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LTC4096/LTC4096X Dual Input Standalone Li-Ion Battery Chargers FEATURES

DESCRIPTION
The LTC(R)4096/LTC4096X are standalone linear chargers that are capable of charging a single-cell Li-Ion or Li-Polymer battery from both wall adapter and USB inputs. The chargers can detect power at the inputs and automatically select the appropriate power source for charging. No external sense resistor or blocking diode is required for charging due to the internal MOSFET architecture. Internal thermal feedback regulates the battery charge current to maintain a constant die temperature during high power operation or high ambient temperature conditions. The float voltage is fixed at 4.2V and the charge current is programmed with an external resistor. The LTC4096 terminates the charge cycle when the charge current drops below the user programmed termination threshold after the final float voltage is reached. The LTC4096 can be put into shutdown mode reducing the DCIN supply current to 20A, the USBIN supply current to 10A, and the battery drain current to less than 2A even with power applied to both inputs. Other features include trickle charge (LTC4096 only), automatic recharge, undervoltage lockout, charge status output and power present output with 120mA drive capability.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents including 6522118.
Charges Single-Cell Li-Ion Battery from Wall Adapter and USB Inputs Automatic Input Detection (DC Input has Charging Priority) Charge Current Programmable up to 1.2A from Wall Adapter Input C/X Charge Current Termination Input Power Present Output (PWR) with 120mA Drive Capability Independent DC, USB Charge Current Programming Preset Float Voltage with 0.6% Accuracy Thermal Regulation Maximizes Charge Rate Without Risk of Overheating* Charge Status Output Automatic Recharge 20A Charger Quiescent Current in Shutdown Available in a Thermally Enhanced, Low Profile (0.75mm) 10-Lead (3mm x 3mm) DFN Package
APPLICATIONS

Cellular Telephones MP3 Players Portable Handheld Devices
TYPICAL APPLICATION
Dual Input Battery Charger for Single-Cell Li-Ion Battery
WALL ADAPTER USB PORT 1mF 1.24k 2k 1mF LTC4096 DCIN USBIN ON OFF SUSP IDC IUSB CHRG ITERM GND BAT PWR 1k 800mA (WALL) 500mA (USB)
Complete Charge Cycle (1100mAh Battery)
1000 800 600 400 200 0 4.2 4.0 3.8 3.6 3.4 5.0 2.5 0 0 0.5 1.0 2.0 1.5 TIME (HR) 2.5 3.0
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4.2V Li-Ion BATTERY
BATTERY CHARGE VOLTAGE (V) CURRENT (mA)
CONSTANT VOLTAGE USBIN = 5V TA = 25C RIDC = 1.24k RIUSB = 2k
4096 TA01
DCIN VOLTAGE (V)
2k
4096 TA01b
1
LTC4096/LTC4096X ABSOLUTE MAXIMUM RATINGS
(Note 1,7)
PACKAGE/ORDER INFORMATION
TOP VIEW DCIN USBIN PWR CHRG SUSP 1 2 3 4 5 11 10 BAT 9 IDC 8 GND 7 IUSB 6 ITERM
VDCIN, VUSBIN t < 1ms and Duty Cycle < 1% .................. -0.3V to 7V Steady State............................................. -0.3V to 6V BAT, CHRG, SUSP ........................................ -0.3V to 6V IDC, IUSB, ITERM ...........................-0.3V to VCC + 0.3V BAT Short-Circuit Duration............................Continuous PWR Short-Circuit Duration ..........................Continuous BAT, DCIN Pin Current (Note 6)..............................1.25A USBIN Pin Current (Note 6) .....................................1.1A IDC, IUSB, ITERM Pin Current ............................1.25mA Junction Temperature ........................................... 125C Operating Temperature Range (Note 2) ... -40C to 85C Storage Temperature Range................... -65C to 125C
DD PACKAGE 10-LEAD (3mm x 3mm) PLASTIC DFN TJMAX = 125C, JA = 40C/W (Note 3) EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER LTC4096EDD LTC4096XEDD
DD PART MARKING LCSJ LCLM
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL VDCIN VUSBIN IDCIN PARAMETER Adapter Supply Voltage USB Supply Voltage DCIN Supply Current
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VDCIN = 5V, VUSBIN = 5V, RIDC = 1k, RIUSB = 2k, RITERM = 2k unless otherwise noted.
CONDITIONS

MIN 4.25 4.25
TYP
MAX 5.5 5.5
UNITS V V A A A A A A A V V mA mA mA A A A V V
Charge Mode (Note 4), RIDC = 10k Standby Mode; Charge Terminated Shutdown Mode (SUSP = 5V) Charge Mode (Note 5), RIUSB = 10k, VDCIN = 0V Standby Mode; Charge Terminated, VDCIN = 0V Shutdown (VDCIN = 0V, SUSP = 5V) VDCIN > VUSBIN IBAT = 1mA IBAT = 1mA, 0C TA 85C RIDC = 1.25k, Constant-Current Mode RIUSB = 2.1k, Constant-Current Mode RIDC = 10k or RIUSB = 10k Standby Mode, Charge Terminated Shutdown Mode (Charger Disabled) Sleep Mode (VDCIN = 0V, VUSBIN = 0V) Constant-Current Mode, RIDC = 1.25k Constant-Current Mode, RIUSB = 2k
250 50 20 250 50 20 10 4.179 4.158 750 450 88 4.2 4.2 800 476 100 -5 -2 -5 1 1
800 100 40 800 100 40 20 4.221 4.242 850 500 112 -8 -4 -8
IUSBIN
USBIN Supply Current
VFLOAT IBAT
Regulated Output (Float) Voltage BAT Pin Current
VIDC VIUSB
IDC Pin Regulated Voltage IUSB Pin Regulated Voltage
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LTC4096/LTC4096X ELECTRICAL CHARACTERISTICS
SYMBOL ITERMINATE PARAMETER Charge Current Termination Threshold Trickle Charge Current (LTC4096 Only)
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VDCIN = 5V, VUSBIN = 5V, RIDC = 1k, RIUSB = 2k, RITERM = 2k unless otherwise noted.
CONDITIONS RITERM = 1k RITERM = 2k RITERM = 10k VBAT < VTRIKL; RIDC = 1k VBAT < VTRIKL; RIUSB = 2k
MIN 88 42 6 85 42 2.8 4 3.8 5 5
TYP 100 50 9.5 100 50 2.9 135 4.22 200 4 200 30 100 30 150
MAX 112 58 13 115 58 3 4.4 4.2 55 55 0.5
UNITS mA mA mA mA mA V mV V mV V mV mV mV mV mV V V M mV mV ms ms m m C
ITRIKL VTRIKL VUVDC VUVUSB VASD-DC VASD-USB VSUSP RSUSP VCHRG VRECHRG tRECHRG tTERMINATE RON-DC RON-USB RDC-PWR RUSB-PWR TLIM
Trickle Charge Threshold Voltage VBAT Rising (LTC4096 Only) Hysteresis DCIN Undervoltage Lockout Voltage USBIN Undervoltage Lockout Voltage VDCIN - VBAT Lockout Threshold Voltage From Low to High Hysteresis From Low to High Hysteresis VDCIN from High to Low, VBAT = 4.3V VDCIN from Low to High, VBAT = 4.3V
VUSBIN - VBAT Lockout Threshold VUSBIN from High to Low, VBAT = 4.3V Voltage VUSBIN from Low to High, VBAT = 4.3V VIL, Logic Low Voltage VIH, Logic High Voltage SUSP Pulldown Resistance CHRG Output Low Voltage Recharge Battery Threshold Voltage Termination Comparator Filter Time Power FET "ON" Resistance (Between DCIN and BAT) Power FET "ON" Resistance (Between USBIN and BAT) Power FET "ON" Resistance (Between DCIN and PWR) Power FET "ON" Resistance (Between USBIN and PWR) Junction Temperature in Constant-Temperature Mode VDCIN = 5V, VUSBIN = 0V VDCIN = 0V, VUSBIN = 5V ICHRG = 5mA VFLOAT - VRECHRG

1.2 1.3 30 3.4 62 50 1.6 3 420 470 15 6.6 115 7 150 80
Recharge Comparator Filter Time VBAT from High to Low IBAT Drops Below Termination Threshold
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC4096 is guaranteed to meet the performance specifications from 0C to 85C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Failure to correctly solder the Exposed Pad of the package to the PC board will result in a thermal resistance much higher than 40C/W. See Thermal Considerations.
Note 4: Supply current includes IDC and ITERM pin current (approximately 100A each) but does not include any current delivered to the battery through the BAT pin. Note 5: Supply current includes IUSB and ITERM pin current (approximately 100A each) but does not include any current delivered to the battery through the BAT pin. Note 6: Guaranteed by long term current density limitations. Note 7: VCC is greater of DCIN or USBIN
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LTC4096/LTC4096X TYPICAL PERFORMANCE CHARACTERISTICS
Battery Regulated Output (Float) Voltage vs Charge Current
4.26 4.24 4.22 VBAT (V) VBAT (V) 4.20 4.18 4.16 4.14 4.12 4.10 0 200 400 600 800 1000 CHARGE CURRENT (mA) 1200 VDCIN = 5V RIDC = 1k 4.26 4.24 4.22 VBAT (V) 4.20 4.18 4.16 4.14 4.12 4.10 0 100 300 400 500 CHARGE CURRENT (mA) 200 600
4096 G02
TA = 25C, unless otherwise noted. Battery Regulated Output (Float) Voltage vs Temperature
4.215 4.210 4.205 4.200 4.195 4.190 4.185 4.180 4.175 -50 -25 0 25 50 TEMPERATURE (C) 75 100
4096 G03
Battery Regulated Output (Float) Voltage vs Charge Current
VUSBIN = 5V RIUSB = 2k
VDCIN = 5V RIDC = 1k VUSBIN = 5V RIUSB = 2k
4096 G01
Battery Regulated Output (Float) Voltage vs DCIN Voltage
4.26 4.24 4.22 VBAT (V) VBAT (V) 4.20 4.18 4.16 4.14 4.12 4.10 4.25 4.50 4.75 5.00 VDCIN (V) 5.25 5.50
4096 G04
Battery Regulated Output (Float) Voltage vs USBIN Voltage
4.26 4.24 4.22 IBAT (mA) 4.20 4.18 4.16 4.14 4.12 4.10 4.25 4.50 4.75 5.00 VUSBIN (V) 5.25 5.50
4096 G05
Charge Current vs IDC Pin Voltage
1200 1000 800 600 400 200 0 0 0.2 0.4 0.6 0.8 VIDC (V) 1.0 1.2
4096 G06
IBAT = 10mA RIDC = 1k
IBAT = 10mA RIUSB = 2k
VDCIN = 5V RIDC = 1k
Charge Current vs IUSB Pin Voltage
600 500 400 IBAT (mA) 300 200 100 0 0 0.2 0.4 0.6 VIUSB (V)
4096 G07
IDC Pin Voltage vs Temperature (Constant-Current Mode)
1.006 1.004 1.002 1.000 0.998 0.996 0.994 -50 VIUSB (V) VIDC (V) VDCIN = 5V RIDC = 10k 1.006 1.004 1.002 1.000 0.998 0.996
IUSB Pin Voltage vs Temperature (Constant-Current Mode)
VUSBIN = 5V RIUSB = 10k
VUSBIN = 5V RIUSB = 2k
0.8
1.0
1.2
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G08
0.994 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G09
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LTC4096/LTC4096X TYPICAL PERFORMANCE CHARACTERISTICS
IDC Pin Voltage vs VDCIN (Constant-Current Mode)
1.006 1.004 1.002 1.000 0.998 0.996 0.994 4.25 VIUSB (V) VIDC (V) VBAT = 3.7V RIDC = 10k 1.006 1.004 VRECHRG (mV) 1.002 1.000 0.998 0.996 0.994 4.25
TA = 25C, unless otherwise noted. Recharge Threshold Voltage vs Temperature
70 65 60 55 50 45 40 35 VDCIN = VUSBIN = 5V
IUSB Pin Voltage vs VUSBIN (Constant-Current Mode)
VBAT = 3.7V RIUSB = 10k
4.50
4.75
5.00 VDCIN (V)
5.25
5.50
4096 G10
4.50
4.75
5.00 VUSBIN (V)
5.25
5.50
4096 G11
30 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G12
Charge Current vs Battery Voltage
1200 1150 1100 IBAT (mA) IBAT (mA) 1050 1000 950 900 850 800 3.0 3.2 3.4 3.6 VBAT (V) 3.8 4.0
4096 G13
Charge Current vs Battery Voltage
600 575 550 IBAT (mA) 525 500 475 450 425 400 3.0 3.2 3.4 3.6 VBAT (V) 3.8 4.0
4096 G14
Charge Current vs Ambient Temperature with Thermal Regulation
1200 RIDC = 1k 1000 800 600 R IUSB = 2k 400 200 VDCIN = VUSBIN = 5V VBAT = 3.7V JA = 40C/W 0 -50 -25 0 25 50 75 TEMPERATURE (C) THERMAL REGULATION
VDCIN = 5V RIDC = 1k
VUSBIN = 5V RIUSB = 2k
100
125
4096 G15
Charge Current vs Supply Voltage
104 VBAT = 3.7V 1200
Charge Current vs Battery Voltage
600 LTC4096X 1000 500 400 IBAT (mA) 300 200 VDCIN = 5V RIDC = 1k JA = 40C/W 3.0 3.5 VBAT (V) 4.0 4.5
4096 G17
Charge Current vs Battery Voltage
LTC4096X
102 IBAT (mA) IBAT (mA) RIDC = 10k 100 RIUSB = 10k 800 600 400 98 200 96 4.25 0 2.0 LTC4096 2.5 100 LTC4096 0 2.0 2.5 VUSBIN = 5V RIUSB = 2k JA = 40C/W 3.0 3.5 VBAT (V) 4.0 4.5
4096 G18
4.50
5.00 VDCIN, VUSBIN (V)
4.75
5.25
5.50
4096 G16
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LTC4096/LTC4096X TYPICAL PERFORMANCE CHARACTERISTICS
DCIN Power FET On-Resistance vs Temperature
550 VDCIN = 4V IBAT = 200mA 550
TA = 25C, unless otherwise noted. PWR-DCIN and PWR-USBIN Power FET On-Resistance vs Temperature
20 VDCIN = 5V IPWR = 30mA 15 RPWRON ()
USBIN Power FET On-Resistance vs Temperature
VUSBIN = 4V IBAT = 200mA
500 RUSBON (m) RDCON (m)
500
450
450
10
400
400
350
350
5
VUSBIN = 5V IPWR = 30mA
300 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G19
300 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G20
0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G21
VPWR vs IPWR
6 5 4 ICHRG (mA) VPWR (V) 3 2 1 0 0 25 50 75 100 IPWR (mA) 125 150
4096 G22
CHRG Pin I-V Curve
120 100 80 VDCIN = VUSBIN = 5V VBAT = 4V 100
CHRG Pin Output Low Voltage vs Temperature
ICHRG = 5mA VDCIN = VUSBIN = 5.5V
VUSBIN = 5V
80 VCHRG (mV)
60 VDCIN = VUSBIN = 4.25V 40
VDCIN = 5V
60 40 20 0 0 1 2 3 VCHRG (V)
4096 G23
20
4
5
6
0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G24
SUSP Pin Threshold Voltage (On-to-Off) vs Temperature
1000 950 4.0 RSUSP (M) VSUSP (mV) 900 850 800 3.0 750 700 -50 VDCIN = VUSBIN = 5V 4.5
SUSP Pin Pulldown Resistance vs Temperature
60 50 40 3.5 IDCIN (A) 30
Shutdown Supply Current vs Temperature and VDCIN
SUSP = VDCIN VUSBIN = VDCIN
VDCIN = 5.5V 20 VDCIN = 4.25V 10
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G25
2.5 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G26
0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G27
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LTC4096/LTC4096X TYPICAL PERFORMANCE CHARACTERISTICS
Shutdown Supply Current vs Temperature and VUSBIN
60 50 40 IUSBIN (A) VUV (V) 30 VUSBIN = 5.5V 20 10 0 -50 VUSBIN = 4.25V SUSP = VUSBIN VDCIN = 0V 4.10 4.05 DCIN UVLO 4.00 3.95 3.90 3.85 3.80 3.75 -25 0 25 50 TEMPERATURE (C) 75 100
4096 G28
TA = 25C, unless otherwise noted. Undervoltage Lockout Voltage (Falling) vs Temperature
USBIN UVLO
3.70 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4096 G29
PIN FUNCTIONS
DCIN (Pin 1): Wall Adapter Input Supply Pin. Provides power to the battery charger. The maximum supply current is 1.2A. This pin should be bypassed with a 1F capacitor. USBIN (Pin 2): USB Input Supply Pin. Provides power to the battery charger. The maximum supply current is 1A. This pin should be bypassed with a 1F capacitor. PWR (Pin 3): Power Present Output. When the DCIN or USBIN pin voltage is sufficient to begin charging (i.e. when the DCIN or USBIN supply is greater than the undervoltage lockout thresholds and at least 100mV or 150mV, respectively, above the battery terminal), the PWR pin is connected to the appropriate input through an internal P-channel MOSFET. If sufficient voltage to charge is not present on DCIN or USBIN the PWR pin is high impedance. This output is able to source up to 120mA. CHRG (Pin 4): Open-Drain Charge Status Output. When the LTC4096 is charging, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed, CHRG becomes high impedance. This output is capable of sinking up to 10mA, making it suitable for driving an LED. SUSP (Pin 5): Charge Enable Input. A logic low on this pin enables the charger. If left floating, an internal 3.4M pull-down resistor defaults the LTC4096 to charge mode. Pull this pin high for shutdown. ITERM (Pin 6): Charge Termination Current Threshold Program. The termination current threshold, ITERMINATE, is set by connecting a resistor, RITERM, to ground. ITERMINATE is set by the following formula: ITERMINATE = 100V RITERM
When the battery current, IBAT, falls below the termination threshold, charging stops and the CHRG output becomes high impedance. IUSB (Pin 7): Charge Current Program for USB Power. The charge current is set by connecting a resistor, RIUSB, to ground. When charging in constant-current mode, this pin servos to 1V. The voltage on this pin can be used to measure the battery current delivered from the USBIN input using the following formula: IBAT = VIUSB * 1000 RIUSB
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LTC4096/LTC4096X PIN FUNCTIONS
GND (Pin 8): Ground. IDC (Pin 9): Charge Current Program for Wall Adapter Power. The charge current is set by connecting a resistor, RIDC, to ground. When charging in constant-current mode, this pin servos to 1V. The voltage on this pin can be used to measure the battery current delivered from the DCIN input using the following formula: IBAT = VIDC *1000 RIDC BAT (Pin 10): Charger Output. This pin provides charge current to the battery and regulates the final float voltage to 4.2V. Exposed Pad (Pin 11): GND. The exposed backside of the package is ground and must be soldered to PC board ground for electrical connection and maximum heat transfer.
BLOCK DIAGRAM
DCIN 1 BAT 10 USBIN 2 CC/CV REGULATOR CC/CV REGULATOR
+
4.2V
DCON
USBON
+ -
4V
-
DCIN UVLO USBIN UVLO
+
BAT CHRG 4 10mA MAX
+ -
RDC-PWR DCIN HIGH-Z 3 PWR RUSB-PWR BAT
-
+
RECHARGE LOGIC RECHRG
4.15V
USBIN
-
BAT DC_ENABLE USB_ENABLE
TRICKLE TERM TRICKLE CHARGE*
SUSP
5 RSUSP
TERMINATION
*NOT PRESENT IN THE "X" VERSION RITERM RIDC RIUSB
8
-
2.9V
CHARGER CONTROL THERMAL REGULATION AND SHUTDOWN 100mV IBAT/1000 IBAT/1000 IBAT/1000
+ - -
TDIE 115C 150C
+ + -
ITERM 6 9
IDC 7
IUSB
GND 8, 11
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LTC4096/LTC4096X OPERATION
The LTC4096 is designed to efficiently manage charging a single-cell lithium-ion battery from two separate voltage sources: a wall adapter and USB power bus. Using the constant-current/constant-voltage algorithm, the charger can deliver up to 1.2A of charge current from the wall adapter supply or up to 1A of charge current from the USB supply with a final float voltage accuracy of 0.6%. The LTC4096 has two internal P-channel power MOSFETs, thermal regulation and shut down circuitry. No blocking diodes or external sense resistors are required. Power Source Selection The LTC4096 can charge a battery from either the wall adapter input or the USB port input. The LTC4096 automatically senses the presence of voltage at each input. If both voltage sources are present, the LTC4096 defaults to the wall adapter source provided sufficient voltage is present at the DCIN input. "Sufficient voltage" is defined as: * Supply voltage is greater than the UVLO threshold. * Supply voltage is greater than the battery voltage by 30mV (100mV or 150mV rising, 30mV falling). The power present output pin (PWR) indicates that sufficient input voltage is available. Table 1 describes the behavior of this status output.
Table 1. Power Source Selection
VUSBIN > 4V and VUSBIN > BAT + 30mV VDCIN > 4.2V and VDCIN > BAT + 30mV VDCIN < 4.2V or VDCIN < BAT + 30mV VUSBIN < 4V or VUSBIN < BAT + 30mV
Programming and Monitoring Charge Current The charge current delivered to the battery from the wall adapter supply is programmed using a single resistor from the IDC pin to ground. RIDC = 1000 V ICHRG(DC) , ICHRG(DC) = 1000 V RIDC
Similarly, the charge current from the USB supply is programmed using a single resistor from the IUSB pin to ground. RIUSB = 1000 V ICHRG(USB) , ICHRG(USB) = 1000 V RIUSB
Charge current out of the BAT pin can be determined at any time by monitoring the IDC or IUSB pin voltage and applying the following equations: IBAT = IBAT = VIDC * 1000, (ch arg ing from wall adapter ) RIDC VIUSB * 1000, (ch arg ing from USB sup ply) RIUSB
Charger powered from wall adapter source; Charger powered from wall adapter source VPWR = VDCIN - RDC-PWR * IPWR VPWR = VDCIN - RDC-PWR * IPWR USBIN current < 25A Charger powered from USB source; VPWR = VUSBIN - RUSB-PWR * IPWR No charging PWR: Hi-Z
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LTC4096/LTC4096X OPERATION
Programming Charge Termination The charge cycle terminates when the charge current falls below the programmed termination threshold during constant-voltage mode. This threshold is set by connecting an external resistor, RITERM, from the ITERM pin to ground. The charge termination current threshold (ITERMINATE) is set by the following equation: RITERM = 100V ITERMINATE , ITERMINATE = 100V RITERM during trickle charge mode would be 80mA and 50mA, respectively. The LTC4096X has no trickle charge mode. Automatic Recharge In standby mode, the charger sits idle and monitors the battery voltage using a comparator with a 1.6ms filter time (tRECHRG). A charge cycle automatically restarts when the battery voltage falls below 4.15V (which corresponds to approximately 80%-90% battery capacity). This ensures that the battery is kept at, or near, a fully charged condition and eliminates the need for periodic charge cycle initiations. If the battery is removed from the charger, a sawtooth waveform appears at the battery output. This is caused by the repeated cycling between termination and recharge events. This cycling results in pulsing at the CHRG output; an LED connected to this pin will exhibit a blinking pattern, indicating to the user that a battery is not present. The frequency of the sawtooth is dependent on the amount of output capacitance. Status Indicators The charge status output (CHRG) has two states: pull-down and high impedance. The pull-down state indicates that the LTC4096 is in a charge cycle. Once the charge cycle has terminated or the LTC4096 is disabled, the pin state becomes high impedance. The pull-down state is capable of sinking up to 10mA. The power present output (PWR) has two states: DCIN/ USBIN voltages and high impedance. These states are described in Table 1 and the circuit is shown in Figure 2. The high impedance state indicates that voltage is not present at either DCIN or USBIN, so LTC4096 lacks sufficient power to charge the battery. The PWR present output is capable of sourcing up to 120mA steady state and includes short circuit protection.
*Any external sources that hold the ITERM pin above 100mV will prevent the LTC4096 from terminating a charge cycle.
The termination condition is detected by using an internal filtered comparator to monitor the ITERM pin. When the ITERM pin voltage drops below 100mV* for longer than tTERMINATE (typically 3ms), the charge cycle terminates, charge current latches off and the LTC4096 enters standby mode. When charging, transient loads on the BAT pin can cause the ITERM pin to fall below 100mV for short periods of time before the DC charge current has dropped below the programmed termination current. The 3ms filter time (tTERMINATE) on the termination comparator ensures that transient loads of this nature do not result in premature charge cycle termination. Once the average charge current drops below the programmed termination threshold, the LTC4096 terminates the charge cycle and stops providing any current out of the BAT pin. In this state, any load on the BAT pin must be supplied by the battery. Low-Battery Charge Conditioning (Trickle Charge) This feature ensures that deeply discharged batteries are gradually charged before applying full charge current. If the BAT pin voltage is below 2.9V, the LTC4096 supplies 1/10th of the full charge current to the battery until the BAT pin rises above 2.9V. For example, if the charger is programmed to charge at 800mA from the wall adapter input and 500mA from the USB input, the charge current
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LTC4096/LTC4096X APPLICATIONS INFORMATION
Manual Shutdown The SUSP pin has a 3.4M pulldown resistor to GND. A logic low enables the charger and logic high disables it (the pulldown defaults the charger to the charging state). The DCIN input draws 20A when the charger is in shutdown. The USBIN input draws 20A during shutdown if no power is applied to DCIN, but draws only 10A when VDCIN > VUSBIN. Thermal Limiting An internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 115C. This feature protects the LTC4096 from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the device. The charge current can be set according to typical (not worst case) ambient temperature with the assurance that the charger will automatically reduce the current in worst case conditions. A safety thermal shut down circuit will turn off the charger if the die temperature rises above a value of approximately 150C. DFN power considerations are discussed further in the Applications Information section.
STARTUP DCIN POWER APPLIED POWER SELECTION DCIN POWER REMOVED TRICKLE CHARGE* MODE BAT < 2.9V 1/10th FULL CURRENT CHRG STATE: PULLDOWN PWR STATE: DCIN BAT > 2.9V 2.9V < BAT CHARGE MODE FULL CURRENT CHRG STATE: PULLDOWN PWR STATE: DCIN IBAT < ITERMINATE IN VOLTAGE MODE STANDBY MODE BAT < 4.15V NO CHARGE CURRENT CHRG STATE: Hi-Z PWR STATE: DCIN 1/10th FULL CURRENT CHRG STATE: PULLDOWN PWR STATE: USBIN BAT > 2.9V CHARGE MODE FULL CURRENT CHRG STATE: PULLDOWN PWR STATE: USBIN IBAT < ITERMINATE IN VOLTAGE MODE STANDBY MODE NO CHARGE CURRENT CHRG STATE: Hi-Z PWR STATE: USBIN BAT < 4.15V 2.9V < BAT USBIN POWER REMOVED OR DCIN POWER APPLIED ONLY USB POWER APPLIED
TRICKLE CHARGE* MODE BAT < 2.9V
SUSP DRIVEN LOW
SHUTDOWN MODE IDCIN DROPS TO 20A CHRG STATE: Hi-Z PWR STATE: DCIN
SUSP DRIVEN HIGH
SUSP DRIVEN HIGH
SHUTDOWN MODE IUSBIN DROPS TO 20A
SUSP DRIVEN LOW
DCIN POWER REMOVED
*NOT PRESENT IN THE "X" VERSION
USBIN POWER REMOVED OR DCIN POWER APPLIED
CHRG STATE: Hi-Z PWR STATE: USBIN
4096 F01
Figure 1. LTC4096 State Diagram of a Charge Cycle
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LTC4096/LTC4096X APPLICATIONS INFORMATION
Using a Single Charge Current Program Resistor In applications where the programmed wall adapter charge current and USB charge current are the same, a single program resistor can be used to set both charge currents. Figure 3 shows a charger circuit that uses one charge current program resistor. In this circuit, one resistor programs the same charge current for each input supply. ICHRG(DC) = ICHRG(USB) = 1000 V RISET Stability Considerations The constant-voltage mode feedback loop is stable without any compensation provided a battery is connected to the charger output. However, a 4.7F capacitor with a 1 series resistor is recommended at the BAT pin to keep the ripple voltage low when the battery is disconnected. When the charger is in constant-current mode, the charge current program pin (IDC or IUSB) is in the feedback loop, not the battery. The constant-current mode stability is affected by the impedance at the charge current program pin. With no additional capacitance on this pin, the charger is stable with program resistor values as high as 20K (ICHRG = 50mA); however, additional capacitance on these nodes reduces the maximum allowed program resistor.
The LTC4096 can also program the wall adapter charge current and USB charge current independently using two program resistors, RIDC and RIUSB. Figure 4 shows a charger circuit that sets the wall adapter charge current to 800mA and the USB charge current to 500mA.
DCIN 1
USBIN 2
+
4.2V
+ -
DCIN UVLO DCON DCON USBON USBIN UVLO 4V
-
+
BAT 10
+ -
BAT 10
-
V
V
CURR-LIM
CURR-LIM
3 120mA MAX PWR
Figure 2. Input Power Present Output (PWR) Circuit
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- +
+-
+
-
-+
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LTC4096/LTC4096X APPLICATIONS INFORMATION
WALL ADAPTER USB PORT 4.2V 1-CELL Li-Ion BATTERY RIUSB 2k 1%
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LTC4096 DCIN USBIN 1F 1F PWR 1k IUSB RIDC 1.24k 1% IDC CHRG ITERM GND BAT
800mA (WALL) 500mA (USB)
WALL ADAPTER USB PORT 1F 1F RISET 2k 1%
LTC4096 DCIN USBIN IUSB IDC ITERM GND BAT
500mA
+
RITERM 1k 1%
+
RITERM 1k 1%
4.2V 1-CELL Li-Ion BATTERY
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Figure 3. Dual Input Charger Circuit. The Wall Adapter Charge Current and USB Charge Current are Both Programmed to be 500mA
Figure 4. Full Featured Dual Input Charger Circuit
TA = 115C - (5V - 3.3V) * (800mA) * 40C/W TA = 115C - 1.36W * 40C/W = 115C - 54.4C TA = 60.6C The LTC4096 can be used above 60.6C ambient, but the charge current will be reduced from 800mA. The approximate current at a given ambient temperature can be approximated by: IBAT = 105C - TA (VIN - VBAT ) * JA
Power Dissipation When designing the battery charger circuit, it is not necessary to design for worst-case power dissipation scenarios because the LTC4096 automatically reduces the charge current during high power conditions. The conditions that cause the LTC4096 to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the IC. Most of the power dissipation is generated from the internal MOSFET pass device. Thus, the power dissipation is calculated to be: PD = (VIN - VBAT) * IBAT PD is the power dissipated, VIN is the input supply voltage (either DCIN or USBIN), VBAT is the battery voltage and IBAT is the charge current. The approximate ambient temperature at which the thermal feedback begins to protect the IC is: TA = 115C - PD * JA TA = 115C - (VIN - VBAT) * IBAT * JA Example: An LTC4096 operating from a 5V wall adapter (on the DCIN input) is programmed to supply 800mA full-scale current to a discharged Li-Ion battery with a voltage of 3.3V. Assuming JA is 40C/W (see Thermal Considerations), the ambient temperature at which the LTC4096 will begin to reduce the charge current is approximately:
Using the previous example with an ambient temperature of 70C, the charge current will be reduced to approximately: IBAT = IBAT 105C - 60C 45C = (5V - 3.3V)* 40C / W 68C / A = 662mA
It is important to remember that LTC4096 applications do not need to be designed for worst-case thermal conditions, since the IC will automatically reduce power dissipation when the junction temperature reaches approximately 115C. Moreover a thermal shut down protection circuit around 150C safely prevents any damage putting LTC4096 into shut down mode.
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LTC4096/LTC4096X APPLICATIONS INFORMATION
Thermal Considerations In order to deliver maximum charge current under all conditions, it is critical that the exposed metal pad on the backside of the LTC4096 package is properly soldered to the PC board ground. When correctly soldered to a 2500mm2 double sided 1oz copper board, the LTC4096 has a thermal resistance of approximately 40C/W. Failure to make thermal contact between the exposed pad on the backside of the package and the copper board will result in thermal resistances far greater than 40C/W. As an example, a correctly soldered LTC4096 can deliver over 800mA to a battery from a 5V supply at room temperature. Without a good backside thermal connection, this number would drop to much less than 500mA. Protecting the USB Pin and Wall Adapter Input from Overvoltage Transients Caution must be exercised when using ceramic capacitors to bypass the USBIN pin or the wall adapter inputs. High voltage transients can be generated when the USB or wall
DRAIN-BULK DIODE OF FET WALL ADAPTER LTC4096 DCIN
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adapter is hot plugged. When power is supplied via the USB bus or wall adapter, the cable inductance along with the self resonant and high Q characteristics of ceramic capacitors can cause substantial ringing which could exceed the maximum voltage ratings and damage the LTC4096. Refer to Linear Technology Application Note 88, entitled "Ceramic Input Capacitors Can Cause Overvoltage Transients" for a detailed discussion of this problem. Always use an oscilloscope to check the voltage waveforms at the USBIN and DCIN pins during USB and wall adapter hot-plug events to ensure that overvoltage transients have been adequately removed. Reverse Polarity Input Voltage Protection In some applications, protection from reverse polarity voltage on the input supply pins is desired. If the supply voltage is high enough, a series blocking diode can be used. In other cases where the voltage drop must be kept low, a P-channel MOSFET can be used (as shown in Figure 5).
Figure 5. Low Loss Input Reverse Polarity Protection
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LTC4096/LTC4096X PACKAGE DESCRIPTION
DD Package 10-Lead Plastic DFN (3mm x 3mm)
(Reference LTC DWG # 05-08-1698)
0.675 0.05
3.50 0.05 1.65 0.05 2.15 0.05 (2 SIDES) PACKAGE OUTLINE 0.25 0.05 0.50 BSC 2.38 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 6 0.38 0.10 10
3.00 0.10 (4 SIDES) PIN 1 TOP MARK (SEE NOTE 6)
1.65 0.10 (2 SIDES)
(DD10) DFN 1103
5 0.200 REF 0.75 0.05 2.38 0.10 (2 SIDES)
1
0.25 0.05 0.50 BSC
0.00 - 0.05
BOTTOM VIEW--EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC4096/LTC4096X RELATED PARTS
PART NUMBER LTC3455 LTC4053 DESCRIPTION Dual DC/DC Converter with USB Power Management and Li-Ion Battery Charger USB Compatible Monolithic Li-Ion Battery Charger COMMENTS Efficiency >96%, Accurate USB Current Limiting (500mA/100mA), 4mm x 4mm QFN-24 Package Standalone Charger with Programmable Timer, Up to 1.25A Charge Current Thermal Regulation Prevents Overheating, C/10 Termination, C/10 Indicator, Up to 800mA Charge Current Charges Single-Cell Li-Ion Batteries Directly from USB Port, Thermal Regulation, 4mm x 4mm QFN-16 Package C/10 Charge Termination, Battery Kelvin Sensing, 7% Charge Accuracy
LTC4054/LTC4054X Standalone Linear Li-Ion Battery Charger with Integrated Pass Transistor in ThinSOTTM LTC4055 USB Power Controller and Battery Charger
LTC4058/LTC4058X Standalone 950mA Lithium-Ion Charger in DFN LTC4061 LTC4061-4.4 LTC4062
Standalone Li-Ion Charger with Thermistor Interface 4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN-10 Package Standalone Li-Ion Charger with Thermistor Interface 4.4V, 0.4% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN-10 Package Standalone Li-Ion Charger with Micropower Comparator 4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN-10 Package 4.2V, 0.6% Float Voltage, Up to 750mA Charge Current, 2mm x 2mm DFN-6 Package Seamless Transition Between Input Power Sources: Li-Ion Battery, USB and Wall Adapter, Low-Loss (50m) Ideal Diode, 4mm x 4mm QFN-24 Package Charge Current up to 950mA, Thermal Regulation, 3mm x 3mm DFN-8 Package 4.2V, 0.6% Float Voltage, Up to 750mA Charge Current, Timer Termination + C/10 Detection Output Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs with Automatic Input Power Detection and Selection, 950mA Charger Current, Thermal Regulation, C/X Charge Termination, 3mm x 3mm DFN Package Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs with Automatic Input Power Detection and Selection, 950mA Charger Current, Thermal Regulation, C/X Charge Termination, 3mm x 3mm DFN Package Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs with Automatic Input Power Detection and Selection, 950mA Charger Current, Thermal Regulation, C/10 Charge Termination, 3mm x 3mm DFN Package Charges Single-Cell Li-Ion Batteries Directly from a USB Port, Thermal Regulation, 200m Ideal Diode with <50m option, 4mm x 3mm DFN-14 Package
LTC4065/LTC4065A Standalone 750mA Li-Ion Charger in 2mm x 2mm DFN LTC4066 USB Power Controller and Li-Ion Linear Battery Charger with Low-Loss Ideal Diode
LTC4068/LTC4068X Standalone Linear Li-Ion Battery Charger with Programmable Termination LTC4069 LTC4075 Standalone Li-Ion Battery Charger with NTC Thermistor Input in 2mm x 2mm DFN Dual Input Standalone Li-Ion Battery Charger
LTC4076
Dual Input Standalone Li-Ion Battery Charger
LTC4077
Dual Input Standalone Li-Ion Battery Charger
LTC4085
USB Power Manager with Ideal Diode Controller and Li-Ion Charger
LTC4089/ LTC4089-5
USB Power Manager with Ideal Diode Controller and High Efficiency 1.2A Charger from 6V to 36V (40V Max) Input, Charges Single High Efficiency Li-Ion Battery Charger Cell Li-Ion Batteries Directly from a USB Port, Thermal Regulation; 200m Ideal Diode with <50m Option, 4mm x 3mm DFN-14 Package, Bat-Track Adaptive Output Control (LTC4089); Fixed 5V Output (LTC4089-5) USB Power Manager and Battery Charger Low Loss PowerPathTM Controller in ThinSOT Manages Total Power Between a USB Peripheral and Battery Charger, Ultralow Battery Drain: 1A, ThinSOT Package Automatic Switching Between DC Sources, Load Sharing, Replaces ORing Diodes
LTC4410 LTC4411/LTC4412
ThinSOT and PowerPath are trademarks of Linear Technology Corporation
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16 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 1006 * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2006

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