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LX2205
TM (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
DESCRIPTION
KEY FEATURES Single Cell Li-Ion Battery Charger Power Source Management Up to 1A Charging Current Integrated Power MOSFET USB Current Compliance 25A Quiescent Current in Discharge Mode Taper Current Termination Protection features: USB Reverse Current Blocking Unsafe Battery Temp Lockout Internal IC Temperature Limiter USB Current Limiter
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
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.
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o o o o
APPLICATIONS
IMPORTANT: For the most current data, consult MICROSEMI's website: http://www.microsemi.com Patents Pending.
Navigation Devices Portable USB Devices Multi-Media Player PDA Phones Digital Cameras
PRODUCT HIGHLIGHT
DC OK Wall Adapter USB Power
Suspend High/Low Shutdown
Adapter Present
MDC USB SUSP UCL SHDN GND CCP CTP
CMP SYS
System Load
LX2205
BAT
CHG DONE CUS TFB
Thermistor
Charge/ Discharge
Li-Ion
LX2205 LX2205
PACKAGE ORDER INFO
TA (C) -40 to 85
LQ
Plastic MLP 4 x 4mm 16 pin
RoHS Compliant / Pb-free
LX2205ILQ
Note: Available in Tape & Reel. Append the letters "TR" to the part number. (i.e. LX2205ILQ-TR)
Copyright (c) 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 (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
ABSOLUTE MAXIMUM RATINGS 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) ..............................................-45C to 125C Maximum Operating Junction Temperature (TJ) ....................................................... 150C Storage Temperature Range.........................................................................-65C to 150C Lead Temperature (Soldering 10 seconds)................................................................. 300C Package Peak Temp. for Solder Reflow (40 seconds maximum exposure) ... 260C (+0 -5)
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. to
PACKAGE PIN OUT
DC OK DONE CHG
TFB
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16
15
14
13 12 11 10 9 8
CMP BAT SYS USB
1 2 3 4 5 Connect Bottom Pad to GND 6 7
CTP CCP GND CUS
MDC
SHDN
LQ PACKAGE
THERMAL DATA
(Top View)
RoHS / Pb-free 100% Matte Tin Pin Finish
LQ
Plastic 4 x 4mm 16-Pin 28C/W*
THERMAL RESISTANCE-JUNCTION TO AMBIENT, JA
Junction Temperature Calculation: TJ = TA + (PD x JA). *The JA 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 Name BAT CCP Pin 2 11 14 1 12 9 13 15 10 Description Battery Connection - This pin is wired to the positive terminal of a single cell lithium ion/polymer battery. 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 k and ICCP in amps. 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. Compensation - Connect a 0.1F capacitor from CMP to SYS. 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 k and ITERM in amps. 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. Main DC Present - A low level on this logic output indicates that the Main DC power source (typically the wall adapter) is applied. 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. Common Ground - Used as chip ground and as a reference for the battery return.
CHG
CMP CTP CUS
DC OK
SUSP
UCL
LX2205 LX2205
DONE
GND
Copyright (c) 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 2
LX2205
TM (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
FUNCTIONAL PIN DESCRIPTION (CONTINUED)
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Name MDC SHDN SUSP SYS TFB USB UCL
Pin 5 6 7 3 16 4 8
Description 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. 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. 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. 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. 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 Power Input - USB compliant input. 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.
LX2205 LX2205
Copyright (c) 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 (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
ELECTRICAL CHARACTERISTICS Unless otherwise specified, the following specifications apply over the operating temperature -40C TA 85 C 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 Parameter
MAIN CIRCUITRY Input Voltage Under Voltage Charging Lockout SYS UVLO Hysteresis USB UVLO SYS Input Supply Current VUSB(UVLO) ISYS VSUPPLY VSYS(UVLO) USB or SYS Rising input; VBAT = 3.2V Guaranteed by design Rising input; VBAT = 3.2V VBAT = VCVL; (battery charged), VSYS = 5.0V SHDN = High (Shutdown Mode), VSYS = 5.0V VBAT = VCVL; (battery charged), , VMDC = 0V USB Input Supply Current IUSB SUSP = High (Suspend Mode), , VMDC = 0V SHDN = High (Shutdown Mode), , VMDC = 0V VMDC = 0V, VUSB = 0V VBAT = VCVL; (battery charged) Battery Drain Current IBAT VMDC=0V; SUSP = High (Suspend Mode) SHDN = High (Shutdown Mode) VUSB = 0V; VMDC = 0V; Discharge with no load BATTERY CHARGER Constant Voltage Charge Voltage CTP Bias Voltage CCP Bias Voltage VCVL VCTP VCCP ICCL Max Battery Charge Current VSYS = 5.0V VMDC=0V IBAT VMDC=0V; ISYS = 200mA (out of pin) VMDC=0V; UCL = Low Conditioning Current Conditioning Current Threshold Voltage Charge Termination Current Top Off Charge Droop Threshold ICOND VCCT IBAT VDRP Expressed as a % of VCVL VBAT =2.5V, as a % of ICCL 2.5 2.55 40 96 0.85 IBAT > 100mA 4.16 4.2 1.30 1.25 0.98 465 261 92 5 2.7 50 97 7.5 2.9 60 98 1.10 4.24 V V V A mA mA mA % V mA % -1.5 0.5 25 0.5 25 4.25 4.35 3.55 3.7 140 4.30 1.5 25 2 25 25 -6 10 50 10 50 4.34 2.5 6 3.95 V V mV V mA A mA A A A A A A A
Symbol
Test Conditions
Min
LX2205 Typ Max
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Units
LX2205 LX2205
Copyright (c) 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 (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
ELECTRICAL CHARACTERISTICS (CONTINUED) Unless otherwise specified, the following specifications apply over the operating temperature -40C TA 85 C 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
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Parameter
USB CURRENT LIMIT USB Low Current Limit USB High Current Limit Reverse Leakage Current CUS Bias Voltage LOGIC
CHG , DONE Logic High Output CHG , DONE Logic Low Output
Symbol
Test Conditions
Min
85 425
LX2205 Typ Max
93 463 2 2.5 100 500 10
Units
IUSB IUSB ILEAK VCUS VOH VOL VLOG(IN)
VMDC = 0V, UCL = Low VMDC = 0V VUSB = 0V
mA mA A V V
VSYS = 5.0V, IOH = -25uA VSYS = 5.0V, IOL = 5mA Logic Hi, Logic Lo Logic Hi, VLOG = 2V Logic Lo, VLOG = 0V Logic Hi, 10K to 3.3V Logic Lo, ILOG = 100A
4.0
4.5 0.4
V V
Input Logic : UCL, SUSP, SHDN Input Logic Current : UCL, SUSP, SHDN Output Logic : DC OK THERMAL DIE PROTECTION Battery Charger Thermal Limiter
1.2 0.4 0 -2 3.2 0.4 2 0 4 2
ILOG(IN)
A
VLOG(OUT)
V
TCTL
140
C
BI-DIRECTIONAL PASS ELEMENT CONTROL Discharge Switch On Resistance Charging Threshold Discharging Threshold Pass Element Switch Mode Delay Charging headroom Discharging headroom MDC INPUT
DC OK Voltage Threshold
RDS(ON) VCHG VDCH tsw
IBAT = -1A VSYS - VBAT VBAT - VSYS Charge-To-Discharge or Discharge-To-Charge VSYS - VBAT, IBAT = 5mA VBAT - VSYS, IBAT = -20mA
275 40 40 2.5 80 80
m mV mV s mV mV
VMDC VMDC(HYS) IMDC
Rising
4.0
4.15 35 15
4.3
V mV
Hysteresis MDC Input current
35
A
BATTERY TEMPERATURE MONITOR Cold Temp Fault Threshold VTFB(COLD) Rising Threshold ; as % of VSYS Falling Threshold; as % of VSYS Falling Threshold; as % of VSYS Rising Threshold; as % of VSYS 73 71 27 28 70 75 73 28.5 29.5 100 77 75 30 31 150 % % % % mV
LX2205 LX2205
Hot Temp Fault Threshold TFB Disable Voltage Threshold
VTFB(HOT) VTFB(DIS)
Copyright (c) 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 5
LX2205
TM (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
CHARGER CONTROL FLOW DIAGRAM
START
RETURN TO START IF VSYS > VBAT, UVLO, SUSP, OR SHDN CHANGE STATE. A TMP FAULT CAUSES THE CHARGER TO SUSPEND CHARGING. ONCE THE FAULT CLEARS, CHARGING RESUMES AT THE SAME POINT.
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SHDN
NO
YES
SWITCH OFF VOLTAGE MONITORING MODE (STATE).
VSYS > VBAT
YES
NO
DISCHARGE MODE VBAT<97%
NO
UVLO
NO
YES
YES
DC OK
YES
NO
SUSP
NO
YES
USB SUSPEND
VBAT>60%
YES
NO
CONDITION CHARGE MODE
CONSTANT CURRENT CHARGE MODE
IUCL DETERMINED BY THE STATE OF UCL.
CONSTANT VOLTAGE CHARGE MODE
TEMP < 140 YES
NO
TEMP < 140 YES
NO
ISYS< IMAX
YES YES DC OK NO
NO
ISYS< IMAX REDUCE CHARGE CURRENT
YES YES
NO
REDUCE CHARGE CURRENT
DC OK NO
LX2205 LX2205
IUSB< IUCL
YES
NO
IUSB< IUCL
YES
NO
NO
NO
VBAT> VCV
YES
IBATYES
Copyright (c) 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 (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
SIMPLIFIED BLOCK DIAGRAM
MDC Wall Adapter
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DC OK
Supervisor
USB USB Power
Input Current Limit Ideal Diode
SYS
System Load
Compensation CMP
Ground
GND
BAT Li-Ion Battery Charger
CHG CTP DONE
Charge Status Indicators
SHDN Shutdown SUSP Suspend UCL High/Low USB Control CCP
Taper Current Setting
Charge Current Setting SYS Battery Temperature Monitor
CUS USB Current Setting
TFB Battery Temp
LX2205 LX2205
Copyright (c) 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 7
LX2205
TM (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
APPLICATION CIRCUITS
Si5441BDC
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1k
DC OK Wall Adapter USB Power
10uF Suspend High/Low Shutdown
0.1uF 10uF
Adapter Present 10k
MDC USB SUSP UCL SHDN GND CCP
49.9k
LX2205
CMP SYS BAT
2.4k
System Load
CHG DONE CTP CUS TFB
2.26k 100k Thermistor 2.4k 88.7k
10uF
953k 9.09k
12.4k
Li-Ion
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 Power
10uF Suspend High/Low Shutdown
0.1uF 10uF
USB SUSP UCL SHDN MDC GND CCP
100k
CMP
LX2205
SYS BAT
2.4k
System Load
Q1 BSS84 10uF 8.87k 2.4k
CHG DONE CTP
20k
CUS TFB
2.26k
95.3k
1.24k
Li-Ion
10k
LX2205 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 (c) 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 (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
THEORY OF OPERATION
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). Two step charger profile:
5
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. 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.
Battery Current w ith 500m A USB Current Lim it 600 Battery Charge (Discharge) 500 400 300 200 100 0 -100 -200 -300 -400 0 200 400 600 800 System Load Current (m A) USB Limit Battery
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Battery Voltage
4
1000
800 3
Volts
2
Battery Current
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). 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.
STATES Charge in process Charge completed Input power removed
CHG DONE
mA
600
LX2205 LX2205
ON OFF OFF
OFF ON OFF
Copyright (c) 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 9
LX2205
TM (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
THEORY OF OPERATION
Battery Current w ith 100m A USB Current Lim it Battery Charge (Discharge) 120 100 80 60 40 20 0 -20 -40 -60 -80 0 40 80 120 160 System Load Current (m A) USB Limit Battery
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 25A during shutdown. CHG and DONE are high impedance (off) in SHDN mode. 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. 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.
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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 25A 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.
LX2205 LX2205
Copyright (c) 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 (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
THEORY OF OPERATION / APPLICATION NOTE
MDC, USB OR-ING, UVLO AND DC OK 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: 1. 2. 3. 4. VUSB < VUSBUVLO USB Suspend pin is asserted. VMDC > VUSB VMDC > V DC OK _THRESHOLD
LAYOUT GUIDELINES It is important when laying out the LX2205 to place 10F 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. 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. The following tables are guidelines for selecting the proper resistor values: 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
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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. 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. 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 140C. 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.
LX2205 LX2205
Copyright (c) 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 11
LX2205
TM (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
APPLICATION NOTE
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 0C to 60C. For this calculation example, a Vishay NTHS0402N01N1003J thermistor was used. This thermistor has the value of 327k at 0C, 100k at 25C and 24.9k at 60C. 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.
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:
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R1 =
R2 =
RTH = 88k K
R1 x RTH = 958k R1 - RTH
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 1/2 the thermistor high temperature trip resistance value works well; therefore, for this example, set the value of RMIN to: 12.4k = R MIN
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%
R = T =60C . 2
This has the effect of adding a fixed 12.4k to the thermistor resistance values so it becomes 339k at 0C, 112k at 25C and 37.3k at 60C. 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 LX2205
0.29 x 0.74 x (RT =0C - RT =60C ) VTH = VSYS (0.29 x RT =0C ) - (0.74 x RT =60C ) = K = 0.916
K RTH = - 1 x RT = 0C = 80.6k 0.74
Copyright (c) 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
TM (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
TYPICAL CHARGING CURRENT VS BATTERY VOLTAGE
1.2 1 Charge Current (A)
TYPICAL CHARGING CURRENT VS VSYS
1.2 1 Charge Current (A) 0.8 0.6 0.4 V BAT = 3.9V 0.2 0 4.2 4.6 5 SYS Voltage 5.4 5.8
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0.8 0.6 0.4 0.2 0 3.2 3.4 3.6 3.8 4 4.2 Battery Voltage
TYPICAL USB CURRENT LIMIT VS USB VOLTAGE
500 450 400 USB Current Limit (mA) 350 300 250 200 150 100 50 0 4 4.5 5 Input Voltage 5.5 6
TYPICAL VCVL DISTRIBUTION
1500
Typical Distribution Frequency
USB Low USB Hi
1250 1000 750 500 250 0 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 VCVL VSY S = 5V TA = 25C
CHARGE TO DISCHARGE SWITCHOVER
VSYS
IBAT
LX2205 LX2205
DC OK
Copyright (c) 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 (R)
1A Li-Ion Battery Charger with Power Source Management
PRODUCTION DATA SHEET
PACKAGE DIMENSIONS
LQ
16-Pin MLPQ Plastic (4x4mm EP / 114x114Cu Exposed Pad)
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D
b
E2 L
E
D2
e A1 A3 A
K
Dim A A1 A3 b D E e D2 E2 K L
Note:
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
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.
LX2205 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 (c) 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 14

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