View LTC4065L_4552670.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

LTC4065L/LTC4065LX Standalone 250mA Li-Ion Battery Charger in 2 x 2 DFN
FEATURES

DESCRIPTIO

Charge Current Programmable up to 250mA with 5% Accuracy Complete Linear Charger in 2mm x 2mm DFN Package C/10 Charge Current Detection Output Timer Termination No External MOSFET, Sense Resistor or Blocking Diode Required Preset 4.2V Float Voltage with 0.6% Accuracy Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charging Rate Without Risk of Overheating Charge Current Monitor Output for Gas Gauging Automatic Recharge Charges Single Cell Li-Ion Batteries Directly from USB Port 20A Supply Current in Shutdown Mode Soft-Start Limits Inrush Current Available Without Trickle Charge (LTC4065LX) Tiny 6-Lead (2mm x 2mm) DFN Package
The LTC(R)4065L is a complete constant-current/constantvoltage linear charger for single-cell lithium-ion batteries. Its small size and ability to accurately regulate low charge currents make the LTC4065L especially well-suited for portable applications using low capacity rechargeable lithium-ion cells. Furthermore, LTC4065L is specifically designed to work within USB power specifications. The CHRG pin indicates when charge current has dropped to ten percent of its programmed value (C/10). An internal timer terminates charging according to battery manufacturer specifications. No external sense resistor or blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates charge current to limit the die temperature during high power operation or high ambient temperature conditions. When the input supply (wall adapter or USB supply) is removed, the LTC4065L automatically enters a low current state, dropping battery drain current to less than 1A. With power applied, LTC4065L can be put into shutdown mode, reducing the supply current to less than 20A. The full-featured LTC4065L also includes automatic recharge, low-battery charge conditioning (trickle charging) and soft-start (to limit inrush current). The LTC4065L is available in a tiny 6-lead, low profile (0.75mm) 2mm x 2mm DFN package.
APPLICATIO S

Charger for Li-Ion Coin Cell Batteries Portable MP3 Players, Wireless Headsets Bluetooth Applications Multifunction Wristwatches
, 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, 6700364.
TYPICAL APPLICATIO
VIN 4.3V TO 5.5V C1 1F VCC R1 510
Complete Charge Cycle (180mAh Battery)
110 100
CHARGE CURRENT (mA)
Standalone Li-Ion Battery Charger
100mA BAT
90 CONSTANT CURRENT 80 70 60 50 40 30 20 10 0 0 VCC = 5V RPROG = 2k 0.5 1 1.5 2 2.5 3 TIME (HOURS)
LTC4065L CHRG PROG EN GND R3 2k
+
4.2V Li-Ion BATTERY
4065L TA01
U
4.3 CONSTANT VOLTAGE CHRG TRANSITION 4.1
BATTERY VOLTAGE (V)
U
U
3.9 3.7
CHARGE TERMINATION
3.5 3.3
3.5
4
4.5
4065 TA02
4065lxfa
1
LTC4065L/LTC4065LX
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW GND 1 CHRG 2 BAT 3 7 6 PROG 5 EN 4 VCC
VCC t < 1ms and Duty Cycle < 1% ................. - 0.3V to 7V Steady State ........................................... - 0.3V to 6V BAT, CHRG ................................................. -0.3V to 6V EN, PROG ....................................... -0.3V to VCC + 0.3V BAT Short-Circuit Duration ...........................Continuous BAT Pin Current ................................................. 275mA PROG Pin Current ........................................... 1.342mA Junction Temperature (Note 6) ............................ 125C Operating Temperature Range (Note 2) .. - 40C to 85C Storage Temperature Range ................ - 65C to 125C
DC PACKAGE 6-LEAD (2mm x 2mm) PLASTIC DFN
TJMAX = 125C, JA = 60C/W (NOTE 3) EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER LTC4065LEDC LTC4065LXEDC
DC PART MARKING LCBD LCKS
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
The denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25C. VCC = 5V, VBAT = 3.8V, VEN = 0V unless otherwise specified. (Note 2)
SYMBOL VCC ICC ICCMS ICCUV VFLOAT IBAT IBMS IBUV VUVLO VPROG VASD VMSH VMSL REN PARAMETER VCC Supply Voltage Quiescent VCC Supply Current VCC Supply Current in Shutdown VCC Supply Current in Undervoltage Lockout VBAT Regulated Output Voltage BAT Pin Current Battery Drain Current in Shutdown Mode CONDITIONS (Note 4) VBAT = 4.5V (Forces IBAT and IPROG = 0) VEN = 5V VCC < VBAT, VCC = 3.5V, VBAT = 4V IBAT = 2mA IBAT = 2mA, 0C < TA < 85C RPROG = 13.3k (0.1%), Current Mode RPROG = 1.33k (0.1%), Current Mode VEN = VCC

MIN 3.75
TYP 120 20 6
MAX 5.5 250 40 11 4.225 4.242 17.5 162 1 4 3.8 3.2 1.02 1.02 100 45 1
UNITS V A A A V V mA mA A A V V V V mV mV V V M
4.175 4.158 13.5 148 -1 0 3.4 2.8 0.98 0.98 60 15 0.6
4.2 4.2 15.5 155 0 1 3.6 3.0 1 1 80 30
Battery Drain Current in Undervoltage VCC = 3.5V, VBAT = 4V Lockout VCC Undervoltage Lockout Voltage PROG Pin Voltage Automatic Shutdown Threshold Voltage Manual Shutdown High Voltage Manual Shutdown Low Voltage EN Pin Input Resistance VCC Rising VCC Falling RPROG = 1.33k, IPROG = 0.75mA RPROG = 13.3k, IPROG = 75A (VCC - VBAT), VCC Low to High (VCC - VBAT), VCC High to Low VEN Rising VEN Falling
0.9
1.5
3.3
4065lxfa
2
U
W
U
U
WW
W
LTC4065L/LTC4065LX
ELECTRICAL CHARACTERISTICS
The denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25C. VCC = 5V, VBAT = 3.8V, VEN = 0V unless otherwise specified. (Note 2)
SYMBOL tSS ITRKL VTRKL VTRHYS VRECHRG VUVCL1 VUVCL2 tTIMER PARAMETER Soft-Start Time Trickle Charge Current Trickle Charge Threshold Voltage Trickle Charge Hysteresis Voltage Recharge Battery Threshold Voltage (VCC - VBAT) Undervoltage Current Limit Termination Timer Recharge Time Low-Battery Trickle Charge Time VCHRG ICHRG IC/10 TLIM RON fBADBAT DBADBAT CHRG Pin Output Low Voltage CHRG Pin Input Current End of Charge Indication Current Level Junction Temperature in Constant Temperature Mode Power FET "ON" Resistance (Between VCC and BAT) Defective Battery Detection CHRG Pulse Frequency Defective Battery Detection CHRG Pulse Frequency Duty Ratio IBAT = 150mA VBAT = 2.5V ICHRG = 5mA VBAT = 4.5V, VCHRG = 5V RPROG = 1.33k (Note 5) VBAT = 2V, RPROG = 1.33k (0.1%) (Note 7) VBAT Rising (Note 7) (Note 7) VFLOAT - VRECHRG, 0C < TA < 85C IBAT = 90%, RPROG = 2k, Programmed Charge Current IBAT = 10%, RPROG = 2k, Programmed Charge Current

CONDITIONS
MIN 13 2.7 70 150 80 3 1.5 0.75
TYP 170 15.5 2.9 90 100 190 125 4.5 2.25 1.125 60 0
MAX 18 3.05 130 300 150 6 3 1.5 105 1 0.11
UNITS s mA V mV mV mV mV Hrs Hrs Hrs mV A mA/mA C Hz %
0.08
0.095 115 1.5 2 75
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 LTC4065L is guaranteed to meet performance specifications from 0C to 70C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Failure to solder the exposed backside of the package to the PC board ground plane will result in a thermal resistance much higher than rated.
Note 4: Although the LTC4065L functions properly at 3.75V input, full charge current requires an input voltage greater than the desired final battery voltage per the VUVCL1 specification. Note 5: IC/10 is expressed as a fraction of measured full charge current with indicated PROG resistor. Note 6: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 7: This parameter is not applicable to the LTC4065LX.
4065lxfa
3
LTC4065L/LTC4065LX TYPICAL PERFOR A CE CHARACTERISTICS
Battery Regulation (Float) Voltage vs Battery Charge Current
4.24 4.23 4.22 VFLOAT (V)
VFLOAT (V)
VCC = 5V TA = 25C RPROG = 800
VFLOAT (V)
4.21 4.20 4.19 4.18 4.17 4.16 0 50 100 150 IBAT (mA) 200 250
4065L G01
Charge Current vs Supply Voltage (Constant Current Mode)
30 25 20
RPROG = 13.3k VBAT = 3.8V TA = 25C
IBAT (mA)
IBAT (mA)
IBAT (mA)
15 10 5 0 4 4.5 5 5.5 SUPPLY VOLTAGE (V) 6
4065L G04
PROG Pin Voltage vs Temperature (Constant Current Mode)
1.02 VCC = 5V VBAT = 3.8V RPROG = 13.3k 1.01
VPROG (V)
VPROG (V)
1.00
0.6 0.4
RDS ()
0.99
0.98 -50
-25
50 25 0 TEMPERATURE (C)
4
UW
75
4065L G07
Battery Regulation (Float) Voltage vs Temperature
4.24 4.23 4.22 4.21 4.20 4.19 4.18 4.17 4.16 -50 - 25 50 25 TEMPERATURE (C) 0 75 100
4065L G02
Battery Regulation (Float) Voltage vs Supply Voltage
4.24 4.23 4.22 4.21 4.20 4.19 4.18 4.17 4.16 4 5 4.5 5.5 SUPPLY VOLTAGE (V) 6
4065L G03
TA = 25C IBAT = 2mA RPROG = 800
Charge Current vs Battery Voltage (LTC4065L)
300 250 200 150 100 50 0 0 1 2 3 VBAT (V) 4 5
4065L G05
Charge Current vs Temperature with Thermal Regulation (Constant Current Mode)
300 250 200 150 100 50 VCC = 5V VBAT = 3.8V RPROG = 800 0 100 50 TEMPERATURE (C) 150
4065L G06
VCC = 5V TA = 25C RPROG = 800
THERMAL CONTROL LOOP IN OPERATION
0 -50
PROG Pin Voltage vs Charge Current
1.2 1.0 0.8
1.6
Power FET On Resistance vs Temperature
2.0 VCC = 4V IBAT = 150mA
VCC = 5V TA = 25C RPROG = 800
1.8
1.4
0.2 0 0 50 100 150 IBAT (mA) 200 250
4065L G08
1.2
100
1.0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4065L G09
4065lxfa
LTC4065L/LTC4065LX TYPICAL PERFOR A CE CHARACTERISTICS
Undervoltage Lockout Threshold Voltage vs Temperature
4.00 3.75 RISE 3.50
RISE 1.0
ICCMS (A)
VCC (V)
VMS (V)
3.25 3.00 FALL
2.75 2.50 -50
0.5 -50
-25
50 0 25 TEMPERATURE (C)
EN Pin Current
4.0 3.5 3.0 VCC = 5V TA = 25C
IBAT (mA)
2.0 1.5 1.0 0.5 0 2 2.5 3 3.5 VEN (V) 4 4.5 5
15 10 5 RPROG = 13.3k 0 4 4.5 5 5.5 SUPPLY VOLTAGE (V) 6
4065L G14
IBAT (mA)
2.5
IEN (A)
CHRG Pin Output Low Voltage vs Temperature
140 120 100 VCC = 5V ICHRG = 5mA
TIMER ACCURACY (%)
VCHRG (mV)
-2 -3 -4 -5 -6
TIMER ACCURACY (%)
80 60 40 20 0 -50
-25
50 25 0 TEMPERATURE (C)
UW
75
4065L G16
4065L G13
Manual Shutdown Threshold Voltage vs Temperature
40
Manual Shutdown Supply Current vs Temperature
VCC = 5V VEN = 5V
0.9
30
0.8 FALL 0.7
20
0.6
10
100
-25
50 25 0 TEMPERATURE (C)
75
100
4065L G11
0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4065L G12
Trickle Charge Current vs Supply Voltage (4065L)
30 25 20 VBAT = 2V TA = 25C RPROG = 800
30 25 20 15 10 5
Trickle Charge Current vs Temperature (4065L)
VCC = 5V VBAT = 2V RPROG = 800
RPROG = 13.3k 0 -50 -25 50 25 0 TEMPERATURE (C) 75 100
4065L G15
Timer Accuracy vs Temperature
1 0 -1 VCC = 5V
2.0 1.5 1.0 0.5 0 -0.5 -1.0 -1.5
Timer Accuracy vs Supply Voltage
TA = 25C
75
100
4065L G10
-7 -50
-25
50 25 TEMPERATURE (C)
0
75
100
4065L G18
-2.0
4
5 4.5 5.5 SUPPLY VOLTAGE (V)
6
4065L G19
4065lxfa
5
LTC4065L/LTC4065LX
PI FU CTIO S
GND (Pin 1): Ground. CHRG (Pin 2): Open-Drain Charge Status Output. The charge status indicator pin has three states: pull-down, pulse at 2Hz and high impedance state. This output can be used as a logic interface or as an LED driver. When the battery is being charged, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge current drops to 10% of the full-scale current, the CHRG pin is forced to a high impedance state. If the battery voltage remains below 2.9V for one quarter of the charge time, the battery is considered defective and the CHRG pin pulses at a frequency of 2Hz. BAT (Pin 3): Charge Current Output. Provides charge current to the battery and regulates the final float voltage to 4.2V. An internal precision resistor divider on this pin sets the float voltage and is disconnected in shutdown mode. VCC (Pin 4): Positive Input Supply Voltage. This pin provides power to the charger. VCC can range from 3.75V to 5.5V. This pin should be bypassed with at least a 1F capacitor. When VCC is within 32mV of the BAT pin voltage, the LTC4065L enters shutdown mode, dropping IBAT to about 1A. EN (Pin 5): Enable Input Pin. Pulling this pin above the manual shutdown threshold (VMS is typically 0.82V) puts the LTC4065L in shutdown mode. In shutdown mode, the LTC4065L has less than 20A supply current and less than 1A battery drain current. Enable is the default state, but the pin should be tied to GND if unused. PROG (Pin 6): Charge Current Program and Charge Current Monitor Pin. Connecting a 1% resistor, RPROG, to ground programs the charge current. When charging in constant-current mode, this pin servos to 1V. In all modes, the voltage on this pin can be used to measure the charge current using the following formula:
IBAT = VPROG * 205 RPROG
6
U
U
U
Floating the PROG pin sets the charge current to zero. Exposed Pad (Pin 7): Ground. The Exposed Pad must be soldered to the PCB ground to provide both electrical contact and rated thermal performance.
4065lxfa
LTC4065L/LTC4065LX
SI PLIFIED BLOCK DIAGRA
TDIE
+
TA
D3
115C EN RENB 0.82V
-
M2 1x M1 205x 3.6V
5
+
C1 SHUTDOWN D1 D2 BAT 3
- -
REF 1.2V R3 MA CA
PROG
0.1V
+
C/10
-
R4
1V
MP 0.1V R2
CHARGE CONTROL
2
CHRG
R5 ENABLE LOBAT BAT SHUTDOWN PROG 6 1 RPROG GND OSCILLATOR
4056L F01
LOGIC
2.9V
TRICKLE CHARGE DISABLED ON THE LTC4065LX
Figure 1. LTC4065L Block Diagram
-
+
W
VCC 4 VCC
+
-
+
-
W
+
C2 UVLO
-
+
R1 VA
+
1.2V
COUNTER
4065lxfa
7
LTC4065L/LTC4065LX
OPERATIO
The LTC4065L is a linear battery charger designed primarily for charging single cell lithium-ion batteries. Featuring an internal P-channel power MOSFET, the charger uses a constant-current/constant-voltage charge algorithm with programmable current. Charge current can be programmed up to 250mA with a final float voltage accuracy of 0.6%. The CHRG open-drain status output indicates if C/10 has been reached. No blocking diode or external sense resistor is required; thus, the basic charger circuit requires only two external components. An internal termination timer and trickle charge low-battery conditioning adhere to battery manufacturer safety guidelines (Note: The LTC4065LX does not include this trickle charge feature). Furthermore, the LTC4065L is capable of operating from a USB power source. An internal thermal limit reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 115C. This feature protects the LTC4065L 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 LTC4065L or external components. Another benefit of the LTC4065L thermal limit is that charge current can be set according to typical, not worst-case, ambient temperatures for a given application with the assurance that the charger will automatically reduce the current in worst-case conditions. The charge cycle begins when the following conditions are met: the voltage at the VCC pin exceeds 3.6V and approximately 80mV above the BAT pin voltage, a program resistor is present from the PROG pin to ground and the EN pin is pulled below the shutdown threshold (typically 0.82V). If the BAT pin voltage is below 2.9V, the charger goes into trickle charge mode, charging the battery at one-tenth the programmed charge current to bring the cell voltage up to a safe level for charging (Note: The LTC4065LX does not include this trickle charge feature). If the BAT pin voltage is above 4.1V, the charger will not charge the battery as the cell is near full capacity. Otherwise, the charger goes into the fast charge constant-current mode.
8
U
When the BAT pin approaches the final float voltage (4.2V), the LTC4065L enters constant-voltage mode and the charge current begins to decrease. When the current drops to 10% of the full-scale charge current, an internal comparator turns off the N-channel MOSFET on the CHRG pin and the pin assumes a high impedance state. An internal timer sets the total charge time, tTIMER (typically 4.5 hours). When this time elapses, the charge cycle terminates and the CHRG pin assumes a high impedance state. To restart the charge cycle, remove the input voltage and reapply it or momentarily force the EN pin above VMS (typically 0.82V). The charge cycle will automatically restart if the BAT pin voltage falls below VRECHRG (typically 4.1V). When the input voltage is not present, the battery drain current is reduced to less than 4A. The LTC4065L can also be shut down by pulling the EN pin above the shutdown threshold voltage. This reduces input quiescent current to less than 20A and battery drain current to less than 1A. Programming Charge Current The charge current is programmed using a single resistor from the PROG pin to ground. The battery charge current is 205 times the current out of the PROG pin. The program resistor and the charge current are calculated using the following equations:
RPROG = 205 *
1V IBAT
, IBAT =
205V RPROG
The charge current out of the BAT pin can be determined at any time by monitoring the PROG pin voltage and using the following equation:
IBAT =
VPROG * 205 RPROG
4065lxfa
LTC4065L/LTC4065LX
OPERATIO
Undervoltage Lockout (UVLO) An internal undervoltage lockout circuit monitors the input voltage and keeps the charger in undervoltage lockout until VCC rises above 3.6V and approximately 80mV above the BAT pin voltage. The 3.6V UVLO circuit has a built-in hysteresis of approximately 0.6V and the automatic shutdown threshold has a built-in hysteresis of approximately 50mV. During undervoltage lockout conditions, maximum battery drain current is 4A and maximum supply current is 11A. Shutdown Mode The LTC4065L can be disabled by pulling the EN pin above the shutdown threshold (approximately 0.82V). In shutdown mode, the battery drain current is reduced to less than 1A and the supply current to about 20A. Timer and Recharge The LTC4065L has an internal termination timer that starts when an input voltage greater than the undervoltage lockout threshold is applied to VCC, or when leaving shutdown the battery voltage is less than the recharge threshold. At power-up or when exiting shutdown, if the battery voltage is less than the recharge threshold, the charge time is set to 4.5 hours. If the battery voltage is greater than the recharge threshold at power-up or when exiting shutdown, the timer will not start and charging is prevented since the battery is at or near full capacity. Once the charge cycle terminates, the LTC4065L continuously monitors the BAT pin voltage using a comparator with a 2ms filter time. When the average battery voltage
U
falls below 4.1V (which corresponds to 80% to 90% battery capacity), a new charge cycle is initiated and a 2.25 hour timer begins. This ensures that the battery is kept at, or near, a fully charged condition and eliminates the need for periodic charge cycle initiations. The CHRG output assumes a strong pull-down state during recharge cycles until C/10 is reached when it transitions to a high impendance state. Trickle Charge and Defective Battery Detection At the beginning of a charge cycle, if the battery voltage is low (below 2.9V), the charger goes into trickle charge, reducing the charge current to 10% of the full-scale current (Note: The LTC4065LX has full charge current at low-battery voltage). If the low-battery voltage persists for one quarter of the total time (1.125 hour), the battery is assumed to be defective, the charge cycle is terminated and the CHRG pin output pulses at a frequency of 2Hz with a 75% duty cycle. If for any reason the battery voltage rises above 2.9V, the charge cycle will be restarted. To restart the charge cycle (i.e., when the defective battery is replaced with a discharged battery), simply remove the input voltage and reapply it or temporarily pull the EN pin above the shutdown threshold. CHRG Status Output Pin The charge status indicator pin has three states: pulldown, pulse at 2Hz (see Trickle Charge and Defective Battery Detection) and high impedance. The pull-down state indicates that the LTC4065L is in a charge cycle. A high impedance state indicates that the charge current has dropped below 10% of the full-scale current or the LTC4065L is disabled. Figure 2 shows the CHRG status under various conditions.
4065lxfa
9
LTC4065L/LTC4065LX
OPERATIO
Charge Current Soft-Start and Soft-Stop The LTC4065L includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. When a charge cycle is initiated, the charge current ramps from zero to the full-scale current over a period of approximately 170s. Likewise, internal circuitry slowly ramps the charge current from full-scale to zero when the charger is shut off or self terminates. This has the effect of minimizing the transient current load on the power supply during start-up and charge termination. Constant-Current/Constant-Voltage/ Constant-Temperature The LTC4065L use a unique architecture to charge a battery in a constant-current, constant-voltage and constant-temperature fashion. Figure 1 shows a simplified block diagram of the LTC4065L. Three of the amplifier feedback loops shown control the constant-current, CA, constant-voltage, VA, and constant-temperature, TA modes. A fourth amplifier feedback loop, MA, is used to increase the output impedance of the current source pair; M1 and M2 (note that M1 is the internal P-channel power MOSFET). It ensures that the drain current of M1 is exactly 205 times greater than the drain current of M2. Amplifiers CA and VA are used in separate feedback loops to force the charger into constant-current or constantvoltage mode, respectively. Diodes D1 and D2 provide priority to either the constant-current or constant-voltage
10
U
loop, whichever is trying to reduce the charge current the most. The output of the other amplifier saturates low which effectively removes its loop from the system. When in constant-current mode, CA servos the voltage at the PROG pin to be precisely 1V. VA servos its inverting input to an internal reference voltage when in constant-voltage mode and the internal resistor divider, made up of R1 and R2, ensures that the battery voltage is maintained at 4.2V. The PROG pin voltage gives an indication of the charge current during constant-voltage mode as discussed in "Programming Charge Current". The transconductance amplifier, TA, limits the die temperature to approximately 115C when in constant-temperature mode. Diode D3 ensures that TA does not affect the charge current when the die temperature is below approximately 115C. The PROG pin voltage continues to give an indication of the charge current. In typical operation, the charge cycle begins in constantcurrent mode with the current delivered to the battery equal to 205V/RPROG. If the power dissipation of the LTC4065L results in the junction temperature approaching 115C, the amplifier (TA) will begin decreasing the charge current to limit the die temperature to approximately 115C. As the battery voltage rises, the LTC4065L either returns to constant-current mode or enters constant-voltage mode straight from constant-temperature mode. Regardless of mode, the voltage at the PROG pin is proportional to the current delivered to the battery.
4065lxfa
LTC4065L/LTC4065LX
OPERATIO
POWER ON
U
ENABLE NO IS EN > SHUTDOWN THRESHOLD? YES SHUTDOWN MODE CHRG HIGH IMPEDANCE IF VCC > 3.6V AND VCC > VBAT + 80mV? YES UVLO NO CHRG HIGH IMPEDANCE UVLO MODE VBAT 2.9V TRICKLE CHARGE MODE* 1/10 FULL CHARGE CURRENT CHRG STRONG PULL-DOWN 1/4 CHARGE CYCLE (1.125 HOURS) DEFECTIVE BATTERY IS VBAT < 2.9V? NO 2.9V < VBAT < 4.1V FAST CHARGE MODE FULL CHARGE CURRENT CHRG STRONG PULL-DOWN CHARGE CYCLE (4.5 HOURS) RECHARGE IS VBAT < 4.1V? NO VBAT > 4.1V STANDBY MODE NO CHARGE CURRENT CHRG HIGH IMPEDANCE YES BAD BATTERY MODE NO CHARGE CURRENT CHRG PULSES (2Hz) VCC < 3V OR EN > SHDN THRESHOLD YES RECHARGE MODE FULL CHARGE CURRENT CHRG STRONG PULL-DOWN 1/2 CHARGE CYCLE (2.25 HOURS)
4065L F02
*LTC4065L ONLY; LTC4065LX HAS FULL CHARGE CURRENT.
Figure 2. State Diagram of LTC4065L Operation
4065lxfa
11
LTC4065L/LTC4065LX
APPLICATIO S I FOR ATIO
Undervoltage Charge Current Limiting (UVCL) The LTC4065L includes undervoltage charge (VUVCL1) current limiting that prevents full charge current until the input supply voltage reaches approximately 200mV above the battery voltage. This feature is particularly useful if the LTC4065L is powered from a supply with long leads (or any relatively high output impedance). For example, USB-powered systems tend to have highly variable source impedances (due primarily to cable quality and length). A transient load combined with such impedance can easily trip the UVLO threshold and turn the charger off unless undervoltage charge current limiting is implemented. Consider a situation where the LTC4065L is operating under normal conditions and the input supply voltage begins to droop (e.g., an external load drags the input supply down). If the input voltage reaches VBAT + VUVCL1 (approximately 220mV above the battery voltage), undervoltage charge current limiting will begin to reduce the charge current in an attempt to maintain VUVCL1 between the VCC input and the BAT output of the IC. The LTC4065L will continue to operate at the reduced charge current until the input supply voltage is increased or voltage mode reduces the charge current further.
5V WALL ADAPTER D1 USB POWER 4 MP1 1k
Figure 3. Combining Wall Adapter and USB Power
12
U
USB and Wall Adapter Power Although the LTC4065L allows charging from a USB port, a wall adapter can also be used to charge Li-Ion batteries. Figure 3 shows an example of how to combine wall adapter and USB power inputs. A P-channel MOSFET, MP1, is used to prevent back conducting into the USB port when a wall adapter is present and Schottky diode, D1, is used to prevent USB power loss through the 1k pull-down resistor. Stability Considerations The LTC4065L contains two control loops: constantvoltage and constant-current. The constant-voltage loop is stable without any compensation when a battery is connected with low impedance leads. Excessive lead length, however, may add enough series inductance to require a bypass capacitor of at least 1F from BAT to GND. Furthermore, a 4.7F capacitor with a 0.2 to 1 series resistor from BAT to GND is required to keep ripple voltage low when the battery is disconnected. High value capacitors with very low ESR (especially ceramic) may reduce the constant-voltage loop phase margin. Ceramic capacitors up to 22F may be used in parallel with a battery, but larger ceramics should be decoupled with 0.2 to 1 of series resistance.
BAT LTC4065L VCC PROG 6 3 IBAT SYSTEM LOAD
W
UU
+
800
Li-Ion BATTERY
4065L F03
4065lxfa
LTC4065L/LTC4065LX
APPLICATIO S I FOR ATIO
In constant-current mode, the PROG pin is in the feedback loop, not the battery. Because of the additional pole created by the PROG pin capacitance, capacitance on this pin must be kept to a minimum. With no additional capacitance on the PROG pin, the charger is stable with program resistor values as high as 25k. However, additional capacitance on this node reduces the maximum allowed program resistor. The pole frequency at the PROG pin should be kept above 100kHz. Therefore, if the PROG pin is loaded with a capacitance, CPROG, the following equation should be used to calculate the maximum resistance value for RPROG: RPROG 2 * 105 1 * CPROG
Average, rather than instantaneous, battery current may be of interest to the user. For example, if a switching power supply operating in low current mode is connected in parallel with the battery, the average current being pulled out of the BAT pin is typically of more interest than the instantaneous current pulses. In such a case, a simple RC filter can be used on the PROG pin to measure the average
LTC4065L PROG GND
Figure 4. Isolating Capacitive Load on the PROG Pin and Filtering
U
battery current as shown in Figure 4. A 10K resistor has been added between the PROG pin and the filter capacitor to ensure stability. Power Dissipation Due to the low charge currents, it is unlikely that the LTC4065L will reduce charge current through thermal feedback. Nonetheless, the LTC4065L power dissipation can be approximated by: PD = (VCC - VBAT) * IBAT Where PD is the power dissipated, VCC is the input supply voltage, VBAT is the battery voltage and IBAT is the charge current. It is not necessary to perform any worst-case power dissipation scenarios because the LTC4065L will automatically reduce the charge current to maintain the die temperature at approximately 115C. However, the approximate ambient temperature at which the thermal feedback begins to protect the IC is: TA = 115C - PD * JA TA = 115C - (VCC - VBAT) * IBAT * JA
10k RPROG
4065L F04
W
UU
CFILTER
CHARGE CURRENT MONITOR CIRCUITRY
4065lxfa
13
LTC4065L/LTC4065LX
APPLICATIO S I FOR ATIO
Example: Consider an LTC4065L operating from a 5.5V wall adapter providing 250mA to a 3V Li-Ion battery. The ambient temperature above which the LTC4065L will begin to reduce the 250mA charge current is approximately: TA = 115C - (5.5V - 3V) * (250mA) * 60C/W TA = 115C - 0.625W * 60C/W = 115C - 37.5C TA = 77.5C Charging at such high ambient temperatures is not recommended by battery manufacturers. Furthermore, the voltage at the PROG pin will change proportionally with the charge current as discussed in the Programming Charge Current section. It is important to remember that LTC4065L 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.
14
U
Board Layout Considerations In order to deliver maximum charge current under all conditions, it is critical that the exposed metal pad on the backside of the LTC4065L package is soldered to the PC board ground. Correctly soldered to a 2500mm2 doublesided 1 oz. copper board the LTC4065L has a thermal resistance of approximately 60C/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 60C/W. VCC Bypass Capacitor Many types of capacitors can be used for input bypassing; however, caution must be exercised when using multilayer ceramic capacitors. Because of the self-resonant and high Q characteristics of some types of ceramic capacitors, high voltage transients can be generated under some start-up conditions, such as connecting the charger input to a live power source. For more information, refer to Application Note 88.
4065lxfa
W
UU
LTC4065L/LTC4065LX
PACKAGE DESCRIPTIO
0.675 0.05
2.50 0.05 1.15 0.05 0.61 0.05 (2 SIDES)
PACKAGE OUTLINE
0.25 0.05 0.50 BSC 1.42 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2) 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
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.
U
DC Package 6-Lead Plastic DFN (2mm x 2mm)
(Reference LTC DWG # 05-08-1703)
R = 0.115 TYP 0.56 0.05 (2 SIDES) 0.38 0.05
4 6 PIN 1 BAR TOP MARK (SEE NOTE 6)
2.00 0.10 (4 SIDES)
PIN 1 CHAMFER OF EXPOSED PAD
3
0.200 REF
1
(DC6) DFN 1103
0.75 0.05
0.25 0.05 0.50 BSC
1.37 0.05 (2 SIDES)
0.00 - 0.05
BOTTOM VIEW--EXPOSED PAD
4065lxfa
15
LTC4065L/LTC4065LX RELATED PARTS
PART NUMBER Battery Chargers LTC1734 LTC1734L LTC4050 LTC4054 LTC4054L LTC4057 LTC4059/LTC4059A LTC4061 LTC4061-4.4 LTC4062 LTC4063 LTC4065/LTC4065A Power Management LTC3405/LTC3405A LTC3406/LTC3406A LTC3411 LTC3440 LTC4411/LTC4412 LTC4413 300mA (IOUT), 1.5MHz, Synchronous Step-Down DC/DC Converter 600mA (IOUT), 1.5MHz, Synchronous Step-Down DC/DC Converter 1.25A (IOUT), 4MHz, Synchronous Step-Down DC/DC Converter 600mA (IOUT), 2MHz, Synchronous Buck-Boost DC/DC Converter Low Loss PowerPathTM Controller in ThinSOT Dual Ideal Diode in DFN 95% Efficiency, VIN: 2.7V to 6V, VOUT = 0.8V, IQ = 20A, ISD < 1A, ThinSOT Package 95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 0.6V, IQ = 20A, ISD < 1A, ThinSOT Package 95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 0.8V, IQ = 60A, ISD < 1A, MS Package 95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 2.5V, IQ = 25A, ISD < 1A, MS Package Automatic Switching Between DC Sources, Load Sharing, Replaces ORing Diodes 2-Channel Ideal Diode ORing, Low Forward ON Resistance, Low Regulated Forward Voltage, 2.5V VIN 5.5V Lithium-Ion Linear Battery Charger in ThinSOTTM Lithium-Ion Linear Battery Charger in ThinSOT Lithium-Ion Linear Battery Charger Controller Standalone Linear Li-Ion Battery Charger with Integrated Pass Transistor in ThinSOT Standalone Linear Li-Ion Battery Charger with Integrated Pass Transistor in ThinSOT Lithium-Ion Linear Battery Charger 900mA Linear Lithium-Ion Battery Charger Standalone Li-Ion Charger with Thermistor Interface Standalone Li-Ion Charger with Thermistor Interface Standalone Linear Li-Ion Battery Charger with Micropower Comparator Li-Ion Charger with Linear Regulator Standalone Li-Ion Battery Chargers Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed Low Current Version of LTC1734, 50mA ICHRG 180mA Features Preset Voltages, C/10 Charger Detection and Programmable Timer, Input Power Good Indication, Thermistor Interface Thermal Regulation Prevents Overheating, C/10 Termination, C/10 Indicator, Up to 800mA Charge Current Low Current Version of LTC4054, Charge Current Up to 150mA Up to 800mA Charge Current, Thermal Regulation, ThinSOT Package 2mm x 2mm DFN Package, Thermal Regulation, Charge Current Monitor Output. A Version has ACPR Function 4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN 4.4V (Max), 0.4% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN 4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN Up to 1A Charge Current, 100mA, 125mV LDO, 3mm x 3mm DFN 4.2V, 0.6% Float Voltage, Up to 750mA Charge Current, 2mm x 2mm DFN; "A" Version Has ACPR Function. DESCRIPTION COMMENTS
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
4065lxfa
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507
LT 0506 REV A * PRINTED IN THE USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2005

▲Up To Search▲

Price & Availability of LTC4065L

	To Download LTC4065L Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .