bq2031 Lead-Acid Fast-Charge IC Features - ➤ Conforms to battery manufacturers' charge recommendations for cyclic and float charge Ideal for high-efficiency switch-mode power conversion - Configurable for linear or gated current use ➤ Pin-selectable charge algorithms - Two-Step Voltage with temperature-compensated constant-voltage maintenance - Two-Step Current with constant-rate pulsed current maintenance - Pulsed Current: hysteretic, on-demand pulsed current ➤ Pin-selectable charge termination by maximum voltage,∆2V, minimum current, and maximum time ➤ Pre-charge qualification detects shorted, opened, or damaged cells and conditions battery ➤ Direct LED control outputs display charge status and fault conditions General Description The bq2031 Lead-Acid Fast Charge IC is designed to optimize charging of lead-acid chemistry batteries. A flexible pulse-width modulation regulator allows the bq2031 to control constant-voltage, constantcurrent, or pulsed-current charging. The regulator frequency is set by an external capacitor for design flexibility. The switch-mode design keeps power dissipation to a minimum for high charge current applications. ➤ Pulse-width modulation control A charge cycle begins when power is applied or the battery is replaced. For safety, charging is inhibited until the battery voltage is within configured limits. If the battery voltage is less than the low-voltage threshold, the bq2031 provides trickle-current Pin Connections Pin Names ➤ Charging continuously qualified by temperature and voltage limits ➤ Internal temperature-compensated voltage reference TMTO Time-out timebase input charging until the voltage rises into the allowed range or an internal timer runs out and places the bq2031 in a Fault condition. This procedure prevents high-current charging of cells that are possibly damaged or reversed. Charging is inhibited anytime the temperature of the battery is outside the configurable, allowed range. All voltage t h r es h old s a r e t em p er a t u r e compensated. The bq2031 terminates fast (bulk) charging based on the following: ■ Maximum voltage ■ Second difference of cell voltage (∆2V) ■ Minimum current (in constantvoltage charging) ■ Maximum time-out (MTO) After bulk charging, the bq2031 provides temperature-compensated maintenance (float) charging to maintain battery capacity. LED3/ QSEL Charge status output 3/ Charge algorithm select input 1 TMTO 1 16 LED2/DSEL FLOAT State control output FLOAT 2 15 LED1/TSEL BAT Battery voltage input COM Common LED output BAT 3 14 MOD VCOMP Voltage loop comp input VSS System ground VCOMP 4 13 VCC ICOMP Current loop comp input VCC 5.0V± 10% power ICOMP 5 12 VSS IGSEL 6 11 COM IGSEL Current gain select input MOD Modulation control output SNS 7 10 LED3/QSEL SNS Sense resistor input TS 8 9 TPWM TS Temperature sense input LED1/ TSEL Charge status output 1/ Charge algorithm select input 2 TPWM Regulator timebase input LED2/ DSEL Charge status output 2/ Display select input 16-Pin Narrow DIP or SOIC PN203101.eps SLUS156–JUNE 1999 E 1 bq2031 TPWM Pin Descriptions TMTO This input uses an external timing capacitor to ground the pulse-width modulation (PWM) frequency. See equation 9. Time-out timebase input This input sets the maximum charge time. The resistor and capacitor values are determined using equation 6. Figure 9 shows the resistor/capacitor connection. FLOAT COM QSEL MOD Voltage loop compensation input LED1–3 Current gain select input DSEL TSEL Termination select input With QSEL, selects the charge algorithm. See Table 1. Charging current sense input VCC Battery current is sensed via the voltage developed on this pin by an external sense resistor, RSNS, connected in series with the low side of the battery. See equation 8. TS Display select input This three-level input controls the LED1–3 charge display modes. See Table 2. Current loop compensation input This input uses an external C or R-C network for current loop stability. SNS Charger display status 1–3 outputs These charger status output drivers are for the direct drive of the LED display. Display modes are shown in Table 2. These outputs are tri-stated during initialization so that QSEL, TSEL, and DSEL can be read. This three-state input is used to set IMIN for fast charge termination in the Two-Step Voltage algorithm and for maintenance current regulation in the Two-Step Current algorithm. See Tables 3 and 4. ICOMP Current-switching control output MOD is a pulse-width modulated push/pull output that is used to control the charging current to the battery. MOD switches high to enable current flow and low to inhibit current flow. This input uses an external C or R-C network for voltage loop stability. IGSEL Charge regulation select input With TSEL, selects the charge algorithm. See Table 1. Battery voltage input BAT is the battery voltage sense input. This potential is generally developed using a highimpedance resistor divider network connected between the positive and the negative terminals of the battery. See Figure 6 and equation 2. VCOMP Common LED output Common output for LED1–3. This output is in a high-impedance state during initialization to read program inputs on TSEL, QSEL, and DSEL. Float state control output This open-drain output uses an external resistor divider network to control the BAT input voltage threshold (VFLT) for the float charge regulation. See Figure 1. BAT Regulation timebase input VCC supply 5.0V, ± 10% power VSS Temperature sense input Ground Functional Description This input is for an external battery temperature monitoring thermistor or probe. An external resistor divider network sets the lower and upper temperature thresholds. See Figures 7 and 8 and equations 4 and 5. The bq2031 functional operation is described in terms of: 2 n Charge algorithms n Charge qualification n Charge status display n Voltage and current monitoring n Temperature monitoring bq2031 n Fast charge termination n Maintenance charging n Charge regulation Chip On VCC 4.5V Charge Algorithms Temperature Checks On Three charge algorithms are available in the bq2031: n Present VLCO < VCELL < VHCO Two-Step Voltage Temperature in Range Test 1 ISNS < ICOND n Two-Step Current n Pulsed Current Temperature Out of Range or Thermistor Absent Voltage Regulation @ VFLT + 0.25V Absent VCELL < VLCO or VCELL > VHCO Battery Status? Fail: t = tQT1 or VCELL > VHCO Fault LED3 = 1 MOD = 0 VCELL VCELL PASS: ISNS > ICOND The state transitions for these algorithms are described in Table 1 and are shown graphically in Figures 2 through 4. The user selects a charge algorithm by configuring pins QSEL and TSEL. Test 2 Fail: t = tQT2 or VCELL < VLCO or VCELL > VHCO VCELL < VMIN Current Regulation @ICOND VLCO or VHCO Charge Pending LED3 Flash MOD = 0 PASS: VCELL > VMIN Charge Qualification VCELL < VLCO or VCELL > VHCO Bulk Charge The bq2031 starts a charge cycle when power is applied while a battery is present or when a battery is inserted. Figure 1 shows the state diagram for pre-charge qualification and temperature monitoring. The bq2031 first checks that the battery temperature is within the allowed, user-configurable range. If the temperature is out-of-range (or the thermistor is missing), the bq2031 enters the Charge Pending state and waits until the battery temperature is within the allowed range. Charge Pending is annunciated by LED3 flashing. Temperature Out of Range or Thermistor Absent Fast Charge Temperature In Range, Return to Original State Termination VCELL < VMIN FG203101.eps Figure 1. Cycle Start/Battery Qualification State Diagram Table 1. bq2031 Charging Algorithms Algorithm/State QSEL TSEL Conditions MOD Output Two-Step Voltage Fast charge, phase 1 Fast charge, phase 2 Primary termination Maintenance Two-Step Current Fast charge Primary termination Maintenance Pulsed Current Fast charge Primary termination L H/LNote 1 - Current regulation Voltage regulation Maintenance Notes: H L H H while VBAT < VBLK, ISNS = IMAX while ISNS > IMIN, VBAT = VBLK ISNS = IMIN VBAT = VFLT while VBAT < VBLK, ISNS = IMAX VBAT = VBLK or ∆2V < -8mVNote 2 ISNS pulsed to average IFLT while VBAT < VBLK, ISNS = IMAX VBAT = VBLK ISNS = IMAX after VBAT = VFLT; ISNS = 0 after VBAT = VBLK Voltage regulation Current regulation Fixed pulse current Current regulation Hysteretic pulsed current 1. May be high or low, but do not float. 2. A Unitrode proprietary algorithm for accumulating successive differences between samples of VBAT. 3 bq2031 test 2 before the bq2031 recognizes its “pass” criterion. If this second test passes, the bq2031 begins fast (bulk) charging. Thermal monitoring continues throughout the charge cycle, and the bq2031 enters the Charge Pending state anytime the temperature is out of range. (There is one exception; if the bq2031 is in the Fault state—see below—the out-of-range temperature is not recognized until the bq2031 leaves the Fault state.) All timers are suspended (but not reset) while the bq2031 is in Charge Pending. When the temperature comes back into range, the bq2031 returns to the point in the charge cycle where the out-of-range temperature was detected. Once in the Fault state, the bq2031 waits until VCC is cycled or a battery insertion is detected. It then starts a new charge cycle and begins the qualification process again. Charge Status Display Charge status is annunciated by the LED driver outputs LED1–LED3. Three display modes are available in the bq2031; the user selects a display mode by configuring pin DSEL. Table 2 shows the three modes and their programming pins. When the temperature is valid, the bq2031 performs two tests on the battery. In test 1, the bq2031 regulates a voltage of VFLT + 0.25V across the battery and observes ISNS. If ISNS does not rise to at least ICOND within a time-out period (e.g., the cell has failed open), the bq2031 enters the Fault state. If test 1 passes, the bq2031 then regulates current to ICOND (= IMAX/5) and watches VCELL (= VBAT - VSNS). If VCELL does not rise to at least VFLT within a time-out period (e.g., the cell has failed short), again the bq2031 enters the Fault state. A hold-off period is enforced at the beginning of qualification The bq2031 does not distinguish between an over-voltage fault and a “battery absent” condition. The bq2031 enters the Fault state, annunciated by turning on LED3, whenever the battery is absent. The bq2031, therefore, gives an indication that the charger is on even when no battery is in place to be charged. Table 2. bq2031 Display Output Summary Mode DSEL = 0 (Mode 1) DSEL = 1 (Mode 2) DSEL = Float (Mode 3) Notes: Charge Action State LED1 LED2 LED3 Battery absent or over-voltage fault Low Low High Pre-charge qualification Flash Low Low Fast charging High Low Low Maintenance charging Low High Low Charge pending (temperature out of range) X X Flash Charging fault X X High Battery absent or over-voltage fault Low Low High Pre-charge qualification High High Low Fast charge Low High Low Maintenance charging High Low Low Charge pending (temperature out of range) X X Flash Charging fault X X High Battery absent or over-voltage fault Low Low High Pre-charge qualification Flash Flash Low Fast charge: current regulation Low High Low Fast charge: voltage regulation High High Low Maintenance charging High Low Low Charge pending (temperature out of range) X X Flash Charging fault X X High 1 = VCC; 0 = VSS; X = LED state when fault occurred; Flash = 1 6 s low, 1 6 s high. In the Pulsed Current algorithm, the bq2031 annunciates maintenance when charging current is off and fast charge whenever charging current is on. 4 VBLK VFLT Voltage Maintenance Fast Charge Phase 1 VMIN Phase 2 ICOND Voltage Current IMAX Qualification bq2031 Current IMIN IFLT Time VBLK Current VFLT Voltage VMIN Maintenance ICOND Fast Charge Voltage Current IMAX Qualification Figure 2. Two-Step Voltage Algorithm Time ICOND Maintenance Current VBLK VFLT Voltage VMIN Voltage Current IMAX Qualification Figure 3. Two-Step Current Algorithm Fast Charge Time Figure 4. Pulsed Current Algorithm 5 bq2031 Configuring Algorithm and Display Modes VCC QSEL/LED 3 , DSEL/LED 2 , and TSEL/LED 1 are bidirectional pins with two functions; they are LED driver pins as outputs and programming pins for the bq2031 as inputs. The selection of pull-up, pull-down, or no pull resistor programs the charging algorithm on QSEL and TSEL per Table 1 and the display mode on DSEL per Table 2. The bq2031 latches the program states when any of the following events occurs: 1. VCC rises to a valid level. 2. The bq2031 leaves the Fault state. 3. The bq2031 detects battery insertion. BAT + FLOAT BAT 13 RB1 2 3 RB3 VCC 12 RB2 VSS SNS bq2031 The LEDs go blank for approximately 750ms (typical) while new programming data is latched. BAT - 7 RSNS VSS For example, Figure 5 shows the bq2031 configured for the Pulsed Current algorithm and display mode 2. FG203102.eps Voltage and Current Monitoring Figure 6. Configuring the Battery Divider The bq2031 monitors battery pack voltage at the BAT pin. A voltage divider between the positive and negative terminals of the battery pack is used to present a scaled battery pack voltage to the BAT pin and an appropriate value for regulation of float (maintenance) voltage to the FLOAT pin. The bq2031 also uses the voltage across a sense resistor (RSNS) between the negative terminal of the battery pack and ground to monitor current. See Figure 6 for the configuration of this network. VCC 10K 10K 16 LED2/DSEL 1K 15 LED1/TSEL 1K 13 VCC 12 VSS 11 COM 10 LED3/QSEL bq2031 1K 10K VSS FG203103.eps Figure 5. Configuring Charging Algorithm and Display Mode 6 bq2031 The user must include a pull-up resistor from the positive terminal of the battery stack to VDC (and a diode to prevent battery discharge through the power supply when the supply is turned off) in order to detect battery removal during periods of voltage regulation. Voltage regulation occurs in pre-charge qualification test 1 prior to all of the fast charge algorithms, and in phase 2 of the Two-Step Voltage fast charge algorithm. The resistor values are calculated from the following: Equation 1 RB1 (N ∗ VFLT ) = −1 RB2 2.2V Equation 2 N ∗ VBLK RB1 RB1 )−1 + =( RB2 RB3 2.2 Temperature Monitoring The bq2031 monitors temperature by examining the voltage presented between the TS and SNS pins (VTEMP) by a resistor network that includes a Negative Temperature Coefficient (NTC) thermistor. Resistance variations around that value are interpreted as being proportional to the battery temperature (see Figure 7). Equation 3 I MAX = 0.250 V R SNS where: n N = Number of cells The temperature thresholds used by the bq2031 and their corresponding TS pin voltage are: n VFLT = Desired float voltage n n VBLK = Desired bulk charging voltage n IMAX = Desired maximum charge current n These parameters are typically specified by the battery manufacturer. The total resistance presented across the battery pack by RB1 + RB2 should be between 150kΩ and 1MΩ. The minimum value ensures that the divider network does not drain the battery excessively when the power source is disconnected. Exceeding the maximum value increases the noise susceptibility of the BAT pin. TCO—Temperature cutoff—Higher limit of the temperature range in which charging is allowed. VTCO = 0.4 * VCC HTF—High-temperature fault—Threshold to which temperature must drop after temperature cutoff is exceeded before charging can begin again. VHTF = 0.44 * V CC VCC Colder An empirical procedure for setting the values in the resistor network is as follows: 2. Determine RB1 from equation 1 given VFLT 3. Determine RB3 from equation 2 given VBLK 4. Calculate RSNS from equation 3 given IMAX VLTF = 0.6V Voltage Set RB2 to 49.9 kΩ. (for 3 to 18 series cells) Battery Insertion and Removal The bq2031 uses VBAT to detect the presence or absence of a battery. The bq2031 determines that a battery is present when VBAT is between the High-Voltage Cutoff (VHCO = 0.6 * VCC) and the Low-Voltage Cutoff (VLCO = 0.8V). When VBAT is outside this range, the bq2031 determines that no battery is present and transitions to the Fault state. Transitions into and out of the range between VLCO and VHCO are treated as battery insertions and removals, respectively. Besides being used to detect battery insertion, the VHCO limit implicitly serves as an over-voltage charge termination, because exceeding this limit causes the bq2031 to believe that the battery has been removed. VHTF = 0.44V VTCO = 0.4V VSS LTF HTF TCO Hotter FG203104.eps Figure 7. Voltage Equivalent of Temperature Thresholds 7 Temperature 1. bq2031 n LTF—Low-temperature fault—Lower limit of the temperature range in which charging is allowed. VLTF = 0.6 * VCC VCC A resistor-divider network must be implemented that presents the defined voltage levels to the TS pin at the desired temperatures (see Figure 8). RT1 bq2031 The equations for determining RT1 and RT2 are: 13 Equation 4 NTC Thermistor VCC 0.6 ∗ VCC = 12 (VCC − 0.250 V ) RT1 ∗ (RT2 + R LTF ) 1+ (RT2 ∗ R LTF ) VSS RT2 t SNS Equation 5 TS 0.44 = RT 7 8 BAT RSNS 1 RT1 ∗ (RT2 + R HTF ) 1+ (RT2 ∗ R HTF ) VSS FG203105.eps where: n RLTF = thermistor resistance at LTF n RHTF = thermistor resistance at HTF Figure 8. Configuring Temperature Sensing TCO is determined by the values of RT1 and RT2. 1% resistors are recommended. Disabling Temperature Sensing Minimum Current Temperature sensing can be disabled by removing RT and using a 100kΩ resistor for RT1 and RT2. Fast charge terminates when the charging current drops below a minimum current threshold programmed by the value of IGSEL (see Table 3). This is used by the TwoStep Voltage algorithm. Temperature Compensation The internal voltage reference used by the bq2031 for all voltage threshold determinations is compensated for temperature. The temperature coefficient is -3.9mV/°C, normalized to 25°C. Voltage thresholds in the bq2031 vary by this proportion as ambient conditions change. Table 3. IMIN Termination Thresholds Fast-Charge Termination Fast-charge termination criteria are programmed with the fast charge algorithm per Table 1. Note that not all criteria are applied in all algorithms. 8 IGSEL IMIN 0 IMAX/10 1 IMAX/20 Z IMAX/30 bq2031 Second Difference (∆2V) VCC Second difference is a Unitrode proprietary algorithm that accumulates the difference between successive samples of VBAT. The bq2031 takes a sample and makes a termination decision at a frequency equal to 0.008 * tMTO. Fast charge terminates when the accumulated difference is ≤ -8mV. Second difference is used only in the Two-Step Current algorithm, and is subject to a hold-off period (see below). R 1 TM C VCC VSS 13 12 Maximum Voltage Fast charge terminates when VCELL ≥ VBLK. VBLK is set per equation 2. Maximum voltage is used for fast charge termination in the Two-Step Current and Pulsed Current algorithms, and for transition from phase 1 to phase 2 in the Two-Step Voltage algorithm. This criterion is subject to a hold-off period. bq2031 VSS FG203112.eps Hold-off Periods Figure 9. R-C Network for Setting MTO Maximum V and ∆2V termination criteria are subject to a hold-off period at the start of fast charge equal to 0.15 * tMTO. During this time, these termination criteria are ignored. Maintenance Charging Three algorithms are used in maintenance charging: Maximum Time-Out Fast charge terminates if the programmed MTO time is reached without some other termination shutting off fast charge. MTO is programmed from 1 to 24 hours by an R-C network on TMTO (see Figure 9) per the equation: n Two-Step Voltage algorithm n Two-Step Current algorithm n Pulsed Current algorithm Two-Step Voltage Algorithm Equation 6 In the Two-Step Voltage algorithm, the bq2031 provides charge maintenance by regulating charging voltage to VFLT. Charge current during maintenance is limited to ICOND. tMTO = 0.5 * R * C where R is in kΩ, C is in µF, and tMTO is in hours. Typically, the maximum value for C of 0.1µF is used. Two-Step Current Algorithm Fast-charge termination by MTO is a Fault only in the Pulsed Current algorithm; the bq2031 enters the Fault state and waits for a new battery insertion, at which time it begins a new charge cycle. In the Two-Step Voltage and Two-Step Current algorithms, the bq2031 transitions to the maintenance phase on MTO time-out. Maintenance charging in the Two-Step Current Algorithm is implemented by varying the period (TP) of a fixed current (ICOND = IMAX/5) and duration (0.2 seconds) pulse to achieve the configured average maintenance current value. See Figure 10. The MTO timer starts at the beginning of fast charge. In the Two-Step Voltage algorithm, it is cleared and restarted when the bq2031 transitions from phase 1 (current regulation) to phase 2 (voltage regulation). The MTO timer is suspended (but not reset) during the outof-range temperature (Charge Pending) state. Maintenance current can be calculated by: Equation 7 Maintenance current = ((0.2) ∗ I COND ) ((0.04) ∗ I MAX ) = TP TP where TP is the period of the waveform in seconds. Table 4 gives the values of P programmed by IGSEL. 9 bq2031 Voltage at the SNS pin is determined by the value of resistor RSNS, so nominal regulated current is set by: Table 4. Fixed-Pulse Period by IGSEL IGSEL TP (sec.) L 0.4 H 0.8 Z 1.6 Equation 8 IMAX = 0.250V/RSNS The switching frequency of the MOD output is determined by an external capacitor (CPWM) between the pin TPWM and ground, per the following: Equation 9 Pulsed Current Algorithm FPWM = 0.1/CPWM In the Pulsed Current algorithm, charging current is turned off after the initial fast charge termination until VCELL falls to VFLT. Full fast charge current (IMAX) is then re-enabled to the battery until VCELL rises to VBLK. This cycle repeats indefinitely. where C is in µF and F is in kHz. A typical switching rate is 100kHz, implying CPWM = 0.001µF. MOD pulse width is modulated between 0 and 80% of the switching period. To prevent oscillation in the voltage and current control loops, frequency compensation networks (C or R-C) are typically required on the VCOMP and ICOMP pins (respectively) to add poles and zeros to the loop control equations. A software program, “CNFG2031,” is available to assist in configuring these networks for buck type regulators. For more detail on the control loops in buck topology, see the application note, “Switch-Mode Power Conversion Using the bq2031.” For assistance with other power supply topologies, contact the factory. Charge Regulation The bq2031 controls charging through pulse-width modulation of the MOD output pin, supporting both constantcurrent and constant-voltage regulation. Charge current is monitored by the voltage at the SNS pin, and charge voltage by voltage at the BAT pin. These voltages are compared to an internal temperature-compensated reference, and the MOD output modulated to maintain the desired value. ICOND IGSEL = L Ave. Current 0 TP = 0.4 Sec 0.2 Sec ICOND IGSEL = H Ave. Current 0 TP = 0.8 Sec ICOND IGSEL = Z Ave. Current 0 TP = 1.6 Sec TD203101.eps Figure 10. Implementation of Fixed-Pulse Maintenance Charge 10 bq2031 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 -20 +70 °C TSTG Storage temperature -55 +125 °C TSOLDER Soldering temperature - +260 °C TBIAS Temperature under bias -40 +85 °C Note: Commercial 10 s. 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 = TOPR; VCC = 5V ± 10%) Parameter Rating Unit Tolerance Internal reference voltage 2.20 V 1% Temperature coefficient -3.9 mV/°C 10% VLTF TS maximum threshold 0.6 * VCC V ± 0.03V Low-temperature fault VHTF TS hysteresis threshold 0.44 * VCC V ± 0.03V High-temperature fault VTCO TS minimum threshold 0.4 * VCC V ± 0.03V Temperature cutoff VHCO High cutoff voltage 0.60 * VCC V ± 0.03V VMIN Under-voltage threshold at BAT 0.34 * VCC V ± 0.03V VLCO Low cutoff voltage 0.8 V ± 0.03V 0.250 V 10% VSNS IMAX Current sense at SNS 0.05 V 10% ICOND VREF 11 Notes TA = 25°C bq2031 Recommended DC Operating Conditions (TA = TOPR) Symbol Parameter Minimum Typical Maximum Unit Notes VCC Supply voltage 4.5 5.0 5.5 V VTEMP TS voltage potential 0 - VCC V VCELL Battery voltage potential 0 - VCC V ICC Supply current - 2 4 mA Outputs unloaded DSEL tri-state open detection -2 - Note 2 IGSEL tri-state open detection -2 IIZ VIH VIL VOH VOL IOH IOL IIL IIH IL Notes: Logic input high Logic input low VCC-1.0 - VTS - VSNS VBAT - VSNS 2 µA 2 µA - V QSEL,TSEL VCC-0.3 - - V DSEL, IGSEL - - VSS+1.0 V QSEL,TSEL - - VSS+0.3 V DSEL, IGSEL LED1, LED2, LED3, output high VCC-0.8 - - V IOH ≤ 10mA MOD output high VCC-0.8 - - V IOH ≤ 10mA LED1, LED2, LED3, output low - - VSS+0.8V V IOL ≤ 10mA MOD output low - - VSS+0.8V V IOL ≤ 10mA FLOAT output low - - VSS+0.8V V IOL ≤ 5mA, Note 3 COM output low - - VSS+0.5 V IOL ≤ 30mA LED1, LED2, LED3, source -10 - - mA VOH =VCC-0.5V MOD source -5.0 - - mA VOH =VCC-0.5V LED1, LED2, LED3, sink 10 - - mA VOL = VSS+0.5V MOD sink 5 - - mA VOL = VSS+0.8V FLOAT sink 5 - - mA VOL = VSS+0.8V, Note 3 COM sink 30 - - mA VOL = VSS+0.5V - - +30 µA V = VSS to VSS+ 0.3V, Note 2 DSEL logic input low source IGSEL logic input low source - - +70 µA V = VSS to VSS+ 0.3V DSEL logic input high source -30 - - µA V = VCC - 0.3V to VCC IGSEL logic input high source -70 - - µA V = VCC - 0.3V to VCC - - ±1 µA QSEL, TSEL, Note 2 Input leakage 1. All voltages relative to VSS except where noted. 2. Conditions during initialization after VCC applied. 3. SNS = 0V. 12 bq2031 Impedance Symbol Parameter Minimum Typical Maximum Unit Notes RBATZ BAT pin input impedance 50 - - MΩ RSNSZ SNS pin input impedance 50 - - MΩ RTSZ TS pin input impedance 50 - - MΩ RPROG1 Soft-programmed pull-up or pull-down resistor value (for programming) - - 10 kΩ DSEL, TSEL, and QSEL RPROG2 Pull-up or pull-down resistor value - - 3 kΩ IGSEL RMTO Charge timer resistor 20 - 480 kΩ Timing (TA = TOPR; VCC = 5V ± 10%) Symbol Parameter Minimum Typical Maximum Unit Notes See Figure 9 tMTO Charge time-out range 1 - 24 hours tQT1 Pre-charge qual test 1 time-out period - 0.02tMTO - - tQT2 Pre-charge qual test 2 time-out period - 0.16tMTO - - 2 tDV ∆ V termination sample frequency - 0.008tMTO - - tH01 Pre-charge qual test 2 hold-off period - 0.002tMTO - - tH02 Bulk charge hold-off period - 0.015tMTO - FPWM PWM regulator frequency range - 100 kHz See Equation 9 Capacitance Symbol Parameter Minimum Typical Maximum Unit CMTO Charge timer capacitor - 0.1 0.1 µF CPWM PWM R-C capacitance - 0.001 - µF 13 bq2031 16-Pin DIP Narrow (PN) 16-Pin PN (0.300" DIP) Inches Dimension Millimeters 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 C 0.008 0.013 0.20 0.33 D 0.740 0.770 18.80 19.56 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 16-Pin SOIC Narrow (SN) 16-Pin SN (0.150" SOIC) Inches D e Dimension B E H A C A1 .004 L 14 Millimeters 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 0.385 0.400 9.78 10.16 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 bq2031 Data Sheet Revision History Change No. Page No. 1 Description Nature of Change Descriptions Clarified and consolidated 1 Renamed Dual-Level Constant Current Mode to Two-Step Current Mode VMCV to VHCO VINT to VLCO tUV1 to tQT1 tUV2 to tQT2 1 Consolidation Tables 1 and 2 1 Added figures Start-up states Temperature sense input voltage thresholds Pulsed maintenance current implementation 1 Updated figures Figures 1 through 6 1 Added equations Thermistor divider network configuration equations 1 Raised condition MOD VOL and VOH parameters from ≤5mA to ≤10µA 1 Corrected Conditions VSNS rating from VMAX and VMIN to IMAX and IMIN 1 Added table Capacitance table for CMTO and CPWM 2 6 Changed values in Figure 5 Was 51K; is now 10K 3 7, 10 Changed values in Equations 3 and 8 Was: IMAX = 0.275V/RSNS; is now IMAX = 0.250V/RSNS 3 8 Changed values in Equation 4 Was: (VCC - 0.275); is now (VCC - 0.250V) 3 11 Changed rating value for VSNS in DC Thresholds table Was 0.275; is now 0.250 4 11 TOPR Deleted industrial temperature range. Notes: Change 1 = Dec. 1995 B changes from June 1995 A. Change 2 = Sept. 1996 C changes from Dec. 1995 B. Change 3 = April 1997 D changes from Sept. 1996 C. Change 4 = June 1999 E changes from April 1997 D. Ordering Information bq2031 Package Option: PN = 16-pin plastic DIP SN = 16-pin narrow SOIC Device: bq2031 Lead Acid Charge IC 15 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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