LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET KEY FEATURES DESCRIPTION two logically selectable levels (100mA and 500mA). When powered by a USB input, the battery is charged with the excess USB current that is not consumed by the system load. If the load exceeds the USB current limit, the battery will discharge to assist the USB power source to power the load. The controller can logically suspend the USB power to allow the system to operate from the battery without loading the USB. When a wall adapter is applied, it takes precedent over the USB power input and disables the USB input to prevent current flow from the adapter to the USB port. Single Cell Li-Ion Battery Charger Power Source Management Up to 1A Charging Current Integrated Power MOSFET USB Current Compliance 25µA Quiescent Current in Discharge Mode Taper Current Termination o o o o APPLICATIONS IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com Patents Pending. Protection features: USB Reverse Current Blocking Unsafe Battery Temp Lockout Internal IC Temperature Limiter USB Current Limiter WWW . Microsemi .C OM The LX2205 is a complete single cell Lithium Ion or Lithium Polymer battery charger and power source manager. In addition to battery charging, power flow control is provided from up to three sources: a wall adapter, a standard USB power plug or the battery. The battery charge current and termination current are independently adjustable. The controller also includes status indicators which show when the controller is powered by an external adapter in addition to charge in progress, and charge completed. The USB input is current limited at Navigation Devices Portable USB Devices Multi-Media Player PDA Phones Digital Cameras PRODUCT HIGHLIGHT DC OK Wall Adapter MDC USB Power USB Suspend SUSP High/Low UCL CMP SYS LX2205 System Load BAT CHG SHDN Shutdown Adapter Present Charge/ Discharge DONE GND CCP CTP CUS TFB Li-Ion Thermistor LX2205 PACKAGE ORDER INFO TA (°C) LQ Plastic MLP 4 x 4mm 16 pin RoHS Compliant / Pb-free -40 to 85 LX2205ILQ Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX2205ILQ-TR) Copyright © 2007 Rev. 1.0a, 2007-03-02 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 1 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET CHG DC OK 16 15 14 13 CMP 1 12 CTP BAT 2 11 CCP SYS 3 10 GND USB 4 9 CUS 7 8 UCL to MDC Note: Exceeding these ratings could cause damage to the device. All voltages are with respect ground. Currents are positive into, negative out of specified terminal. 6 SUSP 5 SHDN Connect Bottom Pad to GND LQ PACKAGE (Top View) THERMAL DATA LQ WWW . Microsemi .C OM Supply Voltages (MDC, SYS, USB) ................................................................ -0.3V to 7V Battery Voltage (BAT) ..................................................................................... -0.3V to 6V All Other Pins .............................................................................................-0.3V to VSUPPLY USB Current .............................................................................................................600mA BAT Discharge Current ................................................................................................1.6A Operating Ambient Temperature Range (TA) ..............................................-45°C to 125°C Maximum Operating Junction Temperature (TJ) ....................................................... 150°C Storage Temperature Range.........................................................................-65°C to 150°C Lead Temperature (Soldering 10 seconds)................................................................. 300°C Package Peak Temp. for Solder Reflow (40 seconds maximum exposure) ... 260°C (+0 -5) DONE PACKAGE PIN OUT TFB ABSOLUTE MAXIMUM RATINGS RoHS / Pb-free 100% Matte Tin Pin Finish Plastic 4 x 4mm 16-Pin THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA 28°C/W* Junction Temperature Calculation: TJ = TA + (PD x θJA). *The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. See layout guidelines section for important details. FUNCTIONAL PIN DESCRIPTION Pin BAT 2 Battery Connection - This pin is wired to the positive terminal of a single cell lithium ion/polymer battery. CCP 11 Charge Current Programming Pin - A resistor (RCCP) is connected between this pin and GND. The constant charging current is determined by the following relationship: RCCP = 50.648 x ICCL-1.0855 with RCCP in kΩ and ICCP in amps. CHG 14 Charge Indicator - This pin is a logic low level when the battery is being charged, provided VSYS is ≥ 4.4V. It is capable of driving the series combination of an LED and resistor that is powered from the SYS pin. CMP 1 Compensation – Connect a 0.1µF capacitor from CMP to SYS. CTP 12 Charge Termination Programming Pin – A resistor (RCTP) is connected between this pin and GND. The -1.0876 charge termination taper current is determined by the following relationship: RCTP =0.7354 x ITERM with RCTP in kΩ and ITERM in amps. CUS 9 USB Current Limit Programming Pin – A resistor (RCUS) is connected between this pin and GND. The high level USB charge current is determined by the following relationship: IUSB = 1050 / RCUS. DC OK 13 Main DC Present – A low level on this logic output indicates that the Main DC power source (typically the wall adapter) is applied. DONE 15 Done Indicator - This pin is a logic low level when the battery charge cycle is complete. It is capable of driving the series combination of an LED and resistor that is powered from the SYS pin. GND 10 Common Ground – Used as chip ground and as a reference for the battery return. Copyright © 2007 Rev. 1.0a, 2007-03-02 Description Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 2 LX2205 Name LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET FUNCTIONAL PIN DESCRIPTION (CONTINUED) Pin Description MDC 5 Main DC Input – This input is a voltage monitoring input (and not a high current input). Its purpose is to determine the presence of the main DC input to provide lockout for the USB power input. SHDN 6 Shutdown – Pulling this pin high will disable the entire device including the battery discharge path and place the device in a low power sleep mode. This pin has an internal pull-down. SUSP 7 Suspend (USB) – Pulling this pin high will prevent current from being drawn from the USB input pin. The rest of the chip functions are unaffected. This pin has an internal pull-down. SYS 3 System Power Node – This pin provides power to user system. SYS voltage provided will range from the battery voltage to the wall adapter and/or USB voltage. TFB 16 Temperature Feedback – Charging is suspended when the TFB pin falls below 29% (typ) of VSYS or rises above 74% (typ) of VSYS. CHG and DONE pins remain in their prior state during a TFB event. Connecting the TFB pin to GND disables the TFB function. USB 4 USB Power Input – USB compliant input. UCL 8 USB Current Limit – A high logic level will select the high USB current level determined by the programming of the CUS pin. A low logic level will select a level that is 20% of the high USB current level. This pin has an internal pull-down. WWW . Microsemi .C OM Name LX2205 Copyright © 2007 Rev. 1.0a, 2007-03-02 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 3 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET ELECTRICAL CHARACTERISTICS Unless otherwise specified, the following specifications apply over the operating temperature -40ºC ≤ TA ≤ 85 ºC and the following test conditions: VMDC = VUSB = 5V, VSYS =Open, VSUSP = VSHDN = Low, VUCL = High, VBAT = 3.9V, RCCP = 49.9k, RCUS = 2.26k, RCTP = 20k ` Symbol Min LX2205 Typ Max Units MAIN CIRCUITRY Input Voltage VSUPPLY Under Voltage Charging Lockout VSYS(UVLO) SYS UVLO Hysteresis USB UVLO USB Input Supply Current Battery Drain Current USB or SYS 4.35 Rising input; VBAT = 3.2V 3.55 Guaranteed by design VUSB(UVLO) SYS Input Supply Current ` Test Conditions ISYS IUSB IBAT Rising input; VBAT = 3.2V 3.7 6 V 3.95 V 140 4.25 mV 4.30 4.34 V VBAT = VCVL; (battery charged), VSYS = 5.0V 1.5 2.5 mA SHDN = High (Shutdown Mode), VSYS = 5.0V 25 µA VBAT = VCVL; (battery charged), , VMDC = 0V 2 mA SUSP = High (Suspend Mode), , VMDC = 0V SHDN = High (Shutdown Mode), , VMDC = 0V 25 µA 25 µA VMDC = 0V, VUSB = 0V -1.5 -6 µA VBAT = VCVL; (battery charged) 0.5 10 µA VMDC=0V; SUSP = High (Suspend Mode) 25 50 µA SHDN = High (Shutdown Mode) 0.5 10 µA VUSB = 0V; VMDC = 0V; Discharge with no load 25 50 µA 4.2 4.24 V WWW . Microsemi .C OM Parameter BATTERY CHARGER Constant Voltage Charge Voltage VCVL CTP Bias Voltage VCTP CCP Bias Voltage VCCP ICCL Max Battery Charge Current IBAT Conditioning Current ICOND Conditioning Current Threshold Voltage 4.16 IBAT > 100mA VSYS = 5.0V 0.85 1.30 V 1.25 V 0.98 1.10 A VMDC=0V 465 mA VMDC=0V; ISYS = 200mA (out of pin) 261 mA VMDC=0V; UCL = Low 92 mA VBAT =2.5V, as a % of ICCL 2.5 5 7.5 % VCCT 2.55 2.7 2.9 V Charge Termination Current IBAT 40 50 60 mA Top Off Charge Droop Threshold VDRP 96 97 98 % Expressed as a % of VCVL LX2205 Copyright © 2007 Rev. 1.0a, 2007-03-02 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 4 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET ELECTRICAL CHARACTERISTICS (CONTINUED) Unless otherwise specified, the following specifications apply over the operating temperature -40ºC ≤ TA ≤ 85 ºC and the following test conditions: VMDC = VUSB = 5V, VSYS =Open, VSUSP = VSHDN = Low, VUCL = High, VBAT = 3.9V, RCCP = 49.9k, RCUS = 2.26k, RCTP = 20k ` ` Units VMDC = 0V, UCL = Low 85 93 100 mA USB High Current Limit IUSB VMDC = 0V 425 463 500 mA Reverse Leakage Current ILEAK VUSB = 0V 2 10 µA CUS Bias Voltage VCUS 2.5 V LOGIC CHG , DONE Logic High Output VOH VSYS = 5.0V, IOH = -25uA CHG , DONE Logic Low Output VOL VSYS = 5.0V, IOL = 5mA Input Logic : UCL, SUSP, SHDN VLOG(IN) Input Logic Current : UCL, SUSP, SHDN ILOG(IN) VLOG(OUT) Logic Hi, 4.0 4.5 V 0.4 1.2 Logic Lo 0.4 Logic Hi, VLOG = 2V 0 2 4 Logic Lo, VLOG = 0V -2 0 2 Logic Hi, 10K to 3.3V 3.2 Logic Lo, ILOG = 100µA 0.4 V V µA V THERMAL DIE PROTECTION TCTL 140 °C BI-DIRECTIONAL PASS ELEMENT CONTROL IBAT = -1A 275 mΩ Charging Threshold RDS(ON) VCHG VSYS – VBAT 40 mV Discharging Threshold VDCH VBAT – VSYS 40 mV Charge–To–Discharge or Discharge–To–Charge 2.5 µs Charging headroom VSYS – VBAT, IBAT = 5mA 80 mV Discharging headroom VBAT – VSYS, IBAT = -20mA 80 mV Pass Element Switch Mode Delay tsw MDC INPUT VMDC DC OK Voltage Threshold Hysteresis Rising 4.0 4.15 VMDC(HYS) 35 IMDC 15 MDC Input current ` LX2205 Typ Max IUSB Discharge Switch On Resistance ` Min USB Low Current Limit Battery Charger Thermal Limiter ` Test Conditions USB CURRENT LIMIT Output Logic : DC OK ` Symbol WWW . Microsemi .C OM Parameter 4.3 V mV 35 µA BATTERY TEMPERATURE MONITOR VTFB(COLD) Hot Temp Fault Threshold VTFB(HOT) TFB Disable Voltage Threshold VTFB(DIS) Copyright © 2007 Rev. 1.0a, 2007-03-02 Rising Threshold ; as % of VSYS 73 75 77 % Falling Threshold; as % of VSYS 71 73 75 % Falling Threshold; as % of VSYS 27 28.5 30 % Rising Threshold; as % of VSYS 28 29.5 31 % 70 100 150 mV Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 LX2205 Cold Temp Fault Threshold Page 5 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET CHARGER CONTROL FLOW DIAGRAM YES WWW . Microsemi .C OM SHDN A TMP FAULT CAUSES THE CHARGER TO SUSPEND CHARGING. ONCE THE FAULT CLEARS, CHARGING RESUMES AT THE SAME POINT. RETURN TO START IF VSYS > VBAT, UVLO, SUSP, OR SHDN CHANGE STATE. START SWITCH OFF VOLTAGE MONITORING MODE (STATE). NO VSYS > VBAT NO DISCHARGE MODE YES VBAT<97% UVLO YES NO YES NO DC OK NO YES SUSP YES USB SUSPEND NO VBAT>60% NO CONDITION CHARGE MODE YES CONSTANT CURRENT CHARGE MODE TEMP < 140 IUCL DETERMINED BY THE STATE OF UCL. CONSTANT VOLTAGE CHARGE MODE TEMP < 140 NO NO YES YES ISYS< IMAX REDUCE CHARGE CURRENT YES YES ISYS< IMAX NO NO REDUCE CHARGE CURRENT YES YES DC OK DC OK NO NO IUSB< IUCL NO NO YES YES NO LX2205 IUSB< IUCL NO VBAT> VCV IBAT<ITAPER YES YES Copyright © 2007 Rev. 1.0a, 2007-03-02 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 6 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET SIMPLIFIED BLOCK DIAGRAM MDC WWW . Microsemi .C OM Wall Adapter DC OK Supervisor SYS Input Current Limit USB USB Power Ideal Diode System Load Compensation CMP Ground GND BAT Li-Ion Battery Charger CHG CTP DONE Charge Status Indicators Taper Current Setting SHDN Shutdown SUSP Suspend USB Control CCP UCL Charge Current Setting High/Low SYS TFB Battery Temp CUS Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 USB Current Setting LX2205 Copyright © 2007 Rev. 1.0a, 2007-03-02 Battery Temperature Monitor Page 7 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET APPLICATION CIRCUITS Si5441BDC DC OK Wall Adapter MDC USB USB Power 10uF Suspend SUSP High/Low UCL Shutdown Adapter Present 0.1uF CMP SYS BAT LX2205 10k 10uF System Load 2.4k CHG SHDN 10uF DONE GND CCP CUS TFB CTP 9.09k 49.9k 2.4k 88.7k 953k 12.4k WWW . Microsemi .C OM 1k Li-Ion 2.26k 100k Thermistor Figure 3 – AC Adapter and USB Supply (Charge and Discharge Modes) with 1A charging and 100mA termination current. In this application, the wall adapter voltage is not well regulated and can dip to less than 4.7V. For this case, a reverse blocking MOSFET is used instead of the reverse blocking diode, shown in the Product Highlight. This extends the operating range of the LX2205 because the drop across the MOSFET is minimal. It also increases efficiency by eliminating the power loss of the schottky diode. DC OK USB CMP Suspend SUSP High/Low UCL SYS BAT USB Power 10uF Shutdown LX2205 SHDN 0.1uF 10uF System Load Q1 BSS84 2.4k CHG MDC 10uF DONE GND CCP 100k CTP 20k CUS TFB 2.26k 8.87k 2.4k 95.3k 1.24k Li-Ion 10k LX2205 Thermistor Figure 4 – This application uses only a USB input with 500mA and 100mA maximum current limit levels and a 50mA termination current level. MOSFET Q1 turns off the TFB resistor string when not in charge mode to prevent battery drain; this is particularly helpful when using a small thermistor resistance value in the battery pack. Copyright © 2007 Rev. 1.0a, 2007-03-02 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 8 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET THEORY OF OPERATION 5 1000 Battery Voltage 4 800 600 mA Volts 3 Battery Current 2 400 1 200 CHG Voltage 0 Time CONDITIONING CURRENT CHARGE MODE A conditioning current is applied to a battery that is deeply discharged and has a terminal voltage less than 60% of the constant voltage level. The conditioning current is 5% of the CCP programmable constant current level. Once the battery terminal voltage exceeds the 60% level, the full constant current level is applied (unless charging current is limited by one of the other charger control loops). TOP OFF CHARGE MODE Once the charger has completed a charge cycle, if power remains applied, the LX2205 enters a voltage monitoring mode. In this mode the LX2205 monitors the battery terminal voltage and applies a top off charge if the battery voltage drops by more than 3% of VCVL. This feature is especially important for charging systems in equipment where usage is infrequent. USB CHARGE MODE AND CURRENT LIMIT The LX2205 is fully compliant with, and supports, the USB specifications – the Low Power Peripheral (100mA) and High Power Peripheral (500mA). The UCL logic input selects the USB charge current level. The LX2205 senses the current flowing from the USB terminal to the SYS terminal. The LX2205 will first try to reduce the combined USB load by scaling back the battery charging current. Once the charger has scaled back the charge current to zero, if the load demands more current than the USB bus can supply the VSYS voltage will drop down to the battery voltage level and the battery will supply the additional current demand. This is illustrated in the following two charts. STATES CHG DONE OFF Charge in process ON Charge completed OFF ON Input power removed OFF OFF Copyright © 2007 Rev. 1.0a, 2007-03-02 600 500 400 USB Limit 300 200 Battery 100 0 -100 -200 LX2205 CHARGE TERMINATION MODE To increase system battery life and avoid float charging, the LX2205 disconnects the charger once the battery has been fully charged. The charge termination state occurs at the end of constant voltage mode. The charge status indicators change state when charging is completed. Battery Current w ith 500m A USB Current Lim it Battery Charge (Discharge) Two step charger profile: Using the taper current to terminate the charge cycle is particularly advantageous in an isolated battery topology such as the LX2205, because when an external power source is applied to the appliance with the appliance turned on, the power to the appliance and the power to the battery take separate paths. This separate path allows the battery charge current to be monitored accurately. Compared with charger controllers that rely on a fixed timeout period terminating by taper current allow for the shortest possible battery charge time. WWW . Microsemi .C OM BATTERY CHARGER GENERAL DESCRIPTION The LX2205 is designed to charge a single cell Lithium Ion or Lithium Polymer battery using two steps: a constant current step followed by a constant voltage step. The basic charger function uses the SYS pin as an input and BAT pin as the output. The LX2205 charger has a programmable maximum current (programmable by the resistor value between the CCP pin and GND) which is the maximum charging current during the Constant Current Mode of the charging profile. The charger will terminate constant voltage charging once the current drops below the taper current setting (programmable by the resistor value between CTP pin and GND). -300 -400 0 200 400 600 800 System Load Current (m A) Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 9 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET THEORY OF OPERATION Battery Charge (Discharge) 120 100 80 USB Limit 60 40 20 0 -20 Battery -40 -60 -80 0 40 80 120 160 System Load Current (m A) REDUCED USB CHARGE TIME The isolated battery topology reduces charge time from the USB port when the appliance is turned on while also charging. Because the system power rail can be a higher voltage than the battery voltage, the system will require less power from the USB source which leaves more power available to charge the battery quickly. For example, if the system draws 1W, and the USB input is 5V, the system draws 1W/5V = 200mA from the USB source; this leaves 300mA to charge the battery. In a topology where the load connects directly to the battery (as is done with conventional non-isolated linear chargers), if the average battery voltage is 3.7V, the system will draw 1W/3.7V = 270mA from the USB source, this leaves only 230mA to charge the battery. In this case the LX2205 will charge the battery 30% faster. USB SUSPEND When the SUSP pin is pulled high, less than 25μA is pulled from the USB port. The rest of the LX2205, however, continues to function normally. If an adapter is applied, the effect of SUSP is negligible. If the system is running off both USB and the battery and SUSP is logic high, the system load will be transferred 100% to the battery. UCL The UCL pin is used to select the current limit level for the USB input. When the UCL pin is a logic high the maximum current level as determined by the CUS resistor is selected; when the UCL pin is a logic low, the current limit is set to 20% of the maximum level. WWW . Microsemi .C OM SHDN When SHDN is logic high, the LX2205 is placed in a total shutdown mode; no current will flow between SYS, USB and BAT. Quiescent current is 25μA during shutdown. CHG and DONE are high impedance (off) in SHDN mode. Battery Current w ith 100m A USB Current Lim it POWER OR-ING (SYS TO BAT AND BAT TO SYS) When the power is removed from both MDC and USB, the battery current flows from BAT to SYS and thus provides power to the load without the need for any external switches or monitoring circuits. There is a circuit equivalent of an ideal diode (patent-pending bi-directional MOSFET) in the LX2205 between the BAT pin and SYS pin. This ideal diode appears as a low impedance to high forward current and presents a high impedance to low discharge currents or potentially reverse charge currents. For small forward currents, the ideal diode regulates a small forward voltage. This small voltage allows the power sense circuitry to determine whether an input power source is present even if the current through the ideal diode is less than 1mA. This feature makes it virtually impossible to charge the battery (unregulated) in reverse through the ideal diode and also enables the battery to assist a current limited input power source without chattering even if only a few mA of battery current are required. LX2205 Copyright © 2007 Rev. 1.0a, 2007-03-02 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 10 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET THEORY OF OPERATION / APPLICATION NOTE MDC, USB OR-ING, UVLO AND DC OK 1. 2. 3. 4. VUSB < VUSBUVLO USB Suspend pin is asserted. VMDC > VUSB VMDC > V DC OK _THRESHOLD The MDC input is a monitoring input only, it is not a high current input. When the voltage at SYS exceeds the UVLO level, (typically 3.7V), the charger portion of the circuit is activated. The DC OK output is pulled low when both of the following conditions are true: 1. 2. The following tables are guidelines for selecting the proper resistor values: VMDC > V DC OK _THRESHOLD VSYS > VBAT Therefore when using a current limited wall adapter it is possible to charge the battery and not assert the DC OK output. Constant Charge Current (in mA) RCCP 50 1270k 100 604k 200 294k 300 187k 400 137k 500 107k 600 88.7k 700 75.0k 800 63.4k 900 56.2k 1000 49.9k* * RCCP minimum value Termination Current (in mA) RCTP 5 237k 10 105k 20 51.1k 40 24.9k 60 15.8k 80 11.8k 100 9.09k 120 7.50k 140 6.34k 160 5.49k 180 4.75k 200 4.22k Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 LX2205 PROTECTION FEATURES Conditioning Current Mode – If the battery terminal voltage is less than 2.7V, the battery charger will reduce the charge current to 5% of full scale. This also protects the appliance from overheating by trying to drive the full charging current into a short circuited battery. Under Voltage Lockout – The charger remains inactive until the under voltage lockout threshold is exceeded at the SYS pin. Thermal Control Loop – The power dissipation of the charger is limited by reducing the charge current with a control loop to prevent the die temperature from exceeded approximately 140°C. Reverse Current Blocking – Current will not flow out of the USB pin. Shutdown Mode – If the SHDN pin is logic high, the charger enters a shutdown mode to prevent draining the battery. Battery Temperature Lockout – If an unsafe temperature is sensed by the TFB input window comparator, battery charging is suspended. Copyright © 2007 Rev. 1.0a, 2007-03-02 CHARGE CURRENT PROGRAMMING The CCP, CTP, and CUS programming pins are used to program the constant charge current, termination current, and USB current, respectively. These pins utilize regulated output voltages that produce a program current across an external resistor to GND. WWW . Microsemi .C OM The power path from the USB input to the SYS pin consists of a current limiter and a bidirectional switch (capable of blocking current in either direction). The USB input is switched off when at least one of the following conditions exists: LAYOUT GUIDELINES It is important when laying out the LX2205 to place 10µF ceramic capacitors as close to the SYS, USB and VBAT IC terminals as possible to filter switching transients. It is important to provide a low thermal impedance path from the thermal pad on the bottom of the LX2205 package to the ground plane of the circuit board to maximize heat dissipation. Generally this is accomplished by the use of multiple thermal vias. The compensation capacitor should be placed close to the CMP pin and connected with a short trace. Page 11 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET APPLICATION NOTE To finish the design it is necessary to create the Thevenin Voltage and resistance using a voltage divider from the SYS pin. The values of R1 and R2 can be calculated as: R1 = R2 = RTH = 88k K R1 × RTH = 958k R1 − RTH WWW . Microsemi .C OM BATTERY TEMPERATURE MONITOR The LX2205 has an input to monitor the battery temperature during battery charging. The SYS voltage must be used to bias this circuitry. During the occurrence of a TMP fault, the charge cycle is suspended; however the status indicators state remains unchanged. A typical Lithium Ion battery should only be charged within a temperature range of 0°C to 60°C. For this calculation example, a Vishay NTHS0402N01N1003J thermistor was used. This thermistor has the value of 327kΩ at 0°C, 100kΩ at 25°C and 24.9kΩ at 60°C. The thermistor must be biased with a Thevenin voltage source and series resistance to achieve the proper TMP thresholds. A fixed value resistor is added in series with the thermistor to prevent it from becoming too low impedance at high temperatures and causing the TMP input to default to off. Actual standard 1% resistor values are: 953k and 88.7k. The final circuit for this example is: VSYS 88.7k TMP 12.4k 953k RNTC Using a value of RMIN that is ½ the thermistor high temperature trip resistance value works well; therefore, for this example, set the value of RMIN to: 12.4k = R MIN R = T =60°C . 2 This has the effect of adding a fixed 12.4k to the thermistor resistance values so it becomes 339kΩ at 0°C, 112kΩ at 25°C and 37.3kΩ at 60°C. The TMP voltages with this circuit are: TEMP (°C) -20 0 25 60 80 RNTC 971k 327k 100k 24.9k 12.6k VTMP (% VSYS) 85% 74% 53% 29% 22% The equations for RTH and VTH are, using Cold Temperature Fault Threshold average of 74% and the Hot Temperature Fault Threshold average of 29% of VSYS: LX2205 0.29 × 0.74 × (RT =0°C − RT =60°C ) VTH = VSYS (0.29 × RT =0°C ) − (0.74 × RT =60°C ) = K = 0.916 ⎞ ⎛ K RTH = ⎜ − 1⎟ × RT = 0°C = 80.6k ⎝ 0.74 ⎠ Copyright © 2007 Rev. 1.0a, 2007-03-02 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 12 LX2205 1A Li-Ion Battery Charger with Power Source Management ® TM P RODUCTION D ATA S HEET TYPICAL CHARGING CURRENT VS VSYS 1.2 1 1 Charge Current (A) 1.2 0.8 0.6 0.4 WWW . Microsemi .C OM Charge Current (A) TYPICAL CHARGING CURRENT VS BATTERY VOLTAGE 0.8 0.6 0.4 V BAT = 3.9V 0.2 0.2 0 0 4.2 3.2 3.4 3.6 3.8 4 4.2 4.6 5 5.4 5.8 SYS Voltage Battery Voltage TYPICAL USB CURRENT LIMIT VS USB VOLTAGE TYPICAL VCVL DISTRIBUTION 500 1500 450 USB Current Limit (mA) 400 Typical Distribution Frequency USB Low USB Hi 350 300 250 200 150 100 1250 VSY S = 5V 1000 TA = 25°C 750 500 250 0 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 50 0 4 4.5 5 5.5 6 VCVL Input Voltage CHARGE TO DISCHARGE SWITCHOVER VSYS IBAT LX2205 DC OK Copyright © 2007 Rev. 1.0a, 2007-03-02 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 13 LX2205 ® TM 1A Li-Ion Battery Charger with Power Source Management P RODUCTION D ATA S HEET PACKAGE DIMENSIONS 16-Pin MLPQ Plastic (4x4mm EP / 114x114Cu Exposed Pad) D b E2 L D2 E e A A1 K Dim A A1 A3 b D E e D2 E2 K L MILLIMETERS MIN MAX 0.80 1.00 0 0.05 0.18 0.30 0.23 0.38 4.00 BSC 4.00 BSC 0.65 BSC 2.55 2.80 2.55 2.80 0.20 0.30 0.50 INCHES MIN MAX 0.031 0.039 0 0.002 0.007 0.012 0.009 0.015 0.157 BSC 0.157 BSC 0.026 BSC 0.100 0.110 0.100 0.110 0.008 0.012 0.020 Note: 1. Dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(.006”) on any side. Lead dimension shall not include solder coverage. A3 LX2205 PRODUCTION DATA – Information contained in this document is proprietary to Microsemi and is current as of publication date. This document may not be modified in any way without the express written consent of Microsemi. Product processing does not necessarily include testing of all parameters. Microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time. Copyright © 2007 Rev. 1.0a, 2007-03-02 WWW . Microsemi .C OM LQ Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 14