芯美电子 Preliminary EUP8080 500mA Li-Ion Charger with Integrated 600mA Synchronous Buck Converter DESCRIPTION FEATURES The EUP8080 is a complete constant-current/ constant-voltage linear battery charger for a single-cell 4.2V lithium-ion battery with an integrated 600mA synchronous buck converter. It is specifically designed to work within USB power specifications. The battery charger offers an integrated pass device, reverse blocking protection, high accuracy current and voltage regulation, charge status, and charge termination. The charging current is programmable via external resistor from 15mA to 500mA. In addition to these standard features, the device offers current limit, thermal protection, and soft-start. The EUP8080 integrates a synchronous buck converter that is powered from the BAT pin internally. It has an adjustable output voltage and can deliver up to 600mA of load current. The buck converter also features low-current high-efficiency Power Save and low output ripple PWM mode operation that can be selected by the MODE pin. The EUP8080 is available in a 10-lead, 3mm × 3mm TDFN package. Battery Charger: - Input Voltage Range : 3.75 V to 5.5V - Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charge Rate Without Risk of Overheating - Internal 4.5 Hour Safety Timer for Termination - Charge Current Programmable Up to 500mA with 5% Accuracy - C/10 Charge Current Detection Output - 5µA Supply Current in Shutdown Mode Synchronous Buck Converter - 600mA Output Current - 2.6V to 4.5V Input Range (Internal Connect from BAT Pin) - 0.6V to VBAT Output Range - 1.5MHz Switching - 2µA BAT Current in Shutdown Mode - 3mm × 3mm TDFN Package - RoHS Compliant and 100% Lead (Pb)-Free APPLICATIONS Wireless Headsets Bluetooth Applications Portable MP3 Players Typical Application Circuit Figure 1. Li-Ion Battery Charger with 1.5V Buck Regulator DS8080 Ver 0.1 Aug. 2007 1 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP8080 Pin Configurations Package Type Pin Configurations TDFN-10 Pin Description Pin 1 PIN DESCRIPTION BAT Charge Current Output and Buck Regulator Input. Provides charge current to the battery and regulates the final float voltage to 4.2V. An internal precision resistor divider from this pin sets the float voltage and is disconnected in charger shutdown mode. This pin should be decoupled with a low ESR capacitor for low-noise buck operation. 2 VCC 3 EN _ CHRG 4 PROG 5 ACPR CHRG 6 Positive Input Supply Voltage. This pin provides power to the battery charger. VCC can range from 3.75V to 5.5V. This pin should be bypassed with at least a 1µF capacitor. When VCC is less than 45mV above the BAT pin voltage, the battery charger enters shutdown mode. Enable Input Pin for the Battery Charger. Pulling this pin above the manual shutdown threshold (VIH) puts the EUP8080 charger in shutdown mode, thus stopping the charge cycle. In battery charger shutdown mode, the EUP8080 has less than 10µA supply current and less than 5µA battery drain current if the regulator is not running. Enable is the default state, but the pin should be tied to GND if unused. Charge Current Program and Charge Current Monitor Pin. Connecting a 1% resistor, RPROG, to ground programs the charge current. When charging in constant-current mode, this pin servos to 1V. In all modes, the voltage on this pin can be used to measure the charge current using the following formula : VPROG I BAT = × 400 R PROG Open-Drain Power Supply Status Output. When VCC is greater than the undervoltage lockout threshold (3.6V) and greater than VBAT 110mV, the ACPR pin will be pulled to ground; otherwise the pin is high impedance. Open-Drain Charge Status Output. The charge status indicator pin has three states: pulldown, high impedance state, and pulse at 2Hz. This output can be used as a logic interface or as an LED driver. When the battery is being charged, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge current drops to 10% of the full-scale current, the CHRG pin is forced to a high impedance state. When the battery voltage remains below 2.9V for one quarter of the full charge time, the battery is considered defective, and the CHRG pin pulses at a frequency of 2Hz with 75% duty cycle. DS8080 Ver 0.1 Aug. 2007 2 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP8080 Description (continued) Pin PIN 7 FB 8 MODE 9 EN_BUCK 10 SW DESCRIPTION Feedback Pin for the Buck Regulator. A resistor divider from the regulator’s output to the FB pin programs the output voltage. Servo value for this pin is 0.6V. Pulling the MODE pin low allows buck operates in PWM mode at high load currents and in PFM mode at light load currents. Pulling the MODE pin to high or floating enables the power save mode. Enable Input Pin for the Switching Regulator. Pull this pin high to enable the regulator, pull low to shut down. Do no float this pin. Switch Pin for the Buck Regulator. Minimize the length of the metal trace connected to this pin. Place the inductor as close to this pin as possible. Order Number Package Type Marking Operating Temperature range EUP8080JIR1 TDFN-10 xxxxx P8080 -40 °C to 85°C EUP8080 □ □ □ □ Lead Free Code 1: Lead Free 0: Lead Packing R: Tape & Reel Operating temperature range I: Industry Standard Package Type J: TDFN DS8080 Ver 0.1 Aug. 2007 3 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP8080 Preliminary Absolute Maximum Ratings Vcc, t < 1ms and Duty Cycle < 1% -------------------------------------------------------------- -0.3V to 7V Vcc Steady State ------------------------------------------------------------------------------------ -0.3V to 6V BAT, CHRG ------------------------------------------------------------------------------------------ -0.3V to 6V EN _ CHRG , PROG , ACPR ---------------------------------------------------------- -0.3V to VCC +0.3V MODE, EN_BUCK ----------------------------------------------------------------------- -0.3V to VBAT +0.3V FB ----------------------------------------------------------------------------------------------------- -0.3V to 2V BAT Short-Circuit Duration ----------------------------------------------------------------------- Continuous BAT Pin Current ------------------------------------------------------------------------------------800mA PROG Pin Current ---------------------------------------------------------------------------------------- 2mA Junction Temperature ------------------------------------------------------------------------------------- 125℃ Operating Temperature Range (Note 2) ------------------------------------------------------ -40℃ to 85℃ Storage Temperature Range ------------------------------------------------------------------ -65℃ to 125℃ Electrical Characteristics (TA = 25℃, VCC = 5V, VBAT = 3.8V, VEN _ CHRG = 0V, VEN_BUCK = VBAT, VMODE = 0V.) Symbol Parameter Conditions EUP8080 Min. Typ. Max. Unit VCC Supply Voltage (Note 4) 3.75 5 5.5 V VBAT Input Voltage for the Switching Regulator (Note 5) 2.6 3.8 4.5 V Quiescent Supply Current (Charger On, Switching Regulator Off) VBAT = 4.5V (Forces IBAT and IPROG = 0), VEN_BUCK = 0 115 300 µA 4.5 10 µA ICC Supply Current in Shutdown (Both Battery Charger and Switching Regulator Off) ICC_SD VEN _ CHRG = 5V, VEN_BUCK = 0, VCC > VBAT VEN _ CHRG = 4V, VEN_BUCK = 0, 5 µA VCC(3.5V) < VBAT(4V) Supply Current in Shutdown (Both Battery Charger and Switching Regulator Off) IBAT_SD VEN _ CHRG = 5V, VEN_BUCK = 0, 0.2 5 µA VCC > VBAT VEN _ CHRG = 4V, VEN_BUCK = 0, 0.7 µA VCC(3.5V) < VBAT(4V) Battery Charger VFLOAT VBAT Regulated Output Voltage IBAT Current Mode Charge Current VUVLO_CHRG DS8080 VCC Undervoltage Lockout Voltage Ver 0.1 Aug. 2007 IBAT = 2mA, 4.3V < VCC < 5.5V 4.158 4.200 4.242 V RPROG = 4k; Current Mode; VEN_BUCK = 0 90 100 110 mA RPROG = 0.8k; Current Mode; VEN_BUCK = 0 475 500 525 mA VCC Rising 3.4 3.6 3.8 V VCC Falling 2.8 3 3.2 V 4 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP8080 Preliminary Electrical Characteristics (TA = 25℃, VCC = 5V, VBAT = 3.8V, VEN _ CHRG = 0V, VEN_BUCK = VBAT, VMODE = 0V.) Symbol Parameter Conditions VPROG PROG Pin Servo Voltage 0.8k ≦ RPROG ≦ 4k VASD Automatic Shutdown Threshold Voltage tSS_CHRG Battery Charger Soft-Start Time 0.975 1 1.025 V (VCC - VBAT), VCC Low to High 85 110 135 mV (VCC - VBAT), VCC High to Low 15 45 70 mV Trickle Charge Current VTRKL Trickle Charge Threshold Voltage VBAT Rising △VRECHRG △VUVCL1 △VUVCL2 tTIMER VBAT = 2V, RPROG = 0.8k Trickle Charge Threshold Voltage Hysteresis Recharge Battery Threshold VFLOAT – VBAT, 0℃< TA < 85℃ Voltage (VCC - VBAT) Undervoltage Current IBAT = 0.9 ICHG Limit Threshold Voltage IBAT = 0.1 ICHG Termination Timer Recharge Time Low-Battery Charge Time IC/10 TLIM RON_CHRG fBADBAT DBADBAT µs 120 ITRKL VTRHYS EUP8080 Unit Min. Typ. Max. VBAT = 2.5V End of Charge Indication Current RPROG = 2k (Note 6) Level Junction Temperature in ConstantTemperature Mode Power FET On-Resistance IBAT = 350mA, VCC = 4V (Between VCC and BAT) Defective Battery Detection CHRG Pulse Frequency Defective Battery Detection CHRG Pulse Frequency Duty Ratio 35 50 65 mA 2.80 2.95 3.10 V 100 255 350 mV 150 mV 180 300 mV 90 130 mV 3 4.5 6 hrs 1.5 2.25 3 hrs 0.75 1.125 1.5 hrs 0.09 0.1 0.12 mA/mA 115 ℃ 1 Ω 2 Hz 75 % Buck Converter VFB FB Servo Voltage IFB FB Pin Input Current fOSC Switching Frequency IBAT_NL_CF 0.588 VFB = 0.85V -50 1.2 No-Load Battery Current (Continuous Frequency Mode) 0.6 No-Load for Regulator, V EN _ CHRG 1.5 0.612 V 50 nA 1.8 MHz 305 µA = 5V, MODE = VBAT, L = 2.2µH, 36 µA C = 10µF VEN _ CHRG = 5V, MODE = VBAT, VOUT > Regulation Voltage VBAT Rising 30 µA 2.5 2.6 2.7 V VBAT Falling 2.3 2.4 2.5 V = 5V, L = 2.2µH, C = 10µF, V(FB)=0.5V IBAT_NL_BM IBAT_SLP No-Load Battery Current (Power Save Mode Operation) Battery Current in SLEEP Mode VUVLO_BUCK Buck Undervoltage Lockout DS8080 Ver 0.1 Aug. 2007 No-Load for Regulator, V EN _ CHRG 5 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP8080 Preliminary Electrical Characteristics (TA = 25℃, VCC = 5V, VBAT = 3.8V, VEN _ CHRG = 0V, VEN_BUCK = VBAT, VMODE = 0V.) Symbol Parameter Conditions EUP8080 Unit Min. Typ. Max. RON_P PMOS Switch On-Resistance 0.26 Ω RON_N PMOS Switch On-Resistance 0.28 Ω IPK Peak Inductor Current 2.1 A tSS_BUCK Buck Soft-Start Time Form the Rising Edge of EN_BUCK to 90% of Buck Regulated Output 120 µs VIH Input High Voltage EN _ CHRG , EN_BUCK, MODE Pin Low to High VIL Input Low Voltage EN _ CHRG , EN_BUCK, MODE Pin High to Low Logic VOL Output Low Voltage ( CHRG ) 1.4 0.4 Input Current High IIL Input Current Low 285 330 90 135 mV EN_BUCK, MODE Pins at 5.5V, VBAT = 5V R EN _ CHRG EN _ CHRG Pin Input Resistance V ISINK = 5mA Output Low Voltage ( ACPR ) IIH V EN _ CHRG , EN_BUCK, MODE Pins at GND = 1V, Internal Pull Low V EN _ CHRG -1 1 µA -1 1 µA 8 MΩ Current=130nA I CHRG CHRG Pin Leakage Current VBAT = 4.5V, V = 5V CHRG 1 µA I ACPR ACPR Pin Leakage Current VCC = 3V, V = 5V CHRG 1 µA Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 5: The 2.6V maximum buck undervoltage lockout (VUVLO_BUCK) exit threshold must first be exceeded before the minimum VBAT specification applies. Note 6: IC/10 is expressed as a fraction of measured full charge current with indicated PROG resistor. Note 2: The EUP8080 is guaranteed to meet performance specifications form 0℃to 85℃. Specifications over the -40℃ to 85℃ 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 43℃/W. Note 4: Although the EUP8080 charger functions properly at 3.75V, full charge current requires an input voltage greater then the desired final battery voltage per △VUVCL1 specification. DS8080 Ver 0.1 Aug. 2007 6 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP8080 Preliminary Typical Operating Characteristics Battery Regulation(Float) Voltage vs Temperature Battery Regulation (Float) Voltage vs Charge Current 4.210 4.21 RPROG = 2k 4.205 4.20 FLOAT VOLTAGE (V) 4.200 FLOAT VOLTAGE (V) 4.19 4.18 4.17 4.16 4.15 4.195 4.190 4.185 4.180 4.175 4.170 4.14 4.165 4.13 0 50 100 150 4.160 -40 200 -20 0 40 60 80 TEMPERATURE ( C) Charge Current vs Battery Current Battery Regulation (Float) Voltage vs Supply Voltage 250 4.25 RPROG = 2k VBAT RISING 4.20 FLOAT VOLTAGE (V) 200 CHARGE CURRENT (mA) 20 o CHARGE CURRENT (mA) 150 100 50 TRICKLE CHARGE 0 4.15 4.10 4.05 4.00 3.95 -50 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 3.90 4.0 5.0 4.5 5.0 5.5 6.0 INPUT VOLTAGE(V) BATTERY VOLTAGE (V) Charge Current vs Temperature with Thermal Regulation(Constant-Current Mode) PROG Pin Voltages vs Charge Current 250 1.0 RPROG = 2k 150 0.8 VCC= 6V VBAT = 3V RPROG =2k 0.6 VPROG (V) CHARGE CURRENT(mA) 200 THERMAL CONTROL LOOP IN OPERATION 100 50 0.2 0.0 0 -25 0 25 50 75 100 0 125 o Ver 0.1 Aug. 2007 25 50 75 100 125 150 CHARGE CURRENT (mA) TEMPERATURE ( C) DS8080 0.4 7 联系电话：１５９９９６４４５７９ ８３１５１７１５ 175 200 芯美电子 EUP8080 Preliminary Typical Operating Characteristics EN_CHRG vs Temperature EN_CHRG Pin Threshold Voltage vs Temperature 10 0.80 9 0.75 RESISTANCE (Mohm) RISING VOLTAGE (V) 0.70 0.65 0.60 FALLING 0.55 8 7 6 5 4 0.50 -40 -20 0 20 40 60 3 -40 80 -20 0 20 40 60 80 o o TEMPERATURE ( C) TEMPERATURE ( C) Normalized Charger Timer Period vs Temperature CHRG and ACPR Pin Output Low Voltage vs Temperature 1.05 0.32 ICHRG,IACPR=5mA 0.30 ACPR 0.26 VOLTAGE (V) NORMALIZED TIME PERIOD 0.28 0.24 0.22 0.20 0.18 0.16 0.14 0.12 CHRG 0.10 1.00 0.95 0.90 0.85 0.08 0.06 -40 -20 0 20 40 60 0.80 -40 80 -30 -20 -10 Charger FET On-Resistance vs Temperature 30 40 50 60 70 80 100 VCC = 4V IBAT = 350mA Power Save 90 80 1.1 1.0 BAT=2.7V 70 EFFICIENCY (%) 0.9 RDS(ON) (ohm) 20 Buck Efficiency vs Load Current (Vout=1.8V) 1.4 1.2 10 TEMPERATURE ( C) TEMPERATURE ( C) 1.3 0 o o 0.8 0.7 0.6 0.5 0.4 0.3 BAT=3.8V 60 BAT=2.7V BAT=4.2V 50 BAT=3.8V 40 BAT=4.2V 30 PWM 20 0.2 10 0.1 0.0 -40 -20 0 20 40 60 0 80 0.1 o TEMPERATURE ( C) DS8080 L=2.2uH C=10uF Ver 0.1 Aug. 2007 1 10 100 LOAD CURRENT (mA) 8 联系电话：１５９９９６４４５７９ ８３１５１７１５ 1000 芯美电子 EUP8080 Preliminary Typical Operating Characteristics (Continued) BUCK Efficiency vs Load Current (Vout=1.5V) BUCK Efficiency vs Load Current (Vout=1.2V) 100 100 Power Save 90 80 80 70 70 BAT=2.7V EFFICIENCY (%) EFFICIENCY (%) Power Save 90 60 BAT=3.8V 50 BAT=2.7V BAT=4.2V 40 BAT=3.8V PWM 30 BAT=4.2V BAT=2.7V BAT=3.8V 50 BAT=3.8V BAT=4.2V 40 BAT=4.2V 30 L=2.2uH C=10uF 20 BAT=2.7V 60 PWM L=2.2uH C=10uF 20 10 10 0 0 0.1 1 10 100 1000 0.1 1 LOAD CURRENT (mA) 10 100 1000 LOAD CURRENT (mA) BUCK Efficiency vs Input Voltage (PWM Vout=1.8V) Reference Voltage vs Temperature (VIN=3.8V) 100 0.610 95 IOUT=100mA REFERENCE VOLTAGE (V) 90 EFFICIENCY (%) 85 IOUT=600mA 80 75 IOUT=10mA 70 65 L=2.2uH C=10uF 60 0.605 0.600 0.595 L=2.2uH C=10uF 0.590 55 50 0.585 2 3 4 5 6 -40 -20 INPUT VOLTAGE (V) 60 80 Output Voltage vs Temperature (BAT=3.8V,ILoad=1mA)(Power Save) 1.90 1.88 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) (PWM) 40 1.92 L=2.2uH C=10uF R1=620Kohm R2=300Kohm 1.86 1.84 1.82 1.80 1.78 1.76 1.74 -40 -20 0 20 40 60 80 -40 100 Aug. 2007 0 20 40 60 TEMPERATURE ( C) TEMPERATURE ( C) Ver 0.1 -20 o o DS8080 20 o Output Voltage vs Temperature (BAT=3.8V,ILoad=1mA)(PWM) 1.96 1.94 1.92 1.90 1.88 1.86 1.84 1.82 1.80 1.78 1.76 1.74 1.72 1.70 1.68 1.66 1.64 1.62 1.60 0 TEMPERATURE ( C) 9 联系电话：１５９９９６４４５７９ ８３１５１７１５ 80 100 芯美电子 EUP8080 Preliminary Typical Operating Characteristics (Continued) Output Voltage vs Input Voltage (BAT=3.8V,ILoad=1mA)(PWM) Output Voltage vs Input Voltage (BAT=3.8V,ILoad=1mA)(Power Save) 1.90 1.96 1.88 1.92 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 1.86 1.84 1.82 1.80 1.78 L=2.2uH C=10uF R1=620Kohm R2=300Kohm 1.76 1.74 1.88 1.84 1.80 1.76 1.72 1.68 1.64 1.72 1.60 2.5 3.0 3.5 4.0 4.5 5.0 2.5 3.0 INPUT VOLTAGE (V) Quiecent Current (uA) Quiecent Current (uA) 360 320 280 240 200 160 120 80 3.5 4.0 4.5 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 2.5 5.0 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) Quiescent Current vs Temperature (No Load)(VFB=0.5V) (PWM) Quiescent Current vs Temperature (No Load)(Power Save) 340 44 320 40 300 36 280 32 Quiescent Current (uA) Quiescent Current (uA) 5.0 L=2.2uH C=10uF INPUT VOLTAGE (V) 260 240 220 200 L=2.2uH C=10uF 180 4.5 Quiescent Current vs Input Voltage (No Load)(Power Save) 400 3.0 4.0 INPUT VOLTAGE (V) Quiescent Current vs Input Voltage (No Load)(VFB=0.5V)(PWM) 2.5 3.5 28 24 20 16 12 L=2.2uH C=10uF 8 160 4 140 -40 -20 0 20 40 60 80 0 100 -40 o TEMPERATURE ( C) DS8080 Ver 0.1 Aug. 2007 -20 0 20 40 60 o TEMPERATURE ( C) 10 联系电话：１５９９９６４４５７９ ８３１５１７１５ 80 100 芯美电子 EUP8080 Preliminary Typical Operating Characteristics (Continued) Switching Frequency vs Temperature Switching Frequency vs Input Voltage 1.70 1.8 1.68 1.66 1.64 Switching Frequency (MHz) Switching Frequency (MHz) 1.7 1.6 1.5 1.4 L=2.2uH C=10uF 1.3 1.62 1.60 1.58 1.56 1.54 1.52 1.50 1.48 1.46 L=2.2uH C=10uF 1.44 1.42 1.40 1.2 2.5 3.0 3.5 4.0 4.5 5.0 -40 5.5 -20 0 20 40 60 80 100 o TEMPERATURE ( C) INPUT VOLTAGE (V) Ron(PMOS) vs Input Voltage Ron(PMOS) vs Temperature 0.30 0.32 0.30 0.28 0.25 0.26 0.24 RON(PMOS) RON(PMOS) 0.22 0.20 0.18 0.16 0.14 0.20 0.15 0.12 0.10 0.10 L=2.2uH C=10uF 0.08 L=2.2uH C=10uF 0.06 0.05 0.04 2.5 3.0 3.5 4.0 4.5 5.0 -40 5.5 DS8080 Ver 0.1 Aug. 2007 -20 0 20 40 60 o INPUT VOLTAGE (V) TEMPERATURE ( C) 11 联系电话：１５９９９６４４５７９ ８３１５１７１５ 80 100 芯美电子 Preliminary EUP8080 Typical Operating Characteristics (Continued) DS8080 Ver 0.1 Aug. 2007 12 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP8080 Typical Operating Characteristics (Continued) DS8080 Ver 0.1 Aug. 2007 13 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP8080 Block Diagram Figure 2. DS8080 Ver 0.1 Aug. 2007 14 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary OPERATION The EUP8080 is a full-featured linear battery charger with an integrated synchronous buck converter designed primarily for handheld applications. The battery charger is capable of charging single-cell 4.2V Li-Ion batteries. The buck converter is powered from the BAT pin and has a programmable output voltage providing a maximum load current of 600mA. The converter and the battery charger can run simultaneously or independently of each other. BATTERY CHARGER OPERATION Featuring an internal P-channel power MOSFET, MP1, the battery charger uses a constant-current/constantvoltage charge algorithm with programmable current. Charge current can be programmed up to 500mA with a final float voltage of 4.2V ± 1%. The CHRG open-drain status output indicates when C/10 has been reached. No blocking diode or external sense resistor is required; thus, the basic charger circuit requires only two external components. The ACPR open-drain output indicates if the VCC input voltage, and the difference between VCC and BAT, are sufficient for charging. An internal termination timer adheres to battery manufacturer safety guidelines. Furthermore, the EUP8080 battery charger is capable of operating form a USB power source. A charge cycle begins when the voltage at the VCC pin rises above 3.6V and approximately 110mV above the BAT pin voltage, a 1% program resistor is connected form the PROG pin to ground, and the EN_CHRG pin is pulled below the shutdown threshold (VIL). If the battery voltage is less than 2.95V, the battery charger begins trickle charging at 10% of the programmed charge current. When the BAT pin approaches the final float voltage of 4.2V, the battery charger enters constant-voltage mode and the charge current begins to decrease. When the current drops to 10% of the full-scale charge current, an internal comparator turns off the N-channel MOSFET driving the CHRG pin, and the pin becomes high impedance. An internal thermal limit reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 115℃. This feature protects the EUP8080 from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without the risk of damaging the EUP8080 or external components. Another benefit of the thermal limit is that charge current can be set according to typical, rather than worst-case, ambient temperatures for a given application with the assurance that the battery charger will automatically reduce the DS8080 Ver 0.1 Aug. 2007 EUP8080 current in worst-case conditions. An internal timer sets the total charge time, tTIMER (typically 4.5 hours). When this time elapses, the charge cycle terminates and the CHRG pin assumes a high impedance state even if C/10 has not yet been reached. To restart the charge cycle, remove the input voltage and reapply it or momentarily force the EN_CHRG pin above VIH. A new charge cycle will automatically restart if the BAT pin voltage falls below VRECHRG (typically 4.05V). Constant-Current / Constant-Voltage / Constant- Temperature The EUP8080 battery charger uses a unique architecture to charge a battery in a constant-current, constant-voltage and constant-temperature fashion. Figure 3 shows a Simplified Block Diagram of the EUP8080. Three of the amplifier feedback loops shown control the constantcurrent, CA, constant-voltage, VA, and constanttemperature, TA modes. A fourth amplifier feedback loop, MA, is used to increase the output impedance of the current source pair, MP1 and MP3 (note that MP1 is the internal P-channel power MOSFET). It ensures that the drain current of MP1 is exactly 400 times the drain current of MP3. Amplifiers CA and VA are used in separate feedback loops to force the charger into constant-current or constant 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 precisely 1V. VA servos its non-inverting input to 1.22V 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 anytime in the charge cycle, as discussed in “Programming Charge Current” in the Applications Information section. If the die temperature starts to creep up above 115°C due to internal power dissipation, the transconductance amplifier, TA, limits the die temperature to approximately 115°C by reducing the charge current. Diode D3 ensures that TA does not affect the charge current when the die temperature is below 115°C. In thermal regulation, 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 400V/RPROG. If the power dissipation of the EUP8080 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 15 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP8080 either returns to constant-current mode or enters constant-voltage mode straight from constanttemperature mode. Battery Charger Undervoltage Lockout (UVLO) An internal undervoltage lockout circuit monitors the input voltage and keeps the battery charger off until VCC rises above 3.6V and approximately 80mV above the BAT pin voltage. The 3.6V UVLO circuit has a built-in hysteresis of approximately 0.6V, and the 110mV automatic shutdown threshold has a built-in hysteresis of approximately 65mV. During undervoltage lockout conditions, maximum battery drain current is 5µA and maximum supply current is 10µA. Undervoltage Charge Current Limiting (UVCL) The battery charger in the EUP8080 includes undervoltage charge current limiting that prevents full charge current until the input supply voltage reaches approximately 300mV above the battery voltage (∆VUVCL1). This feature is particularly useful if the EUP8080 is powered from a supply with long leads (or any relatively high output impedance). See Applications Information section for further details. Trickle Charge and Defective Battery Detection At the beginning of a charge cycle, if the battery voltage is below 2.95V, the battery charger goes into trickle charge mode, reducing the charge current to 10% of the programmed current. If the low battery voltage persists for one quarter of the total time (1.125 hr), the battery is assumed to be defective, the charge cycle terminates and the CHRG pin output pulses at a frequency of 2Hz with a 75% duty cycle. If, for any reason, the battery voltage rises above 2.95V, the charge cycle will be restarted. To restart the charge cycle (i.e., when the dead battery is replaced with a discharged battery less than 2.95V), the charger must be reset by removing the input voltage and reapplying it or temporarily pulling the EN_CHRG pin above the shutdown threshold. Battery Charger Shutdown Mode The EUP8080’s battery charger can be disabled by pulling the EN_CHRG pin above the shutdown threshold (VIH). In shutdown mode, the battery drain current is reduced to less than 2µA and the VCC supply current to about 5µA provided the regulator is off. When the input voltage is not present, the battery charger is in shutdown and the battery drain current is less than 5µA. Power Supply Status Indicator ( ACPR ) The power supply status output has two states: pulldown and high impedance. The pulldown state indicates that VCC is above the undervoltage lockout threshold and at least 110mV above the BAT voltage (see Undervoltage Lockout). When these conditions are not met, the DS8080 Ver 0.1 Aug. 2007 EUP8080 ACPR pin is high impedance indicating that the EUP8080 is unable to charge the battery. CHRG Status Output Pin The charge status indicator pin has three states: pulldown, pulse at 2Hz (see Defective Battery Detection) and high impedance. The pulldown state indicates that the battery charger is in a charge cycle. A high impedance state indicates that the charge current has dropped below 10% of the full-scale current or the battery charger is disabled. When the timer runs out (4.5 hrs), the CHRG pin is also forced to the high impedance state. If the battery charger is not in constant-voltage mode when the charge current is forced to drop below 10% of the full-scale current by UVCL, CHRG will stay in the strong pulldown state. Charge Current Soft-Start and Soft-Stop The EUP8080’s battery charger includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. When a charge cycle is initiated, the charge current ramps from zero to full-scale current over a period of approximately 120µs. Likewise, internal circuitry slowly ramps the charge current from full-scale to zero when the battery charger is turned off or self terminates. This has the effect of minimizing the transient current load on the power supply during start-up and charge termination. Timer and Recharge The EUP8080’s battery charger has an internal termination timer that starts when the input voltage is greater than the undervoltage lockout threshold and at least 110mV above BAT, and the battery charger is leaving shutdown. At power-up or when exiting shutdown, the charge time is set to 4.5 hours. Once the charge cycle terminates, the battery charger continuously monitors the BAT pin voltage using a comparator with a 2ms filter time. When the average battery voltage falls below 4.05V (which corresponds to 80%-90% battery capacity), a new charge cycle is initiated and a 2.25 hour timer begins. This ensures that the battery is kept at, or near, a fully charged condition and eliminates the need for periodic charge cycle initiations. The CHRG output assumes a strong pulldown state during recharge cycles until C/10 is reached or the recharge cycle terminates. SWITCHING REGULATOR OPERATION: The switching regulator in the EUP8080 can be turned on by pulling the EN_BUCK pin above VIH. It has two user-selectable modes of operation: fixed-frequency (PWM) mode and Power Save Mode Operation. The fixed-frequency mode operation offers low noise at the expense of efficiency whereas the Power Save Mode operation offers increased efficiency at light loads at the cost of increased noise and output voltage ripple. 16 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP8080 Preliminary Main Control Loop APPLICATIONS INFORMATION The switching uses a slop-compensated, fixed frequency, current mode PWM architecture. Both the main (P-Channel MOSFET) and synchronous (N-channel MOSFET) switches are internal. During normal operation, the buck converter regulates output voltage by switching at a constant frequency and then modulating the power transferred to the load each cycle using PWM comparator. It sums three weighted differential signals: the output feedback voltage from an external resistor divider, the main switch current sense, and the slope-compensation ramp. It modulates output power by adjusting the inductor-peak current during the first half of each cycle. An N-channel, synchronous switch turns on during the second half of each cycle (off time). When the inductor current starts to reverse or when the PWM reaches the end of the oscillator period, the synchronous switch turns off. This keep excess current from flowing backward through the inductor, from the output capacitor to GND, or through the main and synchronous switch to GND. BATTERY CHARGER Programming Charge Current The battery charge current is programmed using a single resistor from the PROG pin to ground. The charge current is 400 times the current out of the PROG pin. The program resistor and the charge current are calculated using the following equations: Switching Regulator Undervoltage Lockout Whenever VBAT is less than 2.6V, an undervoltage lockout circuit keeps the regulator off, preventing unreliable operation. However, if the regulator is already running and the battery voltage is dropping, the undervoltage comparator does not shut down the regulator until VBAT drops below 2.4V. Thermal Consideration To avoid the switching regulator from exceeding the maximum junction temperature, the user will need to do a thermal analysis. The goal of the thermal analysis is to determine whether the operating conditions exceed the maximum junction temperature of the part. The temperature rise is given by: TR=(PD)(θJA) Where PD=ILOAD2 × RDS(ON) is the power dissipated by the regulator ; θJA is the thermal resistance from the junction of the die to the ambient temperature. The junction temperature, TJ, is given by: TJ=TA+TR Where TA is the ambient temperature. TJ should be below the maximum junction temperature of 150°C. DS8080 Ver 0.1 Aug. 2007 R PROG = 400 × 1V I BAT , I BAT = 400 × 1V R PROG 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: I BAT = V PROG R PROG × 400 Stability Considerations The EUP8080 battery charger contains two control loops: constant-voltage and constant-current. The constantvoltage 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. In constant-current mode, the PROG pin voltage is in the feedback loop, not the battery voltage. 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 battery charger is stable with program resistor values as high as 25k. However, additional capacitance on this node reduces the maximum allowed program resistor. The pole frequency at the PROG pin should be kept above 100kHz. Therefore, if the PROG pin is loaded with a capacitance, CPROG, the following equation should be used to calculate the maximum resistance value for RPROG: R PROG ≤ 1 5 2π × 10 × C PROG Average, rather than instantaneous, battery current may be of interest to the user. For example, when the switching regulator operating in low-current mode is connected in parallel with the battery, the average current being pulled out of the BAT pin is typically of more interest than the instantaneous current pulses. In such a case, a simple RC filter can be used on the PROG pin to measure the average battery current as shown in Figure 3. A 10k resistor has been added between the PROG pin and the filter capacitor to ensure stability. 17 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP8080 Preliminary power dissipated during this phase of charging is approximately 40mW. That is a ten times improvement over the non-current limited supply power dissipation. USB and Wall Adapter Power Figure 3. Isolating Capacitive Load on PROG Pin and Filtering Undervoltage Charge Current Limiting (UVCL) USB powered systems tend to have highly variable source impedances (due primarily to cable quality and length). A transient load combined with such impedance can easily trip the UVLO threshold and turn the battery charger off unless undervoltage charge current limiting is implemented. Consider a situation where the EUP8080 is operating under normal conditions and the input supply voltage begins to sag (e.g. an external load drags the input supply down). If the input voltage reaches VUVCL (approximately 300mV above the battery voltage, ∆VUVCL), undervoltage charge current limiting will begin to reduce the charge current in an attempt to maintain ∆VUVCL between VCC and BAT. The EUP8080 will continue to operate at the reduced charge current until the input supply voltage is increased or voltage mode reduces the charge current further. Although the EUP8080 allows charging from a USB port, a wall adapter can also be used to charge Li-Ion batteries. Figure 4 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 pulldown resistor. Typically a wall adapter can supply significantly more current than the current-limited USB port. Therefore, an N-channel MOSFET, MN1, and an extra program resistor can be used to increase the charge current when the wall adapter is present. Figure 4. Combining Wall Adapter and USB Power Operation from Current Limited Wall Adapter By using a current limited wall adapter as the input supply, the EUP8080 can dissipate significantly less power when programmed for a current higher than the limit of the supply. Consider a situation where an application requires a 200mA charge current for a discharged 800mAh Li-Ion battery. If a typical 5V (non-current limited) input supply is available then the peak power dissipation inside the part can exceed 300mW. Now consider the same scenario, but with a 5V input supply with a 200mA current limit. To take advantage of the supply, it is necessary to program the EUP8080 to charge at a current greater than 200mA. Assume that the EUP8080 charger is programmed for 300mA (i.e., RPROG = 1.33kΩ) to ensure that part tolerances maintain a programmed current higher than 200mA. Since the battery charger will demand a charge current higher than the current limit of the input supply, the supply voltage will collapse to the battery voltage plus 200mA times the on-resistance of the internal PMOSFET. The on-resistance of the battery charger power device is approximately 1Ω with a 5V supply. The actual on-resistance will be slightly higher due to the fact that the input supply will have collapsed to less than 5V. The DS8080 Ver 0.1 Aug. 2007 Power Dissipation The conditions that cause the EUP8080 battery charger to reduce charge current through thermal feedback can be approximated by considering the total power dissipated in the IC. For high charge currents, the EUP8080 power dissipation is approximately: PD = (V CC − V BAT ) × I BAT + P D _ BUCK Where PD is the total power dissipated within the IC, VCC is the input supply voltage, VBAT is the battery voltage, IBAT is the charge current and PD_BUCK is the power dissipation due to the regulator. PD_BUCK can be calculated as: 1 − 1 η P D _ BUCK = V OUT × I OUT Where VOUT is the regulated output of the switching regulator, IOUT is the regulator load and η is the regulator efficiency at that particular load. 18 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 It is not necessary to perform worst-case power dissipation scenarios because the EUP8080 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: o T A = 115 C − P D θ JA o T A = 115 C − (V CC − V BAT ) × I BAT × θ JA Inductor Selection Example: Consider the extreme case when an EUP8080 is operating from a 6V supply providing 250mA to a 3V Li-Ion battery and the regulator is off. The ambient temperature above which the EUP8080 will begin to reduce the 250mA charge current is approximately: (Correctly soldered to a 2500mm2 double-sided 1 oz. copper board, the EUP8080 has a thermal resistance of approximately 43°C/W.) o o T A = 115 C − (6V − 3V ) × (250mA ) × 43 C / W o o o o T A = 115 C − 0.75W × 43 C / W = 115 C − 32.25 C T A = 82.75 C o If there is more power dissipation due to the regulator, the thermal regulation will kick in at a somewhat lower temperature than this. In the above circumstances, the EUP8080 can be used above 82.75°C, but the charge current will be reduced from 250mA. The approximate current at a given ambient temperature can be calculated: 115 o C − T A (V CC − V BAT) × θ JA Using the previous example with an ambient temperature of 85°C, the charge current will be reduced to approximately: I BAT = 115 o C − 85 o C (6V − 3V ) × 43o C / W = 30 o C = 232.6mA 129 o C / A Note: 1V = 1J/C = 1W/A VCC Bypass Capacitor Many types of capacitors can be used for input bypassing; however, caution must be exercised when using multi-layer ceramic capacitors. Because of the selfVer 0.1 Aug. 2007 The output inductor is selected to limit the ripple current to some predetermined value, typically 20%~40% of the full load current at the maximum input voltage. Large value inductors lower ripple currents. Higher VIN or VOUT also increases the ripple current as shown in equation. A reasonable starting point for setting ripple current is ∆IL=240mA (40% of 600mA). ∆I L = V VOUT 1 − OUT VIN (f)(L) 1 The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. Thus, a 720mA rated inductor should be enough for most applications (600mA+120mA). For better efficiency, choose a low DC-resistance inductor. CIN and COUT Selection In continuous mode, the source current of the top MOSFET is a square wave of duty cycle VOUT/VIN. The primary function of the input capacitor is to provide a low impedance loop for the edges of pulsed current drawn by the EUP8080. A low ESR input capacitor sized for the maximum RMS current must be used. The size required will vary depending on the load, output voltage and input voltage source impedance characteristics. A typical value is around 4.7µF. The input capacitor RMS current varies with the input voltage and the output voltage. The equation for the maximum RMS current in the input capacitor is: I Furthermore, the voltage at the PROG pin will change proportionally with the charge current as discussed in the Programming Charge Current section. DS8080 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 battery charger input to a live power source. Adding a 1Ω series resistor in series with an X5R ceramic capacitor will minimize start-up voltage transients. SWITCHING REGULATOR if the regulator if off. I BAT = EUP8080 Preliminary RMS =I O × V V O × 1 − O V V IN IN The output capacitor COUT has a strong effect on loop stability. The selection of COUT is driven by the required effective series resistance (ESR). ESR is a direct function of the volume of the capacitor; that is, physically larger capacitors have lower ESR. 19 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 Preliminary EUP8080 Once the ESR requirement for COUT has been met, the RMS current rating generally far exceeds the IRIPPLE(P-P) requirement. The output ripple ∆VOUT is determined by: ∆VOUT ≅ ∆I L ESR + 8fC OUT 1 When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best temperature and voltage characteristics of all the ceramics for a given value and size. Output Voltage Programming The output voltage is set by a resistive divider according to the following formula: R1 VOUT = 0.6V 1 + R2 The external resistive divider is connected to the output, allowing remote voltage sensing as shown in Figure 5. Figure 5. DS8080 Ver 0.1 Aug. 2007 20 联系电话：１５９９９６４４５７９ ８３１５１７１５ 芯美电子 EUP8080 Preliminary Packaging Information TDFN-10 SYMBOLS A A1 D E1 E L b e D1 DS8080 Ver 0.1 Aug. 2007 MILLIMETERS MIN. MAX. 0.70 0.80 0.00 0.05 2.90 3.10 1.70 2.90 3.10 0.30 0.50 0.18 0.30 0.50 2.40 INCHES MIN. 0.028 0.000 0.114 MAX. 0.031 0.002 0.122 0.067 0.114 0.012 0.007 0.122 0.020 0.012 0.020 0.094 21 联系电话：１５９９９６４４５７９ ８３１５１７１５