bq2004E/H Fast-Charge ICs Features General Description ture and voltage are within configured limits. ➤ Fast charge and conditioning of nickel cadmium or nickel-metal hydride batteries The bq2004E and bq2004H Fast Charge ICs provide comprehensive fast charge control functions together with high-speed switching power control circuitry on a monolithic CMOS device. Temperature, voltage, and time are monitored throughout fast charge. Fast charge is terminated by any of the following: ➤ Hysteretic PWM switch-mode current regulation or gated control of an external regulator ➤ Easily integrated into systems or used as a stand-alone charger ➤ Pre-charge qualification of temperature and voltage ➤ Configurable, direct LED outputs display battery and charge status ➤ Fast-charge termination by ∆ temperature/∆ time, peak volume detection, -∆V, maximum voltage, maximum temperature, and maximum time ➤ Op t i o n al t o p - o f f cha r g e a nd pulsed current maintenance charging ➤ Logic-level controlled low-power mode (< 5µA standby current) Pin Connections Integration of closed-loop current control circuitry allows the bq2004 to be the basis of a cost-effective solution for stand-alone and systemintegrated chargers for batteries of one or more cells. Switch-activated discharge-beforecharge allows bq2004E/H-based chargers to support battery conditioning and capacity determination. High-efficiency power conversion is accomplished using the bq2004E/H as a hysteretic PWM controller for switch-mode regulation of the charging current. The bq2004E/H may alternatively be used to gate an externally regulated charging current. Fast charge may begin on application of the charging supply, replacement of the battery, or switch depression. For safety, fast charge is inhibited unless/until the battery tempera- Rate of temperature rise (∆T/∆t) n Peak voltage detection (PVD) n Negative delta voltage (-∆V) n Maximum voltage n Maximum temperature n Maximum time After fast charge, optional top-off and pulsed current maintenance phases with appropriate display mode selections are available. T h e b q 2 0 0 4 H d if f er s f r om t h e bq2004E only in that fast charge, hold-off, and top-off time units have been scaled up by a factor of two, and the bq2004H provides different display selections. Timing differences between the two ICs are illustrated in Table 1. Display differences are shown in Table 2. Pin Names DCMD Discharge command SNS Sense resistor input DSEL Display select LED1 Charge status output 1 VSEL Voltage termination select LED2 Charge status output 2 VSS System ground VCC 5.0V ± 10% power MOD Charge current control DIS Discharge control output INH Charge inhibit input DCMD 1 16 INH DSEL 2 15 DIS VSEL 3 14 MOD TM1 4 13 VCC TM1 Timer mode select 1 TM2 5 12 VSS TM2 Timer mode select 2 TCO 6 11 LED2 TCO Temperature cutoff TS 7 10 LED1 BAT 8 9 SNS TS Temperature sense BAT Battery voltage 16-Pin Narrow DIP or Narrow SOIC n PN2004E01.eps 6/99 E 1 bq2004E/H SNS Pin Descriptions DCMD SNS controls the switching of MOD based on an external sense resistor in the current path of the battery. SNS is the reference potential for both the TS and BAT pins. If SNS is connected to VSS, then MOD switches high at the beginning of charge and low at the end of charge. Discharge-before-charge control input The DCMD input controls the conditions that enable discharge-before-charge. DCMD is pulled up internally. A negative-going pulse on DCMD initiates a discharge to endof-discharge voltage (EDV) on the BAT pin, followed by a new charge cycle start. Tying D C M D to g r o und e nabl e s a u t om a t ic discharge-before-charge on every new charge cycle start. DSEL LED1– LED2 Display select input Vss Ground This three-state input configures the charge status display mode of the LED1 and LED2 outputs and can be used to disable top-off and pulsed-trickle. See Table 2. VCC VCC supply input 5.0V, ±10% power input. MOD is a push-pull output that is used to control the charging current to the battery. MOD switches high to enable charging current to flow and low to inhibit charging current flow. DIS Timer mode inputs INH Temperature sense input Input, referenced to SNS, for an external thermister monitoring battery temperature. BAT Charge inhibit input When low, the bq2004E/H suspends all charge actions, drives all outputs to high impedance, and assumes a low-power operational state. When transitioning from low to high, a new charge cycle is started. Temperature cut-off threshold input Input to set maximum allowable battery temperature. If the potential between TS and SNS is less than the voltage at the TCO input, then fast charge or top-off charge is terminated. TS Discharge control output Push-pull output used to control an external transistor to discharge the battery before charging. TM1 and TM2 are three-state inputs that configure the fast charge safety timer, voltage termination hold-off time, “top-off ”, and trickle charge control. See Table 1. TCO Charge current control output Voltage termination select input This three-state input controls the voltagete r m i nat i o n te chni q ue us ed b y t h e bq2004E/H. When high, PVD is active. When floating, -∆V is used. When pulled low, both PVD and -∆V are disabled. TM1– TM2 Charge status outputs Push-pull outputs indicating charging status. See Table 2. MOD VSEL Charging current sense input Battery voltage input BAT is the battery voltage sense input, referenced to SNS. This is created by a highimpedance resistor-divider network connected between the positive and the negative terminals of the battery. 2 bq2004E/H Functional Description Discharge-Before-Charge Figure 2 shows a block diagram and Figure 3 shows a state diagram of the bq2004E/H. The DCMD input is used to command discharge-beforecharge via the DIS output. Once activated, DIS becomes active (high) until VCELL falls below VEDV, at which time DIS goes low and a new fast charge cycle begins. Battery Voltage and Temperature Measurements The DCMD input is internally pulled up to VCC (its inactive state). Leaving the input unconnected, therefore, results in disabling discharge-before-charge. A negative going pulse on DCMD initiates discharge-before-charge at any time regardless of the current state of the bq2004. If DCMD is tied to VSS, discharge-before-charge will be the first step in all newly started charge cycles. Battery voltage and temperature are monitored for maximum allowable values. The voltage presented on the battery sense input, BAT, should represent a two-cell potential for the battery under charge. A resistor-divider ratio of: RB1 N = -1 RB2 2 Starting A Charge Cycle 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. A new charge cycle is started by: 1. Application of VCC power. 2. VCELL falling through the maximum cell voltage, VMCV where: Note: This resistor-divider network input impedance to end-to-end should be at least 200kΩ and less than 1MΩ. VMCV = 0.8 ∗ VCC ± 30mV 3. A ground-referenced negative temperature coefficient thermistor placed in proximity to the battery may be used as a low-cost temperature-to-voltage transducer. The temperature sense voltage input at TS is developed using a resistor-thermistor network between VCC and VSS. See Figure 1. Both the BAT and TS inputs are referenced to SNS, so the signals used inside the IC are: A transition on the INH input from low to high. If DCMD is tied low, a discharge-before-charge will be executed as the first step of the new charge cycle. Otherwise, pre-charge qualification testing will be the first step. The battery must be within the configured temperature and voltage limits before fast charging begins. VBAT - VSNS = VCELL and The valid battery voltage range is VEDV < VBAT < VMCV where: VTS - VSNS = VTEMP VEDV = 0.4 ∗ VCC ± 30mV Negative Temperature Coefficient Thermister VCC PACK + RT1 PACK+ bq2004E/H TS RB1 bq2004E/H BAT RB2 SNS RT2 SNS PACK- N T C PACK - Fg2004a.eps Figure 1. Voltage and Temperature Monitoring 3 bq2004E/H TM1 TM2 TCO Timing Control TCO Check OSC LED1 LED2 DSEL TS LTF Check Display Control VTS - VSNS DCMD DVEN VBAT - VSNS Charge Control State Machine A/D SNS EDV Check Discharge Control MOD Control PWR Control DIS MOD INH MCV Check BAT VCC VSS BD200401.eps Figure 2. Block Diagram Fast charge continues until termination by one or more of the six possible termination conditions: The valid temperature range is VHTF < VTEMP < VLTF, where: VLTF = 0.4 ∗ VCC ± 30mV n Delta temperature/delta time (∆T/∆t) VHTF = [(1/3 ∗ VLTF) + (2/3 ∗ VTCO)] ± 30mV n Peak voltage detection (PVD) n Negative delta voltage (-∆V) n Maximum voltage n Maximum temperature n Maximum time VTCO is the voltage presented at the TCO input pin, and is configured by the user with a resistor divider between VCC and ground. The allowed range is 0.2 to 0.4 ∗ VCC. If the temperature of the battery is out of range, or the voltage is too low, the chip enters the charge pending state and waits for both conditions to fall within their allowed limits. During the charge-pending mode, the IC first applies a top-off charge to the battery. PVD and -∆V Termination The bq2004E/H samples the voltage at the BAT pin once every 34s. When -∆V termination is selected, if VCELL is lower than any previously measured value by 12mV ±4mV (6mV/cell), fast charge is terminated. When PVD termination is selected, if VCELL is lower than any previously measured value by 6mV ±2mV (3mV/cell), fast charge is terminated. The PVD and -∆V tests are valid in the range 0.4 ∗ VCC < VCELL < 0.8 ∗ VCC. The top-off charge, at the rate of 1 8 of the fast charge, continues until the fast-charge conditions are met or the top-off time-out period is exceeded. The IC then trickle charges until the fast-charge conditions are met. There is no time limit on the charge pending state; the charger remains in this state as long as the voltage or temperature conditons are outside of the allowed limits. If the voltage is too high, the chip goes to the battery absent state and waits until a new charge cycle is started. 4 bq2004E/H VSEL Input Low Float High ∆T/∆t Termination Voltage Termination Disabled The bq2004E/H samples at the voltage at the TS pin every 34s, and compares it to the value measured two samples earlier. If VTEMP has fallen 16mV ±4mV or more, fast charge is terminated. The ∆T/∆t termination test is valid only when VTCO < VTEMP < VLTF. -∆V PVD Voltage Sampling Temperature Sampling Each sample is an average of voltage measurements. The IC takes 32 measurements in PVD mode and 16 measurements in -∆V mode. The resulting sample periods (9.17ms and 18.18ms, respectively) filter out harmonics centered around 55Hz and 109Hz. This technique minimizes the effect of any AC line ripple that may feed through the power supply from either 50Hz or 60Hz AC sources. Tolerance on all timing is ±16%. Each sample is an average of 16 voltage measurements. The resulting sample period (18.18ms) filters out harmonics around 55Hz. This technique minimizes the effect of any AC line ripple that may feed through the power supply from either 50Hz or 60Hz AC sources. Tolerance on all timing is ±16%. Maximum Voltage, Temperature, and Time Temperature and Voltage Termination Hold-off Anytime VCELL rises above VMCV, the LEDs go off and current flow into the battery ceases immediately. If VCELL then falls back below VMCV before tMCV = 1.5s ±0.5s, the chip transitions to the Charge Complete state (maximum voltage termination). If VCELL remains above VMCV at the expiration of tMCV, the bq2004E/H transitions to the Battery Absent state (battery removal). See Figure 3. A hold-off period occurs at the start of fast charging. During the hold-off period, -∆V and ∆T/∆t termination are disabled. The MOD pin is enabled at a duty cycle of 260µs active for every 1820µs inactive. This modulation results in an average rate 1/8th that of the fast charge rate. This avoids premature termination on the voltage spikes sometimes produced by older batteries when fast-charge current is first applied. Maximum voltage and maximum temperature terminations are not affected by the hold-off period. Maximum temperature termination occurs anytime V TEMP falls below the temperature cutoff threshold VTCO. Charge will also be terminated if VTEMP rises above the low temperature fault threshold, VLTF, after fast charge begins. Table 1. Fast Charge Safety Time/Hold-Off/Top-Off Table Typical Fast-Charge Safety Time (min) Corresponding Fast-Charge Rate 2004E 2004H C/4 C/8 Low C/2 C/4 1C C/2 2C Typical PVD, -∆V Hold-Off Time (s) 2004E 2004H 2004E Low 325 650 137 Float Low 154 325 High Low 77 154 1C Low Float 39 77 137 TM1 TM2 Top-Off Rate 2004H 2004E 2004H PulseTrickle Rate PulseTrickle Period (Hz) 2004E 2004H 273 Disabled Disabled 546 546 Disabled C/512 15 273 546 Disabled C/512 7.5 15 273 Disabled C/512 3.75 7.5 30 4C 2C Float Float 19 39 68 137 C/512 1.88 3.75 C/2 C/4 High Float 154 325 546 546 C/16 C/32 C/512 15 30 1C C/2 Low High 77 154 273 546 C/8 C/16 C/512 7.5 15 2C 1C Float High 39 77 137 273 C/4 C/18 C/512 3.75 7.5 4C 2C High High 19 39 68 137 C/2 C/4 C/512 1.88 3.75 Note: Typical conditions = 25°C, VCC = 5.0V. 5 Disabled Disabled bq2004E/H Table 2. bq2004E/H LED Output Summary Mode 1 bq2004E DSEL = VSS Charge Action State LED1 LED2 Battery absent Low Low Fast charge pending or a discharge-before-charge in progress High High Fast charging Low High Fast charge complete, top-off, and/or trickle High Low LED1 LED2 Battery absent Low Low Discharge-before-charge in progress High Mode 1 bq2004H DSEL = VSS Charge Action State Fast charge pending Low High 1 second high second low 8 1 8 Fast charging Low High Fast charge complete, top-off, and/or trickle High Low Mode 2 bq2004E LED1 LED2 Battery absent Charge Action State (See note) Low Low Fast charge pending or discharge-before-charge in progress High High Fast charging Low High Fast charge complete, top-off, and/or trickle High Low LED1 LED2 DSEL = Floating Mode 2 bq2004H Charge Action State (See note) Battery absent Low Low Discharge-before-charge in progress High High DSEL = Floating Fast charge pending Low Low High Fast charge complete, top-off, and/or trickle High Low LED1 LED2 Charge Action State Battery absent Note: second high second low 8 1 8 Fast charging Mode 3 bq2004E/H DSEL = VCC 1 Low Low 1 8 1 8 second high second low Fast charge pending or discharge-before-charge in progress Low Fast charging Low High Fast charge complete, top-off, and/or trickle High Low Pulse trickle is inhibited in Mode 2. 6 bq2004E/H Maximum charge time is configured using the TM pin. Time settings are available for corresponding charge rates of C/4, 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. Charge Current Control Top-off Charge When used in switch mode configuration, the nominal regulated current is: The bq2004E/H controls charge current through the MOD output pin. The current control circuitry is designed to support implementation of a constant-current switching regulator or to gate an externally regulated current source. An optional top-off charge phase may be selected to follow fast charge termination for the C/2 through 4C 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 equal to 0.235∗ the fast-charge safety time (See Table 1.) During top-off, the MOD pin is enabled at a duty cycle of 260µs active for every 1820µs inactive. This modulation results in an average rate 1/8th that of the fast charge rate. Maximum voltage, time, and temperature are the only termination methods enabled during topoff. IREG = 0.225V/RSNS Charge current is monitored at the SNS input by the voltage drop across a sense resistor, RSNS, between the low side of the battery pack and ground. RSNS is sized to provide the desired fast charge current. If the voltage at the SNS pin is less than VSNSLO, the MOD output is switched high to pass charge current to the battery. When the SNS voltage is greater than VSNSHI, the MOD output is switched low—shutting off charging current to the battery. VSNSLO = 0.04 ∗ VCC ± 25mV Pulse-Trickle Charge VSNSHI = 0.05 ∗ VCC ± 25mV Pulse-trickle charging may be configured to follow the fast charge and optional top-off charge phases to compensate for self-discharge of the battery while it is idle in the charger. When used to gate an externally regulated current source, the SNS pin is connected to VSS, and no sense resisitor is required. In the pulse-trickle mode, MOD is active for 260µs of a period specified by the settings of TM1 and TM2. See Table 1. The resulting trickle-charge rate is C/512. Both pulse trickle and top-off may be disabled by tying TM1 and TM2 to VSS or by selecting Mode 2 in the display. Charge Status Indication Charge status is indicated by the LED1 and LED2 outputs. The state of these outputs in the various charge cycle phases is given in Table 2 and illustrated in Figure 3. In all cases, if VCELL exceeds the voltage at the MCV pin, both LED1 and LED2 outputs are held low regardless of other conditions. Both can be used to directly drive an LED. 7 bq2004E/H New Charge Cycle Started by Any One of: Falling Edge on DCMD VCC Rising to Valid Level Yes Battery Replacement (VCELL Falling through VMCV) DCMD Tied to Ground? Inhibit (INH) Released No VEDV < VCELL < VMCV Charge Pending VCELL < VEDV Battery Voltage? VCELL < VEDV VTEMP > VLTF or VTEMP < VHTF Top-Off and Pulse-Trickle Charge Battery Temperature? DischargeBefore-Charge VCELL > VMCV VCELL > VMCV VCELL > VMCV VHTF < VTEMP < VLTF Battery Absent VEDV < VCELL < VMCV and VHTF < VTEMP < VLTF Fast Charge VCELL > VMCV - V or T/ t or VTEMP < VTCO or Maximum Time Out Top-Off Selected? Pulse Trickle Charge t > tMCV Pulse Trickle Charge VCELL < VMCV VCELL > VMCV Top-Off Charge Yes VTEMP < VTCO or 0.235 Maximum Time Out No Charge Complete VCELL > VMCV Pulse Trickle Charge SD2004EH.eps Figure 3. Charge Algorithm State Diagram 8 bq2004E/H 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: VSNSHI VSNSLO 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 = TOPR; VCC ± 10%) Parameter High threshold at SNS resulting in MOD = Low Low threshold at SNS resulting in MOD = High Rating Tolerance Unit 0.05 * VCC ±0.025 V 0.04 * VCC ±0.010 V Notes VTEMP ≥ VLTF inhibits/terminates charge VLTF Low-temperature fault 0.4 * VCC ±0.030 V VHTF High-temperature fault (1/3 * VLTF) + (2/3 * VTCO) ±0.030 V VEDV End-of-discharge voltage 0.4 * VCC ±0.030 V VMCV Maximum cell voltage 0.8 * VCC ±0.030 V VTHERM TS input change for∆T/∆t detection -16 ±4 mV VCC = 5V, TA = 25°C -12 ±4 mV VCC = 5V, TA = 25°C -6 ±2 mV VCC = 5V, TA = 25°C -∆V PVD BAT input change for -∆V detection BAT input change for PVD detection 9 VTEMP ≤ VHTF inhibits charge VCELL < VEDV inhibits fast charge VCELL > VMCV inhibits/ terminates charge bq2004E/H Recommended DC Operating Conditions (TA = TOPR) Symbol Condition Minimum Typical Maximum Unit Notes VCC Supply voltage 4.5 5.0 5.5 V VBAT Battery input 0 - VCC V VCELL BAT voltage potential 0 - VCC V VTS Thermistor input 0 - VCC V VTEMP TS voltage potential 0 - VCC V VTS - VSNS VTCO Temperature cutoff 0.2 * VCC - 0.4 * VCC V Valid ∆T/∆t range Logic input high 2.0 - - V DCMD, INH Logic input high VCC - 0.3 - - V TM1, TM2, DSEL, VSEL Logic input low - - 0.8 V DCMD, INH Logic input low - - 0.3 V TM1, TM2, DSEL, VSEL VBAT - VSNS VIH VIL VOH Logic output high VCC - 0.8 - - V DIS, MOD, LED1, LED2, IOH ≤ -10mA VOL Logic output low - - 0.8 V DIS, MOD, LED1, LED2, IOL ≤ 10mA ICC Supply current - 1 3 mA Outputs unloaded ISB Standby current - - 1 µA INH = VIL IOH DIS, LED1, LED2, MOD source -10 - - mA @VOH = VCC - 0.8V IOL DIS, LED1, LED2, MOD sink 10 - - mA @VOL = VSS + 0.8V Input leakage - - ±1 µA INH, BAT, V = VSS to VCC Input leakage 50 - 400 µA DCMD, V = VSS to VCC IL IIL Logic input low source - - 70 µA TM1, TM2, DSEL, VSEL, V = VSS to VSS + 0.3V IIH Logic input high source -70 - - µA TM1, TM2, DSEL, VSEL, V = VCC - 0.3V to VCC IIZ Tri-state -2 - 2 µA TM1, TM2, DSEL, and VSEL should be left disconnected (floating) for Z logic input state Note: All voltages relative to VSS except as noted. 10 bq2004E/H Impedance Symbol Parameter Minimum Typical Maximum Unit RBAT Battery input impedance 50 - - MΩ RTS TS input impedance 50 - - MΩ RTCO TCO input impedance 50 - - MΩ RSNS SNS input impedance 50 - - MΩ Timing Symbol (TA = 0 to +70°C; VCC ± 10%) Parameter tPW Pulse width for DCMD and INH pulse command dFCV Time base variation fREG Minimum Typical Maximum Unit Notes 1 - - µs Pulse start for charge or discharge before charge -16 - 16 % VCC = 4.75V to 5.25V MOD output regulation frequency - - 300 kHz tMCV Maximum voltage termination time limit 1 - 2 s Note: Typical is at TA = 25°C, VCC = 5.0V. 11 Time limit to distinguish battery removed from charge complete. bq2004E/H 16-Pin DIP Narrow (PN) 16-Pin PN (0.300" DIP) Inches 12 Millimeters Dimension 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 bq2004E/H 16-Pin SOIC Narrow (SN) 16-Pin SN (0.150" SOIC) Inches D e B E H A C A1 .004 L 13 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 0.385 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 bq2004E/H Data Sheet Revision History Change No. Page No. 1 All 2 3 Description Nature of Change Combined bq2004E and bq2004H, revised and expanded format of this data sheet Clarification 7 Separated bq2004E and bq2004H in Table 2, LED Output Summary Clarification 5 Description of charge-pending state Clarification 4 Note: Change 1 = Oct. 1997 B changes from Sept. 1996 (bq2004E), Feb. 1997 (bq2004H). Change 2 = Feb. 1998 C changes from Oct. 1997 B. Change 3 = Dec. 1998 D changes from Feb. 1998 C. Change 4 = June 1999 E changes from Dec. 1998 D. 14 bq2004E/H Ordering Information bq2004 Package Option: PN = 16-pin narrow plastic DIP SN = 16-pin narrow SOIC Device: E = bq2004E Fast-Charge IC H= bq2004H Fast-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. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. 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