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19-2024; Rev 2; 6/03
USB-Powered Li+ Charger
General Description
The MAX1811 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 0.5% overall battery regulation voltage accuracy to allow maximum utilization of the battery capacity. The charger uses an internal FET to deliver up to 500mA 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 100mA or 500mA. An open-drain output (CHG) indicates charge status. The MAX1811 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 MAX1811 is available in a small 1.4W thermally enhanced 8-pin SO package.
Features
o Charges Single-Cell Li+ Batteries Directly from USB Port o 0.5% Overall Charging Accuracy o Minimal External Components o Input Diode Not Required o Automatic IC Thermal Regulation o Preconditions Near-Depleted Cells o Convenient Power SO-8 Package (1.4W) o Protected by U.S. Patent # 6,507,172
MAX1811
________________________Applications
PDAs and Palmtops Digital Still Cameras MP3 Players Cell Phones Two-Way Pagers Hand-Held Computers
PART MAX1811ESA
Ordering Information
TEMP RANGE -40C to +85C PIN-PACKAGE 8 SO
Typical Operating Circuit
TO LOAD SINGLE Li+ CELL TO IN LED GND CHG SELI GND CHG LOGIC OUT 3
Pin Configuration
TOP VIEW
BATT 4.35V TO 6.5V 4.2V 4.1V ON OFF 500mA 100mA EN SELV IN
SELV SELI
1 2
8 7
CHG EN GND BATT
MAX1811
MAX1811
6 5 IN 4
SO
* Protected by U.S. Patent # 6,507,172 ________________________________________________________________ Maxim Integrated Products 1
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.
USB-Powered Li+ Charger MAX1811
ABSOLUTE MAXIMUM RATINGS
IN, BATT, SELI, CHG, EN to GND ..............................-0.3V to 7V SELV to GND ...............................................-0.3V to (VIN + 0.3V) Continuous Power Dissipation (TA = +70C) 8-Pin SO (derate 17.5mW/C above +70C)....................1.4W Short-Circuit Duration.................................................Continuous Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Maximum Die Temperature..............................................+150C Lead Temperature (soldering, 10s) .................................+300C
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
(VIN = 4.5V, EN = IN, TA = 0C to +85C, unless otherwise noted.)
PARAMETER Input Supply Voltage Input Undervoltage Lockout Input Undervoltage Lockout Hysteresis Input Supply Current Operating, EN = IN, no load Shutdown, EN = GND SELI = GND (100mA mode), VIN = 4.35V SELI = IN (500mA mode) BATT rising, transition from precondition to charge mode VIN = V CHG = 6.5V ISINK = 10mA VSELI = VIN = 5.5V, VBATT = 2.7V SELI = GND, VIN = 5.5V, VBATT = 2.7V VBATT = 2V, SELI = GND or IN SELV = GND, IBATT = 0 SELV = IN, IBATT = 0 VBATT = 4.2V, EN = IN = GND EN = GND, VBATT = 4.2V VIN = 4.35V to 6.5V VIN = 4.35V to 6.5V VIN = 0 to 6.5V; VSELI, VEN = 6.5V or GND VIN = 0 to 6.5V, VSELV = VIN or GND Die temperature beyond which charging current is reduced 125 2.0 1 1 2.3 IIN rising CONDITIONS MIN 4.35 3.75 50 0.9 2.5 100 200 2.5 80 0.1 455 85 43 4.10 4.20 1 0.1 1.0 0.4 500 100 70 4.12 4.22 5 2 0.8 2.7 V mV A V mA 2.0 5.0 TYP MAX 6.50 4.05 UNITS V V mV mA A mV
Charging Headroom
Precondition Threshold Precondition Threshold Hysteresis CHG Output Leakage Current CHG Output Low Voltage Charging Current
BATT Regulation Voltage BATT Leakage Current (Input Power Removed) BATT Shutdown Current Logic Input Low Voltage (EN, SELI, SELV) Logic Input High Voltage (EN, SELI, SELV) Logic Input Leakage Current (EN, SELI) Logic Input Leakage Current (SELV) Thermal Regulation
20 4.08 4.18
V A A V V A A C
2
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USB-Powered Li+ Charger
ELECTRICAL CHARACTERISTICS
(VIN = 4.5V, TA = -40C to +85C, unless otherwise noted.) (Note1)
PARAMETER Input Supply Voltage Input Undervoltage Lockout Input Supply Current Precondition Threshold BATT Regulation Voltage BATT Leakage Current (Input Power Removed) BATT Shutdown Current IIN rising Operating, EN = IN, no load Shutdown, EN = GND BATT rising, transition from precondition to charge mode SELV = GND, IBATT = 0 SELV = IN, IBATT = 0 VBATT = 4.2V, IN = GND EN = GND, VBATT = 4.2V 2.3 4.06 4.16 CONDITIONS MIN 4.35 3.75 TYP MAX 6.50 4.05 3 6 2.7 4.14 4.24 10 3 UNITS V V mA A V V A A
MAX1811
Note 1: Specifications to -40C are guaranteed by design and not production tested.
Typical Operating Characteristics
(CHG unconnected, CBATT = 2.2F, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. INPUT VOLTAGE (ENABLED)
0.9 0.8 0.7 IIN (mA) IIN (A) 0.6 0.5 0.4 0.3 0.2 0.1 0 0 1 2 3 4 5 6 7 VIN (V) VSELI = VIN VSELI = 0 VIN = VEN = VSELV
MAX1811 toc01
SUPPLY CURRENT vs. INPUT VOLTAGE (SHUTDOWN)
MAX1811 toc02
CHARGE CURRENT vs. INPUT VOLTAGE HEADROOM
450 400 350 IBATT (mA) 300 250 200 150 100 50 0 VSELI = 0 VBATT = 4.1V VSELV = VIN VSELI = VIN
MAX1811 toc03
1.0
4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 1 2 3 4 5 6 7 VIN (V) VIN = VSELV VEN = 0
500
0
0.5
1.0
1.5
2.0
2.5
3.0
VIN - VBATT (V)
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3
USB-Powered Li+ Charger MAX1811
Typical Operating Characteristics (continued)
(CHG unconnected, CBATT = 2.2F, TA = +25C, unless otherwise noted.)
CHARGE CURRENT vs. BATTERY CURRENT
MAX1811 toc04
CHARGE CURENT vs. INPUT VOLTAGE
MAX1811 toc05
BATTERY REGULATION VOLTAGE vs. TEMPERATURE
MAX1811 toc06
500 450 400 350 IBATT (mA) 300 250 200 150 100 50 0 -50 0 VSELI = 0 VSELI = VIN VIN = VEN = VSELV = 5.5V
500 450 400 350 IBATT (mA) VBATT = 4.1V VSELV = VIN
4.22 4.20 4.18 VBATT (V) VSELV = VIN
300 250 200 150 100 50 0
VSELI = VIN VSELI = 0
4.16 4.14 4.12 4.10 4.08
VIN = VSELI = VEN = 4.5V IBATT = 0
VSELV = 0 -40 -15 10 35 60 85
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 VBATT (V)
0
1
2
3
4
5
6
7
VIN (V)
TEMPERATURE (C)
CHARGE CURRENT vs. TEMPERATURE
MAX1811 toc07
CHARGE CURRENT vs. TEMPERATURE WITH THERMAL REGULATION
VIN = VSELV = VEN = 6.5V, VBATT = 2.7V
MAX1811 toc08
600 500 400 IBATT (mA) 300 200 100 0 -40
VIN = VSELV = VEN = 5.5V, VBATT = 2.7V
600 500
VSELI = VIN IBATT (mA)
VSELI = VIN 400 300 200 THERMAL CONTROL LOOP IN OPERATION
VSELI = 0
100 0
VSELI = 0
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
4
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USB-Powered Li+ Charger MAX1811
Pin Description
PIN 1 NAME SELV DESCRIPTION Battery Regulation Voltage-Select Input. A low (< 0.8V) selects a 4.1V battery regulation set point. A high (> 2.0V) selects a 4.2V battery regulation set point. Battery Regulation Current-Select Input. A low (< 0.8V) selects a 100mA maximum battery regulation current. A high (> 2.0V) selects a 500mA maximum battery regulation current. SELI is not diode clamped to IN, and the voltage at VSELI can exceed the voltage at VIN. Ground. Connect pins 3 and 6 to a large copper trace for maximum power dissipation. Input Supply Voltage. Bypass with a 4.7F capacitor to GND. Li+ Battery Connection. Bypass with a capacitor no less than 2.2F to GND. High impedance in shutdown. Enable Input. A high (> 2.0V) enables the device. A low (< 0.8V) disables the device and places it into shutdown mode. BATT is high impedance when disabled. Charging Indicator Open-Drain Output. CHG pulls low while the device is in charge mode (2.5V < VBATT < BATT Regulation Voltage).
SELI IN
2 3, 6 4 5 7 8
SELI GND IN BATT EN CHG
VOLTAGE LOOP
CURRENT SELECTOR
REGULATOR
THERMAL LOOP 3V
BATT
CHG EN BIAS OVERCURRENT DETECTOR VOLTAGE SELECTOR (2.5V, 4.2V) BATTERY OVERVOLTAGE DETECTOR 4.7V
2V MAX DETECTOR CIRCUIT
CURRENT LOOP
MAX1811
CURRENTSENSE CIRCUIT
SELV
GND
Figure 1. Functional Diagram _______________________________________________________________________________________ 5
USB-Powered Li+ Charger MAX1811
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 +125C. The MAX1811 is in current mode when the BATT voltage is below the regulation set point and in voltage mode when the BATT voltage is near the regulation set point. The CHG output indicates whether the part is in current mode (CHG = low) or voltage mode (CHG = high impedance). Battery voltages less than 2.5V activate a 43mA preconditioning mode (CHG = high impedance). Normal charging resumes when the battery voltage exceeds 2.5V. providing 500mA, and an unpowered USB hub is limited to only 100mA. Drive SELI low to set the charge current to the 100mA mode. Use a 10k pulldown resistor to ground on SELI, if necessary, to ensure that the MAX1811 defaults to the 100mA mode in the event that no logic signal is present. Drive SELI high to increase the charge current to the 500mA mode only if the polled USB port can provide the required current.
Thermal-Control Circuitry
The thermal loop limits the MAX1811 die temperature to +125C by reducing the charging current as necessary. The MAX1811 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 (VIN - VBATT) ICHG. The power dissipation rating for the thermally enhanced 8-pin SO package is 1.4W at +50C ambient (assuming a 1in2 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 MAX1811's thermal regulation loop.
System Configuration
The MAX1811 is designed to operate seamlessly with a universal serial bus (USB) port. In a typical design, the USB connects to the MAX1811 input, and the MAX1811 drives the load and charges the battery when enabled.
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 MAX1811 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 MAX1811's thermal loop may limit the charge current until the cell voltage rises.
Charge-Current Selection
The MAX1811 charges a single cell Li+ battery in either 100mA or 500mA modes. The MAX1811 expects the system to poll the USB host to determine if the USB is capable of providing 100mA or 500mA 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
USB* PORT 4.35V TO 5.5V
IN
BATT
MAX1811
SINGLE Li+ CELL
SYSTEM LOAD
*WHEN USING WALL ADAPTER, IN VOLTAGE RANGE IS FROM 4.35V TO 6.5V.
Figure 2. System Configuration
6
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USB-Powered Li+ Charger
Charging from AC Adapters
The MAX1811 also operates from sources other than USB ports. The full charging input voltage range is 4.35V to 6.5V. When charging in the 500mA 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. Use a larger input bypass capacitor for high input voltages or high charging current to reduce supply noise.
MAX1811
Chip Information
TRANSISTOR COUNT: 1907 PROCESS: BiCMOS
Capacitor Selection
Use a minimum of 2.2F placed close to BATT for proper stability. Bypass IN to GND with a 4.7F capacitor.
HOST OR POWERED HUB 4.750V 4.735V 4.640V
BUS-POWERED HUB 4.625V *4.400V 4.397V 4.378V
LOW-POWER FUNCTION 4.375V
4.500V
4.350V
0.000V
0.015V
0.110V
0.125V
0.000V
0.003V
0.002V
0.025V
REFERENCED REFERENCED TO SOURCE TO HUB *UNDER TRANSIENT CONDITIONS, SUPPLY AT HUB CAN DROP FROM 4.00V TO 4.070V.
Figure 3. USB Voltage Specification
BATT 4.35V TO 6.5V 4.2V 4.1V ON OFF 500mA 100mA 10k SELI EN CHG GND GND SELV IN
TO LOAD SINGLE Li+ CELL TO IN LED
MAX1811
CHG LOGIC OUT
Figure 4. Charging from a USB Port
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7
USB-Powered Li+ Charger MAX1811
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.)
SOICN .EPS
INCHES DIM A A1 B C e E H L
MILLIMETERS
MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20
0.40 1.27
N
E
H
MAX MIN 0.069 0.053 0.010 0.004 0.019 0.014 0.010 0.007 0.050 BSC 0.157 0.150 0.228 0.244 0.050 0.016
VARIATIONS:
1
INCHES
MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00
N MS012 8 AA 14 AB 16 AC
TOP VIEW
DIM D D D
MIN 0.189 0.337 0.386
MAX 0.197 0.344 0.394
D
A
C
e
B
A1
L
0 -8
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL
DOCUMENT CONTROL NO.
REV.
21-0041
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, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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