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General Description

The MAX1508 is an intelligent, stand-alone constant-cur-

rent, 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 elimi-

nates 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 full-

charge indication.

Proprietary thermal-regulation circuitry limits the die

temperature to +100°C when fast charging or while

exposed to high ambient temperatures, allowing maxi-

mum 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 active-

low-input power-source detection output (ACOK).

The MAX1508 accepts a +4.25V to +13V supply, but dis-

ables 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 pack-

age 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

ACOK

ISET

CHG

BATT

GND

3mm x 3mm THIN DFN

TOP VIEW

MAX1508

Pin Configuration

Ordering Information

MAX1508

1µF

INPUT

4.25V TO 13V

2.80kΩ

CHG

1µF

Li+

4.2V

BATT

ISET

GND

0.47µF

OFF

ACOK

PART TEMP RANGE PIN-PACKAGE

TOP

MARK

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

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.

Summary of content (11 pages)

PAGE 1
9-2890; Rev 0; 6/03 KIT ATION EVALU LE B A IL A AV Linear Li+ Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN 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.
PAGE 2
MAX1508 Linear Li+ Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN ABSOLUTE MAXIMUM RATINGS 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.
PAGE 3
Li+ Linear Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN (VIN = 5V, VBATT = 4.0V, ACOK = EN = CHG = unconnected, RISET = 2.8kΩ to GND, CVL = 0.47µF, BATT bypassed to GND with 1µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS MIN BATT Removal Detection-Threshold Hysteresis Minimum BATT Bypass Capacitance Fast-Charge Current-Loop System Accuracy VBATT = 3.
PAGE 4
Typical Operating Characteristics (VIN = 5V, VBATT = 4.0V, ACOK = EN = CHG = unconnected, RISET = 2.8kΩ to GND, CIN = 1µF, CBATT = 1µF, CVL = 0.47µF, TA = +25°C, unless otherwise noted.) DISABLED-MODE SUPPLY CURRENT vs. INPUT VOLTAGE 1.0 0.5 1.5 1.0 0.5 550 500 4 6 8 10 12 300 250 200 2 4 6 8 10 12 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) INPUT VOLTAGE (V) BATTERY VOLTAGE (V) CHARGE CURRENT vs. INPUT VOLTAGE CHARGE CURRENT vs.
PAGE 5
Li+ Linear Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN PIN NAME 1 VL Internally Generated Logic Supply for Chip. Bypass VL to GND with a 0.47µF capacitor. FUNCTION 2 IN Input Supply Voltage. Bypass IN to GND with a 1µF capacitor to improve line noise and transient rejection. 3 GND Ground. Connect GND and exposed pad to a large copper trace for maximum power dissipation. 4 ISET Charge-Current Program and Fast-Charge Current Monitor.
PAGE 6
MAX1508 Linear Li+ Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN CHG Charge Indicator Output Soft-Start CHG is an open-drain current source for indicating charge status. Table 1 describes the state of CHG during different stages of operation. An analog soft-start algorithm activates when entering fast-charge mode. When the prequalification state is complete (VBATT exceeds +2.5V), the charging current ramps up in 3ms to the full charging current.
PAGE 7
Li+ Linear Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN MAX1508 ASYNCHRONOUS FROM ANYWHERE VIN > 7V + VBATT > VIN + EN = HIGH SHUTDOWN VBATT < 2.5V D AN D 7V T AN < T V IN > V BA V IN = LOW EN PRECHARGE 100% CHARGE CURRENT LED = ON CHARGER = OFF LED = OFF VIN > 7V + VBATT > VIN + EN = HIGH VBATT < 2.4V VBATT > 2.
PAGE 8
MAX1508 Linear Li+ Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN Microprocessor-Interfaced Charger Figure 3 shows the MAX1508 as a µP-cooperated Li+ battery charger. The MAX1508 starts charging the battery when EN is low. The µP can drive EN high to disable the charger. The MAX1508’s ACOK output indicates the presence of a valid AC adapter to the µP. CHG can be used to detect the charge status of a battery.
PAGE 9
Li+ Linear Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN MAX1508 4.2V Li+ IN AC/DC ADAPTER BATT 1µF 1µF MAX1508 VI/O GND CHG SYSTEM VL ACOK 0.47µF ISET EN 2.8kΩ CHARGE-CURRENT MONITOR VI/O LOW: CHARGE, HIGH: FULL OR OFF Figure 3. µP-Interfaced Li+ Battery Charger 4.2V Li+ VBUS GND IN BATT 1µF 1µF MAX1508 VI/O GND CHG SYSTEM VL ACOK 0.47µF USB PORT EN ISET 15.4kΩ HIGH: 435mA, LOW: 95mA 4.3kΩ N VI/O D+ D- Figure 4.
PAGE 10
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) 6, 8, &10L, QFN THIN.EPS MAX1508 Linear Li+ Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN L A D D2 A2 PIN 1 ID 1 N 1 C0.35 b E PIN 1 INDEX AREA [(N/2)-1] x e REF.
PAGE 11
Li+ Linear Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOK in 3mm x 3mm TDFN COMMON DIMENSIONS SYMBOL A MIN. MAX. 0.70 0.80 D 2.90 3.10 E 2.90 3.10 A1 0.00 0.05 L k 0.20 0.40 0.25 MIN. A2 0.20 REF. PACKAGE VARIATIONS PKG. CODE N D2 E2 e JEDEC SPEC b T633-1 6 1.50–0.10 2.30–0.10 0.95 BSC MO229 / WEEA 0.40–0.05 1.90 REF T833-1 8 1.50–0.10 2.30–0.10 0.65 BSC MO229 / WEEC 0.30–0.05 1.95 REF T1033-1 10 1.50–0.10 2.30–0.10 0.