UNISONIC TECHNOLOGIES CO., LTD UB2012 LINEAR INTEGRATED CIRCUIT ADVANCED LINEAR CHARGE MANAGEMENT IC FOR SINGLE AND TWO-CELL LITHIUM-ION AND LITHIUM-POLYMER DESCRIPTION UTC UB2012 is designed for portable electronics with lower cost. Its advantages of high-accuracy voltage/current regulation, charging status indication, temperature monitoring, and automatic charge-rate compensation. In applications, the battery temperature is continuously under monitor by using an external thermistor, if the temperature is over user-defined threshold; UTC UB2012 inhibits charge for safety concern. Generally, the UTC UB2012 charges the battery in conditioning, constant voltage and constant current phases. If the battery voltage is lower than the low-voltage threshold (VMIN), a low current is used for conditioning the battery. The conditioning charge rate is around 10% of the regulation current and the heat dissipation in the external pass element during the initial stage of the charge is minimized by the conditioning current. After the conditioning phase, the UTC UB2012 applies a constant current that be set by an external sense-resistor to the battery. The sense-resistor can be on the battery without additional components. The constant current phase continues until the battery reaches the charge-regulation voltage, then the constant voltage phase is beginning. UTC UB2012 offers 4.1V, 4.2V, 8.4V and 8.4V fixed-voltage for single and dual cells. Charge stops when the current tapers to the charge termination threshold (ITERM) and will recharge if the battery voltage falls below the VRCH. The automatic charge-rate compensation feature reduces the charging time of batteries. For the internal impedance of battery pack during charge, this advanced technique offers safe and dynamic compensation. * * * * * * * * * * * * FEATURES Ideal for Single 4.1V,4.2V and Dual-Cell 8.2V,8.4V Li-Ion or Li-Pol Packs 0.3V Dropout Voltage for Minimizing Heat Dissipation Better than ±1% Accuracy of Voltage Regulation With Preset Voltages Dynamic Compensation of Battery Pack’s Internal Impedance to short Charging Time Optional Cell-Temperature Monitoring Integrated Voltage and Current Regulation With Programmable Charge-Current Integrated Cell Conditioning for Reviving Deeply Discharged Cells and Minimizing Heat Dissipation During Initial Charge Stage Charge Status Output for Single or Dual Led or Host Processor Interface Automatic Battery-Recharge Feature Charge Termination by Minimum Current Automatic Low-Power Sleep Mode When VCC is Removed EVMs Available for Quick Evaluation www.unisonic.com.tw Copyright © 2015 Unisonic Technologies Co., Ltd 1 of 17 QW-R121-018.D UB2012 ORDERING INFORMATION Note: LINEAR INTEGRATED CIRCUIT Ordering Number UB2012xG-S08-R x: Output Voltage, refer to Marking Information. Package SOP-8 Packing Tape Reel MARKING INFORMATION PACKAGE VOLTAGE CODE SOP-8 A: 4.1V B: 4.2V C: 8.2V D: 8.4V MARKING UTC UB2012xG Date Code Voltage Code Lot Code PIN CONFIGURATION SNS 1 8 BAT 2 7 CC VCC 3 6 VSS TS 4 5 STAT COMP PIN DESCRIPTION PIN NO. 1 2 3 4 5 6 7 8 PIN NAME SNS BAT VCC TS STAT VSS CC COMP I/O I I I I O O I PIN DESCRIPTION Current sense input Voltage sense input Supply voltage Temperature sense input Charge status output Ground Charge control output Charge-Rate compensation input (Auto Comp) UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT BLOCK DIAGRAM VCC Reference VO(REG) V(TS) TS VCC V(TS) VO(REG) V(BAT) TS2 Sleep Mode V(BAT) COMP V(TS) G(COMP) Voltage Regulation TS1 V(BAT) CC Battery Recharge Control Logic V(BAT) Battery Conditioning SNS V(SNS) V(SNS) VCC-V(SNS) VSS-V(SNS) Driver VCC High/Low SNS Set Driver VCC/2 V(SNS) STAT Current Regulation Driver Voltage Termination VSS UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT ABSOLUTE MAXIMUM RATING (unless otherwise specified.) PARAMETER SYMBOL RATINGS UNIT VCC -0.3 ~ +8.0 V VCC -0.3 ~ +15 V UB2012A UB2012B UB2012C UB2012D Supply Voltage (VCC with respect to GND) Input Voltage, SNS, BAT,TS, COMP VIN -0.3 ~ VCC +0.3 V (all with respect to GND) Sink Current (Note 2) STAT pin ISINK 20 mA Source Current (Note 2) STAT pin ISOURCE 10 mA Output Current (Note 2) CC pin IOUT 40 mA Power Dissipation (TA=25°C) PD 300 mW Operating Temperature TOPR -20 ~ +85 °C Storage Temperature TSTG -40 ~ +125 °C Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. 2. Not to exceed PD. RECOMMENDED OPERATING CONDITIONS PARAMETER SYMBOL MIN VCC UB2012A UB2012B Supply Voltage UB2012C UB2012D Operating Free-Air Temperature Range TYP MAX UNITS 4.5 7.0 V VCC 8.6 12 V TA -20 85 °C ELECTRICAL CHARACTERISTICS PARAMETER VCC Current SYMBOL I(VCC) VCC Sleep Current I(VCCS) BAT Pin IIB(BAT) SNS Pin IIB(SNS) Input Bias Current TS Pin IIB(TS) COMP Pin IIB(COMP) BATTERY VOLTAGE REGULATION Output Voltage CONDITIONS VCC>VCC(MIN), Excluding external loads V(BAT)≥V(MIN) V(BAT)-VCC≥0.8V MIN UB2012A UB2012B UB2012C UB2012D UB2012A UB2012B UB2012C UB2012D TYP MAX UNITS 2 5 mA 3 7 mA 3 6 μA 15 μA 3 5 5 5 μA μA μA μA V(BAT)=V(REG) V(SNS)=5V V(TS)=5V V(COMP)=5V VO(REG) See Notes UB2012A UB2012B UB2012C UB2012D 4.050 4.150 8.100 8.300 4.10 4.20 8.20 8.40 4.150 4.250 8.300 8.500 V V V V 80 100 120 mV 90 115 140 mV -24 -14 -4 mV CURRENT REGULATION Current Regulation Threshold V(SNS) current sensing configuration UB2012A UB2012B UB2012C UB2012D CHARGE TERMINATION DETECTION Charge Termination Current V(TERM) Voltage at pin SNS, 0°C≤TA≤50°C Detect Threshold UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT ELECTRICAL CHARACTERISTICS TEMPERATURE COMPARATOR Lower V(TS1) Temperature Threshold Upper V(TS2) PRECHARGE COMPARATOR Precharge Threshold TS Pin Voltage V(MIN) UB2012A UB2012B UB2012C UB2012D 29.1 58.2 30 60 30.9 61.8 %VCC %VCC 2.94 3.04 5.88 6.08 3.0 3.1 6.0 6.2 3.06 3.16 6.12 6.32 V V V V PRECHARGE CURRENT REGULATION Voltage at pin SNS, 0°C≤TA≤50°C V(PRECHG) Voltage at pin SNS, 0°C≤TA≤50°C, VCC = 5 V VRCH COMPARATOR (BATTERY RECHARGE THRESHOLD) UB2012A UB2012B Recharge Threshold V(RCH) UB2012C UB2012D CHARGE-RATE COMPENSATION (Automatic Charge-Rate Compensation) Automatic Charge-Rate G(COMP) V(BAT)+0.3V≤VCC≤VCC(MAX), Compensation Gain STAT PIN Output (Low) Voltage VOL(STAT) IOL=10mA Output (High) Voltage VOH(STAT) IOH=5mA CC PIN Output Low Voltage VOL(CC) IO(CC)=5mA (sink) Sink Current IO(CC) Not to exceed power rating (PD) Note: V(BAT) +0.3 V≤VCC≤VCC(MAX) Precharge Current Regulation UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 13 3 13 mV 22 mV VO(REG) VO(REG- VO(REG) -70mV -100mV -130mV VO(REG) VO(REG) VO(REG) -140mV -200mV -260mV 1.7 2.2 V 2.7 V/V 0.7 V V 1.6 40 V mA VCC-0.5 5 V 5 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT TYPICAL APPLICATION CIRCUIT DC+ PACK+ RSNS 0.2Ω Q1 2SB1151 D1 C1 10μF VCC R1 1kΩ PACKNTC VCC CC SNS VCC C2 10μF VSS COMP UB2012 RT1 BAT TS STAT GND D2 RT2 TEMP Battery Pack R2 2kΩ Fig. 1 0.5A Low Dropout Li-Lon/Li-Pol Charger FUNCTIONAL DESCRIPTION The UTC UB2012 is designed for the applications of single or two-cell Li-Ion or Li-Pol batteries. Fig. 1 is the schematic of using this advanced linear charge controller with a PNP pass transistor. Fig. 2 is the operation flowchart of UTC UB2012. Fig. 3 shows the typical charge profile. Fig. 4 is the application schematic of a charger using P-channel MOSFET. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION POR Sleep Mode VCC>V(BAT) Checked at All Times No Indicate SLEEP MODE (STAT=Hi-Z) Yes Suspend Charge TS Pin in TS1 to TS2 Range No Indicate CHARGE SUSPEND (STAT=Hi-Z) Yes Regulate I(PRECHG) Yes V(BAT)<V(MIN) Indicate Charge In-Progress (STAT=High) Suspend Charge No TS Pin in TS1 to TS2 Range Regulate Current or Voltage No Indicate Charge In-Progress (STAT=High) Yes No Suspend Charge TS Pin in TS1 to TS2 Range No Yes Yes Indicate CHARGE SUSPEND (STAT=Hi-Z) Indicate CHARGE SUSPEND (STAT=Hi-Z) TS Pin in TS1 to TS2 Range TS Pin in TS1 to TS2 Range V(BAT)<V(MIN) No Yes No Yes V(BAT)<V(MIN) No Terminate Charge Yes I(TERM) Delected Yes Indicate CHARGE DONE (STAT=Low) V(BAT)<V(RCH) No Yes Fig. 2 Operation Flowchart UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) Preconditionin g Phase Current Regulation Phase Voltage Regulation and Charge Termination Phase Regulation Voltage Regulation Current Minimum Charge Voltage Preconditioning and Taper Detect Fig. 3 Typical Charge Profile QUALIFICATION AND PRECHARGE When the battery is present and power is applied, the UTC UB2012 starts a charge-cycle. Charge qualification is affected by battery temperature and voltage. If the battery temperature is out of the VTS1 to VTS2 range; the UTC UB2012 will suspend charge. In addition, if the battery voltage is below the precharge threshold V(MIN), the UTC UB2012 uses precharge to condition the battery. The conditioning charge rate I(PRECHG) is set at approximately 10% of the regulation current, and the conditioning current minimizes heat dissipation in the external pass-element during the beginning of charge, refer to Fig. 3. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 8 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) PACK+ DC+ Q1 UT4101 RSNS 0.2Ω D1 C2 10μF VCC R2 1kΩ CC UTC UB2012 PACKNTC VCC COMP SNS BAT VCC TS VSS STAT RT1 TEMP RT2 Battery Pack R4 511Ω GND C1 10μF R5 1kΩ R3 1kΩ CMD6722SRU Fig. 4 0.5-A Charger Using P-Channel MOSFET CURRENT REGULATION PHASE When the battery-pack voltage is less than the regulation voltage, VO(REG), the current is regulated by the UTC UB2012. This advanced linear charge management IC monitors charge current at the SNS input by the voltage drop across a sense-resistor, RSNS, in series with the battery pack. In current sensing configuration (Fig. 5), RSNS is between the VCC and SNS pins. Charge-current feedback, applied through pin SNS, maintains a voltage of VSNS across the current sense resistor. The following formula calculates the value of the sense resistor: V(SNS) R SNS (1) IO(REG) Where IO(REG) is the desired charging current. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 9 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) VOLTAGE REGULATION PHASE The voltage regulation feedback is through the BAT pin. This input is tied directly to the positive side of the battery pack. The UTC UB2012 monitors the battery-pack voltage between the BAT and VSS pins. According to the voltage regulation, there are four versions of UTC UB2012, namely, 4.1V, 4.2V, 8.2V and 8.4V. Other regulation voltages can be achieved by adding a voltage divider between the positive and negative terminals of the battery pack and using UTC UB2012C or UTC UB2012D. The voltage divider presents scaled battery-pack voltage to BAT input. (See Fig. 7, 8) The resistor values RB1 and RB2 for the voltage divider are calculated by the following equation: RB1 V(CELL) = (N × ) -1 RB2 VO(REG) (2) Where: N = Number of cells in series, V(CELL) = Desired regulation voltage per cell CHARGE TERMINATION AND RECHARGE The UTC UB2012 monitors the charging current during the voltage-regulation phase. The UTC UB2012 declares a done condition and terminates charge when the current tapers off to the charge termination threshold, I(TERM). A new charge cycle begins when the battery voltage falls below the V(RCH) threshold. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 10 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) BATTERY TEMPERATURE MONITORING The UTC UB2012 continuously monitors temperature by measuring the voltage between the TS and VSS pins. A negative- or a positive-temperature coefficient thermistor (NTC, PTC) and an external voltage divider typically develop this voltage. (See Fig. 9) The UTC UB2012 compares this voltage against its internal V(TS1) and V(TS2) thresholds to determine if charging is allowed. (See Fig. 10) The temperature sensing circuit is immune to any fluctuation in VCC, since both the external voltage divider and the internal thresholds (V(TS1) and V(TS2) ) are referenced to VCC. The resistor values of R(T1) and R(T2) are calculated by the following equations: For NTC Thermistors: RT1 = 5 × R TH × R TC 3 × (RTC - RTH ) RT 2 = (3) 5 × RTH × RTC [(2 × RTC ) - (7 × RTH )] (4) For PTC Thermistors: RT1 = 5 × R TH × R TC 3 × (RTH - R TC ) RT 2 = (5) 5 × RTH × RTC [(2 × RTH ) - (7 × R TC )] (6) Where R(TC) is the cold temperature resistance and R(TH) is the hot temperature resistance of thermistor, as specified by the thermistor manufacturer. RT1 or RT2 can be omitted If only one temperature (hot or cold) setting is required. Applying a voltage between the V(TS1) and V(TS2) thresholds to pin TS disables the temperature-sensing feature. RSNS DC+ BAT+ UTC UB2012 SNS COMP RT1 BAT VCC DC- TS CC VSS STAT RT2 BATThermistor Fig. 7 Temperature Sensing Circuits Fig. 8 UTC UB2012 TS Input Thresholds UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 11 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) CHARGE INHIBIT FUNCTION The TS pin can be used as charge-inhibit input. The user can inhibit charge by connecting the TS pin to VCC or VSS (or any level outside the V(TS1) to V(TS2) thresholds). Applying a voltage between the V(TS1) and V(TS2) thresholds to pin TS returns the charger to normal operation. CHARGE STATUS INDICATION The UTC UB2012 reports the status of the charger on the 3-state STAT pin. The following table summarized the operation of the STAT pin. CONDITION STAT PIN Battery conditioning and charging High Charge complete (Done) Low Temperature fault or sleep mode Hi-Z The STAT pin can be used to drive a single LED (Figure 1), dual-chip LEDs (Fig. 4) or for interface to a host or system processor (Fig. 11). When interfacing the UTC UB2012 to a processor, the user can use an output port, as shown in Figure 11, to recognize the high-Z state of the STAT pin. In this configuration, the user needs to read the input pin, toggle the output port and read the STAT pin again. In a high-Z condition, the input port always matches the signal level on the output port. Host Processor UTC UB2012 SNS COMP BAT CC VCC VSS TS STAT OUT IN Figure 9 Interfacing the UTC UB2012 to a Host Processor LOW-POWER SLEEP MODE The UTC UB2012 enters the sleep mode if the VCC falls below the voltage at the BAT input. This feature prevents draining the battery pack during the absence of VCC. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 12 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) SELECTING AN EXTERNAL PASS-TRANSISTOR The UTC UB2012 is designed to work with both PNP transistor and P-channel MOSFET. The device should be chosen to handle the required power dissipation, given the circuit parameters, PCB layout and heat sink configuration. The following examples illustrate the design process for either device: PNP TRANSISTOR: Selection steps for a PNP bipolar transistor: Example: VI = 4.5V, I(REG) = 1A, 4.2-V single-cell Li-Ion (UTC UB2012C). VI is the input voltage to the charger and I (REG) is the desired charge current (see Fig. 1). 1. Determine the maximum power dissipation, PD, in the transistor. The worst case power dissipation happens when the cell voltage, V(BAT), is at its lowest (typically 3V at the beginning of current regulation phase) and VI is at its maximum. Where VCS is the voltage drop across the current sense resistor. PD = (VI-V(CS)-V(BAT))×I(REG) (7) PD = (4.5-0.1-3)×1A PD = 1.4W 2. Determine the package size needed in order to keep the junction temperature below the manufacturer’s recommended value, TJMAX. Calculate the total theta, θ (°C/W), needed. (TMAX(J) - TA(MAX) ) θJA = (8) PD (150 - 40) θJA = 1 .4 θJA = 78°C/W Now choose a device package with a theta at least 10% below this value to account for additional thetas other than the device. A SOT-223 package, for instance, has typically a theta of 60°C/W. 3. Select a collector-emitter voltage, V(CE), rating greater than the maximum input voltage. A 15-V device will be adequate in this example. 4. Select a device that has at least 50% higher drain current IC rating than the desired charge current I(REG). 5. Using the following equation calculate the minimum beta (β or hFE) needed: βMIN =ICMAX / IB βMIN =1 / 0.035 βMIN =28 (9) Where IMAX(C)) is the maximum collector current (in this case same as I (REG)), and IB is the base current (chosen to be 35 mA in this example). Now choose a PNP transistor that is rated for V(CE) ≥15 V, θJA ≤ 78°C /W, IC ≥ 1.5 A, βMIN ≥ 28 and that is in a SOT-223 package. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 13 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) SELECTING AN EXTERNAL PASS-TRANSISTOR (Cont.) P-CHANNEL MOSFET: Selection steps for a P-channel MOSFET: Example: VI = 5.5 V, I(REG) = 500mA, 4.2-V single-cell Li-Ion (UTC UB2012C). VI is the input voltage to the charger and I (REG) is the desired charge current (see Figure 4). 1. Determine the maximum power dissipation, PD , in the transistor. The worst case power dissipation happens when the cell voltage, V (BAT), is at its lowest (typically 3 V at the beginning of current regulation phase) and VI is at its maximum. Where VD is the forward voltage drop across the reverse-blocking diode (if one is used), and VCS is the voltage drop across the current sense resistor. PD = (VI-VD-V(CS)-V(BAT))×I(REG) (10) PD = (5.5-0.4-0.1-3)×0.5A PD = 1W 2. Determine the package size needed in order to keep the junction temperature below the manufacturer’s recommended value, TJMAX. Calculate the total theta, θ(°C/W), needed. (TMAX(J) - TA(MAX) ) θJA = (11) PD (150 - 40) θJA = 1 θJA = 110°C/W Now choose a device package with a theta at least 10% below this value to account for additional thetas other than the device. A SOP-8 package, for instance, has typically a theta of 70°C/W. 3. Select a drain-source voltage, V(DS), rating greater than the maximum input voltage. A 12V device will be adequate in this example. 4. Select a device that has at least 50% higher drain current (ID) rating than the desired charge current I(REG). 5. Verify that the available drive is large enough to supply the desired charge current. V(GS) = (VD+V(CS)+VOL(CC))-VI V(GS) = ( 0.4+0.1+1.5)-5.5 V(GS) = -3.5 (12) Where V(GS) is the gate-to-source voltage, VD is the forward voltage drop across the reverse-blocking diode (if one is used), and VCS is the voltage drop across the current sense resistor, and VOL(CC) is the CC pin output low voltage specification for the UTC UB2012. Select a MOSFET with gate threshold voltage, V(GSTH), rating less than the calculated V(GS). Now choose a P-channel MOSFET transistor that is rated for VDS≤-15V, θJA ≤110°C /W, ID ≥1A, V(GSTH)≥-3.5V and in a SOP package. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 14 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) SELECTING INPUT CAPACITOR In most applications, a high-frequency decoupling capacitor is required. A 0.1μF ceramic, placed in proximity to VCC and VSS pins, works well. The UTC UB2012 works with both regulated and unregulated external dc supplies. If a non-regulated supply is chosen, the supply unit should have enough capacitance to hold up the supply voltage to the minimum required input voltage at maximum load, otherwise more capacitance must be added to the input of the charger. SELECTING OUTPUT CAPACITOR For loop stability, the UTC UB2012 does not require any output capacitor. However, when a battery is not present, the user can add output capacitance in order to control the output voltage. The charger quickly charges the output capacitor to the regulation voltage, but the output voltage decays slowly, because of the low leakage current on the BAT pin, down to the recharge threshold. Addition of a 0.1μF ceramic capacitor, for instance, results in a 100 mV (pp) ripple waveform, with an approximate frequency of 25Hz. Higher capacitor values can be used if a lower frequency is desired. AUTOMATIC CHARGE-RATE COMPENSATION In order to compensate safely for internal impedance of the battery pack, the UTC UB2012 uses the automatic charge-rate compensation technique to reduce charging time. The automatic charge-rate compensation feature is disabled by connecting the COMP pin to VCC in current-sensing configuration. Fig. 12 outlines the main components of a single-cell Li-Ion battery pack. The Li-Ion battery pack consists of a cell, protection circuit, fuse, current sense-resistors, connector, and some wiring. There are some resistances in each of these components. Total impedance of the battery pack is equal to the sum of the minimum resistances of all battery-pack components. Using the minimum resistance values reduces the odds for overcompensating. Overcompensating may activate the safety circuit of the battery pack. BAT+ Terminal Wire Fuse Cell Protection Controller BATTerminal Wire Wire Discharge Wire Charge Fig. 10 Typical Components of a Single-Cell Li-lon Pack Compensation is achieved through input pin COMP (Fig. 13). A portion of the current-sense voltage, presented through this pin, is scaled by a factor of G(COMP) and summed with the regulation threshold, VO(REG). This process increases the output voltage to compensate for the battery pack’s internal impedance and for undesired voltage drops in the circuit. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 15 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) Automatic charge-rate compensation setup requires the following information: * Total impedance of battery pack (Z(PACK)) * Maximum charging current (I(REG)) The voltage drop across the internal impedance of battery pack, V(Z), can then be calculated using the following equation: (13) V( Z ) = Z(PACK ) × I(REG ) The required compensation is then calculated using the following equations: V( COMP ) = V( Z ) G( COMP ) (14) V(PACK ) = VO(REG ) + (G( COMP ) × V( COMP ) ) Where V(COMP) is the voltage on COMP pin. This voltage is referenced to VCC in current sensing configuration. V(PACK) is the voltage across the battery pack. The values of R(COMP1) and R(COMP2) can be calculated using the following equation: V( COMP ) RCOMP 2 = V( SNS ) RCOMP1 + RCOMP 2 (15) BAT+ DC+ RCOMP2 RCOMP1 RSNS DC- UTC UB2012 SNS COMP BAT CC VCC VSS TS STAT Fig. 11 Automatic Charge-Rate Compensation Circuits UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 16 of 17 QW-R121-018 .D UB2012 LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) The following example illustrates these calculations: Assume Z(PACK) = 100 mΩ , I(REG) = 500 mA, current sensing UTC UB2012B V( Z ) = Z(PACK ) × I(REG ) (16) V(Z)=0.1×0.5 V(Z)=50mV V( COMP ) = V( Z ) G( COMP ) (17) V(COMP)=0.05/2.2 V(COMP)=22.7mV Let RCOMP2 = 10 kΩ RCOMP1 = RCOMP 2 × ( V( SNS ) - V( COMP ) ) V( COMP ) RCOMP1 = 10k × (18) (105mV - 22.7mV ) 22.7mV R COMP1 36.25kΩ Use the closest standard value (36.0 kΩ) for RCOMP1 UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 17 of 17 QW-R121-018 .D