Freescale Semiconductor Advance Information Document Number: MC34674 Rev. 2.0, 11/2008 High Input Voltage Travel Charger for Single-cell Li-Ion Batteries 34674 The MC34674 is a fully integrated single-cell Li-Ion and Li-Polymer battery charger optimized for travel charger applications. The few external components required include a dual-color LED for chargestatus indication, a negative temperature coefficient (NTC) thermistor circuit for setting the charge temperature window, and two decoupling capacitors. The high input voltage, up to 28 V, allows low-cost AC/DC converters to be used for further system cost reduction. A typical charge cycle of the MC34674 includes trickle, constant-current (CC) and constant-voltage (CV) charge modes. The CC-mode current is selectable from 50 mA to 1.05 A with 8% accuracy and the constantoutput voltage in the CV-mode is fixed at 4.2 V with 0.4% accuracy over -20°C to 70°C temperature range. The MC34674 has all the features such as trickle charging for a deeply discharged battery, an internal timer for termination to prevent charging a failed battery, charger current thermal foldback for thermal protection, and smart battery connection verification to prevent charging in case there is no battery connected. It also protects the system with its input over-voltage protection (OVP) feature. In addition, it has a 2.6 V falling power-on-reset (POR) threshold, making it perfect to work with current limited power supplies. When the charger is disabled, the BAT pin leaks less than 1.0 μA current from the battery. All the above functions are fit into a small 8-lead 2X3 UDFN package. Features • No external MOSFET, reverse-blocking diode or currentsense resistor are required • 28 V maximum input voltage rating with 11 V over-voltage protection threshold • Factory programmable charge current • Trickle charge for fully discharged batteries • ±0.4% voltage accuracy over -20°C to 70°C POWER MANAGEMENT IC EP SUFFIX (PB-FREE) 98ASA10774D 8-PIN UDFN ORDERING INFORMATION Device Refer to Table 1, Device Variations Temperature Range (TA) Package -40°C to 85°C 8 UDFN-EP • Driving a dual-color LED and smart battery connection verification optimized for travel charger applications • Interface to NTC thermistor • Internal timer and thermal current limit • Small 2X3 mm2 thermally enhanced UDFN package • Pb-free packaging designated by suffix code EP 34674 VIN VIN BAT CIN COUT RPU TO BATTERY VREF RED TEMP RS GRN OFF ON EN GND Figure 1. 34674 Simplified Application Diagram This document contains certain information on a new product. Specifications and information herein are subject to change without notice. © Freescale Semiconductor, Inc., 2007-8. All rights reserved. TO BATTERY NTC (THERMISTOR) DEVICE VARIATIONS DEVICE VARIATIONS Table 1. Device Variations Freescale Part No.(1) CC-Mode Current (ICHG) Reference Location MC34674AEP/R2 1.05A Table 6 MC34674BEP/R2 850mA Table 6 MC34674CEP/R2 650mA Table 6 MC34674DEP/R2 450mA Table 6 Notes 1. Freescale offers a series of MC34674 variations. Each variation has an increment of 50 mA or 100 mA for the CC-mode current. 34674 2 Analog Integrated Circuit Device Data Freescale Semiconductor INTERNAL BLOCK DIAGRAM INTERNAL BLOCK DIAGRAM VIN BAT – VIN Monitor Internal Supply + Charge Control 6 mA REF – + VREF Die Temp 110°C RED VOS VIN + – + – + BAT – + 6 mA – GRN Logic Control EN IREF IEOC NTC Interface VREF TEMP GND Figure 2. 34674 Simplified Internal Block Diagram 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 3 PIN CONNECTIONS PIN CONNECTIONS VIN 1 8 BAT GRN 2 7 VREF RED 3 6 TEMP EN 4 5 GND EPAD Figure 3. 34674 Pin Connections Table 2. 34674 Pin Definitions A functional description of each pin can be found in the Functional Pin Description section beginning on page 12. Pin Number Pin Name Pin Function Formal Name Definition 1 VIN Input Input supply 2 GRN Output Green indicator Indication of the charge status. Open drain output with 6 mA current limit. 3 RED Output Red indicator Indication of the charge status. Open drain output with 6 mA current limit. 4 EN Input Enable Active-low enable logic input. 5 GND Ground Ground Ground. 6 TEMP Input NTC interface input The NTC thermistor interface pin. 7 VREF Output NTC interface bias voltage The bias voltage for the NTC interface circuit. 8 BAT Output Charger output EPAD EPAD N/A Exposed pad The supply input. The charger output pin to the battery. Exposed pad for thermal dissipation enhancement. Must be soldered on the large ground plane on the PCB to increase the thermal dissipation. The pad must be connected to GND electrically. 34674 4 Analog Integrated Circuit Device Data Freescale Semiconductor ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS Table 3. Maximum Ratings All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or permanent damage to the device. Ratings Symbol Value Unit ELECTRICAL RATINGS Input voltage range V VIN Pin VIN -0.3 to 28 GRN and RED Pins VGRN, VRED -0.3 to 12 EN, BAT, REF and TEMP Pins VEN, VBAT, VREF, VTEMP -0.3 to 5.5 ESD Voltage(2) V VESD Human Body Model (HBM) ±2000 Machine Model (MM) ±200 THERMAL RATINGS Operating Temperature °C Ambient TA -40 to 85 Junction TJ -40 to 150 TSTG -65 to 150 RθJC 10 RθJA 70 TPPRT Note 5 Storage Temperature Thermal Resistance(3) °C/W Junction-to-Case Junction-to-Ambient Peak Package Reflow Temperature During °C Reflow(4),(5) °C Notes 2. ESD testing is performed in accordance with the Human Body Model (HBM) (CZAP = 100 pF, RZAP = 1500 Ω), and the Machine Model (MM) (CZAP = 200 pF, RZAP = 0 Ω). 3. 4. 5. Device mounted on the Freescale EVB test board per JEDEC DESD51-2. Pin soldering temperature limit is for 10 seconds maximum duration. Not designed for immersion soldering. Exceeding these limits may cause malfunction or permanent damage to the device. Freescale’s Package Reflow capability meets Pb-free requirements for JEDEC standard J-STD-020C. For Peak Package Reflow Temperature and Moisture Sensitivity Levels (MSL), Go to www.freescale.com, search by part number [e.g. remove prefixes/suffixes and enter the core ID to view all orderable parts. (i.e. MC33xxxD enter 33xxx), and review parametrics. 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 5 ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 4. Static Electrical Characteristics Characteristics noted under conditions VIN = 5.0 V, -40°C ≤ TA ≤ 85°C, CIN = COUT = 1.0 μF (see Figure 1), unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5.0 V and TA = 25°C under nominal conditions, unless otherwise noted. Characteristic Symbol Min Input Voltage Range(6) VIN 4.3 VIN Pin Supply Current IIN Typ Max Unit 10 V POWER INPUT μA Charger enabled(7) - 1400 - Charger disabled - 300 350 Power On Reset VPOR V Rising VIN threshold 3.0 - 3.9 Falling VIN threshold - 2.4 2.6 VOVP 10 11 12 V VOVPHYS - 400 - mV Over-voltage Protection Rising Threshold Over-voltage-Protection Threshold Hysteresis VIN-BAT Offset Voltage VOS mV Rising threshold - - 60 Falling threshold 1.0 - 22 VIN = 5.0 V; IBAT = 10 mA; TA = 25°C 4.190 4.20 4.210 VIN = 5.0 V; IBAT = 10 mA; TA = -20 to 70°C 4.183 4.20 4.217 VIN = 5.0 V; IBAT = 10 mA; TA = -40 to 85°C 4.179 4.20 4.221 - 265 450 - - 1.0 -2.0 - 4.0 MC34674A 966 1050 1134 MC34674B 782 850 918 MC34674C 598 650 702 MC34674D 414 450 486 MC34674A 74 105 136 MC34674B 60 85 110 MC34674C 46 65 84 MC34674D 32 45 58 OUTPUT Regulated Output Voltage(8) VBAT Power MOSFET On Resistance V RDS(ON) mΩ VBAT = 4.0 V; IBAT = 0.5 A; ICHG = 1.05 A BAT Pin Standby Current μA ISTDBY VIN not powered or charger disabled VIN powered and in charge completion state (average over 2 seconds)(7) CHARGE CURRENT Constant-Current-Mode Charge Current ICHG Trickle-Mode Charge Current(9) mA ITRKL ICHG Notes 6. Refer to the Power-on-Reset parameter for VIN turn on and turn off values. 7. 8. 9. Supply current does not include the current delivered to the battery through the BAT pin. In the test mode, the charger still operates in CV mode after EOC. Characterized over the temperature range -40°C ≤ TA ≤ 85°C 34674 6 Analog Integrated Circuit Device Data Freescale Semiconductor ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 4. Static Electrical Characteristics (continued) Characteristics noted under conditions VIN = 5.0 V, -40°C ≤ TA ≤ 85°C, CIN = COUT = 1.0 μF (see Figure 1), unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5.0 V and TA = 25°C under nominal conditions, unless otherwise noted. Characteristic Symbol Min Typ Max MC34674A 84 105 126 MC34674B 68 85 102 MC34674C 52 65 78 MC34674D 34 45 57 VTRKL 2.8 2.9 3.0 V VTRKLHYS - 100 - mV VRECH 4.07 4.10 4.135 V VTHRCHG - 25 50 mV IDCHG 4.5 6.0 7.5 mA ICHGCM - 24 - μA IDCC - 585 - μA Low Temperature Rising Threshold(11) VLTRT 0.6592 2/3 0.6741 VREF Threshold(11) VLTFT - 0.6468 - VREF (11) VHTFT 0.3297 1/3 0.3389 VREF Threshold(11) VHTRT - 0.3441 - VREF TLIM 95 110 125 °C EN Input High Threshold Voltage VIH 1.5 - - V EN Input Low Threshold Voltage VIL - - 0.5 V EN Pin Internal Pull-down Current IEN - 2.0 7.5 μA 5.0 6.0 7.0 - - 1.0 End-of-Charge (EOC) Threshold IEOC Unit mA CHARGE THRESHOLDS Trickle-mode Rising Threshold Voltage Trickle-mode Threshold Voltage Hysteresis Recharge Falling Threshold Voltage Recharge Threshold Voltage Hysteresis BATTERY CONNECTION VERIFICATION Battery Connection Verification Discharge Current (Over 0.8 to 5.0 V)(10) Output Current in Charge Completion State (10) Discharge Current in Charge Completion State During the 82 ms(10) NTC INTERFACE Low Temperature Falling High Temperature Falling Threshold High Temperature Rising Die Thermal Limit LOGIC INPUT AND OUTPUT GRN and RED Sink Current IGRSINK Pin voltage is between 0.8 V and 5.0 V Open-Drain Off Leakage Biased at 5.0 V mA μA IODLEAK Notes 10. Not tested. Guaranteed by design. 11. These threshold parameters are specified as a ratio of VTEMP/VREF. Due to the negative temperature coefficient thermistor, VTEMP rises when the temperature is falling from high to low, and VTEMP falls when the temperature is rising from low to high. 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 7 ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS Table 5. Dynamic Electrical Characteristics Characteristics noted under conditions VIN = 5.0 V, -40°C ≤ TA ≤ 85°C, CIN = COUT = 1.0 μF (see Figure 1), unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5.0 V and TA = 25°C under nominal conditions, unless otherwise noted. Characteristic Symbol Min Typ Max Unit tEOC 500 - 1000 ms fOSC 40.0 50.0 60.0 kHz Safety Timer for Fast Charge Mode tFCM 3.68 4.6 5.52 Hour Safety Timer for Trickle Charge Mode tTCM 0.46 0.575 0.69 Hour tEV - 100 - ms tDCCC - 82 - ms tDR - 1968 - ms END OF CHARGE EOC Filtering Time(12) OSCILLATOR Oscillator Frequency INTERNAL TIMER ENABLE VERIFICATION Enable Verification Time BATTERY CONNECTION VERIFICATION Discharge Time in Charge Completion State(12) Discharge Repeating Time(12) Notes 12. Not tested. Guaranteed by design. 34674 8 Analog Integrated Circuit Device Data Freescale Semiconductor ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES 5.0 700 4.5 600 Battery Voltage 4.0 3.5 400 Charge Current 3.0 300 2.5 200 2.0 100 1.5 0 20 40 60 80 IBAT (mA) VBAT (V) 500 0 120 100 Constant Charge Current (mA) ELECTRICAL PERFORMANCE CURVES 700 600 500 400 300 200 100 4 5 6 Trickle Charge Current (mA) VBAT (V) 4.25 4.20 4.15 4.10 4.05 6 7 8 9 10 11 75 70 65 60 55 50 2 4 6 2500 600 Charge Current (mA) VIN Pin Supply Current (µA) 700 2000 Charger Enabled 1000 Charger Disabled 4 10 12 VIN (V) 3000 0 2 8 Figure 8. Trickle Charge Current vs VIN ICHG = 650 mA, VBAT = 2.0 V, TA = 25°C Figure 5. VBAT vs VIN ICHG = 650 mA, IBAT = 0 mA, TA = 25°C 500 10 80 VIN (V) 1500 9 Figure 7. Constant Charge Current vs VIN ICHG = 650 mA, VBAT = 3.0 V, TA = 25°C 4.30 5 8 VIN (V) Time (min) Figure 4. Complete Charge Cycle VIN = 5.0 V, ICHG = 650 mA, TA = 25°C 4.00 4 7 6 8 10 VIN (V) Figure 6. VIN Pin Supply Current vs VIN ICHG = 650 mA, IBAT = 100 mA, TA = 25°C 12 500 400 300 200 100 0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 VBAT (V) Figure 9. Charge Current vs VBAT ICHG = 650 mA, VIN = 5.0 V, TA = 25°C 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 9 ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES 4.210 450 RDS(ON) (mΩ) VBAT (V) 4.205 4.200 4.195 4.190 350 300 250 4.185 4.180 -40 400 -20 0 20 40 60 200 -40 80 -20 640 620 600 20 40 60 80 Recharge Voltage Threshold (V) Constant Charge Current (mA) 660 0 75 70 65 60 55 0 20 40 80 4.14 4.12 4.10 4.08 4.06 4.04 -40 -20 60 80 Temperature (°C) Figure 12. Trickle Charge Current vs Temperature ICHG = 650 mA, VIN = 5.0 V, VBAT = 2 V 0 20 40 60 Temperature (°C) 80 Figure 14. Recharge Voltage Threshold vs Temperature VIN = 5.0 V, ICHG = 650 mA BAT Pin Supply Current (µA) Trickle Charge Current (mA) 80 -20 60 4.16 Temperature (°C) Figure 11. Constant Charge Current vs Temperature ICHG = 650 mA, VIN = 5.0 V, VBAT = 3.9 V 50 -40 40 Figure 13. RDS(ON) vs Temperature ICHG =650 mA, VBAT = 4.0 V, IBAT = 600 mA 680 -20 20 Temperature (°C) Temperature (°C) Figure 10. VBAT vs Temperature VIN = 5.0 V, ICHG = 650 mA, IBAT = 100 mA 580 -40 0 4 3 VIN = 5V, Charger Disabled 2 1 VIN Pin Not Powered 0 -1 -40 -20 0 20 40 60 80 Temperature (°C) Figure 15. BAT Pin Supply Current vs Temperature ICHG = 650 mA, VBAT = 5.0 V 34674 10 Analog Integrated Circuit Device Data Freescale Semiconductor VIN Pin Supply Current (µA) ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES 3000 2500 2000 Charger Enabled 1500 1000 500 0 -40 Charger Disabled -20 0 20 40 60 80 Temperature (°C) Figure 16. VIN Pin Supply Current vs Temperature ICHG = 650 mA, VBAT = 5.0 V, IBAT = 0 mA 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 11 FUNCTIONAL DESCRIPTION INTRODUCTION FUNCTIONAL DESCRIPTION INTRODUCTION The MC34674 is a fully-integrated Li-Ion and Li-Polymer battery charger optimized for travel charger or cradle charger applications. It offers 28 V input-voltage rating for protection against failed AC/DC converters, 0.2% output voltage accuracy at room temperature, and the ability to operate with a current-limited AC/DC output for minimum heat generation. The MC34674 follows the standard charging profile with trickle, constant-current (CC) and constant-voltage (CV) charge modes, as shown in Figure 17. The trickle-mode current ITRKL is pre-set to 10% of the CC-mode current ICHG when the battery voltage is lower than the trickle-mode threshold VTRKL. In the CC-mode, the output voltage increases until it reaches 4.2 V. Then the charger enters the CV-mode with the output voltage regulated at 4.2 V. The endof-charge (EOC) current threshold IEOC, which is utilized to indicate the termination of a charge cycle, is preset to 10% of the CC-mode current. Other features include automatic recharging, internal thermal regulation to prevent overheating the device, an external NTC interface to prevent charging when the ambient temperature is out of a set window, an internal timer for safety, and smart battery connection verification. Two indication outputs make it easy to report the input power status and the charge status to users via LEDs. Trickle CC CV 4.2V ICHG Charge Voltage Charge Current VTRKL IEOC ITRKL Figure 17. Charge Profile FUNCTIONAL PIN DESCRIPTION INPUT SUPPLY VOLTAGE (VIN) The supply input. This pin should be bypassed to ground with a 1.0 μF capacitor. GROUND (GND) Ground. NTC INTERFACE INPUT (TEMP) GREEN INDICATOR (GRN) Open-drain logic output to indicate the charging status. This pin drives the green-color LED in a dual-color LED pack with an internal 6.0 mA current source. Negative temperature coefficient (NTC) thermistor interface pin. This pin is connected to an NTC thermistor in the battery pack to monitor the battery temperature. A pull-up resistor is required between the TEMP pin and VREF pin. RED INDICATOR (RED) NTC INTERFACE BIAS VOLTAGE (VREF) Open-drain logic output to indicate the charging status. This pin drives the red-color LED in a dual-color LED pack with an internal 6.0 mA current source. ENABLE (EN) Active-low enable logic input. This pin is internally pulled to ground by a weak current source. When the pin is left floating, the charger is enabled. Pulling this pin to high voltage externally disables the charger. To supply bias voltage for the NTC interface circuit. CHARGER OUTPUT (BAT) Charger output pin. Connect this pin to the battery. This pin should be bypassed to ground with a 1.0 μF or higher capacitor. EXPOSED PAD (EPAD) Exposed pad. The pad must be soldered on the large ground plane on the PCB to enhance the thermal conductivity. The pad must be connected to GND electrically. 34674 12 Analog Integrated Circuit Device Data Freescale Semiconductor FUNCTIONAL DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION MC34674 - Functional Block Diagram Integrated Supply Internal Supply & Reference Sensing & Control VIN Monitor Charge Control End of Charge VIN - BAT Compare Die Temperature Feedback Power MOSFET NTC Thermistor Interface Logic Logic Control Status Indication Integrated Supply Sensing & Control Logic MOSFET Figure 18. 34674 Functional Internal Block Diagram INTEGRATED SUPPLY conditions are reached, this block outputs a logic signal to indicate the end of the charge. INTERNAL SUPPLY AND REFERENCE The internal supply and reference block steps down the high input voltage to a lower voltage to power all the internal control blocks. In addition, this block generates the reference voltages for other functional blocks. SENSING AND CONTROL VIN MONITOR The VIN monitor block monitors the input voltage for two thresholds, power-on-reset (POR) and over-voltage protection (OVP). If the input is lower than the POR or higher than the OVP threshold, this block outputs a logic signal to disable the charger. CHARGE CONTROL The charge-control block controls the gate voltage of the power MOSFET to regulate the charge current, the battery voltage, or the die temperature. It can also completely turn off the power MOSFET to stop the current flow between the input and the battery. EOC (END OF CHARGE) The EOC block monitors the charge current and the battery voltage for the EOC conditions. Once the EOC VIN-BAT COMPARATOR The VIN-BAT comparator monitors the voltage difference between the input voltage VIN and the battery voltage VBAT, as shown in Figure 2. The input voltage has to be higher than the battery voltage for the charger to be enabled. If the input voltage falls below the battery voltage, this block outputs a signal to disable the charger to prevent the leakage current from the battery to the input. Due to the intrinsic input offset voltage of the VIN-BAT comparator, a small voltage, VOS, is added. The added VOS guarantees that the power MOSFET is turned off when the input voltage is lower than the battery voltage. DIE TEMPERATURE FEEDBACK The die temperature feedback block monitors the die temperature. Once the die temperature reaches a threshold of 110°C, the charge-control block can reduce the charge current to prevent further temperature rise. NTC INTERFACE The NTC interface block offers an interface to an external NTC thermistor circuit to monitor the battery temperature and to set the charge temperature window. 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 13 FUNCTIONAL DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION LOGIC LOGIC CONTROL AND STATUS INDICATION The logic control block determines the on and off states of the charger. It takes the signals from the VIN Monitor, VINBAT comparator, EOC, NTC interface blocks, and the external enable signal EN, and determines the on and off states as well as the charge status indication outputs of the charger. This block also contains the logic circuit for the battery connection verification and the internal timer. POWER MOSFET The power MOSFET passes the charging current from the input to the output. 34674 14 Analog Integrated Circuit Device Data Freescale Semiconductor FUNCTIONAL DESCRIPTION FUNCTIONAL DEVICE OPERATION FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES The MC34674 moves through various charge states after being powered, as shown in Figure 23. The following describes each state in detail. When the input voltage rises above the rising power-onreset (POR) threshold, the charger resets the internal timer, preparing for the start of a charging cycle. The falling edge of the POR threshold is less than 2.6 V, making the MC34674 ideal for working with a current-limited AC/DC converter. mode, an internal timer is reset to start counting the total trickle-charge time. In the meantime, the charger begins to measure the battery voltage. If the battery voltage rises above the trickle-charge threshold before the timer finishes, the charge cycle will enter the fast-charge mode that is described next. If the timer expires before the voltage reaching the trickle-charge threshold, the battery is determined to be a faulty battery and a TIMEOUT fault indication is issued. Then the charger turns off and the LED indicates a yellow color. POWER-PRESENCE VERIFICATION FAST CHARGE MODE After the POR, the MC34674 indicates the power presence to the users via a dual-color LED driven by the GRN and RED pins. The indication is a sequence of four colors using the dual-color LED in the sequence of red, green, yellow (by turning on both colors) and OFF (by turning off both colors). Each color is on for 0.5 seconds. The fast charge contains two modes, the constant-current (CC)-mode and the constant-voltage (CV)-mode. As shown in Figure 17, the charge current is regulated at a constant value in the CC-mode and the charger output voltage is regulated at a constant 4.2 V in the CV-mode. The charge current can be reduced by the die temperature regulation loop when the die temperature reached 110°C. The CCmode current is set internally by Freescale. Available values are given in Table 6. Consult Freescale for values that are not listed in Table 1. POWER-ON RESET (POR) ENABLE/DISABLE VERIFICATION The charger then tries to validate the logic level of the EN input. The EN input is an active-low input with a weak internal pull-down circuit. Leaving the EN pin floating is equivalent to a low input. If the EN stays at the low state for more than 100ms, the charger is enabled. This 100ms filter applies to both the rising and the falling edges of the EN input to prevent mis-triggering of the EN signal by any transient event such as an ESD event. The EN input has to stay in a new state continuously for more than 100ms for the new state to be recognized. The VIN-BAT comparator output is also a condition for enabling the charger. When the input voltage VIN is lower than the BAT pin voltage VBAT by the VOS, the charger is disabled and stays in the Enable Verification state. BATTERY CONNECTION VERIFICATION Once enabled, the charger starts to verify if a battery is connected. The battery connection verification takes 0.5 seconds, during which the dual-color LED and the charger are off. If a battery is found, the charger starts to enter the trickle-charge mode; otherwise, it turns on the yellow color LED for 1 second, then turns off the LED for 0.5 seconds, and then tries to verify the connection again. The verification flow creates an equivalent 0.5 Hz yellow blinking LED indication if there is no battery connected. Once a battery is inserted, the charger will detect it and enter the trickle-charge mode. TRICKLE-CHARGE MODE The charger always starts charging with the trickle-charge mode. The trickle-charge mode current is set to 10% of the constant-current (CC) charge mode current that is described next. In trickle-charge mode the charger is on and the LED indicates the red color. When entering the trickle-charge Table 6. Customer Selectable CC-Mode Current Values. No. ICHG (mA) No. ICHG (mA) 1 50 9 450 2 100 10 500 3 150 11 550 4 200 12 650 5 250 13 750 6 300 14 850 7 350 15 950 8 400 16 1050 When entering the fast charge mode, the internal timer is reset again to limit the total fast charge time. The time limit for the fast charge mode is 8 times of that of the trickle-charge mode. When the charge completion conditions are detected or when the total charge time limit is reached, the charger enters the charge completion state. The LED indicates the red color in the fast charge mode. CHARGE COMPLETION The criterion for the charge completion is for the charge current to drop below the end-of-charge (EOC) threshold in the CV-mode. The EOC threshold is set to 10% of the CCmode current. To ensure that no transient current will mistrigger the EOC indication, two additional criteria are required to be met. The first one is, the battery voltage needs to be above the recharge threshold. The second is, the charge 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 15 FUNCTIONAL DESCRIPTION FUNCTIONAL DEVICE OPERATION current needs to stay below the EOC threshold for more than 0.5 seconds. The charger is turned off and the LED indication is green when charge completes. If the total fast charge time limit is exceeded, the charger also enters the charge completion state. RECHARGE MODE If the battery voltage drops below the recharge threshold after charge completion, the charger will try to recharge the battery to 4.2 V. Because the battery voltage drop can also be caused by the removal of the battery, before starting recharge, the charger tries to verify if the battery is still present. If the battery is not found, then the connection fault is issued again. If the battery is still connected, the charger restarts charging to bring the battery to a full state. The LED indication remains green in this mode. The recharge mode has the same total charge time limit as the fast charge mode. For any reason the battery voltage falls below the trickle-charge threshold in the recharge mode, the charger will enter the battery connection verification state again, as shown in Figure 23. TEMPERATURE AND OVER-VOLTAGE FAULT The NTC interface block offers an interface to an external NTC thermistor circuit to monitor the battery temperature. When the battery temperature is out of a user-programmable window, the charger is disabled and a fault condition is issued with a yellow LED indication. When the fault conditions are removed, the charger enters the battery connection verification state. More detailed description on the NTC interface is offered later in this datasheet. The charger has an 11 V (typ.) input OVP threshold. When the input voltage is higher than this threshold, the charging is stopped and a fault condition is issued with a yellow LED indication. When the input voltage falls below the OVP threshold, the charger restarts charging and resets the internal digital logic control block. TIMEOUT FAULT The TIMEOUT fault can only occur when the charger stays in the trickle-charge mode for a period longer than the time limit. The charger is turned off and a yellow LED indication is issued when this fault occurs. The only path to exit this fault is by toggling the EN input or by recycling the power input. DETAILED FUNCTIONAL DEVICE OPERATION NTC INTERFACE The MC34674 offers an interface to an external NTC thermistor to monitor the battery temperature. The low and high temperature thresholds in the Table 4 allow users to set a temperature window (such as 0°C to 50°C), within which the charging is allowed. If the battery temperature is out of such a window, a temperature fault is issued and the LED indicates a yellow color. Figure 19 shows the internal equivalent circuit for the NTC interface and the external NTC thermistor circuit. An internal resistor divider that is powered by the VREF pin voltage, VVREF, creates two reference voltages, 1/3 VVREF and 2/3 VVREF. An external resistor divider also powered by VVREF generates the voltage VTEMP to represent the battery temperature. Because the resistance of the NTC thermistor, RNTC, decreases as temperature rises, as shown in Figure 20, VTEMP decreases as the battery temperature increases. Assume TCOLD and THOT are the two temperature thresholds, such as 0°C and 50°C. When the battery temperature falls below TCOLD, VTEMP rises above 2/3 VVREF and an under-temperature fault is issued. Similarly, when the battery temperature rises above THOT, VTEMP falls below 1/3 VVREF, so an over-temperature fault is issued. The relationship between the internal and the external divider voltages at the triggering points can be expressed as the following: R NTC + R S ---------------------------------------- = Kx R NTC + R S + R U equ. 1 where RNTC is the thermistor resistance at the given temperature, and KX is the ratio of the internal divider at the given triggering points (see Table 4). RU and RS represent a pull-up resistor and a series resistor in the external resistor divider respectively. The resistance selection of RU and RS can be figured out by the following two equations: R HOT + R S ---------------------------------------- = K HOT R HOT + R S + R U equ. 2 R COLD + R S -------------------------------------------- = K COLD R COLD + R S + R U equ. 3 where KHOT and KCOLD are the resistor divider ratios for the temperature thresholds THOT and TCOLD respectively; RHOT and RCOLD are the NTC thermistor resistance at THOT and TCOLD respectively. The typical values for KHOT and KCOLD are 1/3 and 2/3 respectively, as given in Table 4. Refer to the Application Information section for more details regarding the RU and RS selection. 34674 16 Analog Integrated Circuit Device Data Freescale Semiconductor FUNCTIONAL DESCRIPTION FUNCTIONAL DEVICE OPERATION Resistance VREF RU R Under Tem p CP1 - RCOLD 2/3V VREF TEM P + O ver Tem p CP2 + R RS 1/3V VREF RHOT R NTC R TCOLD G ND Figure 19. Equivalent Circuit for the NTC Interface THOT Temperature Figure 20. NTC Thermistor Resistance Characteristics START Set VTRKL to 1.5V Discharge the output with 6mA current for 250ms VBAT < VTRKL ? No Set VTRKL back to normal voltage Good connection Yes Trickle charge for 250ms VTRKL < VBAT < VRECH ? No Set VTRKL back to normal voltage Yes Battery Connection Verification Good connection Bad connection Bad connection Figure 21. Battery Connection Verification Flow Chart 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 17 FUNCTIONAL DESCRIPTION FUNCTIONAL DEVICE OPERATION BATTERY CONNECTION VERIFICATION Battery connection verification is to ensure that the battery is properly connected before the charging starts. The charger does not start if the battery is short-circuited or opencircuited. A fault indication is issued if the battery is not connected properly. During the connection fault state, the connection verification operates every 2 seconds in order for the charger to recognize a newly inserted battery within 2 seconds. The verification utilizes the fact that a battery voltage cannot change very fast when being charged or discharged. The charger first discharges the battery with 6mA current for 250 ms. If the battery voltage does not fall below the 1.5 V threshold, then the battery is connected. Otherwise, the charger charges the battery. If the voltage moves above the recharge threshold or stays below 1.5 V within 250 ms, then the battery is not connected properly (either open-circuited or short-circuited). Figure 21 shows the flow chart for the battery connection verification. The MC34674 has a built-in mechanism to detect if the battery is removed within 1.968 seconds during the charge completion state. Figure 22 shows the simplified analog circuit for this function. In each 1.968 second period, the MC34674 tries to discharge the output with a 585 μA current for 82ms. If during the 82 ms, the output voltage drops below the recharge threshold, the charger will enter the battery connection verification state. Otherwise, the charger remains in the charge completion state. To compensate for the discharge caused by the 585 μA current, the charger outputs a 24 μA current to the output during the whole 1.968 seconds. Both the current and time values for this purpose are well matched, the net output current is guaranteed within -4.0 μA to +2.0 μA to the output. 24uA BAT 585uA COUT ON OFF Figure 22. Simplified Battery Removal Detection Circuit. THERMAL REGULATION The charger has an internal thermal regulation loop. When the internal temperature reaches 110°C, the charger starts to reduce the charge current to prevent further temperature rise. The current is reduced just enough to maintain the internal temperature at 110°C. The thermal regulation loop removes the concern of thermal failure. INTERNAL TIMER An internal timer is offered to set the time reference for the charge time limit. The fast charge time is limited to 4.6 hours (typ.) and the trickle-charge time is limited to 1/8 of the above time. FLEXIBLE LED INDICATION The MC34674 has multiple LED indication schemes built in. Consult Freescale for additional indication schemes. CURRENT-LIMITED AC/DC REGULATOR The MC34674 has a special low thermal charging operation when powered with a current-limited AC/DC regulator. In the operation, the charge current is limited by the AC/DC regulator and the MC34674 operates as a switch during the CC-mode to minimize the heat generation. Refer to the Typical Applications section for more details. 34674 18 Analog Integrated Circuit Device Data Freescale Semiconductor FUNCTIONAL DESCRIPTION STATE DIAGRAMS STATE DIAGRAMS PWR OFF Charger: OFF LED: OFF VIN > VPOR Not Enabled ENABLE VERIFICATION DISABLE VERIFICATION POWER PRESENCE INDICATION Charger: OFF LED: RGYO Charger: OFF LED: OFF Disable verified Charger: unchange LED: no change Anytime EN pin Disable not verified, changes to resume to previous disable operation POR Charger: OFF LED: OFF Enabled 0.5-sec DELAY Charger: OFF LED: OFF BATTERY CONNECTION FAULT BATTERY CONNECTION VERIFICAION Charger: OFF LED: OFF TEMP and OV fault removed TEMP/OV FAULT Bad connection Charger: OFF LED: YELLOW Good connection Charger: OFF LED: YELLOW VBAT < VTRKL when 1/8 TIMEOUT completes TRICKLE CHARGE Anytime a TEMP or OV Fault occurs (except in TIMEOUT fault) Charger: ON LED: RED VBAT drops below VTRKL VBAT > VTRKL before 1/8 TIMEOUT completes Charger: OFF LED: YELLOW EN pin changes to Disable To Disable Verification FAST CHARGE Charger: ON LED: RED VBAT > VRECH and ICHG < IEOC TIMEOUT FAULT TIMEOUT CHARGE COMPLETION VBAT > VRECH and ICHG < IEOC or TIMEOUT completes Charger: OFF LED: GREEN VBAT < VRECH BATTERY CONNECTION VERIFICATION VBAT drops below VTRKL Bad connection Charger: OFF LED: GREEN Good connection RECHARGE Charger: ON LED: GREEN Figure 23. 34674 Flow Chart 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 19 TYPICAL APPLICATIONS INTRODUCTION TYPICAL APPLICATIONS INTRODUCTION The MC34674 can be used as a regular linear charger with the charge current set internally. However, the best way of using this device in the travel charger application is to use this IC together with a current-limited AC/DC regulator. Select a version with the internally set current higher than the target charge current and then power the charger with an AC/DC regulator whose output current is limited to a value lower. This section introduces how to use the MC34674 with a current-limited AC/DC regulator. Also discussed in this section is the application information. The trickle-charge mode can be illustrated both on the I/V characteristics plot in Figure 25 and the time domain charge curve in Figure 26. In the I/V characteristics trajectory, the battery voltage moves from point a to point b, representing that the current remains at the trickle mode charge current, ITRKL while the battery voltage moves from a value below the trickle-charge threshold, VTRKL, to the trickle-charge threshold. The AC/DC regulator output stays at point A during the trickle mode with no changes for its output current and voltage. CURRENT-LIMITED AC/DC REGULATOR A current-limited AC/DC regulator has an output current and voltage characteristics shown in Figure 24. The regulator outputs a no load voltage, VNL, when the supply is not loaded. As the load current increases, the output voltage remains relatively constant. When the load current reaches the current limit of the regulator, ILIM, the regulator output behaves as a constant current source. Usually a currentlimited regulator output is specified in a range, as the range limited by the dotted lines. OPERATION WITH CURRENT-LIMITED AC/DC REGULATOR The operation of the MC34674 when powered by a current-limited regulator is dependent on the battery voltage. Figure 25 and Figure 26 assist the explanation of the operation. When the battery voltage is lower than the trickle-charge threshold, the MC34674 is in the trickle mode. The trickle mode current is typically lower than the current limit, ILIM, and hence the AC/DC regulator output is a constant-voltage. The MC34674 operates same as a regular linear charger. V VNL E ac/dc regulator output A D d C 4.2V e VTRKL B b a c MC34674 output IEOC ITRKL ILIM I Figure 25. AC/DC Regulator Output and MC34674 Output I/V Characteristics. VIN V VBAT VNL IBAT Time ILIM ITRKL Time a ILIM I A b c A B d e C D E Figure 24. AC/DC Regulator Output I/V Characteristics. Figure 26. Charging Waveforms When Powered with Current-Limited Regulators. 34674 20 Analog Integrated Circuit Device Data Freescale Semiconductor TYPICAL APPLICATIONS INTRODUCTION When the battery voltage rises above the trickle charge threshold, the charger enters the CC-mode. The MC34674 tries to raise the charge current to the internally set reference, such as 1.05 A, by enhancing the power MOSFET. However, since the current provided by the AC/DC regulator is limited and can never reach the set reference, the charger will keep enhancing the MOSFET until it is fully enhanced and is fully turned on. In this mode, the internal power MOSFET behaves as a switch instead of a linearly regulating device. The voltage difference between the input and the output is determined by the on resistance, RDS(ON), of the power MOSFET and the limited output current of the ad/dc regulator. V IN – V OUT = I LIM × R DS ( ON ) The power dissipation, PD, in the MOSFET can be calculated as, P D = I LIM × I LIM × R DS ( ON ) The charge current in CC-mode is not determined by the MC34674, instead, it is determined by the AC/DC regulator current limit, ILIM, which is a value lower than the charger internally set current reference. The internally set current reference is used as a secondary protection threshold, in case if an AC/DC regulator with a wrong current limit is connected to the input. The key advantage of using the MC34674 with a currentlimited AC/DC regulator is the significant reduction of the power dissipation during the CC-mode. Figure 26 illustrates the small voltage difference between the input and the output of the charger, which is directly proportional to the power dissipation. When entering the CC-mode, the charger output I/V trajectory jumps from point b to c and then moves from c to d as the battery voltage rises to 4.2 V. The AC/DC regulator output trajectory moves from B to C, as shown in Figure 25. When the battery voltage reaches the target 4.2V, the charger enters the CV-mode. The charge current starts to decline and the AC/DC regulator output enters its constantvoltage mode. The charger then operates as a regular linear charger again until the charging completes. The battery I/V trajectory moves from d to the EOC moment (point e) while the AC/DC regulator output trajectory jumps from C to D and then moves to E at the EOC moment. BALANCING YELLOW COLOR IN LED The red and the green colors in the LED are driven by two matched 6.0 mA current sources. Such design ensured a consistent brightness of the LED over a large range of the input voltage. When both colors are turned on, the resulting color should be yellow. One can adjust the resulting color by adjusting the brightness of the individual color. A resistor can be added to reduce the brightness of one color, such as the R1 shown in Figure 27. VIN GRN R1 RED Figure 27. LED Color Balancing Scheme. INPUT CAPACITOR The input capacitor is used to reduce the input voltage transient that may cause instability. A 1.0 μF, X5R, 16 V rated ceramic capacitor is recommended for most applications. OUTPUT CAPACITOR For stable operation, an X5R ceramic capacitor with a minimum 1.0 μF nominal value is recommended at the output. The output capacitance should not be larger than 240 μF to allow the 585 μA current to discharge the capacitor voltage to the recharge threshold within 82 ms. NTC INTERFACE DESIGN The NTC interface is designed to be able to work with most types of NTC thermistors. This section describes in details how to select the two resistors RU and RS shown in Figure 19. In addition, the hysteresis and the tolerance of the temperature thresholds are discussed. The NCP15W104F03RC from Murata is used as an example for the calculations in this section. The partial temperature characteristics of the NCP15W104F03RC are given in Table 7. Table 7. NTC Thermistor Temperature Characteristics. Temp (°C) R-low (kΩ) R-center (kΩ) R-high (kΩ) -2 389.2453 398.6521 408.2455 -1 368.4960 377.1927 386.0560 0 348.9722 357.0117 365.1999 2 313.2543 320.1216 327.1067 3 296.9408 303.2866 309.7370 46 38.4596 39.2132 39.9778 47 36.8626 37.6010 28.3503 50 32.5022 33.1946 33.8983 53 28.7183 29.3660 30.0253 54 27.5694 28.2026 28.8474 ... 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 21 TYPICAL APPLICATIONS APPLICATIONS RU and RS Calculation Temperature Tolerance The two equations (equ. 2 and equ. 3) on page 16 can be further simplified as the following by substituting the KHOT and KCOLD with their typical values: R S = ( R COLD – ( 4 × R HOT ) ) ⁄ 3 equ. 4 R U = 2 × ( R COLD – R HOT ) ⁄ 3 equ. 5 The equ. 6 is also the basis for tolerance calculation. The errors of the internal voltage thresholds, external resistors and the thermistor resistance all contribute to the temperature error. For the low temperature threshold, TCOLD, the maximum thermistor resistance happens when the internal threshold is at its maximum, RU at its maximum and the RS at its minimum value. Assuming 1% accuracy for both RU and RS and taking the maximum value for the low temperature threshold from Table 4, the maximum thermistor resistance at the cold temperature is found to be R COLD, MAX = equ. 7 The RS equation requires R COLD ≥ 4 × R HOT , otherwise, the RS calculation results in a negative value. Assuming the target temperature window is from 0°C to 50°C, from Table 7 it can be found that RHOT = 33.1946 kΩ and RCOLD = 357.0117 kΩ. Using equ. 4 and equ. 5, one can find that R S = 74.74kΩ R U = 215.9kΩ Temperature Hysteresis The thermistor resistance can be found with equ. 1 on page 16, which can be simplified as KX ⋅ ( RS + RU ) – RS R NTC = -------------------------------------------------1 – KX equ. 6 Since the RS and RU have already been determined, the thermistor resistance can be found by replacing the KX with the Low Temperature Falling Threshold and the High Temperature Rising Threshold given in Table 4. The thermistor resistance at these two thresholds can be found as ′ R HOT = 38.51kΩ ′ R COLD = 320.6kΩ From Table 7 it is found that rising threshold for the cold temperature is about 2°C and the falling threshold for the hot temperature is between 46 to 47°C. Therefore the hystereses for the cold and the hot temperature is 2°C and 2 to 3°C respectively. 0.6741 × ( 74.74 × 0.99 + 215.9 × 1.01 ) – ( 74.74 × 0.99 ) --------------------------------------------------------------------------------------------------------------------------------------1 – 0.6741 = 377.0kΩ which corresponds to -1.4°C in the R-low column of Table 7. Similarly, the minimum thermistor resistance at the hot temperature, RHOT,MIN, happens when the internal threshold is at its minimum, RU at this minimum, and the RS at its maximum. Using the same method, the RHOT,MIN can be found to be 29.73 kΩ, which corresponds to 53°C approximately. Based on the above calculation, the tolerances for the cold and the hot temperatures are about 1.4°C and 3°C respectively. ESD ENHANCEMENT All pins in the MC34674 are rated 2.0 kV for the ESD performance with the Human Body Model (HBM). The end product usually requires higher ESP performance for the nodes that can be touched by human hands in normal usage of the end product. Three additional capacitors can be used to pass the ESD tests. Figure 28 shows how the three capacitors (C3, C4, and C5) are connected in the circuit. APPLICATIONS VIN Current Limited AC/DC Regulator BAT RU VREF C2 TEMP RED C1 GRN C3 C4 C5 GND RS NTC EN Figure 28. 34674 Typical Application Circuit C1 and C2 are for decoupling purposes. C3, C4 and C5 the cradle charger. C1 = 1.0 μF/16 V/X5R, C2 = 1.0μ F/6.3 V/ are to enhance the ESD performance of the travel charger or X5R, C3 = C4 = 0.1 μF/16 V/X5R, C5 = 0.1 μF/6.3 V/X5R. 34674 22 Analog Integrated Circuit Device Data Freescale Semiconductor PACKAGING PACKAGING DIMENSIONS PACKAGING PACKAGING DIMENSIONS For the most current package revision, visit www.freescale.com and perform a keyword search using the “98A” listed below. EP SUFFIX 8-PIN 98ASA10774D REVISION 0 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 23 PACKAGING PACKAGING DIMENSIONS EP SUFFIX 8-PIN 98ASA10774D REVISION 0 34674 24 Analog Integrated Circuit Device Data Freescale Semiconductor REVISION HISTORY REVISION HISTORY REVISION DATE DESCRIPTION OF CHANGES 1.0 1/2007 • Initial Release 2.0 11/2008 • • • Updated Freescale form and style Added Device Variations Made corrections to coincide with Device Variation table 34674 Analog Integrated Circuit Device Data Freescale Semiconductor 25 How to Reach Us: Home Page: www.freescale.com Web Support: http://www.freescale.com/support USA/Europe or Locations Not Listed: Freescale Semiconductor, Inc. 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