Microsemi LX2205ILQ 1a li-ion battery charger with power source management Datasheet

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
ƒ Taper Current Termination
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APPLICATIONS
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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
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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
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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.
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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
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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
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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.
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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.
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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
ƒ 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.
ƒ 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.
ƒ 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
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