bq2057 Advanced Li-Ion Linear Charge Management IC Features General Description Ideal for single- and dual-cell Li-Ion packs with coke or graphite anodes The BENCHMARQ bq2057 series advanced Li-Ion linear charge-management ICs are designed for cost-sensitive and compact portable electronics. They combine high-accuracy current and voltage regulation, battery conditioning, temperature monitoring, charge termination, ch a r g e - s t a t u s i n d i c a t i o n , a n d AutoComp charge-rate compensation in a single 8-pin IC. Dropout voltage as low as 0.3V AutoCompTM dynamic compensation of battery pack's internal impedance Optional temperature-monitoring before and during charge Integrated voltage and current regulation with programmable charge-current and high- or low-side current sensing Integrated cell conditioning for reviving deeply discharged cells and minimizing heat dissipation during initial stage of charge Better than 1% voltage regulation accuracy Charge status output for LED or host processor interface Automatic battery-recharge feature Charge termination by minimum current Low-power sleep mode The bq2057 continuously measures battery temperature using an external thermistor. For safety reasons, the bq2057 inhibits charge until the battery temperature is within user-defined thresholds. The bq2057 then charges the battery in three phases: conditioning, constant current, and constant voltage. If the battery voltage is below the low-voltage threshold V MIN, the bq2057 trickle-charges to condition the battery. The conditioning charge rate is set at 10% of the regulation current. The conditioning current also minimizes heat dissipation in the external pass-element during the initial stage of charge. Packaging: 8-pin SOIC, 8-pin TSSOP After conditioning, the bq2057 applies a constant current to the battery. An external sense-resistor sets Pin Connections Pin Names SNS 1 8 COMP BAT 2 7 CC VCC 3 6 VSS TS 4 5 STAT the magnitude of the current. The sense-resistor can be on either the low or the high side of the battery without additional components. The constant-current phase continues until the battery reaches the charge-regulation voltage. The bq2057 then begins the constant-voltage phase. The accuracy of the voltage regulation is better than 1% over the operating-temperature and supply-voltage ranges. For single and dual cells with either coke or graphite anodes, the bq2057 is offered in four fixed-voltage versions: 4.1V, 4.2V, 8.2V, and 8.4V. Charge stops when the current tapers to the ch a r g e t e r m i n a t i o n t h r e s h o l d , VTERM. The bq2057 automatically restarts the charge if the battery voltage falls below the VRCH threshold. The designer also may use the AutoComp feature to reduce charging time. This proprietary technique allows safe and dynamic compensation for the internal impedance of the battery pack during charge. SNS Current-sense input STAT Charge status output BAT Battery-voltage input VSS Ground input VCC Supply voltage CC Charge control output TS Temperature sense input COMP Charge-rate compensation input 8-Pin PDIP, Narrow SOIC, or TSSOP PN-205701.eps SLUS025A - JANUARY 2000 - REVISED MAY 2000 1 bq2057 STAT Pin Descriptions SNS Charge status output Tri-state indication of charge-in-progress, charge-complete, and temperature fault. Current-sense input Battery current is sensed via the voltage developed on this pin by an external sense resistor. BAT VSS Ground input CC Charge-control output Battery voltage input Source-follower output that drives an external pass-transistor for current and voltage regulation. Voltage sense-input tied directly to the positive side of the battery. COMP VCC VCC supply input TS Temperature sense input Sets the charge-rate compensation level. The voltage-regulation output may be programmed to vary as a function of the charge current delivered to the battery. Input for an external battery-temperature monitoring circuit. Connecting this input to Vcc/2 disables this feature. VCC VSS POWER ON RESET BAT COMP Charge-rate compensation input KCOMP CC VREG VCC CONTROL BLOCK SNS VSNS LED STAT STAT TS VTS1, VTS2 2057FBD.eps Figure 1. Functional Block Diagram 2 bq2057 Sleep Mode LED = Hi-Z NO VCC > VBAT YES YES VBAT VMIN YES Temperature Check TS > VTS1 TS < VTS2 NO Temperature Fault LED = Hi-Z Conditioning Phase LED = High NO Current Regulation Phase LED = High Voltage Regulation Phase LED = HIGH NO IBAT IREG 10 YES Charge Complete LED = LOW VBAT VRCH YES NO 2057OFC.eps Figure 2. bq2057 Operational Flow Chart serted. Charge qualification is based on battery temperature and voltage. The bq2057 suspends charge if the battery temperature is outside the VTS1 to VTS2 range and suspends charge until the battery temperature is within the allowed range. The bq2057 also checks the battery voltage. If the battery voltage is below the low - v olt a g e t h r es h old V M I N , t h e b q 2 0 5 7 u s e s trickle-charge to condition the battery. The conditioning charge rate ICOND is set at 10% of the regulation current. The conditioning current also minimizes heat dis- Functional Description Figure 1 is a functional block diagram, Figure 2 an operational flow chart, and Figure 3 a typical charger schematic for the bq2057. Charge Qualification and Conditioning When power is applied, the bq2057 starts a charge-cycle if a battery is already present or when a battery is in- 3 bq2057 RSNS 0.2 DC+ Q1 FZT788B D2 * PACK+ C1 0.1F R1 1k VCC PACKNTC VCC 7 1 3 6 C2 0.1F DC- bq2057 CC COMP SNS BAT VCC TS VSS STAT 8 2 RT1 4 TEMP 5 Battery Pack D1 RT2 R2 2k * Optional. 2057ldc.eps Figure 3. Low-Dropout Single- or Dual-Cell Li-Ion Charger sipation in the external pass-element during the initial stage of charge. See Figure 4 for a typical charge-algorithm. either coke or graphite anodes: 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. The voltage divider presents a scaled battery pack voltage to BAT input. (See Figures 7 and 8.) The resistor values RB1 and RB2 for the voltage divider are calculated by the following equation: Current Regulation The bq2057 regulates current while the battery-pack voltage is less than the regulation voltage, VREG. The bq2057 monitors charge current at the SNS input by the voltage drop across a sense-resistor, RSNS, in series with the battery pack. In high-side current sensing configuration (Figure 5), RSNS is placed between the Vcc and SNS pins, and in low-side sensing (Figure 6) the RSNS is placed between Vss (battery negative) and SNS (charger ground) pins. RB1 VCELL = N -1 RB2 VREG where N = Number of cells in series Charge-current feedback, applied through pin SNS, maintains regulation around a threshold of VSNS. The following formula calculates the value of the sense resistor: RSNS = VCELL = Desired regulation voltage per cell Charge Termination and Re-Charge VSNS IREG The bq2057 monitors the charging current during the voltage-regulation phase. The bq2057 declares a "batterycomplete" condition and terminates charge when the current tapers off to the charge termination threshold, VTERM. A new charge cycle begins when the battery voltage falls below the VRCH threshold. where IREG is the desired charging current. Voltage Monitoring and Regulation Voltage regulation feedback is through pin BAT. This input is tied directly to the positive side of the battery pack. The bq2057 monitors the battery-pack voltage between the BAT and VSS pins. The bq2057 is offered in four fixed-voltage versions for single- and dual-cells with 4 bq2057 Low-Current Conditioning Phase Current Regulation Phase Voltage Regulation Phase (Shown with the optional AutoComp feature) VPACK VREG IREG VBAT VMIN IBAT ICOND = IREG 10 IFULL = IREG 10 GR2057b.eps Figure 4. bq2057 Typical Charge Algorithm DC+ DC+ BAT+ RSNS BAT+ bq2057 1 2 3 4 bq2057 1 2 3 4 DC- SNS BAT VCC TS COMP CC VSS STAT 8 7 6 5 SNS BAT VCC TS COMP CC VSS STAT 8 7 6 5 DC- BAT- RSNS BAT2057HSCS.eps 2057LSCS1.eps Figure 5. High-Side Current Sensing Figure 6. Low-Side Current Sensing 5 bq2057 DC+ DC+ BAT+ RSNS BAT+ RB1 RB1 bq2057 DC- bq2057 1 2 3 4 DC- SNS BAT VCC TS 1 2 3 4 COMP CC VSS STAT RB2 8 7 6 5 SNS BAT VCC TS COMP CC VSS STAT 8 7 6 5 RB2 BATRSNS BAT- 2057OVDHSC.eps 2057OVDLSC.eps Figure 8. Optional Voltage Divider for Non-Standard Regulation Voltage, (Low-Side Current Sensing) Figure 7. Optional Voltage Divider for Non-Standard Regulation Voltage, (High-Side Current Sensing) The resistor values of RT1 and RT2 are calculated by the following equations: Temperature Monitoring The bq2057 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 Figure 9.) The bq2057 compares this voltage against its internal VTS1 and VTS2 thresholds to determine if charging is allowed. (See Figure 10.) The temperature sensing circuit is immune to any fluctuation in the VCC, since both the external voltage divider and the internal thresholds (VTS1 and VTS2) are referenced to VCC. For NTC thermistors RT1 = RT2 = ( 5 RTH RTC) ( 3 (RTC - RTH )) (5 RTH RTC ) ( ( 2 R ) - ( 7 R )) TC DC+ TH DC+ RSNS BAT+ BAT+ bq2057 RT1 DC- bq2057 1 2 3 4 SNS BAT VCC TS COMP CC VSS STAT 1 2 3 4 8 7 6 5 SNS BAT VCC TS COMP 8 CC 7 V 6 SS STAT 5 RT1 Thermistor RT2 DCRT2 BAT- BATRSNS Thermistor High-Side Current Sensing Low-Side Current Sensing 2057TSC.eps Figure 9. Temperature Sensing Circuits 6 bq2057 Condition V CC STAT Pin Battery conditioning and charging Charge complete Temperature fault or sleep mode Temp Fault High Low High-Z Automatic Charge-Rate Compensation V TS2 Normal Temp Range To reduce charging time, the bq2057 uses the proprietary AutoComp technique to compensate safely for internal impedance of the battery pack. V TS1 Figure 11 outlines the major components of a single-cell Li-Ion battery pack. The Li-Ion battery pack consists of a cell, protection circuit, fuse, connector, current sense-resistors, and some wiring. Each of these components contains some resistance. Total impedance of the battery pack is 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. Temp Fault V SS 2057TSIT.eps Figure 10. bq2057 TS Input Thresholds Compensation is through input pin COMP (Figure 12). A portion of the current-sense voltage, presented through this pin, is scaled by a factor of KCOMP and summed with the regulation threshold, VREG. This process increases the output voltage to compensate for the battery pack's internal impedance and for undesired voltage drops in the circuit. For PTC thermistors 5 RTH RTC RT1 = ( 3 (RTH - RTC )) RT2 = (5 RTH RTC ) ( ( 2 RTH ) - ( 7 RTC)) where RTC is the cold-temperature resistance and RTH is the hot-temperature resistance of the thermistor, as specified by the thermistor manufacturer. RT1 or RT2 can be omitted if only one temperature setting (Hot or Cold) is required. R2 Terminal Wire BAT+ FUSE Applying a voltage between the VTS1 and VTS2 thresholds to pin TS disables the temperature-sensing feature. Cell Protection Controller Low-Power Mode Terminal Wire Wire BAT- The bq2057 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. Discharge Wire Charge 2057SCLIP.eps Charge Status Display The bq2057 reports the status of the charger on the tri-state STAT pin. The three states include "charge in progress, charge complete, and temperature fault. Figure 11. Typical Components of a Single-Cell Li-Ion Pack 7 bq2057 DC+ DC+ BAT+ BAT+ RCOMP2 1 2 3 4 RCOMP1 DCRSNS bq2057 1 SNS COMP 2 BAT CC 3 V VSS CC 4 STAT TS DC8 7 6 5 bq2057 SNS COMP BAT CC VSS VCC STAT TS 8 7 6 5 RCOMP1 RSNS RCOMP2 BATHigh-Side Current Sensing Low-Side Current Sensing 2057AC.eps Figure 12. AutoComp Circuits AutoComp setup requires the following information: n Total impedance of battery pack (ZPACK) n Maximum charging current (IREG) where VCOMP is the voltage on COMP pin. This voltage is referenced to Vcc in high-side current-sensing configuration and to Vss for low-side sensing. VPACK is the voltage across the battery pack. The voltage drop VZ across the internal impedance of the battery pack can then be calculated by The values of RCOMP1 and RCOMP2 can be calculated using the following equation: VZ = ZPACK IREG VCOMP RCOMP2 = VSNS RCOMP1 + RCOMP2 The required compensation is then calculated using the following equations: VCOMP = VZ KCOMP VPACK = VREG + (KCOMP VCOMP) 8 bq2057 Absolute Maximum Ratings Symbol Parameter Min. Max. Units VCC VCC relative to VSS -0.3 +18 V VT VCC relative to VSS -0.3 VCC + 0.3 V TOPR Operating ambient temperature -20 70 C TSTG Storage temperature -40 125 C PD Power dissipation 300 mW Notes DC voltage applied on any pin (excluding VCC) DC Thresholds (TA=TOPR and VCC = 4.5-15V unless otherwise specified) Symbol VREG Parameter Rating Tolerance Unit 4.10 1% V For bq2057 only; See Note 1,2,3 4.20 1% V For bq2057C only; See Note 1,2,3 8.20 1% V For bq2057T only; See Note 1,2,3 8.40 1% V For bq2057W only; See Note 1,2,3 -110 10% mV VCC = 5V, See Note 4 -115 10% mV VCC = 9V, See Note 4 -115 15% mV All other VCC, See Note 4 3.0 2% V For bq2057 only 3.1 2% V For bq2057C only 6.0 2% V For bq2057T only 6.2 2% V For bq2057W only 2.2 15% Voltage regulation reference VSNS Current regulation reference VMIN Notes Conditioning voltage reference KCOMP AutoComp gain VTS1 Lower temperature threshold 0.3 VCC 3% of VCC V Voltage at pin TS, relative to VSS VTS2 Upper temperature threshold 0.6 VCC 3% of VCC V Voltage at pin TS, relative to VSS VRCH Recharge threshold VREG - 0.1 2% V Voltage on BAT pin, bq2057 and bq2057C only VRCH Recharge threshold VREG - 0.2 2% V Voltage on BAT pin, bq2057T and bq2057W only VTERM Charge termination reference -14 10mV mV Notes: 1. 2. 3. 4. V/V See Note 1 See Note 4 VCC = VBAT + 0.3V to 15V. For high-side current-sensing configuration. For low-side current-sensing, the tolerance is 1% for TA = 25C and 1.2% for TA = TORR. Voltage at pin SNS, relative to VCC for high-side sensing, and to VSS for low-side sensing, 0C <= TA <= 50C abcdefghijklmnopqrstuvwxyz1234567890-=[]\;',./ 9 ABCDEFGHIJKLMNOPQRSTUVWXYZ!@#%^&*()_+{}|:"<>?~ bq2057 DC Electrical Characteristics (TA= TOPR, and VCC = 4.5 - 15V unless otherwise specified)) Symbol Parameter VCC Supply voltage ICC Operating current ICCS Sleep current Min Typical Max Units Notes 4.5 - 15 V - 2 4 mA Excluding external loads - 3 6 A For bq2057 and bq2057C, See note - - 10 A For bq2057T and bq2057W, See note VOL Output-low voltage - 0.4 0.6 V IOL = 10mA; STAT pin VOH Output-high voltage VCC - 0.5 - - V IOH = 5mA; STAT pin - - 1 A BAT input, VBAT = VREG - - 5 A SNS, COMP, and TS inputs, VSNS = VCOMP = VTS = 5V CC pin, not to exceed PD specification IIH Input leakage current ISNK Sink current 5 - 40 mA VOLCC CC pin output-low voltage - - 1.5 V At ISNK (minimum) Note: VBAT VMIN, VBAT - VCC 0.8V, +20C TA 70C. 8-Pin SOIC Narrow (SN) 8-Pin SN (0.150" SOIC) Inches 10 Millimeters Dimension Min. Max. Min. Max. A 0.060 0.070 1.52 1.78 A1 0.004 0.010 0.10 0.25 B 0.013 0.020 0.33 0.51 C 0.007 0.010 0.18 0.25 D 0.185 0.200 4.70 5.08 E 0.150 0.160 3.81 4.06 e 0.045 0.055 1.14 1.40 H 0.225 0.245 5.72 6.22 L 0.015 0.035 0.38 0.89 bq2057 TS: 8-Pin TSSOP Inches Dimension Min. Max. Max. A - 0.043 - 1.10 A1 0.002 0.006 0.05 0.15 B 0.007 0.012 0.18 0.30 C 0.004 0.007 0.09 0.18 D 0.114 0.122 2.90 3.10 E 0.169 0.176 4.30 4.48 e H 0.0256BSC 0.246 0.256 Notes: 1. Controlling dimension: millimeters. Inches shown for reference only. 2 'D' and 'E' do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15mm per side 3 Each lead centerline shall be located within 0.10mm of its exact true position. 4. Leads shall be coplanar within 0.08mm at the seating plane. 5 Dimension 'B' does not include dambar protrusion. The dambar protrusion(s) shall not cause the lead width to exceed 'B' maximum by more than 0.08mm. 6 Dimension applies to the flat section of the lead between 0.10mm and 0.25mm from the lead tip. 7 'A1' is defined as the distance from the seating plane to the lowest point of the package body (base plane). Ordering Information bq2057 Package Option: SN = 8-pin narrow SOIC TS = 8-pin TSSOP Device: bq2057 Advanced Li-Ion Linear Charger for One Cell (4.1V) bq2057C Advanced Li-Ion Linear Charger for One Cell (4.2V) bq2057T Advanced Li-Ion Linear Charger for Two Cells (8.2V) bq2057W Advanced Li-Ion Linear Charger for Two Cells (8.4V) 11 Millimeters Min. 0.65BSC 6.25 6.50 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. 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