BQ24401DR

bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 Programmable NiCd/NiMH Fast-Charge Management IC Check for Samples: bq24401 FEATURES 1 • • • • • • • • Safe Management of Fast Charge for NiCd and NiMH Battery Packs High-Frequency Switching Controller for Efficient and Simple Charger Design Pre-Charge Qualification for Detecting Shorted, Damaged, or Overheated Cells Fast-Charge Termination by ΔT/Δt, Maximum Temperature, and Maximum Charge Time Selectable Top-Off Mode for Achieving Maximum Capacity in NiMH Batteries Programmable Trickle-Charge Mode for Reviving Deeply Discharged Batteries and for Postcharge Maintenance Built-in Battery Removal and Insertion Detection Sleep Mode for Low Power Consumption The bq24401 is a programmable, monolithic IC for fast-charge management of nickel cadmium (NiCd) and nickel metal-hydride (NiMH) in single or multi-cell applications. The bq24401 provides these charge termination criteria: • Rate of temperature rise (ΔT/Δt) • Maximum temperature • Maximum charge time For safety, the bq24401 inhibits fast charge until the battery voltage and temperature are within user-defined limits. If the battery voltage is below the low-voltage threshold, the bq24401 uses trickle-charge to condition the battery. For NiMH batteries, the bq24401 provides an optional top-off charge to maximize the battery capacity. The integrated high-speed comparator allows the bq24401 to be the basis for a complete, high-efficiency battery charger circuit for nickel-based chemistries. APPLICATIONS • • GENERAL DESCRIPTION Nickel Charger High-Power, Multi-Cell Charger 8-Pin DIP or Narrow SOIC or TSSOP spacer between para and illustration Pin Names SNS Current-sense input SNS 1 8 MOD VSS System ground VSS 2 7 VCC LED Charge-status output BAT Battery-voltage input LED 3 6 RC TS Temperature-sense input BAT 4 5 TS RC Timer-program input VCC Supply-voltage input MOD Modulation-control output 1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2001–2010, Texas Instruments Incorporated bq24401 SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. PIN DESCRIPTIONS SNS Current-sense input Enables the bq24401 to sense the battery current via the voltage developed on this pin by an external sense-resistor connected in series with the battery pack VSS System Ground Connect to the battery’s negative terminal LED Charge-status output Open-drain output that indicates the charging status by turning on, turning off, or flashing an external LED, driven through a resistor. BAT Battery-voltage input Battery-voltage sense input. A simple resistive divider, across the battery terminals, generates this input. TS Temperature-sense input Input for an external battery-temperature monitoring circuit. An external resistive divider network with a negative temperature-coefficient thermistor sets the lower and upper temperature thresholds. RC Timer-program input Used to program the maximum fast charge-time, maximum top-off charge-time, hold-off period, trickle charge rate, and to disable or enable top-off charge. A capacitor from VCC and a resistor to ground connect to this pin. VCC Supply-voltage input Recommended bypassing is 10µF + 0.1µF to 0.22µF of decoupling capacitance near the pin. MOD Modulation-control output Push-pull output that controls the charging current to the battery. MOD switches high to enable charging current to flow and low to inhibit charging-current flow. 2 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 FUNCTIONAL DESCRIPTION The bq24401 is a versatile, NiCd and NiMH battery charge control device. See Figure 1 for a functional block diagram and Figure 2 for a state diagram. TS Voltage Reference BAT OSC Voltage Comparators 3x ADC DT/Dt ALU Clock Phase Generator Timer Charge Control LED Voltage Comparators MOD RC Internal OSC SNS VCC VSS Figure 1. Functional Block Diagram Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 3 bq24401 SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 www.ti.com VCC Reset or Battery Replacement at any time 4.0 V < VCC < 6.0 V Charge Initialization VBAT < VSLP Battery Voltage (Voltage at BAT pin checked continuously.) Sleep Mode VMCV < VBAT < VSLP Charge Qualification State VSLP < VBAT < VCC VBAT < VMCV VTS > VHTF Charge Suspended Battery Temperature (Temperature at TS pin checked continuously. Sampled every 8 seconds for DT/Dt.) VTS < VHTF VTS < VHTF VLBAT < VBAT < VMCV and VHTF < VTS < VLTF VBAT < VLBAT or VTS > VLTF VTS > VLTF Battery Conditioning Current Regulation VLBAT < VBAT and VHTF < VTS < VLTF DT/Dt (after hold-off period), or VTS < VTCO or Time = MTO NO Trickle Maintenance Charge Fast Charge State Top-Off Selected? VTS > VLTF YES VTS < VLTF and Time < MTO VTS > VHTF Top-Off Time = MTO VBAT ≥ VMCV Done VBAT ≥ VMCV VTS < VHTF Charge Suspended (See Note) VTS < VHTF VTS > VHTF and Time < MTO VCC Reset or Battery Replacement NOTE: If VTS < VTCO at any time, may only return to Trickle Maintenance Charge state and not to Top-Off. Figure 2. State Diagram 4 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 ABSOLUTE MAXIMUM RATINGS (1) VALUE UNIT –0.3 to 7 V –0.3 to VCC V Operating ambient temperature –20 to 70 °C Storage temperature –40 to 125 °C 260 °C VCC VCC relative to VSS VT DC voltage applied on any pin, relative to VSS TOPR TSTG TSOLDER Soldering temperature (10 s max.) (1) 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 (1) TA = TOPR; VCC = 5V ±20% (unless otherwise specified) PARAMETER TEST CONDITIONS TYPICAL TOLERANCE UNIT VTCO Temperature cutoff Voltage at the TS pin 0.225 × VCC ±5% V VHTF High-temperature fault Voltage at the TS pin 0.25 × VCC ±5% V VLTF Low-temperature fault Voltage at the TS pin 0.5 × VCC ±5% V VMCV Maximum cell voltage Voltage at the BAT pin 2.00 ±2.5% VLBAT Minimum cell voltage Voltage at the BAT pin 950 ±5% mV VTherm TS input change for ΔT/Δt detection Voltage at the TS pin –VCC/161 ±25% V/min VSNSHI High threshold at SNS Voltage at the SNS pin 50 ±10 mV VSNSLO Low threshold at SNS Voltage at the SNS pin –50 ±10 mV VSLP Sleep-mode input threshold Voltage at the BAT pin VCC–1 ±0.5 V (1) V All voltages are relative to VSS except as noted. RECOMMENDED DC OPERATING CONDITIONS over operating free-air temperature range (unless otherwise noted) TEST CONDITIONS VCC Supply voltage ICC Supply current Exclusive of external loads ICCS Sleep current VBAT = VSLP VTS Thermistor input VTS < 0.5 V prohibited VOH Output high input MOD, IOH = 10 mA VOL Output low input MOD, LED, IOL = 10 mA IOZ High-impedance leakage current LED Isnk Sink current MOD, LED RMTO Charge timer resistor CMTO Charge timer capacitor MIN TYP MAX 4 5 6 V 0.5 1 mA 5 µA VCC V 0.5 UNIT VCC–0.4 V 0.2 V 5 µA 20 mA 2 250 kΩ 0.001 1 µF IMPEDANCE PARAMETER MIN TYP MAX UNIT RBAT Battery input impedance 10 MΩ RTS TS input impedance 10 MΩ RSNS SNS input impedance 10 MΩ TIMING TA = TOPR; VCC = 5 V ±20% (unless otherwise noted) PARAMETER dMTO MTO time-base variation fTRKL Pulse-trickle frequency MIN TYP –5% 0.9 MAX UNIT 5% 1 1.1 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 Hz 5 bq24401 SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 www.ti.com Initiation and Charge Qualification The bq24401 initiates a charge cycle when it detects • Application of power to VCC • Battery replacement • Exit from sleep mode Immediately following initiation, the IC enters a charge-qualification mode. The bq24401 charge qualification is based on battery voltage and temperature. If the voltage on the BAT pin is less than the internal threshold, VLBAT, the bq24401 enters the battery conditioning state. This condition indicates the possibility of a defective or shorted battery pack. In an attempt to revive a fully depleted pack, the bq24401 enables the MOD pin to trickle-charge at a rate of once every 1.0s. As explained in the section "Top-Off and Pulse-Trickle Maintenance Charge," the trickle pulse-width is user-selectable and is set by the value of the resistance connected between the RC pin and VSS. During charge qualification, the LED pin blinks at a 1Hz rate, indicating the pending status of the charger. Once battery conditioning (trickle charge) has raised the voltage on the BAT pin above VLBAT, the IC enters fast charge, if the battery temperature is within the VLTF to VHTF range. The bq24401 will stay in the battery conditioning state indefinitely and will not progress to fast charge until the voltage on the BAT pin is above VLBAT and the temperature is within the VLTF and VHTF range. No timer is implemented during battery conditioning. Fast Charge (Current Regulation) Following charge qualification (which includes trickle charge, if required), the bq24401 begins fast charge fast using a current-limited algorithm. During the fast-charge period, it monitors charge time, temperature, and voltage for adherence to the termination criteria. This monitoring is further explained in later sections. While in the fast charge state, the LED pin is pulled low (the LED is on). Following fast charge, the battery is topped off, if top-off is selected. The charging cycle ends with a trickle maintenance-charge that continues as long as the voltage on the BAT pin remains below VMCV. Table 1 summarizes the charging process. Table 1. Charge Algorithm BATTERY CHEMISTRY CHARGE ALGORITHM 1. Charge qualification 2. Trickle charge, if required NiCd or NiMH Batteries (VBAT < VMCV always) 3. Fast charge (constant current) 4. Fast charge termination (rate of temperature rise, maximum charge time = 1 MTO) 5. Top-off (optional) 6. Trickle charge FAST CHARGE TERMINATION Initial Hold-Off Period The bq24401 incorporates a user programmable hold-off period to avoid premature fast charge termination that can occur with brand new nickel cells at the very beginning of fast charge. The values of the external resistor and capacitor connected to the RC pin set the initial hold-off period. During this period, the bq24401 avoids early termination due to an initial rise in the battery temperature by disabling the rate of temperature rise (ΔT/Δt) feature. This period is fixed at the programmed value of the maximum charge time (MTO) divided by 32. MTO hold-off period = 32 (1) 6 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 Maximum Charge Time The bq24401 sets the maximum charge-time through the RC pin. With the proper selection of external resistor and capacitor values, various time-out values may be achieved. If the timer expires while still in fast charge, the bq24401 proceeds to top-off charge (if top-off is enabled) or trickle maintenance charge. If top-off is enabled, the timer is reset on the completion of fast charge before beginning top-off charge. Figure 3 shows a typical connection. 2 VSS VCC 7 bq24401 CMTO RC 6 RMTO Figure 3. Typical Connection for the RC Input The following equation shows the relationship between the RMTO and CMTO values and the maximum charge time (MTO) for the bq24401: MTO = RMTO ´ CMTO ´ 35,988 (2) MTO is measured in minutes, RMTO in ohms, and CMTO in farads. (Note: RMTO and CMTO values also determine other features of the device. See Table 4 for details.) If, during fast charge, VTS > VLTF, then the timer is paused and the IC enters battery conditioning charge until VTS < VLTF. Since the IC is in the battery conditioning state, the LED flashes at the 1 Hz rate. Once VTS VLTF, top-off is suspended, the timer is paused, and trickle charge is started. When VTS falls below VLTF, top-off is resumed. If VTS < VHTF, all charging stops, but the timer keeps counting. When VTS > VHTF, top-off is resumed, if there is still time remaining on the timer. If there is not time left, trickle maintenance charge is entered. If VTS < VTCO, all charging stops. Only trickle maintenance charge may resume after VTS > VHTF. Pulsewidth - ms Following top-off, the bq24401 trickle-charges the battery by enabling the MOD pin to charge at a rate of once every 1.0 second. The trickle pulse-width is user-selectable and is set by the value of the resistor RMTO, connected between the RC pin and VSS. Figure 5 shows the relationship between the trickle pulse-width and the value of RMTO. The typical tolerance of the pulsewidth below 150kΩ is ±10%. 200 180 160 140 120 100 80 60 40 20 4 3 2 1 Shows Tolerance 2 4 6 8 10 50 100 RMTO - kW 150 200 250 Figure 5. Relationship Between Trickle Pulse-Width and Value of RMTO 8 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 Note that with an RMTO value around 150 kΩ, the trickle charge pulse width is nearly identical to the top-off pulse width of 62.5 ms (1/16 of a second for a 1A fast charge current). With RMTO values near 150 kΩ, it can be difficult to tell which state the IC is in (top-off or trickle charge). The best way to tell if the bq24401 is in top-off or trickle charge is to look at the RC pin when the temperature is between the LTF and HTF. In top-off, the RC pin is counting and has a sawtooth waveform on it. In trickle charge, there is no timer and the RC pin is at a DC value. The RC pin contains valuable information in determining what state the bq24401 is in, since it always operates in one of three modes. If the RC pin is low (around VSS potential), the IC is in sleep mode. (If the RC pin is low for brief instants during fast charge, the bq24401 is sampling the TS pin for ΔT/Δt). If the RC pin is at some DC value (usually around 1-2V), then the IC has paused the timer or the timer is inactive. If the RC pin is a sawtooth waveform (similar to Figure 14), then the timer is running and the RC pin is considered “active.” Lastly, the RC pin can be loaded by too large of a C or too small of an R. This will sometimes make the usual sawtooth waveform look like a triangle waveform on an oscilloscope (the rise time is lengthened), or the RC signal could have the appearance of being clipped (flat top or bottom). The timer is unreliable under these conditions and the bq24401 should not be operated in this manner. Table 2 summarizes the different states of the RC pin. Table 2. RC Pin Status bq24401 CHARGE STATE TS PIN STATE RC PIN BEHAVIOR Battery absent N/A 1-2V DC level Sleep mode N/A Ground (Vss) Charge qualification (including battery conditioning (trickle charge) and charge suspended) N/A 1-2V DC level VTS < VLTF Active VTS > VLTF (in battery conditioning state) 1-2V DC level (timer is paused and will resume when VTS < VLTF) VTS > VLTF (in trickle maintenance charge state) 1-2V DC level (timer is paused and will resume when VTS < VLTF) VLTF > VTS > VHTF Active VHTF > VTS > VTCO Active (timer is still counting, even though charging is suspended) Trickle maintenance charge (after fast charge) N/A 1-2V DC level Charge complete N/A Active Fast charge (current regulation) Top-off charge Both top-off and trickle maintenance charge are terminated and the pack never receives any more charge (until a charge initialization occurs) if the voltage on the BAT pin reaches VMCV. During trickle maintenance charge, charging is suspended if VTS < VHTF. It resumes when VTS > VHTF. The bq24401 is designed to remain in trickle maintenance charge forever (excluding the two faults just mentioned) in order to keep the Nickel pack full. Charge Current Control The bq24401 implements a hysteretic control loop that regulates the current being delivered to the battery pack to a user programmable value that is set by the value of the RSNS resistor. A second, outer control loop reduces the average current delivered to the pack in order to clamp the voltage at the BAT pin to a maximum of VMCV. The bq24401 controls the MOD pin to regulate the current and voltage of the pack. The bq24401 monitors charge current at the SNS input by sensing the voltage drop across a sense-resistor, RSNS, in series with the battery pack. See Figure 6 for a typical current-sensing circuit. Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 9 bq24401 SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 www.ti.com Rf 1 SNS RSNS Cf 2 BAT- VSS bq24401 Power supply ground bq24401 ground and BAT- Figure 6. Current-Sensing Circuit RSNS is sized to provide the desired fast-charge current (IMAX). 0.05 IMAX = RSNS (3) If the voltage at the SNS pin is greater than VSNSLO or less than VSNSHI, the bq24401 switches the MOD output high to pass charge current to the battery. When the SNS voltage is less than VSNSLO or greater than VSNSHI, the bq24401 switches the MOD output low to shut off charging current to the battery. A hysteresis capacitor (CHYS) is required between the CMOD pin and the SNS pin to add a healthy amount of hysteresis to the current sense signal (see Figure 7). Typical hysteresis values are between 5 and 25 mV. The amount of hysteresis can be calculated by examining the capacitive divider formed by CHYS and Cf. CHYS Hysteresis (V) = VCC ´ (C HYS + Cf ) (4) Q1 FMMT718 D4 DC+ S1A D3 MMSD914LT C6 47 mF L1 BAT+ 47 mH Q2 MMBT3904LT1 D2 ZHCS1000 R12 120 W D5 MMSD914LT C9 R10 1 KW 1000 PF Q3 MMBT3904LT1 VCC R2 2 KW D6 BZT52-C5V1 C3 10 mF C7 C4 4.7 PF 0.0022 mF R1 D1 U1 1 SNS 2 VSS 3 LED 4 BAT RED C2 0.1 mF R6 210 KW R11 220 W C8 0.33 mF C5 10 mF R4 12.4 KW 100 KW 8 7 6 5 MOD VCC RC TS THERM bq24401 C1 0.1 mF R8 6.81 KW R5 20 KW BATR7 105 KW R13 1.1 KW R3 0.05 W DCNOTES: 1. DC input voltage: 9–16V 2. Charge current: 1A 3. L1: 3L Global P/N PKSMD-1005-470K-1A Figure 7. 3-Cell NiCd/NiMH 1A Charger 10 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 Being a hysteretic controller, the switching frequency of the bq24401 is determined by the values of several of the external circuit components. The components that affect the switching frequency are: input voltage, RSNS value, inductor value, hysteresis capacitor value (CHYS), and the value of the filter on the current sense signal (Rf and Cf values). Rf and Cf have the most impact on the switching frequency and are also the components that are easiest to change to adjust the frequency, as they do not affect anything else in the circuit (besides, of course, the cleanliness and quality of the current sense signal being fed to the bq24401). In general, increasing the input voltage and/or inductor value or decreasing CHYS and/or the Rf × Cf filter corner frequency will increase the switching frequency. Figure 8 and Figure 9 show empirical data on the variation in switching frequency based on adjusting Rf and Cf. This data was taken with an input voltage of 12V, inductor value of 220 µH, RSNS value of 50 mΩ, and CHYS value of 4.7 pF. Typical switching frequencies for the bq24401 are between 100 and 200 kHz, though it is possible to achieve switching frequencies in excess of 300kHz. 180 160 fs - Switching Frequency - kHz Rf = 748W 140 120 100 80 60 40 20 0 220 720 1220 1720 2220 2720 3220 3720 4220 Cf - pF Figure 8. Switching Frequency vs Capacitance 210 fs - Switching Frequency - kHz 190 Cf = 1000pF 170 150 130 110 90 70 50 200 300 400 500 600 700 800 900 1000 1100 1200 Rf - W Figure 9. Switching Frequency vs Resistance Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 11 bq24401 SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 www.ti.com Battery Voltage Input As shown in Figure 10, a resistor voltage-divider between the battery pack's positive terminal and VSS scales the battery voltage measured at the BAT pin. A low-pass filter then smooths out this voltage to present a clean signal to the BAT pin. BAT+ 2 VSS bq24401 4 RB1 BAT RB2 Figure 10. Battery Voltage Divider and Filter The resistor values RB1 and RB2 are calculated by the following equation: RB1 = N -1 RB2 (5) where N is the number of cells in series. RB1 + RB2 should be at least 200kΩ and no more than 1MΩ. TEMPERATURE MONITORING The bq24401 measures the temperature by the voltage at the TS pin. This voltage is typically generated by a negative-temperature-coefficient thermistor. The bq24401 compares this voltage against its internal threshold voltages to determine if charging is safe. These thresholds are the following: • High-temperature cutoff voltage: VTCO = 0.225 × VCC. This voltage corresponds to the maximum temperature (TCO) at which any charging is allowed. The bq24401 terminates charging if the voltage on the TS pin falls below VTCO. • High-temperature fault voltage: VHTF = 0.25 × VCC. This voltage corresponds to a maximum allowed pack temperature (HTF) in all states except for fast charge. During fast charge, HTF faults are disabled to allow for a normal increase in pack temperature. • Low-temperature fault voltage: VLTF = 0.5 × VCC. This voltage corresponds to the minimum temperature (LTF) at which fast charging or top-off is allowed. If the voltage on the TS pin rises above VLTF, the bq24401 suspends either fast charge or top-off and begins a trickle charge. When the voltage falls back below VLTF, fast charge or top-off resumes from the point where suspended. If VTS > VLTF, the charger will always be in trickle charge. Table 3 summarizes these various conditions. Table 3. Temperature-Monitoring Conditions and Actions TEMPERATURE CONDITION ACTION During charge qualification, no effect VTS > VLTF Cold battery – checked at all times VHTF < VTS < VLTF Optimal charging range During fast charge, suspends fast charge and moves into charge qualification, pauses timer, and flashes LED During top-off, suspends top-off and moves into trickle maintenance charge and pauses timer During trickle maintenance charge, no effect 12 Allows all stages of charging Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 Table 3. Temperature-Monitoring Conditions and Actions (continued) TEMPERATURE CONDITION ACTION During charge qualification, stops charging VTS < VHTF Hot battery – checked at all times, except during fast charge During fast charge, no effect During top-off, stops charging During trickle maintenance charge, stops charging During charge qualification, stops charging VTS < VTCO Battery exceeding maximum allowable temperature – checked at all times During fast charge, terminates fast charge and stops charging, turns off LED During top-off, terminates top-off and stops charging During trickle maintenance charge, stops charging Table 4. Summary of NiCd or NiMH Charging Characteristics VALUE (1) PARAMETER Maximum cell voltage (VMCV) 2V Minimum pre-charge qualification voltage (VLBAT) 950 mV High-temperature cutoff voltage (VTCO) 0.225 × VCC High-temperature fault voltage (VHTF) 0.25 × VCC Low-temperature fault voltage (VLTF) 0.5 × VCC bq24401 fast-charge maximum time out (MTO) RMTO × CMTO × 35,988 Fast-charge charging current (IMAX) 0.05/RSNS Hold-off period MTO/32 Top-off charging current (optional) IMAX/16 Top-off period (optional) MTO Trickle-charge frequency 1Hz Trickle-charge pulse-width (1) See Figure 5 See the DC Thresholds Specification for details. Charge Status Display The charge status is indicated by open-drain output LED. Table 5 summarizes the display output of the bq24401. A temperature fault or timer expiring changes the charge state immediately (according to Figure 2) and will thus change the LED status immediately and accordingly. Table 5. Charge Status Display bq24401 CHARGE STATE LED STATUS Charge qualification (including battery conditioning and charge suspended) 1 Hz flash Fast charge (current regulation) Low Top-off charge Trickle maintenance charge (after fast charge) Charge complete High impedance Battery absent Sleep mode Sleep Mode The bq24401 features a sleep mode for low power consumption. This mode is enabled when the voltage at the BAT pin is above the low-power-mode threshold, VSLP. During sleep mode, the bq24401 shuts down all unnecessary internal circuits, drives the LED output to high-impedance state, and drives the MOD pin low. Restoring BAT below the VMCV threshold initiates the IC and starts a fast-charge cycle. Normally, the bq24401 only enters sleep mode when there is no battery connected on the output and the charger is idling with nothing to Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 13 bq24401 SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 www.ti.com charge. In addition, VIN needs to be high enough such that when VIN is present on the output, VBAT would be greater than VSLP. In sleep mode, the output voltage will decay to VMCV at which point the bq24401 turns on and pulses the MOD pin several times. With no battery connected, the output will rise to near VIN at which point the bq24401 re-enters sleep mode. During sleep mode, the RC pin will be at VSS potential. A typical sleep mode waveform is shown in Figure 17. 14 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 TYPICAL CHARACTERISTICS CH1 = RC pin, 2V/div CH1 = RC pin, 2V/div 1 CH2 = MOD pin, 5V/div CH2 = MOD pin, 5V/div Voltage - V Voltage - V 2 CH3 = VO, 5V/div 2 CH3 = VI, 5V/div 3 CH4 = LED pin, 5V/div 1 CH4 = LED pin, 5V/div 4 3 4 Time - 0.2s/div Time - 0.2s/div Figure 11. bq24401 Start-up on Battery Insertion Figure 12. bq24401 Start-up on Vin CH1 = VO, 5V/div CH2 = RC pin, 1V/div CH1 = VO, 5V/div 1 Voltage - V Voltage - V 1 CH2 = BAT pin, 1V/div CH3 = MOD pin, 5V/div 3 2 CH3 = MOD pin, 5V/div 3 2 CH4 = LED pin, 1V/div Time - 0.5s/div 4 Time - 0.5ms/div Figure 13. Battery Removal During Fast Charge Figure 14. bq24401 in Fast Charge Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 15 bq24401 SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 www.ti.com TYPICAL CHARACTERISTICS (continued) CH1 = VO, 5V/div 1 CH2 = RC pin, 1V/div CH1 = SNS pin, 20mV/div CH3 = MOD pin, 5V/div 2 Voltage - V Voltage - V 1 CH2 = MOD pin, 5V/div 3 2 4 CH4 = LED pin, 1V/div Time - 2ms/div Time - 10ms/div Figure 15. bq24401 in Fast Charge Figure 16. bq24401 Fast Charge SNS and MOD Waveforms CH1 = VO, 10V/div Voltage - V 1 CH2 = BAT pin, 1V/div CH3 = RC pin, 2V/div 2 3 4 CH4 = MOD pin, 5V/div Time - 1s/div Figure 17. bq24401 Cycling In and Out of Sleep Mode (No battery present) 16 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 bq24401 www.ti.com SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010 REVISION HISTORY Changes from Revision September 2001 (*) to Revision A • Page Changed the data sheet format. The data sheet was originally from Benchmark Products. In revision A, the data sheet was converted to the TI format, and a re-write of the data sheet was implemented .................................................. 1 Submit Documentation Feedback Copyright © 2001–2010, Texas Instruments Incorporated Product Folder Link(s): bq24401 17 PACKAGE OPTION ADDENDUM www.ti.com 14-Oct-2022 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) BQ24401D ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM -20 to 70 24401 Samples BQ24401DR ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -20 to 70 24401 Samples BQ24401PW ACTIVE TSSOP PW 8 150 RoHS & Green NIPDAU Level-2-260C-1 YEAR -20 to 70 24401 Samples BQ24401PWG4 ACTIVE TSSOP PW 8 150 RoHS & Green NIPDAU Level-2-260C-1 YEAR -20 to 70 24401 Samples BQ24401PWR ACTIVE TSSOP PW 8 2000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -20 to 70 24401 Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of