LTC4059A

FEATURES s s LTC4059/LTC4059A 900mA Linear Li-Ion Battery Chargers with Thermal Regulation in 2 × 2 DFN DESCRIPTIO The LTC®4059/LTC4059A are constant-current/constantvoltage linear chargers for single cell lithium-ion batteries. Their 2mm × 2mm DFN package and low external component count make these chargers especially well suited for portable applications. Furthermore, they are designed to work within USB power specifications. No external sense resistor, MOSFET or blocking diode is required. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient thermal conditions. The charge voltage is fixed at 4.2V and the charge current is programmable. When the input supply (wall adapter or USB supply) is removed, the LTC4059/LTC4059A automatically enter a low current state, dropping the battery current drain to less than 1µA. With power applied, they can be put into shutdown mode, reducing the supply current to 10µA. The LTC4059A features an open-drain status pin to indicate the presence of an input voltage. The LTC4059 can be used as a constant-current source to charge Nickel cells. Other features include undervoltage lockout protection and a current monitor pin which can indicate when to terminate a charge cycle. The LTC4059/LTC4059A are available in a 6-lead, low profile (0.8mm) 2mm × 2mm DFN package. , LTC and LT are registered trademarks of Linear Technology Corporation. *US Patent 6,522,118 s s s s s s s s s Programmable Charge Current Up to 900mA Charge Current Monitor Output for Charge Termination* Constant-Current/Constant-Voltage Operation with Thermal Regulation to Maximize Charging Rate Without Risk of Overheating* Constant-Current Source Mode for Charging Nickel Batteries (LTC4059 Only) ACPR Pin Indicates Presence of Input Supply (LTC4059A Only) No External MOSFET, Sense Resistor or Blocking Diode Required Operating Supply Voltage from 3.75V to 8V Charges Single Cell Li-Ion Batteries Directly from USB Port Preset 4.2V Charge Voltage with 0.6% Accuracy 10µA Supply Current in Shutdown Mode Tiny 6-Lead (2mm × 2mm) DFN Package APPLICATIO S s s s s s Wireless PDAs Cellular Phones Portable Electronics Wireless Headsets Digital Cameras TYPICAL APPLICATIO VIN 4.5V TO 8V VCC 1µF EN GND ACPR Complete Charge Cycle (800mAh Battery) 700 VDD CHARGE CURRENT (mA) 600 500 400 300 200 CONSTANT CURRENT 50k µP 600mA LTC4059A BAT PROG 2k + 4.2V Li-Ion BATTERY 4059 TA01 VCC = 5V 100 RPROG = 2k TA = 25°C 0 0.5 0 U U U CONSTANT VOLTAGE 4.4 4.2 BATTERY VOLTAGE (V) 4.0 3.8 3.6 3.4 3.2 3.0 2.5 4059 TA02 1 1.5 2 TIME (HOURS) 4059fa 1 LTC4059/LTC4059A ABSOLUTE (Note 1) AXI U RATI GS PACKAGE/ORDER I FOR ATIO TOP VIEW GND 1 Li CC/ACPR* 2 BAT 3 7 6 EN 5 PROG 4 VCC Input Supply Voltage (VCC) ...................... –0.3V to 10V BAT, PROG, EN, Li CC, ACPR ................... –0.3V to 10V BAT Short-Circuit Duration ........................... Continuous BAT Pin Current ............................................... 1000mA PROG Pin Current ............................................. 1000µA Junction Temperature .......................................... 125°C Operating Temperature Range (Note 2) .. – 40°C to 85°C Storage Temperature Range ................. – 65°C to 125°C ORDER PART NUMBER LTC4059EDC LTC4059AEDC DC6 PART MARKING LAFU LBJH DC6 PACKAGE 6-LEAD (2mm × 2mm) PLASTIC DFN TJMAX = 125°C, θJA = 60°C/W TO 85°C/W (NOTE 3) *Li CC PIN 2 ON LTC4059EDC, ACPR PIN 2 ON LTC4059AEDC EXPOSED PAD IS GND (PIN 7) MUST BE SOLDERED TO PCB Consult LTC Marketing for parts specified with wider operating temperature ranges. The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V unless otherwise noted. SYMBOL PARAMETER VCC ICC ICCMS ICCUV VFLOAT IBAT IBMS IBUV VUV VPROG VMS VMSHYS REN VLi CC VACPR tLIM RON 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 Battery Drain Current in Undervoltage Lockout VCC – VBAT Undervoltage Lockout Threshold PROG Pin Voltage Manual Shutdown Threshold Manual Shutdown Hysteresis EN Pin Input Resistance Voltage Mode Disable Threshold ACPR Pin Output Low Voltage Junction Temperature In Constant Temperature Mode Power FET “ON” Resistance (Between VCC and BAT) IBAT = 150mA VBAT = 4.5V (Forces IBAT and IPROG = 0) VEN = VCC VCC < VBAT; VCC = 3.5V, VBAT = 4V IBAT = 2mA 4.5V < VCC < 8V, IBAT = 2mA RPROG = 2.43k, Current Mode, VBAT = 3.8V RPROG = 12.1k, Current Mode, VBAT = 3.8V VEN = VCC, VCC > VBAT VCC < VBAT, VBAT = 4V VCC from Low to High, VBAT = 3.7V VCC from High to Low, VBAT = 3.7V RPROG = 2.43k, IPROG = 500µA RPROG = 12.1k, IPROG = 100µA VEN Increasing VEN Decreasing VEN = 5V VLi CC Increasing (LTC4059 Only) VLi CC Decreasing (LTC4059 Only) IACPR = 300µA (LTC4059A Only) q q ELECTRICAL CHARACTERISTICS CONDITIONS q q q q MIN 3.75 TYP 25 10 4 MAX 8 60 25 10 4.225 4.242 525 106 ±1 4 200 80 1.24 1.24 1.2 3 1.2 0.5 UNITS V µA µA µA V V mA mA µA µA mV mV V V V mV MΩ V mV V °C q q q q q q q q q q 4.175 4.158 475 94 0 100 0 1.18 1.18 0.3 1 0.3 4.2 4.2 500 100 0 1 150 35 1.21 1.21 0.92 85 1.85 0.92 85 0.25 115 800 VLi CCHYS Voltage Mode Disable Hysteresis 1200 Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC4059E/LTC4059AE are guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C 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 60°C/W. 4059fa 2 U mΩ W U U WW W LTC4059/LTC4059A TYPICAL PERFOR A CE CHARACTERISTICS Battery Regulation (Float) Voltage vs Battery Charge Current 4.26 4.24 4.22 VCC = 5V TA = 25°C RPROG = 2.43k 4.24 4.23 4.22 VFLOAT (V) VFLOAT (V) 4.18 4.16 4.14 4.12 4.10 0 100 200 300 IBAT (mA) 400 500 4059 G01 4.20 4.19 4.18 4.17 4.16 –50 –25 50 25 TEMPERATURE (°C) 0 75 100 4059 G02 VFLOAT (V) 4.20 Charge Current vs Input Voltage 600 500 RPROG = 2.43k 400 THERMAL LIMITING VBAT = 3.85V TA = 25°C 600 IBAT (mA) IBAT (mA) 300 200 100 0 4 5 6 VCC (V) 4059 G04 300 200 IBAT (mA) RPROG = 12.1k 7 PROG Pin Voltage vs Charge Current 1.4 1.2 1.0 VPROG (V) VPROG (V) VCC = 5V TA = 25°C RPROG = 2.43k RDS(ON) (mΩ) 0.8 0.6 0.4 0.2 0 0 100 200 300 400 500 4059 F07 IBAT (mA) UW 8 Battery Regulation (Float) Voltage vs Temperature VCC = 5V IBAT = 2mA RPROG = 2.43k 4.24 4.23 4.22 4.21 4.20 4.19 4.18 4.17 4.16 Regulated Output (Float) Voltage vs Supply Voltage TA = 25°C IBAT = 10mA RPROG = 2.43k 4.21 4 5 6 VCC (V) 7 8 4059 G03 Charge Current vs Battery Voltage Li CC = 5V LTC4059 ONLY 500 400 Li CC = 0V LTC4059A 600 Charge Current vs Ambient Temperature with Thermal Regulation RPROG = 2.43k 500 400 THERMAL CONTROL LOOP IN OPERATION 300 200 100 0 VCC = 5V TA = 25°C RPROG = 2.43k 2.5 3 3.5 VBAT (V) 4 4.5 4059 G05 100 0 –50 –25 VCC = 5V VBAT = 3.85V RPROG = 12.1k 50 100 25 75 0 AMBIENT TEMPERATURE (°C) 125 4059 G06 PROG Pin Voltage vs Temperature (Constant Current Mode) 1.24 1.23 1.22 RPROG = 12.1k 1.21 1.20 1.19 1.18 –50 –25 RPROG = 2.43k VCC = 5V VBAT = 3.85V Power FET “ON” Resistance vs Temperature 1200 1000 900 800 700 600 500 400 –50 VCC = 5V IBAT = 100mA 50 25 75 0 TEMPERATURE (°C) 100 125 –25 0 25 50 TEMPERATURE (°C) 75 100 4059 G09 4059 G08 4059fa 3 LTC4059/LTC4059A TYPICAL PERFOR A CE CHARACTERISTICS VCC – VBAT Undervoltage Lockout Threshold vs Battery Voltage 500 TA = 25°C 450 RPROG = 12.1k 400 350 2.5 3.5 3.0 TA = 25°C VUV (mV) EN (µA) 2.0 TA = –20°C 1.5 1.0 0.5 0 250 200 150 100 50 0 3 4 6 5 VBAT (V) 7 8 4059 G10 IBUV (µA) 6 4059 G11 300 UVLO Battery Drain Current vs Temperature 2.5 VCC = 0V VBAT = 4V 14 12 10 2.0 ICCMS (µA) IBUV (µA) VMS (V) 1.5 1.0 0.5 2 0 –50 –25 50 25 0 75 TEMPERATURE (°C) ACPR Pin Output Low Voltage vs Temperature (LTC4059A Only) 0.50 VCC = 5V 0.45 VBAT = 4.2V IACPR = 300µA 0.40 IACPR (mA) VACPR (V) 0.30 0.25 0.20 0.15 0.10 – 50 – 25 0 75 50 25 TEMPERATURE (°C) 100 125 2.0 1.5 1.0 0.5 0 0 1 2 3 4 VACPR (V) 5 6 7 8 VLi CC (V) 0.35 4 UW 100 4059 G13 4059 G17 EN Pin Current vs EN Voltage and Temperature 2.0 UVLO Battery Drain Current vs Battery Voltage VCC = 0V 1.8 TA = 25°C 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 TA = 100°C 0 1 2 3 VEN (V) 4 5 0 0 1 3 2 VBAT (V) 4 5 4059 G12 Manual Shutdown Supply Current vs Temperature VCC = 5V VEN = 5V Manual Shutdown Threshold Voltage vs Temperature 1.2 1.1 1.0 RISING 0.9 FALLING 0.8 0.7 0.6 –50 8 6 4 125 0 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 –25 0 25 50 TEMPERATURE (°C) 75 100 4059 F15 4059 G14 ACPR Pin (Pull-Down State) I-V Curve (LTC4059A Only) 4.0 3.5 3.0 2.5 VCC = 5V VBAT = 4.2V TA = 25°C Voltage Mode Disable Threshold Voltage vs Temperature (LTC4059 Only) 1.2 1.1 1.0 RISING 0.9 0.8 0.7 0.6 –50 FALLING –25 0 25 50 TEMPERATURE (°C) 75 100 4059 F16 4059 G18 4059fa LTC4059/LTC4059A PI FU CTIO S GND (Pins 1, 7): Ground/Exposed Pad. The exposed package pad is ground and must be soldered to the PC board for maximum heat transfer. Li CC (Pin 2, LTC4059): Li-Ion/Constant Current Input Pin. Pulling this pin above VLi CC disables voltage mode thereby providing a constant current to the BAT pin. This feature is useful for charging Nickel chemistry batteries. Tie to GND if unused. ACPR (Pin 2, LTC4059A): Open-Drain Power Supply Status Output. When VCC is greater than the undervoltage lockout threshold, the ACPR pin will pull to ground; otherwise the pin is forced to a high impedance state. 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 from this pin sets this 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 8V. This pin should be bypassed with at least a 1µF capacitor. When VCC is within 35mV of the BAT pin voltage, the LTC4059 enters shutdown mode, dropping IBAT to less than 4µA. PROG (Pin 5): Charge Current Program and Charge Current Monitor Pin. Connecting a resistor, RPROG, to ground programs the charge current. When charging in constantcurrent mode, this pin servos to 1.21V. In all modes, the voltage on this pin can be used to measure the charge current using the following formula: U U U IBAT = VPROG • 1000 RPROG EN (Pin 6): Enable Input Pin. Pulling this pin above the manual shutdown threshold (VMS is typically 0.92V) puts the LTC4059 in shutdown mode, thus terminating a charge cycle. In shutdown mode, the LTC4059 has less than 25µA supply current and less than 1µA battery drain current. Enable is the default state, but the pin should be tied to GND if unused. 4059fa 5 LTC4059/LTC4059A BLOCK DIAGRA 6 EN MA CA – 1.2V VOLTAGE REF REFERENCE + TDIE 115°C – + D3 TA R3 PROG 5 Li CC 2 1,7 Figure 1 (LTC4059) 4 VCC M1 1000× 6 EN LOGIC REN M2 1× BAT VCC D1 2 MA CA – 1.2V VOLTAGE REF REFERENCE + TDIE 115°C – + D3 TA R3 PROG 5 1,7 Figure 2 (LTC4059A) 4059fa 6 + – ACPR + – + – W 4 VCC M1 1000× LOGIC REN M2 1× D1 D2 BAT 3 + R1 VA + – REF R2 GND 4059 F01 D2 BAT 3 + R1 VA + – REF R2 GND 4059 F02 LTC4059/LTC4059A OPERATIO The LTC4059/LTC4059A are linear battery chargers designed primarily for charging single cell lithium-ion batteries. Featuring an internal P-channel power MOSFET, the chargers use a constant-current/constant-voltage charge algorithm with programmable current. Charge current can be programmed up to 900mA with a final float voltage accuracy of ± 0.6%. No blocking diode or external sense resistor is required; thus, the basic charger circuit requires only two external components. The ACPR pin (LTC4059A) monitors the status of the input voltage with an open-drain output. The Li CC pin (LTC4059) disables constant-voltage operation and turns the LTC4059 into a precision current source capable of charging Nickel chemistry batteries. Furthermore, the LTC4059/LTC4059A are designed to operate 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 115°C. This feature protects the LTC4059/LTC4059A 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 LTC4059/LTC4059A or external components. Another APPLICATIO S I FOR ATIO Programming Charge Current The charge current is programmed using a single resistor from the PROG pin to ground. The battery charge current is 1000 times the current out of the PROG pin. The program resistor and the charge current are calculated using the following equations: RPROG = 1000 • 1.21V 1.21V , ICHG = 1000 • ICHG RPROG For best stability over temperature and time, 1% metalfilm resistors are recommended. 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 • 1000 RPROG U W UU U benefit of the 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 worstcase conditions. The charge cycle begins when the voltage at the VCC pin rises approximately 150mV above the BAT pin voltage, a program resistor is connected from the PROG pin to ground, and the EN pin is pulled below the shutdown threshold (typically 0.85V). If the BAT pin voltage is below 4.2V, or the Li CC pin is pulled above VLi CC (LTC4059 only), the LTC4059 will charge the battery with the programmed current. This is constant-current mode. When the BAT pin approaches the final float voltage (4.2V), the LTC4059 enters constantvoltage mode and the charge current begins to decrease. To terminate the charge cycle the EN should be pulled above the shutdown threshold. Alternatively, reducing the input voltage below the BAT pin voltage will also terminate the charge cycle. Undervoltage Lockout (UVLO) An internal undervoltage lockout circuit monitors the input voltage and keeps the charger in undervoltage lockout until VCC rises approximately 150mV above the BAT pin voltage. The UVLO circuit has a built-in hysteresis of 115mV. If the BAT pin voltage is below approximately 2.75V, then the charger will remain in undervoltage lockout until VCC rises above approximately 3V. During undervoltage lockout conditions, maximum battery drain current is 4µA. Power Supply Status Indicator (ACPR, LTC4059A Only) The power supply status output has two states: pull-down and high impedance. The pull-down state indicates that VCC is above the undervoltage lockout threshold (see Undervoltage Lockout). When this condition is not met, the ACPR pin is high impedance indicating that the LTC4059A is unable to charge the battery. 4059fa 7 LTC4059/LTC4059A APPLICATIO S I FOR ATIO Shutdown Mode Charging can be terminated by pulling the EN pin above the shutdown threshold (approximately 0.92V). In shutdown mode, the battery drain current is reduced to less than 1µA and the supply current to 10µA. USB and Wall Adapter Power Although the LTC4059/LTC4059A allow 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. Typically a wall adapter can supply significantly more current than the 500mA limited USB port. Therefore, an N-channel MOSFET, MN1, and an extra program resistor are used to increase the charge current to 850mA when the wall adapter is present. 5V WALL ADAPTER 850mA ICHG USB POWER 500mA ICHG 3 ICHG SYSTEM LOAD D1 4 MP1 BAT LTC4059 VCC PROG 5 + Li-Ion BATTERY 1k MN1 3.4k 2.43k 4059 F03 Figure 3. Combining Wall Adapter and USB Power Constant Current/Constant Voltage/ Constant Temperature The LTC4059/LTC4059A use a unique architecture to charge a battery in a constant-current, constant-voltage and constant-temperature fashion. Figures 1 and 2 show simplified block diagrams of the LTC4059 and LTC4059A respectively. 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 imped- 8 U ance 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 1000 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 voltage mode, respectively. Diodes D1 and D2 provide priority to either the constant-current or constant-voltage 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 1.21V. VA servos its inverting input to precisely 1.21V 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 the Programming Charge Current section. Transconductance amplifier, TA, limits the die temperature to approximately 115°C when in constant-temperature mode. TA acts in conjunction with the constant-current loop. When the die temperature exceeds approximately 115°C, TA sources current through R3. This causes CA to reduce the charge current until the PROG pin voltage plus the voltage across R3 equals 1.21V. Diode D3 ensures that TA does not affect the charge current when the die temperature is below approximately 115°C. 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 1210V/RPROG. If the power dissipation of the LTC4059/LTC4059A results in the junction temperature approaching 115°C, the amplifier (TA) will begin decreasing the charge current to limit the die temperature to approximately 115°C. As the battery voltage rises, the LTC4059/LTC4059A either return to constant-current mode or enter constant-voltage mode straight from constanttemperature mode. Regardless of mode, the voltage at the PROG pin is proportional to the current delivered to the battery. 4059fa W UU LTC4059/LTC4059A APPLICATIO S I FOR ATIO Power Dissipation The conditions that cause the LTC4059/LTC4059A to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the IC. For high charge currents, the LTC4059 power dissipation is approximately: 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 LTC4059/ LTC4059A will automatically reduce the charge current to maintain the die temperature at approximately 115°C. However, the approximate ambient temperature at which the thermal feedback begins to protect the IC is: TA = 115°C – PDθJA TA = 115°C – (VCC – VBAT) • IBAT • θJA Example: Consider an LTC4059 operating from a 5V wall adapter providing 900mA to a 3.7V Li-Ion battery. The ambient temperature above which the LTC4059/LTC4059A begin to reduce the 900mA charge current is approximately: TA = 115°C – (5V – 3.7V) • (900mA) • 50°C/W TA = 115°C – 1.17W • 50°C/W = 115°C – 59°C TA = 56°C The LTC4059 can be used above 56°C, but the charge current will be reduced from 900mA. The approximate current at a given ambient temperature can be calculated: IBAT = 115°C – TA ( VCC – VBAT ) • θJA Using the previous example with an ambient temperature of 65°C, the charge current will be reduced to approximately: IBAT = 115°C – 65°C 50°C = (5V – 3.7V) • 50°C/W 65°C/A IBAT = 770mA Furthermore, the voltage at the PROG pin will change proportionally with the charge current as discussed in the Programming Charge Current section. U It is important to remember that LTC4059/LTC4059A 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 115°C. Board Layout Considerations In order to be able to deliver maximum charge current under all conditions, it is critical that the exposed metal pad on the backside of the LTC4059/LTC4059A package is soldered to the PC board ground. Correctly soldered to a 2500mm2 double sided 1oz copper board the LTC4059/ LTC4059A have a thermal resistance of approximately 60°C/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 60°C/W. As an example, a correctly soldered LTC4059/ LTC4059A can deliver over 900mA to a battery from a 5V supply at room temperature. Without a backside thermal connection, this number could drop to less than 500mA. Stability Considerations The LTC4059 contains two control loops: constant voltage 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 1µF from BAT to GND. Furthermore, a 4.7µF capacitor with a 0.2Ω to 1Ω 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) reduce the constant-voltage loop phase margin. Ceramic capacitors up to 22µF may be used in parallel with a battery, but larger ceramics should be decoupled with 0.2Ω to 1Ω of series resistance. In constant-current mode, the PROG pin is in the feedback loop, not the battery. Because of the additional pole created by 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 12k. However, additional capacitance on this node reduces the maximum allowed 4059fa W UU 9 LTC4059/LTC4059A APPLICATIO S I FOR ATIO program resistor. The pole frequency at the PROG pin should be kept above 500kHz. 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 ≤ 1 2π • 5 • 105 • 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 LTC4059 PROG GND Figure 4. Isolating Capacitive Load on PROG Pin and Filtering Figure 5. Photo of Typical Circuit (2.5mm × 2.7mm) 4059fa 10 U filter can be used on the PROG pin to measure the average battery current as shown in Figure 4. A 20k resistor has been added between the PROG pin and the filter capacitor to ensure stability. 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. 20k CHARGE CURRENT MONTIOR CIRCUITRY CFILTER 4059 F04 W UU RPROG LTC4059/LTC4059A PACKAGE DESCRIPTIO 2.50 ± 0.05 1.15 ± 0.05 0.61 ± 0.05 (2 SIDES) PACKAGE OUTLINE PIN 1 TOP MARK (SEE NOTE 5) 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. ALL DIMENSIONS ARE IN MILLIMETERS 3. 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 4. EXPOSED PAD SHALL BE SOLDER PLATED 5. 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 × 2mm) (Reference LTC DWG # 05-08-1703) R = 0.115 TYP 0.56 ± 0.05 (2 SIDES) 2.00 ± 0.10 (4 SIDES) PIN 1 NOTCH (DC6) DFN 0403 0.38 ± 0.05 4 6 0.675 ± 0.05 3 0.200 REF 0.75 ± 0.05 1 0.25 ± 0.05 0.50 BSC 1.37 ± 0.05 (2 SIDES) 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD 4059fa 11 LTC4059/LTC4059A TYPICAL APPLICATIO U VIN 4.5V TO 6.5V VCC 1µF EN Li CC BAT PROG GND 2k 600mA LTC4059 + 4.2V Li-Ion BATTERY 4059 TA03 RELATED PARTS PART NUMBER LTC1733 LTC1734 LTC1998 LTC4050 DESCRIPTION Monolithic Lithium-Ion Linear Battery Charger Lithium-Ion Linear Battery Charger in ThinSOT Lithium-Ion Low Battery Detector Lithium-Ion Linear Battery Charger Controller TM COMMENTS Standalone Charger with Programmable Timer, Up to 1.5A Charge Current Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed 1% Accurate 2.5µA Quiescent Current, SOT-23 Simple Charger uses External FET, Features Preset Voltages, C/10 Charger Detection and Programmable Timer, Input Power Good Indication, Thermistor Interface No Blocking Diode or External Power FET Required Standalone Charger with Programmable Timer, Up to 1.25A Charge Current Thermal Regulation Prevents Overheating, C/10 Termination, C/10 Indicator Standalone Charger with Programmable Timer, No Blocking Diode, No Sense Resistor Needed No External MOSFET, Sense Resistor or Blocking Diode Required, Charge Current Monitor for Gas Gauging For Simultaneous Operation of USB Peripheral and Battery Charging from USB Port, Keeps Current Drawn from USB Port Constant, Keeps Battery Fresh, Use with the LTC4053, LTC1733 or LTC4054 USB Compatible, Thermal Regulation Protects Against Overheating LTC4052 LTC4053 LTC4054 LTC4056 LTC4057 LTC4410 Monolithic Lithium-Ion Battery Pulse Charger USB Compatible Monolithic Li-Ion Battery Charger Standalone Linear Li-Ion Battery Charger with Integrated Pass Transistor in ThinSOT Standalone Lithium-Ion Linear Battery Charger in ThinSOT Monolithic Lithium-Ion Linear Battery Charger with Thermal Regulation in ThinSOT USB Power Manager LTC4058 950mA Standalone Li-Ion Charger in 3mm × 3mm DFN ThinSOT is a trademark of Linear Technology Corporation. 4059fa 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 q FAX: (408) 434-0507 q LT/TP 0304 1K REV A • PRINTED IN USA www.linear.com © LINEAR TECHNOLOGY CORPORATION 2003