bq2002/F NiCd/NiMH Fast-Charge Management ICs Features General Description ➤ Fast charge of nickel cadmium or nickel-metal hydride batteries ➤ Direct LED output displays charge status The bq2002 and bq2002/F Fast-Charge ICs are low-cost CMOS battery-charge controllers providing reliable charge termination for both NiCd and NiMH battery applications. Controlling a current-limited or constant-current supply allows the bq2002/F to be the basis for a cost-effective stand-alone or system-integrated charger. The bq2002/F integrates fast charge with optional top-off and pulsed-trickle control in a single IC for charging one or more NiCd or NiMH battery cells. ➤ Fast-charge termination by -∆V, maximum voltage, maximum temperature, and maximum time ➤ Internal band-gap voltage reference ➤ Optional top-off charge ➤ Selectable pulse trickle charge rates ➤ Low-power mode ➤ 8-pin 300-mil DIP or 150-mil SOIC Fast charge is initiated on application of the charging supply or battery replacement. For safety, fast charge is inhibited if the battery temperature and voltage are outside configured limits. Pin Connections Fast charge is terminated by any of the following: n Peak voltage detection (PVD) n Negative delta voltage (-∆V) n Maximum voltage n Maximum temperature n Maximum time After fast charge, the bq2002/F optionally tops-off and pulse-trickles the battery per the pre-configured limits. Fast charge may be inhibited using the INH pin. The bq2002/F may also be placed in low-standby-power mode to reduce system power consumption. T h e b q 2 0 0 2 F d if f er s f r om t h e bq2002 only in that a slightly different set of fast-charge and top-off time limits is available. All differences between the two ICs are illustrated in Table 1. Pin Names TM 1 8 CC LED 2 7 INH BAT 3 6 VCC VSS 4 5 TS TM Timer mode select input TS Temperature sense input LED Charging status output VCC Supply voltage input BAT Battery voltage input INH Charge inhibit input VSS System ground CC Charge control output 8-Pin DIP or Narrow SOIC PN-200201.eps bq2002/F Selection Guide Part No. TCO HTF LTF 0.5 ∗ VCC None None bq2002F 0.5 ∗ VCC None None bq2002 -∆V PVD ✔ ✔ ✔ ✔ ✔ ✔ Fast Charge tMTO Top-Off Maintenance C/2 1C 2C C/2 1C 2C 160 80 40 160 100 55 C/32 C/16 None C/32 C/16 None C/64 C/64 C/32 C/64 C/64 C/32 SLUS131–JANUARY 1999 D 1 bq2002/F TM Charge control output CC Pin Descriptions An open-drain output used to control the charging current to the battery. CC switching to high impedance (Z) enables charging current to flow, and low to inhibit charging current. CC is modulated to provide top-off, if enabled, and pulse trickle. Timer mode input A three-level input that controls the settings for the fast charge safety timer, voltage termination mode, top-off, pulse-trickle, and voltage hold-off time. LED Functional Description Charging output status Open-drain output that indicates the charging status. BAT Figure 2 shows a state diagram and Figure 3 shows a block diagram of the bq2002/F. Battery input voltage Battery Voltage and Temperature Measurements The battery voltage sense input. The input to this pin is created by a high-impedance resistor divider network connected between the positive and negative terminals of the battery. VSS System ground TS Temperature sense input Battery voltage and temperature are monitored for maximum allowable values. The voltage presented on the battery sense input, BAT, should represent a single-cell potential for the battery under charge. A resistor-divider ratio of RB1 =N-1 RB2 Input for an external battery temperature monitoring thermistor. VCC is recommended to maintain the battery voltage within the valid range, where N is the number of cells, RB1 is the resistor connected to the positive battery terminal, and RB2 is the resistor connected to the negative battery terminal. See Figure 1. Supply voltage input 5.0V ± 20% power input. INH Charge inhibit input Note: This resistor-divider network input impedance to end-to-end should be at least 200kΩ and less than 1 MΩ. When high, INH suspends the fast charge in progress. When returned low, the IC resumes operation at the point where initially suspended. A ground-referenced negative temperature coefficient thermistor placed near the battery may be used as a lowcost temperature-to-voltage transducer. The temperature sense voltage input at TS is developed using a resistorthermistor network between VCC and VSS. See Figure 1. VCC PACK + RT RB1 VCC R3 BAT bq2002/F TM RB2 TS N T C bq2002/F R4 VSS VSS BAT pin connection Mid-level setting for TM Thermistor connection NTC = negative temperature coefficient thermistor. Fg2002/F01.eps Figure 1. Voltage and Temperature Monitoring and TM Pin Configuration 2 bq2002/F Chip on 4.0V VCC Battery Voltage? VBAT > 2V VBAT < 2V VTS > VCC/2 Fast LED = Low Battery Temperature? VBAT > 2V VTS < VCC/2 ((PVD or - V or Maximum Time-Out) and TM = high) (PVD or - V or Maximum Time-Out) and TM = high Top-off LED = Z VTS < VCC/2 VCC 2V Trickle LED = Z Maximum Time-Out or VBAT > 2V or VTS < VCC/2 SD2002/F01 Figure 2. State Diagram Clock Phase Generator OSC TM Timing Control Sample History Voltage Reference PVD, -∆V ALU A to D Converter INH Charge-Control State Machine MCV Check Power-On Reset TCO Check CC LED TS BAT Power Down VCC VSS Bd2002f.eps Figure 3. Block Diagram 3 bq2002/F VCC = 0 Fast Charging Top-Off (optional) Pulse-Trickle 286 s 286 s CC Output Fast Charging See Table 1 4576 s Charge initiated by application of power Charge initiated by battery replacement LED TD2002F1.eps Figure 4. Charge Cycle Phases If the battery voltage or temperature is outside of these limits, the IC pulse-trickle charges until the next new charge cycle begins. Starting A Charge Cycle Either of two events starts a charge cycle (see Figure 4): Fast charge continues until termination by one or more of the five possible termination conditions: 1. Application of power to VCC or 2. Voltage at the BAT pin falling through the maximum cell voltage VMCV where n Peak voltage detection (PVD) VMCV = 2V ±5%. n Negative delta voltage (-∆V) If the battery is within the configured temperature and voltage limits, the IC begins fast charge. The valid battery voltage range is VBAT < VMCV. The valid temperature range is VTS > VTCO where n Maximum voltage n Maximum temperature n Maximum time VTCO = 0.5 ∗ VCC ±5%. Table 1. Fast-Charge Safety Time/Hold-Off Table Typical Fast-Charge and Top-Off Time Limits (minutes) PulseTrickle Rate PulseTrickle Period (ms) C/32 C/64 9.15 300 C/16 C/64 18.3 150 Disabled C/32 18.3 Typical PVD and -∆V Hold-Off Top-Off Time (seconds) Rate Corresponding Fast-Charge Rate TM Termination bq2002 bq2002F C/2 Mid PVD 160 160 600 1C Low PVD 80 100 2C High -∆V 40 40 Notes: Typical conditions = 25°C, VCC = 5.0V. Mid = 0.5 * VCC ± 5V Tolerance on all timing is ± 20%. 4 bq2002/F pin is modulated at a duty cycle of 286µs active for every 4290µs inactive. This modulation results in an average rate 1/16th that of the fast charge rate. Maximum voltage, time, and temperature are the only termination methods enabled during top-off. PVD and -∆V Termination There are two modes for voltage termination depending on the state of TM. For -∆V (TM = high), if VBAT is lower than any previously measured value by 12mV ±3mV, fast charge is terminated. For PVD (TM = low or mid), a decrease of 2.5mV ±2.5mV terminates fast charge. The PVD and -∆V tests are valid in the range 1V < VBAT < 2V. Pulse-Trickle Charge Pulse-trickle is used to compensate for self-discharge while the battery is idle in the charger. The battery is pulse-trickle charged by driving the CC pin active for a period of 286µs for every 18.0ms of inactivity for 1C and 2C selections, and 286µs for every 8.86ms of inactivity for C/2 selection. This results in a trickle rate of C/64 for the top-off enabled mode and C/32 otherwise. Voltage Sampling Voltage is sampled at the BAT pin for PVD and -∆V termination once every 17s. The sample is an average of voltage measurements taken 57µs apart. The IC takes 32 measurements in PVD mode and 16 measurements in -∆V mode. The resulting sample periods (9.17 and 18.18ms, respectively) filter out harmonics centered around 55 and 109Hz. This technique minimizes the effect of any AC line ripple that may feed through the power supply from either 50 or 60Hz AC sources. Tolerance on all timing is ±20%. TM Pin The TM pin is a three-level pin used to select the charge timer, top-off, voltage termination mode, trickle rate, and voltage hold-off period options. Table 1 describes the states selected by the TM pin. The midlevel selection input is developed by a resistor divider between V CC and ground that fixes the voltage on TM at VCC/2 ± 0.5V. See Figure 4. Voltage Termination Hold-off A hold-off period occurs at the start of fast charging. During the hold-off time, the PVD and -∆V terminations are disabled. This avoids premature termination on the voltage spikes sometimes produced by older batteries when fast-charge current is first applied. Maximum voltage and temperature terminations are not affected by the hold-off period. Charge Status Indication A fast charge in progress is uniquely indicated when the LED pin goes low. The LED pin is driven to the high-Z state for all conditions other than fast charge. Figure 2 outlines the state of the LED pin during charge. Maximum Voltage, Temperature, and Time Charge Inhibit Any time the voltage on the BAT pin exceeds the maximum cell voltage,VMCV, fast charge or optional top-off charge is terminated. Fast charge and top-off may be inhibited by using the INH pin. When high, INH suspends all fast charge and top-off activity and the internal charge timer. INH freezes the current state of LED until inhibit is removed. Temperature monitoring is not affected by the INH pin. During charge inhibit, the bq2002/F continues to pulse-trickle charge the battery per the TM selection. When INH returns low, charge control and the charge timer resume from the point where INH became active. Maximum temperature termination occurs anytime the voltage on the TS pin falls below the temperature cut-off threshold VTCO. Maximum charge time is configured using the TM pin. Time settings are available for corresponding charge rates of C/2, 1C, and 2C. Maximum time-out termination is enforced on the fast-charge phase, then reset, and enforced again on the top-off phase, if selected. There is no time limit on the trickle-charge phase. Low-Power Mode The IC enters a low-power state when VBAT is driven above the power-down threshold (VPD) where VPD = VCC - (1V ±0.5V) Top-off Charge Both the CC pin and the LED pin are driven to the high-Z state. The operating current is reduced to less than 1µA in this mode. When VBAT returns to a value below VPD, the IC pulse-trickle charges until the next new charge cycle begins. An optional top-off charge phase may be selected to follow fast charge termination for 1C and C/2 rates. This phase may be necessary on NiMH or other battery chemistries that have a tendency to terminate charge prior to reaching full capacity. With top-off enabled, charging continues at a reduced rate after fast-charge termination for a period of time selected by the TM pin. (See Table 1.) During top-off, the CC 5 bq2002/F Absolute Maximum Ratings Symbol Parameter Minimum Maximum Unit VCC VCC relative to VSS -0.3 +7.0 V VT DC voltage applied on any pin excluding VCC relative to VSS -0.3 +7.0 V TOPR Operating ambient temperature 0 +70 °C TSTG Storage temperature -40 +85 °C TSOLDER Soldering temperature - +260 °C TBIAS Temperature under bias -40 +85 °C Note: Commercial 10 sec max. Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional operation should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to conditions beyond the operational limits for extended periods of time may affect device reliability. DC Thresholds Symbol Notes (TA = 0 to 70°C; VCC ± 20%) Parameter Rating Tolerance Unit 0.5 * VCC ±5% V VTS ≤ VTCO inhibits/terminates fast charge and top-off VBAT ≥ VMCV inhibits/terminates fast charge and top-off VTCO Temperature cutoff VMCV Maximum cell voltage 2 ±5% V -∆V BAT input change for -∆V detection -12 ±3 mV PVD BAT input change for PVD detection -2.5 ±2.5 mV 6 Notes bq2002/F Recommended DC Operating Conditions (TA = 0 to 70°C) Symbol Condition Minimum Typical Maximum Unit 4.0 5.0 6.0 V Notes VCC Supply voltage VDET -∆V, PVD detect voltage 1 - 2 V VBAT Battery input 0 - VCC V VTS Thermistor input 0.5 - VCC V VTS < 0.5V prohibited Logic input high 0.5 - - V INH Logic input high VCC - 0.5 - - V TM + 0.5 V TM VIH VIM Logic input mid VCC - 0.5 2 - VCC 2 Logic input low - - 0.1 V INH Logic input low - - 0.5 V TM Logic output low - - 0.8 V LED, CC, IOL = 10mA VBAT ≥ VPD max. powers down bq2002/F; VBAT < VPD min. = normal operation. VIL VOL VCC - 1.5 - VCC - 0.5 V Supply current - - 250 µA Outputs unloaded, VCC = 5.1V ISB Standby current - - 1 µA VCC = 5.1V, VBAT = VPD IOL LED, CC sink 10 - - mA @VOL = VSS + 0.8V IL Input leakage - - ±1 µA INH, CC, V = VSS to VCC IOZ Output leakage in high-Z state -5 - - µA LED, CC VPD Power down ICC Note: All voltages relative to VSS. 7 bq2002/F Impedance Symbol Parameter Minimum Typical Maximum Unit RBAT Battery input impedance 50 - - MΩ RTS TS input impedance 50 - - MΩ Timing Symbol dFCV Note: (TA = 0 to +70°C; VCC ± 10%) Parameter Base time variation Minimum Typical Maximum Unit -20 - 20 % Typical is at TA = 25°C, VCC = 5.0V. 8 Notes bq2002/F 8-Pin DIP (PN) 8-Pin PN (0.300" DIP) Inches Min. Max. Min. Max. A 0.160 0.180 4.06 4.57 A1 0.015 0.040 0.38 1.02 B 0.015 0.022 0.38 0.56 B1 0.055 0.065 1.40 1.65 D E1 E A B1 A1 L C B S e G 9 Millimeters Dimension C 0.008 0.013 0.20 0.33 D 0.350 0.380 8.89 9.65 E 0.300 0.325 7.62 8.26 E1 0.230 0.280 5.84 7.11 e 0.300 0.370 7.62 9.40 G 0.090 0.110 2.29 2.79 L 0.115 0.150 2.92 3.81 S 0.020 0.040 0.51 1.02 bq2002/F 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 bq2002/F Data Sheet Revision History Change No. Page No. 1 3 Was: Table 1 gave the bq2002/F Operational Summary. Is: Figure 2 gives the bq2002/F Operational Summary. Changed table to figure. 1 5 Added Termination column to table and Top-off values. Added column and values. 2 All 3 1 Notes: Description Revised and expanded this data sheet to include bq2002F Addition of selection guide Change 1 = Sept. 1996 B changes from July 1994. Change 2 = Aug. 1997 C changes from Sept. 1996 B. Change 3 = Jan. 1999 D changes from Aug. 1997 C. Ordering Information bq2002/F Package Option: PN = 8-pin plastic DIP SN = 8-pin narrow SOIC Device: bq2002 Fast-Charge IC bq2002F Fast-Charge IC 11 Nature of Change 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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