LTC4053-4.2 USB Compatible Lithium-Ion Battery Charger with Thermal Regulation

FEATURES DESCRIPTIO U ■ Charges Single-Cell Li-Ion Batteries Directly from The LTC®4053 is a standalone linear charger for lithium- USB Port ion batteries that can be powered directly from a USB port. ■ Thermal Regulation Maximizes Charge Rate The IC contains an on-chip power MOSFET and eliminates without Risk of Overheating* the need for an external sense resistor and blocking diode. ■ Programmable Charge Current with ±7% Accuracy Thermal regulation automatically adjusts charge current ■ Low Dropout Operation to limit die temperature during high power or high ambient ■ No External MOSFET, Sense Resistor or Blocking temperature conditions. This feature protects the end Diode Required product and the LTC4053 from thermal stress while the IC ■ Programmable Charge Termination Timer charges the battery at maximum rate without interruption. ■ Preset Charge Voltage with ±1% Accuracy The charge current and charge time can be set externally ■ C/10 Charge Current Detection Output with a single resistor and capacitor, respectively. When ■ AC Present Logic Output the input supply (wall adapter or USB supply) is removed, ■ 25µA Supply Current in Shutdown Mode the LTC4053 automatically enters a low current sleep ■ Automatic Recharge mode, dropping the battery drain current to less than 5µA. ■ Charge Current Monitor Useful for Gas Gauging ■ Thermistor Input for Temperature Qualified Charging The LTC4053 also includes NTC temperature sensing, ■ Available in 10-pin thermally enhanced MSOP and C/10 detection circuitry, AC present logic, low battery

low profile (0.75mm) 3mm × 3mm DFN packages charge conditioning (trickle charging) and shutdown (25µA U supply current). APPLICATIO S The LTC4053 is available in 10-pin thermally enhanced ■ Cellular Telephones MSOP and low profile (0.75mm) DFN packages. ■ Handheld Computers , LTC and LT are registered trademarks of Linear Technology Corporation. ■ Charging Docks and Cradles Protected by U.S. Patents including 6522118, 6700364. ■ MP3 Players

■ Digital Cameras U

TYPICAL APPLICATIO Charge Current vs Input Voltage USB Powered Standalone Li-Ion Charger 600 TA = 25°C R = 3k V = 3.95V PROG 500 BAT USB PORT 2 9 SYSTEM V BAT 4.35V TO 5.5V CC + LOAD Li-Ion 400 LTC4053-4.2 BATTERY VBAT = 4.05V

(mA) 300 4 8 BAT TIMER SHDN SUSPEND I GND NTC PROG 200 4.7µF USB CONTROL 56 7 3.74k V = 4.15V µC BAT 100 100mA/ 0.1µF 15k 500mA 0 4.0 4.5 5.0 5.5 VCC (V) 4053TA01 4053 G04 4053fa 1

LTC4053-4.2

WW U

ABSOLUTE AXI UW RATI GS (Note 1)

Input Supply Voltage (VCC) ...... 7V Junction Temperature...... 125°C BAT ...... 7V Operating Temperature Range (Note 3) ...–40°C to 85°C NTC, SHDN, TIMER, PROG ...... –0.3V to VCC + 0.3V Storage Temperature Range CHRG, FAULT, ACPR ...... –0.3V to 7V MSE...... – 65°C to 150°C BAT Short-Circuit Duration ...... Continuous DD ...... – 65°C to 125°C BAT Current (Note 2) ...... 1.3A Lead Temperature (Soldering, 10 sec)

PROG Current (Note 2) ...... 1.3mA MSE...... 300°C W

PACKAGE/ORDER IUU FOR ATIO TOP VIEW ORDER PART ORDER PART TOP VIEW CHRG 1 10 ACPR NUMBER CHRG 1 10 ACPR NUMBER V 2 9 BAT CC VCC 2 9 BAT FAULT 3 11 8 SHDN LTC4053EDD-4.2 FAULT 3 11 8 SHDN LTC4053EMSE-4.2 TIMER 4 7 PROG TIMER 4 7 PROG GND 5 6 NTC GND 5 6 NTC MSE EXPOSED PAD PACKAGE 10-LEAD PLASTIC MSOP DD PACKAGE DD PART MARKING MSE PART MARKING 10-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 40°C/W (NOTE 4) TJMAX = 125°C, θJA = 40°C/W (NOTE 4) EXPOSED PAD (PIN 11) IS GND EXPOSED PAD (PIN 11) IS GND LBQC (MUST BE SOLDERED TO PCB) LTZT (MUST BE SOLDERED TO PCB) 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 the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VCC VCC Supply Voltage ● 4.25 6.5 V

ICC VCC Supply Current Charger On; Current Mode; RPROG = 30k (Note 5) ● 12 mA Shutdown Mode; VSHDN = 0V ● 25 50 µA Sleep Mode VCC < VBAT or VCC ≤ 4V ● 25 50 µA

VBAT VBAT Regulated Float Voltage ● 4.158 4.2 4.242 V

IBAT Battery Pin Current RPROG = 3k; Current Mode ● 465 500 535 mA RPROG = 15k; Current Mode ● 93 100 107 mA Shutdown Mode; VSHDN = 0V ±1 ±3 µA Sleep Mode VCC < VBAT or VCC < (VUV – ∆VUV) ±1 ±3 µA

ITRIKL Trickle Charge Current VBAT < 2V; RPROG = 3k ● 35 50 65 mA

VTRIKL Trickle Charge Trip Threshold VBAT Rising 2.48 V

∆VTRIKL Trickle Charge Trip Hysteresis 100 mV

VUV VCC Undervoltage Lockout Voltage VCC Rising ● 4 4.25 V

∆VUV VCC Undervoltage Lockout Hysteresis 200 mV

VMSD Manual Shutdown Threshold Voltage SHDN Pin Voltage 0.6 1.3 V

VASD Automatic Shutdown Threshold Voltage (VCC - VBAT) High to Low 35 mV (VCC - VBAT) Low to High 70 mV 4053fa 2 LTC4053-4.2

ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VPROG PROG Pin Voltage RPROG = 3k, IPROG = 500µA 1.5 V

ICHRG CHRG Pin Weak Pulldown Current VCHRG = 1V 15 30 50 µA

VCHRG CHRG Pin Output Low Voltage ICHRG = 5mA 0.35 0.6 V

VACPR ACPR Pin Output Low Voltage IACPR = 5mA 0.35 0.6 V

VFAULT FAULT Pin Output Low Voltage IFAULT = 5mA 0.35 0.6 V

IC/10 End of Charge Indication Current Level RPROG = 3k 44 50 56 mA tTIMER TIMER Accuracy CTIMER = 0.1µF10%

VRECHRG Recharge Battery Voltage Threshold Battery Voltage Falling 4.035 V

VNTC-HOT NTC Pin Hot Threshold Voltage VNTC Falling 2.5 V

VHOT-HYS NTC Pin Hot Hysteresis Voltage 80 mV

VNTC-COLD NTC Pin Cold Threshold Voltage VNTC Rising 4.375 V

VCOLD-HYS NTC Pin Cold Hystersis Voltage 80 mV

VNTC-DIS NTC Pin Disable Threshold Voltage VNTC Rising 100 mV

VDIS-HYS NTC Pin Disable Hystersis Voltage 10 mV

TLIM Junction Temperature in 105 °C Constant-Temperature Mode

RON Power MOSFET “ON” Resistance 375 mΩ Note 1: Absolute Maximum Ratings are those values beyond which the life temperature range are assured by design, characterization and correlation of a device may be impaired. with statistical process controls. Note 2: The Absolute Maximum BAT Current Rating of 1.3A is guaranteed Note 4: Failure to solder the exposed backside of the package to the PC by design and current density calculations. The Absolute Maximum PROG board will result in a thermal resistance much higher than 40°C/W. Current Rating is guaranteed to be 1/1000 of BAT current rating by design. Note 5: Supply current includes PROG pin current (approximately 50µA) Note 3: The LTC4053E is guaranteed to meet performance specifications but does not include any current delivered to the battery through the BAT from 0°C to 70°C. Specifications over the –40°C to 85°C operating pin (approximately 50mA).

4053fa 3 LTC4053-4.2

TYPICAL PERFOR A CEUW CHARACTERISTICS

Battery Regulation Voltage Battery Regulation Voltage Battery Regulation Voltage vs Battery Charge Current vs Temperature vs VCC 4.22 4.24 4.210 VCC = 5V VCC = 5V TA = 25°C 4.22 4.208 RPROG = 3k 4.21 RPROG = 3k I = 10mA 4.20 4.206 BAT

4.20 4.18 4.204

4.16 4.202 (V) (V) 4.19 (V) 4.200 BAT BAT

4.14 BAT V V V 4.198 4.18 4.12 4.196 4.10 4.194 4.17 VCC = 5V 4.08 RPROG = 3k 4.192 IBAT = 10mA 4.16 4.06 4.190 050 100 150 200 250 300 350 400 450 500 –50 –25 0 2550 75 100 125 4 4.5 5 5.5 6 6.5 7 IBAT (mA) TEMPERATURE (°C) VCC (V)

4053 G01 4053 G02 4053 G03

Charge Current vs Ambient Temperature with Thermal Charge Current vs Input Voltage Charge Current vs Battery Voltage Regulation 600 550 1000 TA = 25°C VCC = 5V 500 RPROG = 3k TA = 25°C 900 VBAT = 3.95V 500 450 RPROG = 3k 800 400 400 700 V = 4.05V 350 BAT 600 300 THERMAL CONTROL (mA) (mA) LOOP IN OPERATION 300 (mA) 500 250 BAT BAT BAT I I 200 I 400 200 150 300 VBAT = 4.15V 200 100 100 VCC = 5V 50 100 VBAT = 3.5V RPROG = 1.5k 0 0 0 4.0 4.5 5.0 5.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 –50 –25 0 25 50 75 100 VCC (V) VBAT (V) TEMPERATURE (°C)

4053 G04 4053 G05 4053 G06

Undervoltage Lockout Voltage Shutdown Supply Current Manual Shutdown Threshold vs Temperature vs Temperature Voltage vs Temperature 4.05 30 1.30 VSHDN = 0V 4.04 1.25 VCC = 6.5V 25 4.03 1.20 VCC = 5.5V 4.02 1.15 VCC = 6V 20 VCC = 5.5V 4.01 1.10 A) (V) µ (V)

4.00 ( 15 VCC = 4.5V 1.05 UV MSD CC V I 3.99 V 1.00 VCC = 5V 3.98 10 0.95 VCC = 4.5V 3.97 0.90 5 3.96 0.85 3.95 0 0.80 –50 –25 0 25 50 75 100 125 –50 –25 0 2550 75 100 125 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C)

4053 G07 4053 G08 4053 G09 4053fa 4 LTC4053-4.2

TYPICAL PERFOR A CEUW CHARACTERISTICS

PROG Pin Voltage PROG Pin Voltage vs VCC PROG Pin Voltage vs Temperature vs Charge Current Constant Current Mode Constant Current Mode 1.6 1.515 1.515 VCC = 5V VBAT = 3.5V VCC = 5V 1.4 TA = 25°C TA = 25°C VBAT = 4V 1.510 1.510 RPROG = 3k RPROG = 3k RPROG = 3k 1.2 1.505 1.505 1.0 (V) (V) (V) 0.8 1.500 1.500 PROG PROG PROG V V V 0.6 1.495 1.495 0.4 1.490 1.490 0.2

0 1.485 1.485 0 50100 150 200 250 300350 400 450 500 4 4.5 5 5.5 6 6.5 7 –50 –25 0255075 100 CHARGE CURRENT (mA) VCC (V) TEMPERATURE (°C)

4052 G10 4053 G11 4053 G12

Trickle Charge Current CHRG Pin Weak Pull-Down CHRG Pin Output Low Voltage vs Temperature Current vs Temperature vs Temperature 12 35 0.6 VBAT = 2V VCC = 5V VCC = 5V 34 TA = 25°C IBAT < C/10 ICHRG = 5mA R = 3k 11 PROG 33 0.5 32 0.4 31

10 A) µ (V) ( 30 0.3 CHRG CHRG I 9 29 V 28 0.2

(% OF PROGRAMMED CURRENT) 8 27 0.1 BAT

I 26

7 25 0 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 –50 –25 0 2550 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C)

4053 G13 LTC1323 • TPC05 4053 G15

Timer Error vs Temperature Timer Error vs VCC 5 5 VCC = 5V TA = 25°C 4 CTIMER = 0.1µF 4 CTIMER = 0.1µF 3 3 2 2 1 1 (%) (%) 0 0 TIMER TIMER t t –1 –1 –2 –2 –3 –3 –4 –4 –5 –5 –50 –25 0 25 50 75 100 125 4 4.5 5 5.5 6 6.5 7 TEMPERATURE (°C) VCC (V)

LTC1323 • TPC05 4056 G17

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LTC4053-4.2 UU

PI U FU CTIO S CHRG: Open-Drain Charge Status Output. When the NTC: Input to the NTC (Negative Temperature Coefficient) battery is being charged, the CHRG pin is pulled low by an Thermistor Temperature Monitoring Circuit. With an ex- internal N-channel MOSFET. When the charge current ternal 10kΩ NTC thermistor to ground and a 1% resistor drops to 10% of the full-scale current, the N-channel to VCC, this pin can sense the temperature of the battery MOSFET latches off and a 30µA current source is con- pack and stop charging when it is out of range. When the nected from the CHRG pin to ground. The C/10 latch can voltage at this pin drops below (0.5)•(VCC) at hot tempera- be cleared by grounding the SHDN pin, momentarily, or tures or rises above (0.875)•(VCC) at cold, charging is toggling VCC. When the timer runs out or the input supply suspended and the internal timer is frozen. The CHRG pin is removed, the current source is disconnected and the output status is not affected in this hold state. The FAULT CHRG pin is forced high impedance. pin will be pulled to ground, but not latched. When the V : Positive Input Supply Voltage. When V is within temperature returns to an acceptable range, charging will CC CC resume and the FAULT pin will be released. The NTC 35mV of V or less than the undervoltage lockout BAT feature can be disabled by grounding the NTC pin. threshold, the LTC4053 enters sleep mode, dropping IBAT to less than 3µA. VCC can range from 4.25V to 6.5V. PROG: Charge Current Program and Charge Current Moni- Bypass this pin with at least a 4.7µF ceramic capacitor to tor Pin. The charge current is programmed by connecting ground. a resistor, RPROG to ground. When in constant-current FAULT: Open-Drain Fault Status Output. The FAULT open- mode, the LTC4053 servos the PROG pin voltage to 1.5V. drain logic signal indicates that the charger has timed out In all modes the voltage on the PROG pin can be used to under trickle charge conditions or the NTC comparator is measure the charge current as follows: indicating an out-of-range battery temperature condition. IBAT = (VPROG/RPROG) • 1000. If V BAT is less that 2.48V, trickle charging begins whereby SHDN: Shutdown Input Pin. Pulling the SHDN pin to the charge current drops to one tenth of its programmed ground will put the LTC4053 into standby mode where the value and the timer period is reduced by a factor of four. BAT drain current is reduced to less than 3µA, and the When one fourth of the timing period has elapsed, if V BAT supply current is reduced to less than 25µA. For normal is still less than 2.48V, trickle charging stops and the operation, pull the SHDN pin up to V . FAULT pin latches to ground. The fault can be cleared by CC toggling VCC, momentarily grounding the SHDN pin or BAT: Charge Current Output. A bypass capacitor of at least pulling the BAT pin above 2.48V. If the NTC comparator is 1µF with a 1Ω series resistor is required to keep the loop indicating an out-of-range battery temperature condition, stable when the battery is not present. A precision internal the FAULT pin will pull to ground until the temperature resistor divider sets the final float potential on this pin. The returns to the acceptable range. internal resistor divider is disconnected in sleep and shutdown mode. TIMER: Timer Capacitor. The timer period is set by placing a capacitor, CTIMER, to ground. The timer period is: ACPR: Open-Drain Power Supply Status Output. When VCC is greater than the undervoltage lockout threshold Time (Hours) = (CTIMER • 3 hr)/(0.1µF) and at least 35mV above VBAT, the ACPR pin will pull to Short the TIMER pin to ground to disable the internal timer ground. Otherwise, the pin is high impedance. function. GND: Ground. The exposed backside of the package is also ground and must be soldered to the PC board for maximum heat transfer.

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LTC4053-4.2 W

SI PLIFIED BLOCK DIAGRA W

VCC

105°C – D1 TA D2 TDIE + M2 M1 D3 ×1 ×1000

– + MA 30µA 9 BAT R1 NTC 6 NTC MP +

VA R2 CA – – +

2.485V REF

CHRG 1 HOT COLD DISABLE

STOP SHDN 8 SHDN

C/10 R3 30µA 1.5V LOGIC ACPR 10 R4 ACPR 0.15V + C/10 C2 FAULT 3 R5 – FAULT

CHARGE

COUNTER

C3 OSCILLATOR – + 2.485V TO BAT 475 TIMER PROG GND 4053 BD

RPROG CTIMER

Figure 1

4053fa 7 LTC4053-4.2

OPERATIOU The LTC4053 is a linear battery charger designed primarily voltage up to a safe level for charging. The charger goes for charging single cell lithium-ion batteries. Featuring an into the fast charge constant-current mode once the internal P-channel power MOSFET, the charger uses a voltage on the BAT pin rises above 2.48V. In constant- constant-current/constant-voltage charge algorithm with current mode, the charge current is set by RPROG. programmable current and a programmable timer for When the battery approaches the final float voltage, the charge termination. Charge current can be programmed charge current begins to decrease as the LTC4053 enters up to 1.25A with a final float voltage accuracy of 1%. No ± the constant-voltage mode. When the current drops to blocking diode or sense resistor is required thus dropping 10% of the full-scale charge current, an internal compara- the external component count to three for the basic tor latches off the MOSFET on the CHRG pin and connects charger circuit. The CHRG, ACPR, and FAULT open-drain a weak current source to ground (30µA) to indicate a near status outputs provide information regarding the status of end-of-charge (C/10) condition. The C/10 latch can be the LTC4053 at all times. An NTC thermistor input pro- cleared by grounding the SHDN pin momentarily, or vides the option of charge qualification using battery momentarily removing and reapplying V . temperature. CC An external capacitor on the TIMER pin sets the total An internal thermal limit reduces the programmed charge charge time. When this time elapses, the charge cycle current if the die temperature attempts to rise above a terminates and the CHRG pin assumes a high impedance preset value of approximately 105 C. This feature protects ° state. To restart the charge cycle, remove the input voltage the LTC4053 from excessive temperature, and allows the and reapply it, or momentarily force the SHDN pin to 0V. user to push the limits of the power handling capability of The charge cycle will also restart if the BAT pin voltage falls a given circuit board without risk of damaging the LTC4053 below the recharge threshold. or the external components. Another benefit of the LTC4053 thermal limit is that charge current can be set according to For lithium-ion and similar batteries that require an accu- typical, not worst-case, ambient temperatures for a given rate final float voltage, the internal reference, voltage application with the assurance that the charger will auto- amplifier and the resistor divider provide regulation with matically reduce the current in worst-case conditions. ±1% (max) accuracy.

The charge cycle begins when the voltage at the VCC pin When the input voltage is not present, the charger goes rises above the UVLO level, a program resistor is con- into a sleep mode, dropping battery drain current, IBAT, to nected from the PROG pin to ground, and the SHDN pin is less than 5µA. This greatly reduces the current drain on the pulled above the shutdown threshold. At the beginning of battery and increases the standby time. The charger can be the charge cycle, if the battery voltage is below 2.48V, the shut down (ICC = 25µA) by forcing the SHDN pin to 0V. charger goes into trickle charge mode to bring the cell

4053fa 8

LTC4053-4.2

U U

APPLICATIO S I FOR ATIOWU Undervoltage Lockout (UVLO) For example, if 500mA charge current is required, An internal undervoltage lockout circuit monitors the input calculate: voltage and keeps the charger in shutdown mode until VCC RPROG = 1500V/0.5A = 3kΩ rises above the undervoltage lockout threshold. The UVLO For best stability over temperature and time, 1% metal- circuit has a built-in hysteresis of 150mV. Furthermore, to film resistors are recommended. protect against reverse current in the power MOSFET, the UVLO circuit keeps the charger in shutdown mode if VCC If the charger is in constant-temperature or constant- falls to within 35mV of the battery voltage. If the UVLO voltage mode, the battery current can be monitored by comparator is tripped, the charger will not come out of measuring the PROG pin voltage as follows: shutdown until V rises 70mV above the battery voltage. CC ICHG = (VPROG / RPROG) • 1000

Trickle Charge And Defective Battery Detection USB and Wall Adapter Power At the beginning of a charge cycle, if the battery voltage is Although the LTC4053 allows charging from a USB port, low (below 2.48V) the charger goes into trickle charge a wall adapter can also be used to charge Li-Ion batteries. reducing the charge current to 10% of the full-scale Figure 2 shows an example of how to combine wall adapter current. If the low battery voltage persists for one quarter and USB power inputs. A P-channel MOSFET, MP1, is of the total charge time, the battery is assumed to be used to prevent back conducting into the USB port when defective, the charge cycle is terminated, the CHRG pin a wall adapter is present and Schottky diode, D1, is used output assumes a high impedance state, and the FAULT to prevent USB power loss through the 1k pull-down pin pulls low. The fault can be cleared by toggling VCC, resistor. temporarily forcing the SHDN pin to 0V, or temporarily forcing the BAT pin voltage above 2.48V. Typically a wall adapter can supply significantly more current than the 500mA-limited USB port. Therefore, an N- Shutdown channel MOSFET, MN1 and an extra 3k program resistor can be used to increase the charge current to 1A when the The LTC4053 can be shut down (I = 25 A) by pulling the CC µ wall adapter is present. SHDN pin to 0V. For normal operation, pull the SHDN pin above the manual shutdown threshold voltage level. Do 5V WALL not leave this pin open. In shutdown the internal linear ADAPTER I 1A ICHG LTC4053 CHG regulator is turned off, and the internal timer is reset. 9 SYSTEM D1 BAT LOAD USB 2 Programming Charge Current POWER VCC 500mA ICHG MP1 7 The formula for the battery charge current (see Figure 1) PROG + Li-Ion is: BATTERY 3k ICHG = (IPROG) • 1000 1k MN1 3k

= (1.5V / RPROG) • 1000 or 4053 F02

RPROG = 1500V/ICHG where RPROG is the total resistance from the PROG pin to Figure 2. Combining Wall Adapter and USB Power ground. Under trickle charge conditions, this current is reduced to 10% of the full-scale value.

4053fa 9

LTC4053-4.2 UU

APPLICATIO S I FOR ATIOWU Programming The Timer Table 1. FAULT CHRG Description The programmable timer is used to terminate the charge High Low Charge cycle has started, C/10 has not been cycle. The timer duration is programmed by an external reached and charging is proceeding normally. capacitor at the TIMER pin. The total charge time is: Low Low Charge cycle has started, C/10 has not been Time (Hours) = (3 Hours) • (C /0.1µF) or reached, but the charge current and timer TIMER have been paused due to an NTC out-of- CTIMER = 0.1µF • Time (Hours)/3 (Hours) temperature condition. High 30µA C/10 has been reached and charging is The timer starts when an input voltage greater than the pull-down proceeding normally. undervoltage lockout threshold level is applied and the SHDN pin is greater than the manual shutdown threshold Low 30µA C/10 has been reached but the charge current voltage level. After a time-out occurs, the charge current pull-down and timer have paused due to an NTC out-of- stops, and the CHRG output assumes a high impedance temperature condition. state to indicate that the charging has stopped. Connect- High High Normal timeout (charging has terminated). ing the TIMER pin to ground disables the timer function. Low High If FAULT goes low and CHRG goes high impedance simultaneously, then the LTC4053 has timed out due to a bad cell (VBAT <2.48V Recharge after one-quarter the programmed charge time). After a charge cycle has terminated, if the battery voltage If CHRG goes high impedance first, then the LTC4053 has timed out normally (charging drops below the recharge threshold of 4.05V a new charge has terminated), but NTC is indicating an out- cycle will begin. The recharge circuit integrates the BAT of-temperature condition. pin voltage for a few milliseconds to prevent a transient from restarting the charge cycle. CHRG Status Output Pin If the battery voltage remains below 2.48V during trickle When the charge cycle starts, the CHRG pin is pulled to charge for 1/4 of the programmed time, the battery may be ground by an internal N-channel MOSFET capable of defective and the charge cycle will end. In addition, the driving an LED. When the charge current drops to 10% of recharge comparator is disabled and a new charge cycle the full-scale current (C/10), the N-channel MOSFET is will not begin unless the input voltage is toggled off-then- latched off and a weak 30µA current source to ground is on, the SHDN pin is momentarily pulled to ground, or the connected to the CHRG pin. After a time-out occurs, BAT pin is pulled above the 2.48V trickle charge threshold. the pin assumes a high impedance state. By using two different value pull-up resistors a microprocessor can Open-Drain Status Outputs detect three states from this pin (charging, C/10 and time- The LTC4053 has three open-drain status outputs: ACPR, out). See Figure 3. CHRG and FAULT. The ACPR pin pulls low when an input When the LTC4053 is in charge mode, the CHRG pin is voltage greater than the undervoltage lockout threshold is pulled low by the internal N-channel MOSFET. To detect applied and becomes high impedance when power (V < IN this mode, force the digital output pin, OUT, high and V ) is removed. CHRG and FAULT work together to UV measure the voltage at the CHRG pin. The N-channel indicate the status of the charge cycle. Table 1 describes MOSFET will pull the pin low even with the 2k pull-up the status of the charge cycle based on the CHRG and resistor. Once the charge current drops to 10% of the FAULT outputs.

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LTC4053-4.2 UU

APPLICATIO S I FOR ATIOWU

+ V VDD VCC

8 7/8 VCC – R VCC HOT TOO COLD 400k 1% LTC4053 µPROCESSOR + 3 2k CHRG OUT NTC

IN RNTC 1/2 VCC + 10k 4053 F03 TOO HOT – Figure 3. Microprocessor Interface full-scale current (C/10), the N-channel MOSFET is turned 3/160 VCC + off and a 30µA current source is connected to the CHRG DISABLE NTC pin. The IN pin will then be pulled high by the 2k pull-up. – LTC4053

By forcing the OUT pin to a high impedance state, the 4053 F04 current source will pull the pin low through the 400k Figure 4 resistor. When the internal timer has expired, the CHRG pin will assume a high impedance state and the 400k Thermistors resistor will then pull the pin high to indicate that charging has terminated. The LTC4053 NTC trip points were designed to work with thermistors whose resistance-temperature characteris- NTC Thermistor tics follow Vishay Dale’s “R-T Curve 2”. The Vishay NTHS0603N02N1002J is an example of such a ther- The battery temperature is measured by placing a negative mistor. However, Vishay Dale has many thermistor prod- temperature coefficient (NTC) thermistor close to the ucts that follow the “R-T Curve 2” characteristic in a variety battery pack. The NTC circuitry is shown in Figure 4. To use of sizes. Futhermore, any thermistor whose ratio of RCOLD this feature, connect a 10k NTC thermistor between the to RHOT is about 7.0 will also work (Vishay Dale R-T Curve NTC pin and ground and a resistor (R ) from the NTC pin HOT 2 shows a ratio of RCOLD to RHOT of 2.816/0.4086 = 6.9). to VCC. RHOT should be a 1% resistor with a value equal to the value of the chosen NTC thermistor at 50°C (this value NTC Layout Considerations is 4.1k for a Vishay NTHS0603N02N1002J thermistor). The LTC4053 goes into hold mode when the resistance of It is important that the NTC thermistor not be in close the NTC thermistor drops below 4.1k which should be thermal contact with the LTC4053. Because the LTC4053 package can reach temperatures in excess of the 50 C trip approximately 50°C. The hold mode freezes the timer and ° stops the charge cycle until the thermistor indicates a point, the NTC function can cause a hysteretic oscillation return to a valid temperature. As the temperature drops, which turns the charge current on and off according to the the resistance of the NTC thermistor rises. The LTC4053 package temperature rather than the battery temperature. is designed to go into hold mode when the value of the NTC This problem can be eliminated by thermally coupling the NTC thermistor to the battery and not to the LTC4053. thermistor increases to seven times the value of RHOT. For a Vishay NTHS0603N02N1002J thermistor, this value is Furthermore, it is essential that the VCC connection to 28.7k which corresponds to approximately 0°C. The hot RHOT is made according to standard Kelvin sense tech- and cold comparators each have approximately 2°C of niques. Since VCC is a high current path into the LTC4053, hysteresis to prevent oscillation about the trip point. The it is essential to minimize voltage drops between the VCC NTC function can be disabled by grounding the NTC pin. input pin and the top of RHOT.

4053fa 11

LTC4053-4.2 UU

APPLICATIO S I FOR ATIOWU NTC Trip Point Errors Constant-Current/Constant-Voltage/ Constant-Temperature When a 1% resistor is used for RHOT, the major error in the 50°C trip point is determined by the tolerance of The LTC4053 uses a unique architecture to charge a the NTC thermistor. A typical 10k NTC thermistor has battery in a constant-current, constant-voltage, constant- a ±10% tolerance. By looking up the temperature temperature fashion. Figure 1 shows a simplified block coefficient of the thermistor at 50°C, the tolerance error diagram of the LTC4053. Three of the amplifier feedback can be calculated in degrees centigrade. Consider the loops shown control the constant-current, CA, constant- Vishay NTHS0603N02N1002J thermistor which has a voltage, VA, and constant-temperature, TA modes. A temperature coefficient of –3.3%/°C at 50°C. Dividing fourth amplifier feedback loop, MA, is used to increase the the tolerance by the temperature coefficient, ±10%/ output impedance of the current source pair, M1 and M2 (3.3%/°C) = ±3°C, gives the temperature error of the hot (note that M1 is the internal P-channel power MOSFET). It trip point. ensures that the drain current of M1 is exactly 1000 times The cold trip point is a little more complicated because its greater than the drain current of M2. error depends on the tolerance of the NTC thermistor and Amplifiers CA, TA, and VA are used in three separate the degree to which the ratio of its value at 0°C and its value feedback loops to force the charger into constant-current, at 50°C varies from 7 to 1. Therefore, the cold trip point temperature, or voltage mode, respectively. Diodes, D1, error can be calculated using the tolerance, TOL, the D2, and D3 provide priority to whichever loop is trying to temperature coefficient of the thermistor at 0°C, TC reduce the charge current the most. The outputs of the (in %/°C), the value of the thermistor at 0°C, RCOLD, and other two amplifiers saturate low which effectively re- the value of the thermistor at 50°C, RHOT. The formula is: moves their loops from the system. When in constant- current mode, CA servos the voltage at the PROG pin to be ⎛ 1+ TOL RCOLD ⎞ precisely 1.50V (or 0.15V when in trickle-charge mode). •–•1 100 TA limits the die temperature to approximately 105 C ⎜ 7 R ⎟ ° Temperature Error (°C) = ⎝ HOT ⎠ when in constant-temperature mode and the PROG pin TC voltage gives an indication of the charge current as dis- For example, the Vishay NTHS0603N02N1002J thermistor cussed in “Programming Charge Current”. VA servos its inverting input to precisely 2.485V when in constant- with a tolerance of ±10%, TC of –4.5%/°C, and RCOLD/ R of 6.89, has a cold trip point error of: voltage mode and the internal resistor divider made up of HOT R1 and R2 ensures that the battery voltage is maintained at 4.2V. Again, the PROG pin voltage gives an indication of ⎛ 1010± . ⎞ •.6 89 – 1 • 100 the charge current. ⎜ 7 ⎟ Temperature Error (°C) = ⎝ ⎠ In typical operation, the charge cycle begins in constant- –.45 current mode with the current delivered to the battery = –1.8°C, +2.5°C equal to 1500V/RPROG. If the power dissipation of the LTC4053 results in the junction temperature approaching If a thermistor with a tolerance less than 10% is used, the ± 105°C, the amplifier (TA) will begin decreasing the charge trip point errors begin to depend on errors other than current to limit the die temperature to approximately thermistor tolerance including the input offset voltage of 105°C. As the battery voltage rises, the LTC4053 either the internal comparators of the LTC4053 and the effects of returns to constant-current mode or it enters constant- internal voltage drops due to high charging currents. voltage mode straight from constant-temperature mode.

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LTC4053-4.2 UU

APPLICATIO S I FOR ATIOWU Regardless of mode, the voltage at the PROG pin is Furthermore, the voltage at the PROG pin will change proportional to the current being delivered to the battery. proportionally with the charge current as discussed in the Programming Charge Current section. Power Dissipation It is important to remember that LTC4053 applications do The conditions that cause the LTC4053 to reduce charge not need to be designed for worst-case thermal conditions current due to the thermal protection feedback can be since the IC will automatically reduce power dissipation approximated by considering the power dissipated in the when the junction temperature reaches approximately IC. For high charge currents, the LTC4053 power dissipa- 105°C. tion is approximately: Board Layout Considerations PD = (VCC – VBAT) • IBAT The ability to deliver maximum charge current under all where P is the power dissipated, V is the input supply D CC conditions require that the exposed metal pad on the voltage, V is the battery voltage, and I is the battery BAT BAT backside of the LTC4053 package be soldered to the PC charge current. It is not necessary to perform any worst- board ground. Correctly soldered to a 2500mm2 case power dissipation scenarios because the LTC4053 double- will automatically reduce the charge current to maintain sided 1oz. copper board the LTC4053 has a thermal resistance of approximately 40 C/W. Failure to make the die temperature at approximately 105°C. However, the ° approximate ambient temperature at which the thermal thermal contact between the exposed pad on the backside feedback begins to protect the IC is: of the package and the copper board will result in thermal resistances far greater than 40°C/W. As an example, a TA = 105°C – PDθJA correctly soldered LTC4053 can deliver over 1250mA to a battery from a 5V supply at room temperature. Without a TA = 105°C – (VCC – VBAT) • IBAT • θJA backside thermal connection, this number could drop to Example: Consider an LTC4053 operating from a 5V wall less than 500mA. adapter providing 1.2A to a 3.75V Li-Ion battery. The ambient temperature above which the LTC4053 will begin VCC Bypass Capacitor to reduce the 1.2A charge current is approximately: Many types of capacitors can be used for input bypassing. TA = 105°C – (5V – 3.75V) • 1.2A • 40°C/W However, caution must be exercised when using multi- layer ceramic capacitors. Because of the self resonant and TA = 105°C – 1.5W • 40°C/W = 105°C – 60°C = 45°C high Q characteristics of some types of ceramic capaci- The LTC4053 can be used above 45°C, but the charge tors, high voltage transients can be generated under some current will be reduced below 1.2A. The approximate start-up conditions, such as connecting the charger input charge current at a given ambient temperature can be to a hot power source. For more information refer to approximated by: Application Note 88.

105°CT – A Stability IBAT = (–VVCC BAT )•θ JA The constant-voltage mode feedback loop is stable Consider the above example with an ambient temperature without any compensation provided that a battery is of 55°C. The charge current will be reduced to approxi- connected. However, a 1µF capacitor with a 1Ω series mately: resistor to GND is recommended at the BAT pin to keep ripple voltage low when the battery is disconnected. 105°°CC– 55 50°C In the constant-current mode it is the PROG pin that is in IBAT = = = 1A (–.)•5VVCW 3 75 40° /50°CA / the feedback loop and not the battery. The constant- current mode stability is affected by the impedance at the 4053fa 13

LTC4053-4.2 UU

APPLICATIO S I FOR ATIOWU PROG pin. With no additional capacitance on the PROG Average, rather than instantaneous, battery current may pin, stability is acceptable with program resistor values as be of interest to the user. For example, if a switching power high as 50k. However, additional capacitance on this node supply operating in low-current mode is connected in reduces the maximum allowed program resistor. The pole parallel with the battery the average current being pulled frequency at the PROG pin should be kept above 500kHz. out of the BAT pin is typically of more interest than the Therefore, if the PROG pin is loaded with a capacitance, C, instantaneous current pulses. In such a case, a simple RC the following equation should be used to calculate the filter can be used on the PROG pin to measure the average maximum resistance value for RPROG: battery current as shown in Figure 5. A 10k resistor is added between the PROG pin and the filter capacitor and R < 1/(6.283 • 5 × 105 • C) PROG monitoring circuit to ensure stability.

LTC4053 CHARGE 7 10k CURRENT PROG MONITOR CIRCUITRY RPROG CFILTER GND 5

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Figure 5. Isolating Capacitive Load on PROG Pin and Filtering

PACKAGE DESCRIPTIO U

DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698)

R = 0.115 0.38 ± 0.10 TYP 6 10 0.675 ±0.05

3.50 ±0.05 1.65 ±0.05 3.00 ±0.10 1.65 ± 0.10 2.15 ±0.05 (2 SIDES) (4 SIDES) (2 SIDES) PIN 1 PACKAGE TOP MARK OUTLINE (SEE NOTE 6) (DD10) DFN 1103 5 1 0.25 ± 0.05 0.200 REF 0.75 ±0.05 0.25 ± 0.05 0.50 0.50 BSC BSC 2.38 ±0.10 (2 SIDES) 2.38 ±0.05 0.00 – 0.05 (2 SIDES) BOTTOM VIEW—EXPOSED PAD RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 2. DRAWING NOT TO SCALE 5. EXPOSED PAD SHALL BE SOLDER PLATED 3. ALL DIMENSIONS ARE IN MILLIMETERS 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE

4053fa 14 LTC4053-4.2

PACKAGE DESCRIPTIO U MSE Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1663)

BOTTOM VIEW OF EXPOSED PAD OPTION 2.06 ± 0.102 2.794 ± 0.102 0.889 ± 0.127 1 (.081 ± .004) (.110 ± .004) (.035 ± .005) 1.83 ± 0.102 (.072 ± .004)

5.23 2.083 ± 0.102 3.2 – 3.45 (.206) (.082 ± .004) (.126 – .136) MIN

0.305 ± 0.038 0.50 3.00 ± 0.102 (.0120 ± .0015) (.0197) (.118 .004) ± 0.497 ± 0.076 TYP BSC (NOTE 3) (.0196 ± .003) RECOMMENDED SOLDER PAD LAYOUT 10 9 8 7 6 REF

3.00 0.102 4.90 ± 0.15 ± (.118 .004) (1.93 ± .006) ± NOTE 4 DETAIL “A” 0.254 (.010) 0° – 6° TYP GAUGE PLANE 123 45

0.53 ± 0.01 1.10 0.86 (.021 ± .006) (.043) (.034) MAX REF DETAIL “A” 0.18 (.007) SEATING PLANE 0.17 – 0.27 0.13 ± 0.076 (.007 – .011) (.005 .003) 0.50 ± TYP MSOP (MSE) 0802 NOTE: (.0197) 1. DIMENSIONS IN MILLIMETER/(INCH) BSC 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX

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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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 15 LTC4053-4.2

TYPICAL APPLICATIO SU USB/Wall Adapter Power Li-Ion Battery Charger

5V WALL ADAPTER LTC4053-4.2 IBAT 9 BAT + Li-Ion USB 2 1µF CELL POWER VCC 1Ω 4.7µF 4 8 TIMER SHDN SUSPEND 1k GND NTC PROG 5 6 7 µC 3.74k 100mA/ 0.1 F µ 15k 500mA

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Li-Ion Battery Charger with Reverse Polarity Input Protection Full Featured Single Cell Li-Ion Charger

VIN = 5V LTC4053-4.2 IBAT = 1A 5V WALL 2 9 V BAT 1k 1k ADAPTER CC 82 1-CELL+ 1k 8 SHDN V SHDN Li-Ion CC 4k 10 BATTERY ACPR 4.7µF 1% 4 7 1 3 TIMER PROG CHRG FAULT 4.7µF LTC4053-4.2 IBAT = 500mA GND NTC 6 9 1.5k NTC BAT 0.1µF 5 6 1% 4 7 1µF TIMER PROG 4053 F07 RNTC Li-Ion 10k GND 3k CELL 1Ω 0.1µF 5 1%

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RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1571 200kHz/500kHz Switching Battery Charger Up to 1.5A Charge Current; Preset and Adjustable Battery Voltages LTC1729 Lithium-Ion Battery Charger Termination Controllers Time or Charge Current Termination, Preconditioning 8-Lead MSOP LTC1730 Lithium-Ion Battery Pulse Charger No Blocking Diode Required, Current Limit for Maximum Safety LTC1731 Lithium-Ion Linear Battery Charger Controller Simple Charger uses External FET, Features Preset Voltages, C/10 Charger Detection and Programmable Timer LTC1732 Lithium-Ion Linear Battery Charger Controller Simple Charger uses External FET, Features Preset Voltages, C/10 Charger Detection and Programmable Timer, Input Power Good Indication LTC1733 Monolithic Lithium-Ion Linear Battery Charger Standalone Charger with Programmable Timer, Up to 1.5A Charge Current LTC1734 Lithium-Ion Linear Battery Charger in ThinSOTTM Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed LTC1734L Lithium-Ion Linear Battery Charger Controller 50mA to 180mA, No Blocking Diode, No Sense Resistor Needed LTC4050 Lithium-Ion Linear Battery Charger Controller Simple Charger uses External FET, Thermistor Input for Battery Temperature Sensing LTC4052 Lithium-Ion Linear Battery Pulse Charger Fully Integrated, Standalone Pulse Charger, Minimal Heat Dissipation, Overcurrent Protection LTC4054 Standalone Lithium-Ion Linear Battery Charger in Up to 800mA Charge Current, Thermal Regulation, USB Compatible, ThinSOT Charge Termination LTC4056 Standalone Lithium-Ion Linear Battery Charger Up to 700mA Charge Current, Charge Termination, Continuous Charging with Controller in ThinSOT Poorly Regulated or High Impedance Input Supplies ThinSOT is a trademark of Linear Technology Corporation. 4053fa Linear Technology Corporation LT/LT 0705 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 16 ● ● (408) 432-1900 FAX: (408) 434-0507 www.linear.com © LINEAR TECHNOLOGY CORPORATION 2001