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| CONSONANCE 1A Linear Lithium Ion Battery Charger CN3056 General Description: The CN3056 is a complete constant-current /constant voltage linear charger for single cell Li-ion and Li Polymer rechargeable batteries. The device contains an on-chip power MOSFET and eliminates the need for the external sense resistor and blocking diode. Furthermore, the CN3056 is specifically designed to work within USB power specifications. Its low external component count makes CN3056 ideally suited for portable applications. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The regulation voltage is fixed at 4.2V with 1% accuracy. The charge current can be programmed externally with a single resistor. When the input supply (wall adapter or USB supply) is removed, the CN3056 automatically enters a low power sleep mode , dropping the battery drain current to less than 3uA. Other features include undervoltage lockout, automatic recharge, chip enable function, battery temperature sensing and a pin to indicate charge status. The CN3056 is available in 10 pin DFN package. Features: Charges Single Cell Li-Ion Batteries Directly from USB Port or AC Adaptor On-chip Power MOSFET No external Blocking Diode or Current Sense Resistors Required Preset 4.2V Regulation Voltage with 1% Accuracy Precharge Conditioning for Reviving Deeply Discharged Cells and Minimizing Heat Dissipation During Initial Stage of Charge Programmable Continuous Charge Current Up to 1A Constant-Current/Constant-Voltage Operation with Thermal Regulation to Maximize Charge Rate Without Risk of Overheating Automatic Low-Power Sleep Mode When Input Supply Voltage is Removed Status Indication for LEDs or uP Interface C/10 Charge Termination Automatic Recharge Battery Temperature Sensing Chip Enable Input Available in 10 pin DFN Package Pb-free available Applications: Cellular Telephones Digital Still Cameras MP4 Players Bluetooth Applications Portable Devices USB Bus-Powered Chargers Chargers Pin Assignment TEMP 1 ISET 2 GND 3 VIN 4 VIN 5 10 9 CE CHRG FAULT BAT BAT CN3056 8 7 6 www.consonance-elec.com REV 1.1 1 Typical Application Circuit Input Supply Voltage 4.35V to 6V 10uF 4,5 10 VIN CE BAT 6,7 0.3 R1 6.8uF LED Bat+ LED CN3056 330 Bat- 330 9 8 CHRG TEMP FAULT 1 2 NTC ISET GND 3 Oc RISET R2 Figure 1 Typical Application Circuit Ordering Information Part Number CN3056 Marking LNG Package DFN Operating Ambient Temperature - 40ae to 85ae REV 1.1 2 Block Diagram VIN Tdie 115 C ISET + + Iamp Tamp BAT Iref Vamp Vref Termination Comparator Recharge Comparator FAULT + TEMP TEMP Comparator UVLO control CHRG CE schmitt GND Figure 2 Block Diagram REV 1.1 3 Pin Description Pin No. Name Function Description Temperature Sense Input. Connecting TEMP pin to NTC thermistor's output in Lithium ion battery pack. If TEMP pin's voltage is below 45% or above 80% of supply voltage VIN for more than 0.15S, this means that battery's pin is temperature is too high or too low, charging is suspended, and pulled low to indicate a battery fault state. If TEMP's voltage level is between 45% and 80%of supply voltage for more than 0.15S, battery fault state is released, pin is in high impedance state, and charging will resume. The temperature sense function can be disabled by grounding the TEMP pin. Constant Charge Current Setting and Charge Current Monitor Pin. The charge current is set by connecting a resistor RISET from this pin to GND. When in precharge mode, the ISET pin's voltage is regulated to 0.2V. When in constant charge current mode, the ISET pin's voltage is regulated to 2V.In all modes during charging, the voltage on ISET pin can be used to measure the charge current as follows: ICH = (VISET RISET)A 3 4,5 GND VIN Ground Terminal. Positive Input Supply Voltage. VIN is the power supply to the internal circuit. When VIN drops to within 40mv of the BAT pin voltage, CN3056 enters low power sleep mode, dropping BAT pin's current to less than 3uA. Battery Connection Pin. Connect the positive terminal of the battery to BAT pin. BAT pin draws less than 3uA current in chip disable mode or in sleep mode. BAT pin provides charge current to the battery and provides regulation voltage of 4.2V. Open-Drain Fault Status Output. When the voltage at TEMP pin is below 8 45% of VIN or above 80% of VIN, this means that battery's temperature is too is pulled low by an internal switch to indicate a high or too low, battery fault state; Otherwise pin is in high impedance state. Open Drain Charge Status Output. When the battery is being charged, the 9 pin is pulled low by an internal switch, otherwise impedance state. CE pin is in high 900 1 TEMP 2 ISET 6,7 BAT 10 Chip Enable Input. A high input will put the device in the normal operating mode. Pulling the CE pin to low level will put the CN3056 into disable mode. The CE pin can be driven by TTL or CMOS logic level. Absolute Maximum Ratings All Terminal Voltage...............- 0.3V to 6.5V BAT Short-Circuit Duration......Continuous ESD Rating(HBM)..................2KV Thermal Resistance (DFN)... ....TBD Maximum Junction Temperature......150ae Operating Temperature......- 40ae to 85ae Storage Temperature........- 65ae to 150ae Lead Temperature(Soldering)...........300ae Stresses beyond those listed under `Absolute Maximum Ratings' may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to Absolute Maximum Rating Conditions for extended periods may affect REV 1.1 4 device reliability. Electrical Characteristics (VIN=5V, TA=Parameters Input Supply Voltage Operating Current Undervoltage Lockout Undervoltage Lockout Hysteresis Regulation Voltage 40ae to 85ae VIN IVIN Vuvlo Huvlo VREG RISET=1.8K, mode BAT pin Current IBAT constant current 4.158 800 50 1.75 CE=VIN, No load at BAT pin Chip disable mode, CE=GND VIN rising 3.83 , Typical Values are measured at TA=25ae Test Conditions ,unless otherwise noted) Min 4.35 400 650 4 4.03 0.1 4.2 1000 100 3.5 4.242 1200 150 7 3 3 2.9 3.0 0.1 3.1 V V uA 4.23 Typ Max 6 950 Unit V uA V V V mA Symbol RISET=1.8K, VBAT1/2 2.3V VBAT=VREG, standby mode CE=GND, disable mode VIN=0V, sleep mode Precharge Threshold Precharge Threshold Precharge Threshold Hysteresis Charge Termination Threshold Recharge Threshold Recharge Threshold Sleep Mode Sleep Mode Threshold Sleep mode Release Threshold ISET Pin ISET Pin Voltage TEMP PIN High Input Threshold Low Input Threshold TEMP input Current CE Pin Logic Input Low Logic Input High CE Pin Current VCEL VCEH ICEL ICEH CE voltage falling, Chip disabled CE voltage rising, Chip enabled CE=GND, VIN=6V CE=VIN=6V 2.0 1 1 0.75 V V uA VHIGH VLOW TEMP to VIN or to GND 42.5 80 45 0.5 82.5 %VIN %VIN uA VISET Precharge mode Constant current mode 0.2 2.0 V VSLP VSLPR VIN from high to low, measures the voltage (VIN- VBAT) VIN from low to high, measures the voltage (VIN- VBAT) 40 90 mv mv VRECH VREG- 0.1 V VPRE HPRE Voltage at BAT pin rising Charge Termination Threshold Vterm Measure voltage at ISET pin 0.18 0.22 0.26 V REV 1.1 5 Electrical Characteristics(Continued from last page) Parameters Pin Pin Sink Current Leakage Current Pin Pin Current Pin Current Leakage Sink IFAULT VFAULT=0.3V,Fault status CE=GND, VFAULT=6V 10 1 mA uA ICHRG VCHRG=0.3V, charge mode CE=GND, VCHRG=6V 10 1 mA uA Symbol Test Conditions Min Typ Max Unit Detailed Description The CN3056 is a linear battery charger designed primarily for charging single cell lithium-ion or lithium-polymer batteries. Featuring an internal P-channel power MOSFET, the charger uses a constant-current/constant-voltage to charge the batteries. Continuous charge current can be programmed up to 1A with an external resistor. No blocking diode or sense resistor is required. The open-drain output and indicates the charger's status. The internal thermal regulation circuit reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 115ae . This feature protects the CN3056 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 CN3056 or the external components. Another benefit of adopting thermal regulation 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 voltage at the VIN pin rises above the UVLO level, a current set resistor is connected from the ISET pin to ground, and the CE pin is pulled above the chip enable threshold. The pin outputs a logic low to indicate that the charge cycle is ongoing. At the beginning of the charge cycle, if the battery voltage is below 3V, the charger is in precharge mode to bring the cell voltage up to a safe level for charging. The charger goes into the fast charge constant-current mode once the voltage on the BAT pin rises above 3V. In constant current mode, the charge current is set by RISET. When the battery approaches the regulation voltage, the charge current begins to decrease as the CN3056 enters the constant-voltage mode. When pin assumes a high the current drops to charge termination threshold, the charge cycle is terminated, and impedance state to indicate that the charge cycle is terminated. The charge termination threshold is 10% of the current in constant current mode. To restart the charge cycle, remove the input voltage and reapply it, or momentarily force CE pin to 0V. The charge cycle can also be automatically restarted if the BAT pin voltage falls below the recharge threshold. The on-chip reference voltage, error amplifier and the resistor divider provide regulation voltage with 1% accuracy which can meet the requirement of lithium-ion and lithium polymer batteries. When the input voltage is not present, the charger goes into a sleep mode, dropping battery drain current to less than 3uA. This greatly reduces the current drain on the battery and increases the standby time. The charger can be shutdown by forcing the CE pin to GND. The charging profile is shown in the following figure: REV 1.1 6 Precharge Phase Constant Current Phase Constant Voltage Phase 4.2V 3V Charge terminated Charge Current Battery Voltage Figure 3 Charging Profile Application Information Undervoltage Lockout (UVLO) An internal undervoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode until VIN rises above the undervoltage lockout voltage. The UVLO circuit has a built-in hysteresis of 0.1V. Sleep mode There is an on-chip sleep comparator. The comparator keeps the charger in sleep mode if VIN falls below sleep mode threshold(VBAT+40mv). Once in sleep mode, the charger will not come out of sleep mode until VIN rises 90mv above the battery voltage. Precharge mode At the beginning of a charge cycle, if the battery voltage is below 3V, the charger goes into precharge mode , and the charge current is 10% of fast charge current in constant current mode. Chip Enable/Disable The CN3056 can be disabled by pulling the CE pin to less than 0.75V. For normal operation, pull the CE pin above 2.0V. Applying a voltage between 0.75V to 2.0V to this pin may cause larger operating current, and the CN3056 may be in uncertain state. When the chip is disabled, the internal linear regulator and the power MOSFET are turned off. Programming Charge Current The formula for the battery charge current in constant current mode is: ICH = 1800V / RISET Where: ICH is the charge current in ampere RISET is the total resistance from the ISET pin to ground in ohm For example, if 1A charge current is required, calculate: RISET = 1800V/1A = 1.8k| For best stability over temperature and time, 1% metal film resistors are recommended. If the charger is in REV 1.1 7 constant-temperature or constant voltage mode, the charge current can be monitored by measuring the ISET pin voltage, and the charge current is calculated as the following equation: ICH = (VISET / RISET) x 900 USB and Wall Adapter Power Although the CN3056 allows charging from a USB port, a wall adapter can also be used to charge Li-Ion/Li-polymer batteries. Figure 4 shows an example of how to combine wall adapter and USB power inputs. A P-channel MOSFET, M1, 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. Wall Adapter D1 USB Power VIN M1 CN3056 1K Figure 4 Combining Wall Adapter and USB Power Battery Temperature Sense To prevent the damage caused by the very high or very low temperature done to the battery pack, the CN3056 continuously senses battery pack temperature by measuring the voltage at TEMP pin determined by the voltage divider circuit and the battery's internal NTC thermistor as shown in Figure 1. The CN3056 compares the voltage at TEMP pin (VTEMP) against its internal VLOW and VHIGH thresholds to determine if charging is allowed. In CN3056, VLOW is fixed at (45%A VIN), while VHIGH is fixed at (80%A VIN). If VTEMP Selecting R1 and R2 The values of R1 and R2 in the application circuit can be determined according to the assumed temperature monitor range and thermistor's values. The Follows is an example: Assume temperature monitor range is TL TH (TL 1/4 TH 1/2 ; the thermistor in battery has negative temperature coefficient (NTC), RTL is thermistor's resistance at TL, RTH is the resistance at TH, so RTL3/4 RTH, then at temperature TL, the voltage at TEMP pin is: At temperature TH, the voltage at TEMP pin is: REV 1.1 8 We know, VTEMPL1/2 VHIGH1/2 VTEMPH1/2 Then we can have: R11/2 k2A k1A VIN (k2=0.8) VIN (k1=0.45) VLOW1/2 R TL R TH (k 2 - k 1 ) (R TL - R TH )k 1k 2 R TL R TH (k 2 - k 1 ) R TL (k 1 - k 1k 2 ) - R TH (k 2 - k 1k 2 ) R21/2 Likewise, for positive temperature coefficient thermistor in battery, we have RTH3/4 calculate: R11/2 R TL R TH (k 2 - k 1 ) (R TH - R TL )k 1k 2 R TL R TH (k 2 - k 1 ) R TH (k 1 - k 1k 2 ) - R TL (k 2 - k 1k 2 ) RTL and we can R21/2 We can conclude that temperature monitor range is independent of power supply voltage VIN and it only depends on R1, R2, RTL and RTH: The values of RTH and RTLcan be found in related battery handbook or deduced from testing data. In actual application, if only one terminal temperature is concerned(normally protecting overheating), there is no need to use R2 but R1. It becomes very simple to calculate R1 in this case. Recharge After a charge cycle has terminated, if the battery voltage drops below the recharge threshold, a new charge cycle will begin automatically. Constant-Current/Constant-Voltage/Constant-Temperature The CN3056 use a unique architecture to charge a battery in a constant-current, constant-voltage, constant temperature fashion as shown in Figure 2. Amplifiers Iamp, Vamp, and Tamp are used in three separate feedback loops to force the charger into constant-current, constant-voltage, or constant-temperature mode, respectively. In constant current mode the charge current delivered to the battery equal to 1800V/RISET. If the power dissipation of the CN3056 results in the junction temperature approaching 115ae , the amplifier Tamp will begin decreasing the charge current to limit the die temperature to approximately 115ae . As the battery voltage rises, the CN3056 either returns to constant-current mode or it enters constant voltage mode straight from constant-temperature mode. Open-Drain Status Outputs The CN3056 have 2 open-drain status outputs: and . is pulled low when the charger is in charging status, otherwise becomes high impedance. is pulled low if battery pack's temperature is in out of temperature condition for more than 0.15S, otherwise becomes high impedance. When the battery is not present, the charger charges the output capacitor to the regulation voltage quickly, then the BAT pin's voltage decays slowly to recharge threshold because of low leakage current at BAT pin, which results in a 100mv ripple waveform at BAT pin, in the meantime, pin outputs a pulse to indicate that the battery's absence. The pulse's frequency is around 7Hz when a 6.8uF output capacitor is used. The open drain status output that is not used should be tied to ground. VIN Bypass Capacitor CIN Many types of capacitors can be used for input bypassing, CIN is typically a 10uF capacitor. Stability Typically a 6.8uF capacitor in series with a 10% 0.3| feedback loop. resistor from BAT pin to GND is required to stabilize the REV 1.1 9 In constant current mode, the stability is also affected by the impedance at the ISET pin . With no additional capacitance on the ISET pin, the loop is stable with current set resistors values as high as 50K| . However, additional capacitance on ISET pin reduces the maximum allowed current set resistor. The pole frequency at ISET pin should be kept above 200KHz. Therefore, if ISET pin is loaded with a capacitance C, the following equation should be used to calculate the maximum resistance value for RISET: RISET < 1 (6.28A 2A 105A C) In order to measure average charge current or isolate capacitive load from ISET pin, a simple RC filter can be used on ISET pin as shown in Figure 5. CN3056 10K ISET RISET Cfilter Figure 5 Isolating Capacitive Load on ISET Pin Board Layout Considerations 1. RISET at ISET pin should be as close to CN3056 as possible, also the parasitic capacitance at ISET pin should be kept as small as possible. 2. The capacitance at VIN pin and BAT pin should be as close to CN3056 as possible. 3. During charging, CN3056's temperature may be high, the NTC thermistor should be placed far enough to CN3056 so that the thermistor can reflect the battery's temperature correctly. 4. It is very important to use a good thermal PC board layout to maximize charging current. The thermal path for the heat generated by the IC is from the die to the copper lead frame through the package lead(especially the ground lead) to the PC board copper, the PC board copper is the heat sink. The footprint copper pads should be as wide as possible and expand out to larger copper areas to spread and dissipate the heat to the surrounding ambient. Feedthrough vias to inner or backside copper layers are also useful in improving the overall thermal performance of the charger. Other heat sources on the board, not related to the charger, must also be considered when designing a PC board layout because they will affect overall temperature rise and the maximum charge current. The ability to deliver maximum charge current under all conditions require that the exposed metal pad on the back side of the CN3056 package be soldered to the PC board ground. Failure to make the thermal contact between the exposed pad on the backside of the package and the copper board will result in larger thermal resistance. REV 1.1 10 Package Information(All dimensions are in millimeters) REV 1.1 11 |
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