bq2002E/G NiCd/NiMH Fast-Charge Management ICs Features General Description ➤ The bq2002E and bq2002G FastCharge 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 bq2002E/G to be the basis for a costeffective stand-alone or system-integrated charger. The bq2002E/G 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 of nickel cadmium or nickel-metal hydride batteries ➤ Direct LED output displays charge status ➤ 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 Pin Connections 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. 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 bq2002E/G optionally tops-off and pulse-trickles the battery per the pre-configured limits. Fast charge may be inhibited using the INH pin. The bq2002E/G may also be placed in low-standby-power mode to reduce system power consumption. T h e b q 2 0 0 2 E d i f f e rs f ro m t he bq2002G 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 bq2002E/G Selection Guide TCO HTF LTF bq2002E 0.175 ∗ VCC Part No. LBAT 0.5 ∗ VCC 0.6 ∗ VCC None bq2002G 0.175 ∗ VCC 0.5 ∗ VCC 0.6 ∗ VCC None -∆V PVD ✔ ✔ ✔ ✔ ✔ ✔ 2/99 1 Fast Charge tMTO Top-Off Maintenance C/2 1C 2C C/2 1C 2C 200 80 40 160 80 40 None C/16 None None C/16 None C/32 C/32 C/32 C/32 C/32 C/32 bq2002E/G sumes operation at the point where initially suspended. Pin Descriptions TM Timer mode input Charge control output CC 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 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. Charging output status Open-drain output that indicates the charging status. BAT Functional Description Battery input voltage Figure 2 shows a state diagram and Figure 3 shows a block diagram of the bq2002E/G. 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 Measurements 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 Input for an external battery temperature monitoring thermistor. VCC RB1 =N-1 RB2 Supply voltage input 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. 5.0V ± 20% power input. INH Charge inhibit input When high, INH suspends the fast charge in progress. When returned low, the IC re- Note: This resistor-divider network input impedance to end-to-end should be at least 200kΩ and less than 1 MΩ. VCC PACK + RT RB1 VCC R3 BAT bq2002E/G TM RB2 TS N T C bq2002E/G R4 VSS VSS BAT pin connection Mid-level setting for TM Thermistor connection NTC = negative temperature coefficient thermistor. Fg2002E/G01.eps Figure 1. Voltage and Temperature Monitoring and TM Pin Configuration 2 bq2002E/G Chip on 4.0V VCC Battery Voltage too High? VBAT > 2V VBAT < 2V Battery Voltage too Low? VBAT < 0.175 VCC 0.175 VCC < VBAT VTS > 0.6 (PVD or - V or Maximum Time Out) and TM = Low VCC Battery Temperature? VTS < 0.6 VCC Charge Pending Fast LED = Low VBAT > 2V or VTS < VCC/2 or ((PVD or - V or Maximum Time Out) Low) and TM Top-off LED = Z VBAT > 0.175 VCC, VBAT < 2V, and VTS > VCC/2 Trickle LED = Flash VBAT > 2V VBAT 2V Trickle LED = Z VBAT 2V or VTS VCC/2 or Maximum Time Out SD2002C.eps 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 LBAT Check HTF TCO Check Check Power-On Reset CC LED TS Power Down VCC MCV Check BAT VSS Bd2002CEG.eps Figure 3. Block Diagram 3 bq2002E/G VCC = 0 Fast Charging Top-Off (optional) See Table 1 73ms CC Output Fast Charging Pulse-Trickle 1.17s 1.17s Charge initiated by application of power Charge initiated by battery replacement LED TD2002EG.eps Figure 4. Charge Cycle Phases 1. Application of power to VCC or A ground-referenced negative temperature coefficient thermistor placed near the battery may be used as a low-cost temperature-to-voltage transducer. The temperature sense voltage input at TS is developed using a resistorthermistor network between VCC and VSS. See Figure 1. 2. Voltage at the BAT pin falling through the maximum cell voltage VMCV where VMCV = 2V ±5%. If the battery is within the configured temperature and voltage limits, the IC begins fast charge. The valid battery voltage range is VLBAT < VBAT < VMCV, where Starting A Charge Cycle Either of two events starts a charge cycle (see Figure 4): Table 1. Fast-Charge Safety Time/Hold-Off/Top-Off Table Typical FastCharge and Top-Off Time Limits (minutes) Top-Off Rate PulseTrickle Rate PulseTrickle Width (ms) Maximum Synchronized Sampling Period (seconds) 300 Disabled C/32 73 18.7 80 150 C/16 C/32 37 18.7 40 75 Disabled C/32 18 9.4 Typical PVD and -∆V Hold-Off Time bq2002E bq2002G (seconds) Corresponding Fast-Charge Rate TM Termination C/2 Mid PVD 200 160 1C Low PVD 80 2C High -∆V 40 Notes: Typical conditions = 25°C, VCC = 5.0V Mid = 0.5 * VCC ± 0.5V Tolerance on all timing is ± 12%. 4 bq2002E/G VLBAT = 0.175 ∗ VCC ±20% The response of the IC to pulses less than 100ns in width or between 3.5ms and 12ms is indeterminate. Tolerance on all timing is ±12%. The valid temperature range is VTS > VHTF where VHTF = 0.6 ∗ VCC ±5%. Voltage Termination Hold-off If the battery voltage or temperature is outside of these limits, the IC pulse-trickle charges until the next new charge cycle begins. 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. If VMCV < VBAT < VPD (see “Low-Power Mode”) when a new battery is inserted, a delay of 0.35 to 0.9s is imposed before the new charge cycle begins. Fast charge continues until termination by one or more of the five possible termination conditions: n Peak voltage detection (PVD) n Negative delta voltage (-∆V) n Maximum voltage n Maximum temperature n Maximum time Maximum Voltage, Temperature, and Time Any time the voltage on the BAT pin exceeds the maximum cell voltage,VMCV, fast charge or optional top-off charge is terminated. Maximum temperature termination occurs anytime the voltage on the TS pin falls below the temperature cut-off threshold VTCO where VTCO = 0.5 ∗ VCC ± 5%. PVD and -∆V Termination 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. 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. Top-off Charge Synchronized Voltage Sampling 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 before 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 pin is modulated at a duty cycle of 73ms active for every 1097ms 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. Voltage sampling at the BAT pin for PVD and -∆V termination may be synchronized to an external stimulus using the INH input. Low-high-low input pulses between 100ns and 3.5ms in width must be applied at the INH pin with a frequency greater than the “maximum synchronized sampling period” set by the state of the TM pin as shown in Table 1. Voltage is sampled on the falling edge of such pulses. If the time between pulses is greater than the synchronizing period, voltage sampling “free-runs” at once every 17 seconds. A sample is taken by averaging together 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. 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 once every 1.17s for the period specified in Table 1. This results in a trickle rate of C/32. If the INH input remains high for more than 12ms, the voltage sample history kept by the IC and used for PVD and -∆V termination decisions is erased and a new history is started. Such a reset is required when transitioning from free-running to synchronized voltage sampling. TM Pin The TM pin is a three-level pin used to select the charge timer, top-off, voltage termination mode, trickle 5 bq2002E/G 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. 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) Charge Status Indication 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. 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. Charge Inhibit 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 bq2002E/G 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. 6 bq2002E/G 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 Notes VTCO Temperature cutoff 0.5 * VCC ± 5% V VTS ≤ VTCO inhibits/terminates fast charge and top-off VHTF High temperature fault 0.6 ∗ VCC ±5% V VTS < VHTF inhibits fast charge start VMCV Maximum cell voltage 2 ± 5% V VBAT ≥ VMCV inhibits/terminates fast charge and top-off VLBAT Minimum cell voltage 0.175 ∗ VCC ±20% V VBAT < VLBAT inhibits fast charge start -∆V BAT input change for -∆V detection -12 ±3 mV PVD BAT input change for PVD detection -2.5 ±2.5 mV 7 bq2002E/G 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 VIH Logic input high 0.5 - - V INH Logic input high VCC - 0.5 - - V TM Logic input mid VCC - + 0.5 V TM VIM - 0.5 2 VCC 2 Logic input low - - 0.1 V INH Logic input low - - 0.5 V TM VOL Logic output low - - 0.8 V LED, CC, IOL = 10mA VPD Power down VCC - 1.5 - VCC - 0.5 V VBAT ≥ VPD max. powers down bq2002E/G; VBAT < VPD min. = normal operation. ICC Supply current - - 500 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 VIL Note: All voltages relative to VSS. 8 bq2002E/G Impedance Symbol Parameter Minimum Typical Maximum Unit RBAT Battery input impedance 50 - - MΩ RTS TS input impedance 50 - - MΩ Timing Symbol (TA = 0 to +70°C; VCC ± 10%) Parameter Minimum Typical Maximum Unit dFCV Time base variation -12 - 12 % tDLY Start-up delay 0.35 - 0.9 s Note: Typical is at TA = 25°C, VCC = 5.0V. 9 Notes Starting from VMCV < VBAT < VPD bq2002E/G 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 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 C B S e Millimeters Dimension 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 G 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 bq2002E/G Data Sheet Revision History Change No. Page No. 1 1 Notes: Description Added selection guide Change 1 = Feb. 1999 B changes from Sept. 1997 Ordering Information bq2002E/G Package Option: PN = 8-pin plastic DIP SN = 8-pin narrow SOIC Device: bq2002E Fast Charge IC bq2002G 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. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER’S RISK. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof. Copyright 1999, Texas Instruments Incorporated 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. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER’S RISK. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof. Copyright 1999, Texas Instruments Incorporated