Rainbow Electronics MAX1508 User Manual

General Description

The MAX1508 is an intelligent, stand-alone constant-cur­rent, constant-voltage (CCCV), thermally regulated linear
charger for a single-cell lithium-ion (Li+) battery. The
MAX1508 integrates the current-sense circuit, MOS pass
element, and thermal-regulation circuitry, and also elimi­nates the reverse-blocking Schottky diode, to create the
simplest and smallest charging solution for hand-held
equipment.

The MAX1508 functions as a stand-alone charger to
control the charging sequence from the prequalification
state through fast-charge, top-off charge, and full­charge indication.

Proprietary thermal-regulation circuitry limits the die
temperature to +100°C when fast charging or while
exposed to high ambient temperatures, allowing maxi­mum charging current without damaging the IC.

The MAX1508 achieves high flexibility by providing an
adjustable fast-charge current by an external resistor.
Other features include the charging status (CHG) of the
battery, an active-low control input (EN), and an active­low-input power-source detection output (ACOK).

The MAX1508 accepts a +4.25V to +13V supply, but dis­ables charging when the input voltage exceeds +7V to
protect against unqualified or faulty AC adapters. The
MAX1508 operates over the extended temperature
range (-40°C to +85°C) and is available in a compact
8-pin thermally enhanced 3mm x 3mm thin DFN pack­age with 0.8mm height.

Applications

Cellular and Cordless Phones
PDAs
Digital Cameras and MP3 Players
USB Appliances
Charging Cradles and Docks
Bluetooth™ Equipment

Features

♦ Stand-Alone Linear 1-Cell Li+ Battery Charger

♦ No External FET, Reverse-Blocking Diode, or

Current-Sense Resistor Required

♦ Programmable Fast-Charge Current (0.8A max)

♦ Proprietary Die-Temperature Regulation Control

(+100°C)

♦ +4.25V to +13V Input Voltage Range with Input

Overvoltage Protection (OVP) Above +7V

♦ Charge-Current Monitor for Fuel Gauging

♦ Low Dropout Voltage—130mV at 0.425A
♦ Input Power-Source Detection Output (ACOK) and

Charge-Enable Input (EN)

♦ Soft-Start Limits Inrush Current
♦ Charge Status Output (CHG) for LED or

Microprocessor Interface

♦ Small 3mm x 3mm 8-Pin Thin DFN Package,

0.8mm High

MAX1508

Linear Li+ Battery Charger with Integrated Pass FET,

Thermal Regulation, and

ACOK

in 3mm x 3mm TDFN

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

Ordering Information

Typical Operating Circuit

19-2890; Rev 0; 6/03

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

Bluetooth is a trademark of Ericsson.

*EP = Exposed paddle.

TOP VIEW

EN

BATT

ACOK

CHG

8

76

5

PART TEMP RANGE PIN-PACKAGE

MAX1508ETA -40°C to +85°C 8 Thin DFN-EP* AHF

INPUT

4.25V TO 13V

1µF

IN

BATT

1µF

MAX1508

TOP

MARK

Li+

4.2V

MAX1508

3

2

1

IN

VL

3mm x 3mm THIN DFN

GND

OFF

ON

4

ISET

0.47µF

CHG

EN

VL

ISET

ACOK

GND

2.80kΩ

MAX1508

Linear Li+ Battery Charger with Integrated Pass FET,
Thermal Regulation, and

ACOK

in 3mm x 3mm TDFN

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= 5V, V

BATT

= 4.0V, ACOK = EN = CHG = unconnected, R

ISET

= 2.8kΩ to GND, CVL= 0.47µF, BATT bypassed to GND with

1µF, T

A

= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

IN, CHG to GND .....................................................-0.3V to +14V

VL, BATT, ISET, EN, ACOK to GND .........................-0.3V to +6V

VL to IN...................................................................-14V to +0.3V

IN to BATT Continuous Current.............................................0.9A

Continuous Power Dissipation (T

A

= +70°C)

8-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW

Short-Circuit Duration.................................................Continuous

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

Input Voltage Range 013V

Input Operating Range 4.25 6.50 V

ACOK Trip Point, IN

Overvoltage Lockout Trip Point

VL Output Voltage IVL = 100µA 3.3 V

VL Load Regulation IVL = 100µA to 2mA -71 -200 mV

VL Temperature Coefficient IVL = 100µA -2 mV/°C

VL Undervoltage Lockout Trip Point

BATT Input Current

Maximum RMS Charge Current 0.8 A

Battery Regulation Voltage I

BATT Removal Detection Threshold V

PARAMETER CONDITIONS MIN TYP MAX UNITS

VIN - V

V

IN

VIN rising 6.5 7 7.5

V

IN

Charging (IIN - I
Disabled, EN = VL 0.8 1.5IN Input Current

OFF state (V

VIN rising 2.95

Hysteresis 0.17

V

IN

EN = VL 4 10

BATT

BATT

, VIN rising 20 40 60

BATT

- V

, VIN falling 15 30 45

BATT

hysteresis 0.11

IN

= 0 to 4V 3 10

= 0

rising 4.4 4.67 4.9 V

)12

BATT

= V

= 4.0V) 0.065

BATT

= 0°C to +85°C 4.162 4.2 4.238

T

A

= -40°C to +85°C 4.150 4.2 4.250

T

A

mV

V

mA

V

µA

V

MAX1508

Li+ Linear Battery Charger with Integrated Pass FET,

Thermal Regulation, and

ACOK

in 3mm x 3mm TDFN

_______________________________________________________________________________________ 3

Note 1: Limits are 100% production tested at TA= +25°C. Limits over operating temperature range are guaranteed through correla-

tion using statistical quality control (SQC) methods.

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 5V, V

BATT

= 4.0V, ACOK = EN = CHG = unconnected, R

ISET

= 2.8kΩ to GND, CVL= 0.47µF, BATT bypassed to GND with

1µF, T

A

= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

BATT Removal Detection-Threshold Hysteresis 200 mV

Minimum BATT Bypass Capacitance 1 µF/A

Fast-Charge Current-Loop System Accuracy V

Precharge Current System Accuracy

Die-Temperature-Regulation Set Point 100 °C

V

Precharge Threshold Voltage V

BATT

Current-Sense Amplifier Gain, I
Fast-Charge Mode

Regulator Dropout Voltage (V

EN Logic Input Low Voltage 4.25V < VIN < 6.5V 0.52 V
EN Logic Input High Voltage 4.25V < VIN < 6.5V 1.3 V
EN Internal Pulldown Resistor 100 200 400 kΩ
CHG Output Low Current V

CHG Output High Leakage Current V

ACOK Output Low Voltage I

ACOK Output High Leakage Current V

Full-Battery Detection Current Threshold
(as a Percentage of the Fast-Charge Current)

PARAMETER CONDITIONS MIN TYP MAX UNITS

= 3.5V 478 520 562 mA

BATT

Percentage of the fast-charge current,

= 2.2V

V

BATT

rising 2.3 2.5 2.7 V

BATT

IN

SET

- V

to I

BATT

in

BATT

)V

I

BATT

BATT

CHG

CHG

ACOK

ACOK

I

BATT

= 500mA, V

= 4.1V, I

= 1V 5 12 20 mA

= 13V

= 0.5mA 0.4 V

= 5.5V

falling 5 10 15 %

51015%

= 1.4V 0.880 0.958 1.035 mA/A

ISET

= 425mA 130 200 mV

BATT

TA = +25°C1

= +85°C 0.002

T

A

TA = +25°C1

= +85°C 0.002

T

A

µA

µA

MAX1508

Linear Li+ Battery Charger with Integrated Pass FET,
Thermal Regulation, and

ACOK

in 3mm x 3mm TDFN

4 _______________________________________________________________________________________

Typical Operating Characteristics

(VIN= 5V, V

BATT

= 4.0V, ACOK = EN = CHG = unconnected, R

ISET

= 2.8kΩ to GND, CIN= 1µF, C

BATT

= 1µF, CVL= 0.47µF, TA=

+25°C, unless otherwise noted.)

0

0.5

1.0

1.5

2.0

SUPPLY CURRENT

vs. INPUT VOLTAGE

MAX1508 toc01

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

0

6

8

2

410

12

I

BATT

= 0

0

0.5

1.0

1.5

2.0

DISABLED-MODE SUPPLY

CURRENT vs. INPUT VOLTAGE

MAX1508 toc02

INPUT VOLTAGE (V)

DISABLED-MODE SUPPLY CURRENT (mA)

0

EN = VL

6

8

4210

12

0

250

150

450

350

550

200

100

400

300

500

600

02.01.0 3.0 4.00.5 2.51.5 3.5 4.5

CHARGE CURRENT

vs. BATTERY VOLTAGE

MAX1508 toc03

BATTERY VOLTAGE (V)

CHARGE CURRENT (mA)

0

50

250

150

450

350

550

200

100

400

300

500

600

06824 101217935 1113

CHARGE CURRENT

vs. INPUT VOLTAGE

MAX1508 toc04

INPUT VOLTAGE (V)

CHARGE CURRENT (mA)

0

200

100

400

300

500

50

250

150

450

350

550

600

0 0.160.08 0.24 0.400.04 0.200.12 0.28 0.32 0.36

CHARGE CURRENT

vs. INPUT-VOLTAGE HEADROOM

MAX1508 toc05

VIN - V

BATT

(V)

CHARGE CURRENT (mA)

4.180

4.186

4.198

4.192

4.204

4.189

4.183

4.201

4.195

4.207

4.210

-40 10-15 35 60 85

BATTERY REGULATION VOLTAGE

vs. TEMPERATURE

MAX1508 toc06

TEMPERATURE (°C)

BATTERY REGULATION VOLTAGE (V)

600

560

520

460

420

580

540

480

500

440

-40 10-15 35 60 85

CHARGE CURRENT

vs. AMBIENT TEMPERATURE

MAX1508 toc07

AMBIENT TEMPERATURE (°C)

CHARGE CURRENT (mA)

0

200

600

400

800

100

300

700

500

900

1000

-40 10-15 35 60 85

CHARGE CURRENT

vs. AMBIENT TEMPERATURE

MAX1508 toc09

AMBIENT TEMPERATURE (°C)

CHARGE CURRENT (mA)

V

BATT

= 4.0V

V

BATT

= 3.6V

R

ISET

= 1.87kΩ