Dual Level Li-Ion Battery Charger Manufactured by: Microsemi Corporation Integrated Product Group Garden Grove, Telephone: 714 898-8121 More than solutions enabling possibilities
PRODUCT DESCRIPTION The LX2206 charges a single cell lithium ion (or lithium polymer) battery from a DC power source. It is a linear battery charger (as opposed to a pulse charger or switching power supply charger). The linear charger is the simplest type and requires few additional external components. The LX2206 is a two step charger the first step charges with a fixed current level until the battery voltage reaches 4.2V; then the charger holds the battery terminal at 4.2V, and lets the charge current taper off until the battery is fully charged. Dual Level Charging The LX2206 is unique in that it can change charge currents between two different levels under logic control. This can be used for USB charging because in some situations you want to charge at up to 500mA and in other situations only 100mA. Another application for dual level control is where the input power connector accepts power from two unrelated DC power sources (for example an AC adapter and a USB input). Most chargers have application notes on how to implement switching between two levels, but with the LX2206, it is all built in. The resistor attached to the HCP (LCP) programming pin sets the high (low) level maximum charge current. Up to Three Status Indicators The unique design of the LX2206 status indicator circuitry allows the possibility of driving three status LEDs using two programming pins (STAT and #DCOK). The three possible indicators are Charge in progress, Charge complete/battery Full and Input power source is connected. When the input power is removed, both the STAT and #DCOK become high impedances which shut off all three LEDs. It is possible to use any combination of the three LEDs depending on what the designer wants to annunciate. The #DCOK can also be used as a logic indicator but since it is open collector, it requires an external pull up resistor. Battery Pack Temperature Lock Out Every Lithium Ion battery pack has a built in temperature monitoring device called a NTC (negative temperature coefficient) resistor. Most battery manufacturers recommend not to charge the battery if it gets too hot (over 60 C) or too cold (<0 C). The LX2206 has an input (TMP) that can be configured to monitor the value of the NTC resistor and shut off charging if the battery temperature is out of range. It is possible to ground the TMP pin if this feature is not required. Other Safety Features The LX2206 has other built in safety features to protect the battery from being overcharged: The battery terminal voltage is regulated to a precise 0.5% level in constant voltage mode. If the battery is deeply discharged, the charge current is reduced to condition the battery. The pass element has reverse blocking to prevent current flow from the battery to the input power port should the input pin be shorted to ground. The LX2206 has a thermal control loop to scale back the charge current to reduce the device power dissipation to keep the LX2206 cool. The LX2206 will start a charge cycle automatically if the terminal voltage drops below 97% of the full charge level. Programming/Pinning Options The output voltage for the LX2206 can be factory set to be 4.4V rather than 4.2V this is to support newer chemistry batteries that require a higher charge voltage. The LX2206 has a pin out option which allows it to provide three charge levels rather than two this will support an adapter and two USB levels. The LX2206 has a metal option to allow it to change how the charge cycle terminates normally the charge indicator signals the battery is full and the charger shuts off, but this option makes it is possible for the charger to stay on after the battery indicator indicates the battery is full. (In cases where the battery charger also serves as a regulator for system power, this may be desirable.) Consult the factory for any of these options. Copyright 2001 Page 2
KEY PRODUCT INFORMATION KEY FEATURES Two independent programmable charge currents that can be used for two unrelated power sources like an Adapter or USB plug. Two independent charge levels and shut down features fully support the three standard USB current limit modes: USB high (<500mA), USB low (<100mA), and Suspend (< 100µA). Programmable constant charge currents ranging from 50mA to 750mA suitable for batteries ranging from 75mAmp-Hour (blue tooth headset) up to 1.5 Amp-Hour (Personal Media Player). Supports the use of three status LEDs which offers an easy way to indicate all aspects of the charger status. These LEDs draw no current from the battery after the external power source is removed. Thermal Efficient 3x3 package can handle twice the power of a 2x2 so it has the thermal mass to drive currents higher than 500mA. (Under certain conditions a 2x2 will scale back current much more extending the time needed to charge the battery.) Precision charge level tolerance (0.5%) insures a full battery without the risk of overcharge. Battery temperature lock out prevents charging a battery that is too hot or too cold. Thermal control loop prevents the die from getting too hot. Droop detection and charger restart will top off a battery that droops by 3% terminal voltage. Conditioning charge mode applies a trickle charge to a severely discharged battery or shorted battery. Reverse current blocking prevents current flow from Battery to shorted input connector. APPLICATIONS Appliances that charge from a USB Port Appliances with more than one power source but only one connector (multiple power cables) MP3 player PDA PMC Digital Camera Charge Cradle Copyright 2001 Page 3
TYPICAL APPLICATION This is an example of an appliance using a single input connect or that can plug into an AC adapter or a USB port. A grounded pin programs the charger for USB. Adapter or USB Power Pin Grounded Pin in USB cable. Leave open in Adapter Cable. Shutdown Control Logic 10k 0.47u 12.1k 19.6k Current Programming IN CMP H/L SD HCP LCP LX2206 GND STAT DCOK TMP BAT Battery Status Charging Full Power On 24.9k 121k Battery Temperature Lockout Sensing This is an example of a charger where the termination current is being set by the HCP resistor and the charge current is set by the LCP resistor. This illustrates that the termination current is always 10% of the charge current value programmed by the HCP resistor whether or not the mode is high or low charge current. A DCOK logic signal indicates when the input power is applied. A single charge indicator is used in this example. Shutdown 0.47u 121k 80.6k IN CMP SD H/L HCP LCP LX2206 GND STAT DCOK TMP BAT Battery Charging 10k VCC DCOK Copyright 2001 Page 4
COMPETITIVE ANALYSIS Competitor Device Package V IN Range Rating Disadvantage to LX2206 Microsemi LX2206 3 x 3 4.35 to 6V 750mA Texas Instr BQ24013 3 X 3 4.3 to 18V 1A Intersil ISL6294 2 X 3 4.3 to 28V 750mA Linear Tech LTC4065 2 X 2 3.7 to 5.5V 750mA Microchip MCP73831 2 X 3 3.7 to 6V 500mA Maxim MAX8808 2 X 2 4.2 to 15V 500mA Alternative Microsemi Solutions No thermal die temp control Charger doesn t shut off (float charges the battery) Tiny package is power limited No Power present (DCOK) Only rated to 500mA Only rated to 500mA Device Package Rating Differences (Pros and Cons) LX2202 LX2203 LX2205 4 x 4 3 X 3 4 X 4 2A 1A 750mA Isolated battery topology charge and discharge Limited support for simultaneous adapter and USB Charging current up to 2A. No Adapter present logic (DCOK) Charging Current up to 1A Only one programmable charge current No Adapter present logic (DCOK) Isolated battery topology charge and discharge Full support for simultaneous adapter and USB Full USB compliance Charging current up to 1A. Copyright 2001 Page 5
SALES STRATEGY Look for handheld portable appliances such as MP3 players, Digital cameras, smart phones, PDAs, Personal Media Players, etc. Of these units, find those with a rechargeable battery it will likely be a lithium ion or lithium polymer battery. Find those units with batteries that have 1500 milli-amp-hours capacity or less. PRODUCT POSITIONING The LX2206 is particularly well suited for: a) Appliances that are charging from a USB port on a computer. b) Appliances that are charging from an adapter and USB port but that just have one input power connector typically these units have multiple power cords and a wall adapter with a unique power output receptacle. c) Appliances with very small batteries. d) Applications where the designer wants to independently set termination current and charge current. e) Applications where designers want up to three logic selectable charge current levels. f) Applications where the designers want multiple status LEDs. g) Applications that require a power applied #DCOK logic signal. h) Applications that require thermal shutdown if the battery gets too hot and or too cold. i) Applications that want a small size battery charger IC (space limited) with a self regulating die temperature feature. The 3 x 3 package of the LX2206 is more thermally efficient than a smaller package and can charge at higher currents than a 2x2 package without throttling back the charge current. This results in a faster charge more of the time. j) Applications that may eventually convert from a 4.2V battery to a 4.4V battery. Copyright 2001 Page 6
SUMMARY Pricing Device Package Industrial (-40 to 125 C) DC 1000+ LX2206ILD 3x3 10 pin $0.48 $0.60 Note: Availability Options Samples: April 2006 Production: July 2006 Packages: Available in Tape and Reel: Parts Per Reel: 3000 Temperature: Technical Support Datasheet: Application Note: Evaluation Board: Factory Contacts Technical Questions: Marketing Manager: LD 3x3 plastic 10 pin -40C to 85C Yes See www.microsemi.com See data sheet LX2206 EVAL KIT Bruce Ferguson (714) 372-8094 bferguson@microsemi.com Erich Volk evolk@microsemi.com Copyright 2001 Page 7