SD8017

SD8017 Shouding Description Features SD8017 is a complete constant-current & constant voltage linear charger for single cell lithium-ion and Lithium-Polymer batteries. Its SOT-23 package and low external component count make SD8017 ideally suited for portable applications. Furthermore, the SD8017 is specifically designed to work within USB power specification. At the same time, SD8017 can also be used in the standalone lithium-ion and Lithium-polymer battery chargers. No external sense resistor is needed, and no blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The SD8017 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the SD8017 automatically enters a low current stage, dropping the battery drain current to less than 2uA. The SD8017 can be put into shutdown mode, reducing the supply current to 20uA. Other features include charge current monitor, undervoltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input voltage. SD8017 is intentionally designed to have slightly negative Tempco. This provides extra protection to Lithium battery during charging. ¾ Programmable Charge Current Up to 800mA. ¾ No MOSFET, Sense Resistor or Blocking Diode Required. ¾ Constant-Current/Constant-Voltage Operation with Thermal Protection to Maximize Charge Rate without Risk of Overheating. ¾ Charges Single Cell Li-Ion Batteries Directly from USB Port. ¾ Preset 4.2V Charge Voltage with ±1% Accuracy. ¾ 20uA Supply Current in Shutdown. ¾ 2.9V Trickle Charge Threshold ¾ Soft-Start Limits Inrush Current. ¾ Available in 5-Lead SOT-23 and PSOP-8 (Exposed Pad) Packages. ¾ RoHS Compliant and 100% Lead (Pb)-Free Application ¾ Cellular Telephones, PDA’s, MP3 Players. ¾ Charging Docks and Cradles ¾ Bluetooth Applications Application Diagram Pin Configuration SD8017 Revision 10/9/2008 www.shouding.net 1 SD8017 Shouding Absolute Maximum Rating (1) Parameter Symbol Value Units Input Supply Voltage VCC 7 V PROG Voltage VPROG VCC+0.3 V BAT Voltage VBAT 7 V CHRG Voltage VCHRG 7 V BAT Short-Circuit Duration Continuous 250 (SOT-23-6) Thermal Resistance, Junction-to-Ambient ΘJA BAT Pin Current IBAT 800 mA PROG Pin Current IPROG 800 μA Maximum Junction Temperature TJ 125 °C Storage Temperature TS -65 to +125 °C 300 °C 75(PSOP8) Lead Temperature (Soldering, 10 sec) °C/W Operating Rating (2) Parameter Symbol Value Units Supply Input Voltage VIN -0.3 to +7 V Junction Temperature TJ -40 to +85 °C Electrical Characteristics VIN = 5V; TJ = 25°C; unless otherwise specified. Symbol VCC ICC Parameter Conditions Min Input Supply Voltage Input Supply Current Typ 4.25 (3) Max Unit 6 V 500 µA Charge Mode , RPROG = 10k 110 Standby Mode (Charge Terminated) 70 20 40 µA µA Shutdown Mode(RPROG Not Connected, VCC < VBAT, or VCC < VUV) VFLOAT Regulated Output (Float) Voltage IBAT = 30mA, ICHRG = 5mA 4.158 4.2 4.242 V IBAT BAT Pin Current RPROG = 10k, Current Mode 90 106 130 mA +/-1 +/-5 mA µA +/-0.5 +/-5 µA +/-1 +/-5 µA RPROG = 2k, Current Mode Standby Mode, VBAT = 4.2V 530 0 Shutdown Mode (RPROG Not Connected) Sleep Mode, VCC = 0V ITRIKL Trickle Charge Current VBAT < VTRIKL, RPROG = 10k VTRIKL Trickle Charge Threshold Voltage RPROG = 10k, VBAT Rising Revision 10/9/2008 10 2.8 2.9 www.shouding.net 2 mA 3.0 V SD8017 Shouding Electrical Characteristics (Continued) VIN = 5V; TJ = 25°C; unless otherwise specified Symbol Parameter Conditions VUV VCC Undervoltage Lockout Threshold VUVHYS VCC Undervoltage Lockout Hysteresis VMSD Manual Shutdown Threshold Voltage VASD From VCC Low to High VCC – VBAT Lockout Threshold Voltage ITERM Min C/10 Termination Current Threshold Typ Max Unit 3.4 V 100 mV PROG Pin Rising 1.25 V PROG Pin Falling 1.2 V VCC from Low to High 100 mV VCC from High to Low 30 mV 0.1 mA/mA 0.1 mA/mA RPROG = 10k (4) RPROG = 2k VPROG PROG Pin Voltage RPROG = 10k, Current Mode 0.9 1.03 1.1 V ICHRG CHRG Pin Weak Pull-Down Current VCHRG = 3V 15 µA VCHRG CHRG Pin Output Low Voltage ICHRG = 5mA 0.6 V ΔVRECHRG Recharge Battery Threshold Voltage VFLOAT - VRECHRG 100 mV TLIM Thermal Protection Temperature 120 °C tSS Soft-Start Time IBAT = 0 to 1000V/RPROG 100 µs tRECHARGE Recharge Comparator Filter Time VBAT High to Low 1 ms tTERM Termination Comparator Filter Time IBAT Falling Below ICHG/10 1000 µs IPROG PROG Pin Pull-Up Current 1 µA Note 1: Exceeding the absolute maximum rating may damage the device. Note 2: The device is not guaranteed to function outside its operating rating. Note 3: Supply current includes PROG pin current (approximately 100µA) but does not include any current delivered to the battery through the BAT pin (approximately 100mA). Note 4: ITERM is expressed as a fraction of measured full charge current with indicated PROG resistor. Pin Functions Pin Pin Function Description Pin P Positive Input Supply Voltage. Provides VCC power to the charger. VCC can range from 4.25V to 6.5V and should be Open-Drain Charge Status Output. When the battery is charging, the CHRG bypassed with at least a 1μF capacitor. Ground. GND Pin Function Description CHRG pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed, a weak pull-down of approximately 20uA is connected to the CHRG pin, indicating an “AC present” condition. PROG Charge Current Program, Charge Current Monitor and Shutdown Pin. Open-Drain Charge Termination Status Output. When the battery is Charge Current Output. Provides BAT charge current to the battery and charging, the CHRGT pin is pulled high by an external CHRGT regulates the final float voltage to 4.2V. compenent such as an LED. After the charging is completed, this pin is pulled low by internal N-channel MOSFET and it can be used as a charging termination indicator. Revision 10/9/2008 www.shouding.net 3 SD8017 Shouding BLOCK DIAGRAM Revision 10/9/2008 www.shouding.net 4 SD8017 Shouding Charge Current vs Supply Voltage Float Voltage vs Supply Voltage 600 4.230 RPROG=2k 4.225 4.220 TA=25℃ 4.210 4.205 4.200 4.195 VBAT=4V 300 TA=25℃ 200 100 4.190 4.5 5.0 5.5 VCC (V) 6.0 RPROG=10k 0 4.0 4.185 4.0 6.5 5.0 5.5 6.0 6.5 7.0 Float Voltage vs Temperature Trickle Charge Current vs Supply Voltage 4.215 60 4.210 RPROG=2k 50 V FLOAT (V) 4.205 40 ITR IKL (mA) 4.5 VCC (V) 70 VBAT=2.5V TA=25℃ 30 20 RPROG=10k 10 0 4.0 ONSET OF THERMAL REGULATION 400 IBAT (m A ) 4.215 V BAT (V) 500 RPROG=10k 4.200 4.195 4.190 4.185 4.5 5.0 5.5 VCC (V) 6.0 6.5 7.0 Revision 10/9/2008 20 40 60 80 Temperature (℃) www.shouding.net 5 100 120 SD8017 Shouding Operation The SD8017 is a single cell lithium-ion battery current are calculated using the following equations: charger using a constant-current/constant-voltage RPROG = algorithm. It can deliver up to 800mA of charge 1060V 1060V , I CHG = , I CHG RPROG current (using a good thermal PCB layout) with a The charge current out of the BAT pin can be final float voltage accuracy of ±1%. The SD8017 determined at any time by monitoring the PROG pin includes an internal P-channel power MOSFET and voltage using the following equation: thermal regulation circuitry. No blocking diode or I BAT = external current sense resistor is required; thus, the VPROG • 1060 RPROG basic charger circuit requires only two external This actual current will vary from IC to IC. The typical components. Furthermore, the SD8017 is capable variation is within +/-20%. of operating from a USB power source. Normal Charge Cycle Charge Termination A charge cycle begins when the voltage at the VCC A charge cycle is terminated when the charge current pin rises above the UVLO threshold level and a 1% falls to 1/10th the programmed value after the final program resistor is connected from the PROG pin to float voltage is reached. This condition is detected by ground or when a battery is connected to the using an internal, filtered comparator to monitor the charger output. If the BAT pin is less than 2.8V, the PROG pin. When the PROG pin voltage falls below charger enters trickle charge mode. In this mode, 100mV for longer than tTERM (typically 1ms), charging the SD8017 supplies approximately 1/10 the is terminated. The charge current is latched off and programmed charge current to bring the battery the SD8017 enters standby mode, where the input voltage up to a safe level for full current charging. supply When the BAT pin voltage rises above 2.8V, the termination is disabled in trickle charging and thermal charger enters constant-current mode, where the limiting modes). programmed charge current is supplied to the When charging, transient loads on the BAT pin can battery. When the BAT pin approaches the final cause the PROG pin to fall below 100mV for short float enters periods of time before the DC charge current has constant-voltage mode and the charge current dropped to 1/10th the programmed value. The 1ms begins to decrease. When the charge current drops filter time (tTERM) on the termination comparator to 1/10 of the programmed value, the charge cycle ensures that transient loads of this nature do not ends. result in premature charge cycle termination. Once voltage (4.2V), the SD8017 current drops to 200mA. (Note: C/10 the average charge current drops below 1/10th the Programming Charge Current programmed value, the SD8017 terminates the The charge current is programmed using a single charge cycle and ceases to provide any current resistor from the PROG pin to ground. The battery through the BAT pin. In this state, all loads on the charge current is 1060 times the current out of the BAT pin must be supplied by the battery. PROG pin. The program resistor and the charge The SD8017 constantly monitors the BAT pin voltage Revision 10/9/2008 www.shouding.net 6 SD8017 Shouding in standby mode. If this voltage drops below the4.05V Undervoltage Lockout (UVLO) recharge threshold (VRECHRG), another charge cycle An internal undervoltage lockout circuit monitors the begins and current is once again supplied to the input voltage and keeps the charger in shutdown battery. To manually restart a charge cycle when in mode until VCC rises above the undervoltage lockout standby mode, the input voltage must be removed threshold. The UVLO circuit has a built-in hysteresis and reapplied, or the charger must be shut down and of 200mV. Furthermore, to protect against reverse restarted using the PROG pin. Figure 1 shows the current in the power MOSFET, the UVLO circuit state diagram of a typical charge cycle. keeps the charger in shutdown mode if VCC falls to within 30mV of the battery voltage. If the UVLO Charge Status Indicator (CHRG) comparator is tripped, the charger will not come out of The charge status output has three different states: shutdown mode until VCC rises 100mV above the strong pull-down (~10mA), weak pull-down (~20μA) battery voltage. and high impedance. The strong pull-down state indicates that the SD8017 is in a charge cycle. Once the charge cycle has terminated, the pin state is determined by undervoltage lockout conditions. A Power On weak pull-down indicates that VCC meets the UVLO VBAT2.8V Thermal Limiting Shutdown Mode CC/CV Charge Mode ICC Drops to < 20μA Full Current Chrg: Hi-Z In UVLO WeakPull-Dn An internal thermal feedback loop reduces the Otherwise to rise above a preset value Chrg LED: Strong Pull-Dn VPROG2.8V Standby Mode of No Charge Current approximately 120℃. This feature protects the PROG Floated Or UVLO Connection SD8017 from excessive temperature and allows the user to push the limits of the power handling Chrg LED: Weak Pull-Dn 4.05V>VBAT>2.8V capability of a given circuit board without risk of damaging the SD8017. The charge current can be set according to typical (not worst-case) Figure1. State Diagram of a Typical Charge Cycle ambient temperature with the assurance that the charger will automatically reduce the current in worst-case conditions. Revision 10/9/2008 www.shouding.net 7 SD8017 Shouding Application Hints Stability Considerations Power Dissipation The constant-voltage mode feedback loop is stable The conditions that cause the SD8017 to reduce without an output capacitor provided a battery is charge current through thermal feedback can be connected to the charger output. With no battery approximated by considering the power dissipated present, an output capacitor is recommended to in the IC. Nearly all of this power dissipation is reduce ripple voltage. When using high value, low generated ESR ceramic capacitors, it is recommended to add calculated to be approximately: a 1Ω resistor in series with the capacitor. No series feedback loop, not the battery. The constant-current the internal MOSFET—this is PD = (VCC – VBAT) • IBAT resistor is needed if tantalum capacitors are used. In constant-current mode, the PROG pin is in the by The approximate ambient temperature at which the thermal feedback begins to protect the IC is: TA = 120°C – PDθJA mode stability is affected by the impedance at the PROG pin. With no additional capacitance on the TA = 120°C – (VCC – VBAT) • IBAT • θJA PROG pin, the charger is stable with program resistor values as high as 20k. However, additional capacitance on this node reduces the maximum Thermal Considerations allowed program resistor. The pole frequency at the Because of the small size of the thin SOT23 PROG pin should be kept above 100kHz. package, it is very important to use a good thermal PC board layout to maximize the available charge current. The thermal path for the heat generated by VCC Bypass Capacitor the IC is from the die to the copper lead frame, Many types of capacitors can be used for input through the package leads, (especially the ground bypassing, however, caution must be exercised lead) to the PC board copper. The PC board copper when using multilayer ceramic capacitors. Because is the heat sink. The footprint copper pads should of the self-resonant and high Q characteristics of be as wide as possible and expand out to larger some types of ceramic capacitors, high voltage copper areas to spread and dissipate the heat to transients can be generated under some start-up the surrounding ambient. Other heat sources on the conditions, such as connecting the charger input to board, not related to the charger, must also be a live power source. Adding a 1.5Ω resistor in series considered when designing a PC board layout with a ceramic capacitor will minimize start-up because they will affect overall temperature rise and voltage transients. the maximum charge current. Revision 10/9/2008 8 www.shouding.net SD8017 Shouding OUTLINE DRAWING SOT-23-6L 017XX OUTLINE DRAWING PSOP-8 Revision 10/9/2008 www.shouding.net 9