

OPTIONAL, SEE APPLICATIONS INFORMATION

1510 F01

C1

0.22

µF

10

µF

L1**

10

µH

LT1510-5

D1

MBRM120T3

D3

MBRM120T3

D2

MMBD914L

OVP

+

22

µF

4.2V

+

+

–

0.1

µF

1k

1

µF

300

Ω

*

**

***

†

SW

BOOST

GND

SENSE

PROG

BAT

3.83k

11V TO 28V

+

+

R3

240k

0.25%

R4

100k

0.25%

VN2222

NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED

* TOKIN OR MARCON CERAMIC SURFACE MOUNT

** COILTRONICS CTX33-2

1510 F02

C1

0.22

µF

10

µF

L1**

33

µH

LT1510

D1

1N5819

D3

1N5819

D2

1N914

OVP

+

22

µF

TANT

4.2V

4.2V

+

+

–

0.1

µF

1k

1

µF

300

Ω