PART TOP VIEW. TO LOAD SINGLE Li+ CELL TO IN LOGIC OUT. Maxim Integrated Products 1

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1 19-224; Rev 2; 6/3 USB-Powered Li+ Charger General Description The is a single-cell lithium-ion (Li+) battery charger that can be powered directly from a USB port* or from an external supply up to 6.5V. It has a.5% overall battery regulation voltage accuracy to allow maximum utilization of the battery capacity. The charger uses an internal FET to deliver up to 5mA charging current to the battery. The device can be configured for either a 4.1V or 4.2V battery, using the SELV input. The SELI input sets the charge current to either 1mA or 5mA. An open-drain output () indicates charge status. The has preconditioning that soft-starts a near-dead battery cell before charging. Other safety features include continuous monitoring of voltage and current and initial checking for fault conditions before charging. The is available in a small 1.4W thermally enhanced 8-pin SO package. Features Charges Single-Cell Li+ Batteries Directly from USB Port.5% Overall Charging Accuracy Minimal External Components Input Diode Not Required Automatic IC Thermal Regulation Preconditions Near-Depleted Cells Convenient Power SO-8 Package (1.4W) Protected by U.S. Patent # 6,57,172 Applications PDAs and Palmtops Digital Still Cameras MP3 Players Cell Phones Two-Way Pagers Hand-Held Computers PART ESA Ordering Information TEMP RANGE P-PACKAGE -4 C to +85 C 8 SO Typical Operating Circuit Pin Configuration 4.35V TO 6.5V 4.2V 4.1V ON OFF 5mA 1mA SELV EN SELI LED TO LOAD SGLE Li+ CELL TO LOGIC OUT TOP VIEW SELV SELI EN SO * Protected by U.S. Patent # 6,57,172 Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at , or visit Maxim s website at

2 ABSOLUTE MAXIMUM RATGS,, SELI,, EN to...-.3v to 7V SELV to...-.3v to (V +.3V) Continuous Power Dissipation (T A = +7 C) 8-Pin SO (derate 17.5mW/ C above +7 C)...1.4W Short-Circuit Duration...Continuous Operating Temperature Range...-4 C to +85 C Storage Temperature Range C to +15 C Maximum Die Temperature C Lead Temperature (soldering, 1s)...+3 C 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. ELECTRICAL CHARACTERISTICS (V = 4.5V, EN =, T A = C to +85 C, unless otherwise noted.) PARAMETER CONDITIONS M TYP MAX UNITS Input Supply Voltage V Input Undervoltage Lockout I rising V Input Undervoltage Lockout Hysteresis 5 mv Input Supply Current Charging Headroom Precondition Threshold Operating, EN =, no load.9 2. ma Shutdown, EN = µa SELI = (1mA mode), V = 4.35V 1 SELI = (5mA mode) 2 rising, transition from precondition to charge mode mv V Precondition Threshold Hysteresis 8 mv Output Leakage Current V = V = 6.5V.1 1. µa Output Low Voltage I SK = 1mA.4 V Charging Current Regulation Voltage Leakage Current (Input Power Removed) = 5.5V, V = 2.7V SELI =, V = 5.5V, V = 2.7V 85 1 V = 2V, SELI = or SELV =, I = SELV =, I = V = 4.2V, EN = = 1 5 µa Shutdown Current EN =, V = 4.2V.1 2 µa Logic Input Low Voltage (EN, SELI, SELV) V = 4.35V to 6.5V.8 V Logic Input High Voltage (EN, SELI, SELV) V = 4.35V to 6.5V 2. V Logic Input Leakage Current (EN, SELI) V = to 6.5V; V SELI, V EN = 6.5V or 1 µa Logic Input Leakage Current (SELV) V = to 6.5V, V SELV = V or 1 µa Thermal Regulation Die temperature beyond which charging current is reduced ma V 125 C 2

3 ELECTRICAL CHARACTERISTICS (V = 4.5V, T A = -4 C to +85 C, unless otherwise noted.) (Note1) PARAMETER CONDITIONS M TYP MAX UNITS Input Supply Voltage V Input Undervoltage Lockout I rising V Input Supply Current Precondition Threshold Regulation Voltage Operating, EN =, no load 3 ma Shutdown, EN = 6 µa rising, transition from precondition to charge mode V SELV =, I = SELV =, I = V Leakage Current (Input Power Removed) V = 4.2V, = 1 µa Shutdown Current EN =, V = 4.2V 3 µa Note 1: Specifications to -4 C are guaranteed by design and not production tested. Typical Operating Characteristics ( unconnected, C = 2.2µF, T A = +25 C, unless otherwise noted.) I (ma) SUPPLY CURRENT vs. PUT VOLTAGE (ENABLED) V = V EN = V SELV V SELI = toc1 I (µa) SUPPLY CURRENT vs. PUT VOLTAGE (SHUTDOWN) V = V SELV V EN = toc CHARGE CURRENT vs. PUT VOLTAGE HEADROOM V SELI = V = 4.1V V SELV = V toc V (V) V (V) V - V (V) 3

4 ( unconnected, C = 2.2µF, T A = +25 C, unless otherwise noted.) CHARGE CURRENT vs. ERY CURRENT V = V EN = V SELV = 5.5V V SELI = V (V) toc Typical Operating Characteristics (continued) V = 4.1V V SELV = V CHARGE CURENT vs. PUT VOLTAGE V SELI = V (V) toc5 V (V) ERY REGULATION VOLTAGE vs. TEMPERATURE V SELV = V V = V SELI = V EN = 4.5V I = V SELV = TEMPERATURE ( C) toc6 6 5 CHARGE CURRENT vs. TEMPERATURE V = V SELV = V EN = 5.5V, V = 2.7V toc7 6 5 CHARGE CURRENT vs. TEMPERATURE WITH THERMAL REGULATION V = V SELV = V EN = 6.5V, V = 2.7V toc V SELI = 2 1 V SELI = THERMAL CONTROL LOOP OPERATION TEMPERATURE ( C) TEMPERATURE ( C) 4

5 P NAME DESCRIPTION 1 SELV 2 SELI Pin Description Battery Regulation Voltage-Select Input. A low (<.8V) selects a 4.1V battery regulation set point. A high (> 2.V) selects a 4.2V battery regulation set point. Battery Regulation Current-Select Input. A low (<.8V) selects a 1mA maximum battery regulation current. A high (> 2.V) selects a 5mA maximum battery regulation current. SELI is not diode clamped to, and the voltage at V SELI can exceed the voltage at V. 3, 6 Ground. Connect pins 3 and 6 to a large copper trace for maximum power dissipation. 4 Input Supply Voltage. Bypass with a 4.7µF capacitor to. 5 7 EN 8 Li+ Battery Connection. Bypass with a capacitor no less than 2.2µF to. High impedance in shutdown. Enable Input. A high (> 2.V) enables the device. A low (<.8V) disables the device and places it into shutdown mode. is high impedance when disabled. Charging Indicator Open-Drain Output. pulls low while the device is in charge mode (2.5V < V < Regulation Voltage). SELI VOLTAGE LOOP CURRENT SELECTOR REGULATOR 3V THERMAL LOOP EN BIAS VOLTAGE SELECTOR OVERCURRENT DETECTOR (2.5V, 4.2V) 4.7V 2V MAX DETECTOR CIRCUIT ERY OVERVOLTAGE DETECTOR CURRENT LOOP CURRENT- SENSE CIRCUIT SELV Figure 1. Functional Diagram 5

6 Detailed Description Charger-Control Circuitry The voltage/current regulator consists of a voltage control loop, a current control loop, and a thermal control loop (Figure 1). Use the SELV input to set the battery regulation voltage to a 4.1V or 4.2V single Li+ cell. The current and thermal loops are internally compensated and require no external compensation. The outputs from all loops drive an internal linear regulator. The thermal loop modulates the current loop by limiting the charge current if the die temperature exceeds +125 C. The is in current mode when the voltage is below the regulation set point and in voltage mode when the voltage is near the regulation set point. The output indicates whether the part is in current mode ( = low) or voltage mode ( = high impedance). Battery voltages less than 2.5V activate a 43mA preconditioning mode ( = high impedance). Normal charging resumes when the battery voltage exceeds 2.5V. System Configuration The is designed to operate seamlessly with a universal serial bus (USB) port. In a typical design, the USB connects to the input, and the drives the load and charges the battery when enabled. Charge-Current Selection The charges a single cell Li+ battery in either 1mA or 5mA modes. The expects the system to poll the USB host to determine if the USB is capable of providing 1mA or 5mA and regulates the charging current accordingly (Figure 2). This is to maintain compatibility with both powered and unpowered USB hosts. A powered USB host is capable of providing 5mA, and an unpowered USB hub is limited to only 1mA. Drive SELI low to set the charge current to the 1mA mode. Use a 1kΩ pulldown resistor to ground on SELI, if necessary, to ensure that the defaults to the 1mA mode in the event that no logic signal is present. Drive SELI high to increase the charge current to the 5mA mode only if the polled USB port can provide the required current. Thermal-Control Circuitry The thermal loop limits the die temperature to +125 C by reducing the charging current as necessary. The can operate normally with the thermal loop active. This is not a fault condition and can be used continuously. The power dissipated by the internal power FET is determined by (V - V ) I. The power dissipation rating for the thermally enhanced 8-pin SO package is 1.4W at +5 C ambient (assuming a 1in 2 PC board radiating area), which is the maximum ambient temperature at which most Li+ battery manufacturers allow charging. The 1.4W power dissipation may never be reached due to the s thermal regulation loop. Applications Information USB Output Voltage The minimum voltage to a USB-powered device may be as low as 4.35V when cable and connector drops are considered (Figure 3). The is optimized for operation at these low input voltage levels. USB hubs may also provide as much as 5.5V. At high input voltages (5.5V) and low cell voltages (2.7V), the s thermal loop may limit the charge current until the cell voltage rises. USB* PORT 4.35V TO 5.5V SGLE Li+ CELL SYSTEM LOAD *WHEN USG WALL ADAPTER, VOLTAGE RANGE IS FROM 4.35V TO 6.5V. Figure 2. System Configuration 6

7 Charging from AC Adapters The also operates from sources other than USB ports. The full charging input voltage range is 4.35V to 6.5V. When charging in the 5mA mode with an AC adapter, rely on the thermal loop to limit the power dissipation by limiting the charge current at higher input voltages if limited PC board area is available to dissipate heat. Capacitor Selection Use a minimum of 2.2µF placed close to for proper stability. Bypass to with a 4.7µF capacitor. Use a larger input bypass capacitor for high input voltages or high charging current to reduce supply noise. Chip Information TRANSISTOR COUNT: 197 PROCESS: BiCMOS HOST OR POWERED HUB BUS-POWERED HUB LOW-POWER FUNCTION 4.75V 4.735V 4.64V 4.625V *4.4V 4.397V 4.378V 4.375V 4.5V 4.35V.V.15V.11V.125V.V.3V.2V.25V REFERENCED TO SOURCE REFERENCED TO HUB *UNDER TRANSIENT CONDITIONS, SUPPLY AT HUB CAN DROP FROM 4.V TO 4.7V. Figure 3. USB Voltage Specification 4.35V TO 6.5V 4.2V 4.1V ON OFF 5mA 1mA 1kΩ SELV EN SELI LED TO LOAD SGLE Li+ CELL TO LOGIC OUT Figure 4. Charging from a USB Port 7

8 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 N E H CHES MILLIMETERS DIM A A1 M.53.4 MAX.69.1 M MAX B C e.5 BSC 1.27 BSC E H L SOICN.EPS 1 TOP VIEW VARIATIONS: DIM D D D CHES MILLIMETERS M MAX M MAX N MS AA AB AC D A C e B A1 FRONT VIEW L SIDE VIEW -8 PROPRIETARY FORMATION TITLE: PACKAGE OUTLE,.15" SOIC APPROVAL DOCUMENT CONTROL NO. REV B 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 8 Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.