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| Freescale Semiconductor Advance Information Document Number: MC34673 Rev. 1.0, 01/2008 High Input Voltage 1.2A Charger for Single-cell Li-Ion Batteries The MC34673 is a cost-effective fully-integrated battery charger for Li-Ion or Li-Polymer batteries. The high input voltage, up to 28V, eliminates the input over-voltage protection circuit required in handheld devices such as PDAs, cell phones, portable video game players and digital still cameras. A typical charge cycle includes trickle, constant-current (CC) and constant-voltage (CV) charge modes. The CC-mode current is programmable up to 1.2A with an external resistor. The voltage across the external resistor is also used to monitor the actual charge current. The constant voltage is fixed at 4.2V with 0.7% accuracy over a -20C to 70C temperature range. The trickle-mode current is preset to 20% of the CC-mode current when the battery voltage is lower than the trickle-mode threshold. The end-of-charge (EOC) current threshold is preset to 10% of the CC-mode current to save the board space and cost. A charge current thermal foldback feature limits the charge current when the IC internal temperature rises to a preset threshold. The MC34673 also protects the system with its input over-voltage protection (OVP) feature. In addition, the MC34673 has a 2.6V falling power-on-reset (POR) threshold, making it perfect to work with current limited power supplies. Three indication pins (PPR, CHG and FAST) can be simply interfaced to a microprocessor or LEDs. When no power supply is connected, or when disabled, the charger draws less than 1.0A leakage current from the battery. 34673 POWER MANAGEMENT IC EP SUFFIX (PB-FREE) 98ASA10774D 8-PIN UDFN ORDERING INFORMATION Device MC34673AEP/R2 Temperature Range (TA) -40C to 85C Package 8-UDFN Features * No external MOSFET, reverse-blocking diode or current-sense resistor are required * Guaranteed maximum 1.2A programmable CC-mode current * 0.7% voltage accuracy over -20C to 70C * 6% current accuracy over -40C to 85C * 28V maximum voltage for the power input with 6.8V over-voltage protection threshold * 2.6V minimum input operating voltage * Trickle charge for fully discharged batteries * Charge current monitor * Charge current thermal foldback * Pb-free packaging designated by suffix code EP VIN CIN 34673 VIN GND BAT COUT ISET TO BATTERY CHG OFF ON RISET PPR EN FAST VIO TO MCU Figure 1. 34673 Simplified Application Diagram * This document contains certain information on a new product. Specifications and information herein are subject to change without notice. (c) Freescale Semiconductor, Inc., 2007-8. All rights reserved. INTERNAL BLOCK DIAGRAM INTERNAL BLOCK DIAGRAM VIN BAT - VIN Monitor Internal Supply Charge Control REF + VREF - + ISET IREF PPR VIN + - BAT CHG EN Logic Control VOS + - - + Die Temp 110C + - IEOC FAST GND Figure 2. 34673 Simplified Internal Block Diagram 34673 2 Analog Integrated Circuit Device Data Freescale Semiconductor PIN CONNECTIONS PIN CONNECTIONS VIN PPR CHG EN 1 2 EPAD 3 4 8 7 6 5 BAT ISET FAST GND Figure 3. 34673 Pin Connections Table 1. 34673 Pin Definitions A functional description of each pin can be found in the Functional Pin Description section beginning on page 11. Pin Number 1 2 3 4 5 6 7 Pin Name VIN PPR CHG EN GND FAST ISET Pin Function Input Output Output Input Ground Output Output Formal Name Input supply Power present indicator Charge indicator Enable Ground Fast charge indicator CC-mode current setting and charge current monitor Charger output Exposed pad The supply input. Indication of the input power status. Open drain output. Indication of the charge status. Open drain output. Enable logic input. Ground. Indication of the fast charge status. Open drain output. CC-mode current setting and monitoring pin. Definition 8 EPAD BAT EPAD Output N/A The charger output pin. Connect this pin to the Li-Ion 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. 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 3 ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS Table 2. 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 ELECTRICAL RATINGS Input Voltage Range VIN Pin PPR and CHG Pins EN, BAT, ISET, and FAST Pins ESD Voltage(1) Human Body Model (HBM) Machine Model (MM) THERMAL RATINGS Operating Temperature Ambient Junction Storage Temperature Thermal Resistance(2) RJC RJA Reflow(3),(4) TPPRT 10 70 Note 4 C TA TJ TSTG -40 to 85 -40 to 150 -65 to +150 C C/W C VESD 2000 200 VIN VPPR, VCHG VEN, VBAT, VISET, VFAST -0.3 to 28 -0.3 to 12 -0.3 to 5.5 V V Symbol Value Unit Junction-to-Case Junction-to-Ambient Peak Package Reflow Temperature During Notes 1. ESD testing is performed in accordance with the Human Body Model (HBM) (CZAP = 100pF, RZAP = 1500), and the Machine Model (MM) (CZAP = 200pF, RZAP = 0). 2. 3. 4. 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. 34673 4 Analog Integrated Circuit Device Data Freescale Semiconductor ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 3. Static Electrical Characteristics Characteristics noted under conditions VIN = 5.0V, -40C TA 85C, CIN =1F, COUT = 2.2F (see Figure 1), unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5.0V and TA = 25C under nominal conditions, unless otherwise noted. Characteristic POWER INPUT Input Voltage Range(5) VIN Pin Supply Current Charger enabled(6) Charger disabled Regulated Output Voltage VIN = 5.0V; IBAT = 10mA; TA = 25C VIN = 5.0V; IBAT = 10mA; TA = -20 to 70C VIN = 5.0V; IBAT = 10mA; TA = -40 to 85C Power MOSFET On Resistance VBAT = 4.0V; IBAT = 500mA; ICHG = 600mA BAT Pin Standby Current VIN not powered or charger disabled Power On Reset Rising VIN threshold Falling VIN threshold VIN-BAT Offset Voltage Rising threshold Falling threshold Over-voltage Protection Rising Threshold Over-voltage Protection-Threshold Hysteresis CHARGE CURRENT Constant-current Mode Charge Current Range(7) ICHG Accuracy For ICHG between 300mA to 1200mA (Tested at 450mA) For ICHG between 50mA to 300mA(7) Trickle-Mode Charge Current End-of-Charge (EOC) Threshold When ICHG is set to 450mA ISET Pin Voltage for ICHG Reference(7) VISET ITRKL IEOC 35 45 1.0 55 V ICHG ICHG 94 90 16 100 100 20 106 110 24 % ICHG mA 0.05 1.2 A % VOVP VOVPHYS VOS 1.0 6.6 6.8 400 60 22 7.0 V mV VPOR 3.0 2.4 3.9 2.6 mV ISTDBY 1.0 V RDS(ON) 330 475 A VBAT 4.185 4.170 4.158 4.20 4.20 4.20 4.215 4.230 4.230 m VIN IIN 1400 350 V 2.6 6.6 V A Symbol Min Typ Max Unit Notes 5. Refer to the Power-on-Reset parameter for VIN turn on and turn off values. 6. 7. Supply current does not include the current delivered to the battery through the BAT pin. Not tested. Guaranteed by design. 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 5 ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 3. Static Electrical Characteristics (continued) Characteristics noted under conditions VIN = 5.0V, -40C TA 85C, CIN =1F, COUT = 2.2F (see Figure 1), unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5.0V and TA = 25C under nominal conditions, unless otherwise noted. Characteristic CHARGE THRESHOLDS Trickle-Mode Rising Threshold Voltage Trickle-Mode Threshold Voltage Hysteresis Recharge Threshold Voltage Recharge Falling Threshold Voltage Hysteresis LOGIC INPUT AND OUTPUT EN Input High Threshold Voltage EN Input Low Threshold Voltage EN Input Leakage Current VEN = 3.0V PPR and CHG Sink Current When the Output is Low VCHG =VPPR = 0.6V PPR and CHG Leakage Current When the Output is High-impedance VCHG =VPPR = 5.0V FAST Sink Current When the Output is Low VFAST = 0.5.0V FAST Leakage Current When the Output is High-impedance VFAST = 3.0V CHARGE CURRENT THERMAL FOLDBACK Current Foldback Die Temperature Limit TLIMIT 95 110 125 C IFLEAKH 1.0 IFSINKL 0.3 A IPCLEAKH 1.0 mA IPCSINKL 12 15 A VIH VIL IEN 2.0 7.5 mA 1.5 0.5 V V A VTRKL VTRKLHYS VRECH VTHRCHG Symbol Min Typ Max Unit 2.6 40 4.060 - 2.7 100 4.100 25 2.8 150 4.140 50 V mV V mV 34673 6 Analog Integrated Circuit Device Data Freescale Semiconductor ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS Table 4. Dynamic Electrical Characteristics Characteristics noted under conditions VIN = 5.0V, -40C TA 85C, CIN =1F, COUT = 2.2F (Figure 1), unless otherwise noted. Typical values noted reflect the approximate parameter means at VIN = 5.0V and TA = 25C under nominal conditions, unless otherwise noted. Characteristic END OF CHARGE EOC Filter Time OSCILLATOR Oscillation Frequency fOSC 40.0 50.0 60.0 kHz tEOC 5.5 8.0 11 ms Symbol Min Typ Max Unit 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 7 ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES ELECTRICAL PERFORMANCE CURVES Constant Charge Current ( mA) 5.0 4.5 Battery Voltage (V) 4.0 3.5 3.0 2.5 2.0 1.5 0 20 40 Charge Current Battery Voltage 350 1500 RISET=3.23 k 250 200 150 100 50 Charge Current (mA) 300 1200 900 600 300 RISET=6.57 k RISET=13.3 k 60 80 0 100 120 3.5 4.0 4.5 Figure 4. Complete Charge Cycle VIN = 5.0V, ICHG=300mA, TA = 25C Charge Time ( min) 5.0 VIN (V) 5.5 6.0 6.5 Figure 7. Constant Charge Current vs VIN VBAT = 3.0V, TA = 25C Trickle Charge Current ( mA) 4.4 4.2 VBAT ( V) 4.0 3.8 3.6 4.0 4.5 5.0 5.5 VIN (V) 6.0 6.5 250 200 150 100 RISET=3.23 k RISET=6.57 k RISET=13.3 k 50 0 3.5 4.0 4.5 5.0 VIN (V) 5.5 6.0 6.5 Figure 5. VBAT vs VIN IBAT = 0mA, TA = 25C Figure 8. Trickle Charge Current vs VIN VBAT = 2.0V, TA = 25C 3000 VIN Pin Supply Current ( A) 2500 2000 1500 1000 500 Charger Disabled 1.2 1.0 0.8 VISET ( V) Charger Enabled 0.6 0.4 0.2 0.0 4.4 4.8 5.2 5.6 VIN (V) 6.0 6.4 6.8 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 VIN (V) Figure 6. VIN Pin Supply Current vs VIN IBAT=0mA, TA = 25C Figure 9. VISET vs VIN VBAT = 3.9V, TA = 25C 34673 8 Analog Integrated Circuit Device Data Freescale Semiconductor ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES 1.0 0.8 VISET (V) 0.6 0.4 0.2 0.0 0 RISET=13.3 k RISET=6.57 k RISET=3.23 k Constant Charge Current ( mA) 1.2 1200 1000 800 600 400 200 0 -40 -20 0 20 40 o RISET=3.95 k RISET=6.11 k RISET=19.36 k 200 400 600 800 1000 1200 Charge Current (mA) 60 80 Temperature ( C) Figure 13. Constant Charge Current vs Temperature VIN = 5.0V, VBAT = 3.9V Figure 10. VISET vs Charge Current VIN = 5.0V, TA = 25C Charge Current ( mA) 1200 900 600 300 RISET=3.23 k Trickle Charge Current ( mA) 1500 250 200 150 100 50 0 -40 -20 0 20 40 o RISET=3.95 k RISET=6.11 k RISET=6.57 k RISET=13.3 k RISET=19.36 k 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 VBAT (V) Figure 11. Charge Current vs VBAT VIN = 5.0V, TA = 25C 60 80 Temperature ( C) Figure 14. Trickle Charge Current vs Temperature VIN = 5.0V, VBAT = 2.0V 4.30 4.25 4.20 VBAT (V) 1.2 1.0 0.8 VISET (V) 4.15 4.10 4.05 4.00 -40 -20 0 20 40 o 0.6 0.4 0.2 60 80 0.0 -40 -20 0 20 40 o 60 80 Temperature ( C) Figure 12. VBAT vs Temperature VIN = 5.0V, IBAT = 0mA Figure 15. VISET vs Temperature VIN = 5.0V Temperature ( C) 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 9 ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES BAT Pin Supply Current ( A) 450 400 RDS(ON) ( m) 350 300 250 -40 1.0 0.8 0.6 0.4 0.2 0.0 -40 -20 0 20 40 o -20 0 20 40 o 60 80 60 80 Figure 16. RDS(ON) vs Temperature VBAT = 4.0V, ICHG=300mA, IBAT= 250mA Temperature ( C) Temperature ( C) Figure 18. BAT Pin Supply Current vs Temperature VBAT = 5.0V, VIN Not Powered or Charger Disabled Recharge Voltage Threshold (V) 4.20 VIN Pin Supply Current ( A) 2000 1750 1500 1250 1000 750 500 250 0 -40 -20 0 20 Charger Disabled Charger Enabled 4.15 4.10 4.05 4.00 3.95 3.90 -40 -20 0 20 40 o 60 80 40 o 60 80 Temperature ( C) Temperature ( C) Figure 19. VIN Pin Supply Current vs Temperature VIN = 5.0V Figure 17. Recharge Voltage Threshold vs Temperature RISET = 25.86k, VIN = 5.0V 34673 10 Analog Integrated Circuit Device Data Freescale Semiconductor FUNCTIONAL DESCRIPTION INTRODUCTION FUNCTIONAL DESCRIPTION INTRODUCTION The MC34673 is a fully-integrated Li-Ion and Li-Polymer battery charger in a tiny package. It uses current, voltage and temperature control loops to regulate the charge current. It has up to 28V input voltage rating, which makes the handheld device safe even when connected to a wrong AC adapter. The MC34673 requires only two external capacitors and one resistor to build a fully functional charger for spacelimited applications such as PDAs, cell phones, portable video game players and digital still cameras. Its ultra highaccuracy (0.7%) output voltage and temperature-limited charging current offer additional battery safety during charging. The CC-mode current can be programmed with an external resistor (RISET). The voltage across this resistor is proportional to the charge current, so the system can monitor the charge current during the whole charge cycle. The EOC current threshold is preset to 10% of the CC-mode current. For a deeply discharged battery with a voltage lower than 2.7V, the MC34673 charges the battery with a trickle-mode current, which is 20% of the CC-mode current. Three indication outputs make it easy to report the input power status and the charge status to MCUs, or users via LEDs. FUNCTIONAL PIN DESCRIPTION INPUT SUPPLY (VIN) The supply input. This pin should be bypassed to ground with a 1.0F capacitor. mode threshold. This pin is capable to sink more than 0.3mA current. When the charger is on, this pin outputs a logic low signal if the battery voltage is higher than the trickle-mode threshold. When the charger is in the shutdown mode or in any fault conditions, this pin outputs high-impedance. POWER PRESENT INDICATOR (PPR) Open-drain logic output to indicate the input power status. The PPR-pin output is only determined by the input voltage, not other conditions such as the EN pin input. The output is low if VIN is higher than VPOR. This pin is capable to sink at least 12.0mA current to drive a LED indicator. CC-MODE CURRENT SETTING AND CHARGE CURRENT MONITOR (ISET) The CC-mode current, ICHG, is programmed by connecting a resistor, RISET, between this pin and the ground. When charging in the CC-mode, the voltage at this pin is 1.0V. The voltage reduces proportionally as the charge current reduces in the CV-mode. During the whole charge cycle, the voltage at this pin can be used to monitor the charge current using the following equation: V ISET I BAT = -------------- I CHG 1.0V equ. 1 CHARGE INDICATOR (CHG) Open-drain logic output to indicate the charge status. The output is low when the MC34673 is charging, until the EOC conditions are reached. This pin is capable to sink at least 12.0mA current to drive a LED indicator. ENABLE (EN) Active-low enable logic Input. This pin is internally pulled to ground by a weak current source. When left floating, the charger is enabled. Pulling this pin to high voltage externally disables the charger. where IBAT is the actual charge current, ICHG is the programmed CC-mode current, and VISET is the voltage of the ISET pin during the whole charge cycle. CHARGER OUTPUT (BAT) Charger output pin. Connect this pin to the battery being charged. Bypass to ground with a 2.2F or higher capacitor. GROUND (GND) Ground. FAST CHARGE INDICATOR (FAST) When charging, this open-drain logic output indicates whether or not the battery voltage is higher than the trickle- EXPOSED PAD (EPAD) Exposed 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. 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 11 FUNCTIONAL DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION MC34673 - Functional Block Diagram Integrated Supply Internal Supply & Reference Sensing & Control VIN Monitor Charge Control Current Setting Current Monitor End of Charge VIN - BAT Compare Power MOSFET Die Temperature Feedback Logic Logic Control Status Indication Integrated Supply Sensing & Control Logic MOSFET Figure 20. 34673 Functional Internal Block Diagram INTEGRATED SUPPLY INTERNAL SUPPLY AND REFERENCE This block steps down the high input voltage to a lower voltage to power all the internal blocks. In addition, this block generates the reference voltage for the charge-control block. CURRENT SETTING AND MONITOR This block programs the charge current in the constantcurrent mode and monitors the actual charge current during the whole charge cycle. EOC (END OF CHARGE) The EOC block monitors the charge current and the battery voltage for the EOC conditions. Once the EOC conditions are reached, this block outputs a logic signal to indicate the end of the charge. SENSING AND CONTROL VIN MONITOR The input voltage 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. VIN-BAT COMPARATOR The VIN-BAT comparator monitors the voltage difference between the input voltage and the battery voltage. 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. 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. Also, monitoring of the charge current and the charger output voltage determines the trickle-charge mode and the recharge cycle. DIE TEMPERATURE FEEDBACK The die temperature feedback block monitors the die temperature. Once the die temperature reaches the threshold temperature, the charge-control block can reduce the charge current to prevent further die temperature rise. 34673 12 Analog Integrated Circuit Device Data Freescale Semiconductor FUNCTIONAL DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION LOGIC LOGIC CONTROL AND STATUS INDICATION The logic control block determines the on and off of the charger. It takes the signals from the VIN Monitor, VIN-BAT Comparator, EOC, and the external enable signal, and determines the on and off states as well as the charge status indication outputs of the charger (CHG, PPR, and FAST). POWER MOSFET The power MOSFET passes the charging current from the input to the output. 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 13 FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES CHARGE CYCLE The MC34673 uses the standard charge profile with trickle, constant-current (CC), and constant-voltage (CV) charge modes, as shown in Figure 21. Both the CC and the CV charge modes are also called fast-charge mode. When the input voltage rises above an internal power-on-reset threshold, the PPR pin outputs a low voltage to indicate the power-supply presence. The charger starts with the tricklecharge mode until the battery voltage is above 2.7V. The CHG pin outputs logic low voltage at the beginning of the trickle-charge mode. If the battery voltage is unable to rise due to a battery failure, charging will remain in the tricklecharge mode. When the battery voltage reaches the 2.7V threshold, the MC34673 softly changes to the CC-mode. The soft transition minimizes the input-voltage drop and reduces the requirement of the input decoupling capacitance. In the fast-charge mode, the FAST pin outputs a low voltage. When the battery voltage reaches 4.2V, the MC34673 enters the CV-mode and regulates the output voltage at 4.2V. The charge current decreases gradually in the CV-mode. When the current drops to the EOC current threshold, the MC34673 outputs logic high voltage at the CHG pin to indicate that the charging is completed. After the charging is completed, the MC34673 continues to regulate the output to 4.2V, and monitors the output voltage. If a load is in parallel with the battery, the charger continues to output the current to the load even the charge is completed. If the load current exceeds the programmed CCmode current, the battery will supply the additional current to the load and the battery voltage will decline. Once the battery voltage drops below the recharge voltage threshold, the MC34673 returns to the fast-charge mode and indicates a low voltage at the CHG pin. When one of the following three conditions happens, the MC34673 is disabled. 1. VIN > VOVP 2. VIN - VBAT < VOS 3. EN pin is high where VOS is the offset voltage for the comparator that monitors the input and the battery voltages. Figure 22 shows the complete charge-cycle state diagram. Trickle Constant Current Constant Voltage ILOAD >ICHG 4.2V ICHG Charge Voltage 100mV 2.7V ITRKL Charge Current IEOC TIME CHG TIME FAST TIME Figure 21. Charge Profile CHARGE CURRENT SETTING An external resistor between the ISET pin and the ground programmes the CC-mode current with the following equation: 4000 I CHG = -------------------------R ISET + 96 equ. 2 where RISET is the resistor between the ISET pin and the ground in . In addition, the current out of the ISET pin is proportional to the charge current. The system may measure 34673 14 Analog Integrated Circuit Device Data Freescale Semiconductor FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES the ISET pin voltage to monitor the actual charge current as given in equ. 1 during the whole charging cycle. INPUT POWER PRESENCE INDICATOR When VIN is applied and the voltage is above the power-onreset voltage threshold (VPOR), the PPR pin outputs a low voltage to indicate the input power presence. The PPR output is only controlled by the input voltage. All other functions, such as the EN pin, the over-voltage protection, and the VINBAT comparator, do not affect the PPR output. The PPR pin is capable to sink at least 12.0mA current when outputting a low voltage to drive an external LED. CHARGE CURRENT LIMITATION The charge current is limited by multiple factors. When the voltage difference between the input and the battery (VIN - VBAT) is low, (VIN - VBAT) / RDS(ON), where RDS(ON) is the on resistance of the power MOSFET, may be less than the programmed CC-mode current ICHG. The charge current is limited by (VIN - VBAT) / RDS(ON) in this case. When the voltage difference between the input and the battery is too high, the large power dissipation may lead to the charge-current thermal-foldback operation due to the die temperature regulation. The charge current is reduced to prevent further temperature rise (See Charge Current Thermal Foldback). CHARGE STATUS INDICATORS The MC34673 has two charge status indicators, CHG and FAST. CHG outputs a low voltage when the charger is enabled and the charging is in progress. When the charge cycle completes, CHG outputs high-impedance. If the charger is disabled or the input voltage is out of the powergood range, the CHG pin outputs high-impedance as well. The CHG pin has at least 12.0mA current-sinking capability to drive an external LED, same as the PPR pin. FAST indicates whether the MC34673 is in the fast-charge mode or not. When the charger is on and the battery voltage is higher than the trickle-mode threshold, the charger enters the fast-charge mode and FAST outputs a low voltage. The open-drain FAST pin requires a pull-up resistor to output the logic signal. If the charger is in the trickle-charge mode or is disabled, or when the input voltage is out of the power-good range, the FAST pin outputs high-impedance. DC INPUT VOLTAGE The MC34673 accepts up to 28V DC input. When all of the following conditions are satisfied, the input is in a power-good range for the charger to start charging. The conditions include: 1. VIN > VPOR 2. VIN - VBAT > VOS 3. VIN < VOVP where VOS is the offset voltage for the comparator that monitors the input and the battery voltages. The VOS is for preventing the reverse leakage current from the battery when the power supply is off. VOVP is the over-voltage protection threshold. When the DC input voltage is above the overvoltage protection threshold, the charger is disabled internally. The 28V input voltage rating eliminates the need of any additional input over-voltage protection circuitry. CHARGE CURRENT THERMAL FOLDBACK An internal thermal feedback loop begins to reduce the charge current when the die temperature reaches 110C to prevent further temperature rise. This feature protects the MC34673 from over-temperature failures and allows the user to push the limits of the power handling capability of a given circuit board without the risk of damaging the MC34673. The charge current can be programmed according to the typical (not the worst-case) ambient temperature with the assurance that the charger will automatically reduce the current in worstcase conditions. CHARGE-ENABLE INPUT The charge-enable input, EN, has a weak internal pulldown current. Driving it to a low logic voltage, leaving it floating, or shorting it to the ground will enable the charger, if the input voltage is in the power-good range. Whenever the EN pin is driven to a high logic voltage, the charger is disabled. 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 15 FUNCTIONAL DEVICE OPERATION STATE DIAGRAM STATE DIAGRAM Charger: OFF VIN>VPOR EN=high or VIN>VOVP or VIN VIN Charger: OFF VBAT < 2.7V EN=low and VIN VBAT > 2.7V Charger: ON TRICKLE CHARGE VBAT < 2.7V FAST CHARGE Charger: ON VBAT=4.2V and IBAT < IEOC VBAT<4.10V CHARGE COMPLETE Charger: ON Figure 22. Charge Cycle State Diagram 34673 16 Analog Integrated Circuit Device Data Freescale Semiconductor TYPICAL APPLICATIONS INTRODUCTION TYPICAL APPLICATIONS INTRODUCTION INPUT CAPACITOR The input capacitor is used to reduce the input voltage transient that may cause instability. A 1.0F, X5R, 16V rated ceramic capacitor is recommended for most applications. DROPOUT VOLTAGE If the DC input voltage is too low, it may not maintain the programmed CC-mode charge current due to the voltage dropout over the power MOSFET. The worst case of the RDS(ON) is 475m. The input voltage should be at least higher than VBAT + ICHG x 475m to guarantee the programmed CC-mode current. OUTPUT CAPACITOR For stable operation, an X5R ceramic capacitor with a minimum 2.2F nominal value is recommended at the output. Depending on the load transient current, larger capacitance may be required. THERMAL CONSIDERATIONS The MC34673 is available in a tiny 2x3 thermallyenhanced UDFN package. A careful thermal design must be considered. The exposed pad needs to be well soldered to a large copper ground plane on the component layer. If the component layer is space limited and does not allow for a large copper plane, the thermal pad must be connected to other ground layers through a via array. This allows MC34673 to charge the battery with the maximum current, while minimizing the die temperature. CC-MODE CURRENT SETTING The CC-mode current can be programmed by the external resistor, RISET. A 1% accuracy resistor is recommended to guarantee 6% current accuracy. APPLICATIONS STAND-ALONE CHARGER The MC34673 can be used in a standalone charger without MCUs. Figure 23 shows such an application. The green LED indicates the power presence and the red LED indicates the charge status. In total, only 7 external components are required. Input 1F GREEN RED VIN GND BAT MC34673 ISET 5.23k 2.2F Li+ 470 470 CHG PPR EN FAST Figure 23. Stand Alone Li+ Battery Charger 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 17 TYPICAL APPLICATIONS APPLICATIONS MCU INTERFACED CHARGER When the charger is used in handheld systems with MCU control, the MC34673 uses PPR to report the DC input status to the MCU. After the MCU pulls the EN pin to a logic-low voltage to start charging, the MC34673 reports the charge status through CHG and FAST pins to the MCU. The MCU can also monitor the charge current by measuring the voltage at the ISET pin. Figure 24 is the typical application circuit. Input 1F VIN GND BAT 2.2F Li+ VIO 100kx3 ISET CHG 5.23k PPR FAST EN MCU OFF ON Figure 24. MCU Interfaced Charger 34673 18 Analog Integrated Circuit Device Data Freescale Semiconductor TYPICAL APPLICATIONS PACKAGE DIMENSIONS PACKAGE 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 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 19 TYPICAL APPLICATIONS PACKAGE DIMENSIONS EP SUFFIX 8-PIN 98ASA10774D REVISION 0 34673 20 Analog Integrated Circuit Device Data Freescale Semiconductor REVISION HISTORY REVISION HISTORY REVISION 1.0 DATE 1/2008 DESCRIPTION OF CHANGES * Initial Release 34673 Analog Integrated Circuit Device Data Freescale Semiconductor 21 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. Technical Information Center, EL516 2100 East Elliot Road Tempe, Arizona 85284 +1-800-521-6274 or +1-480-768-2130 www.freescale.com/support Europe, Middle East, and Africa: Freescale Halbleiter Deutschland GmbH Technical Information Center Schatzbogen 7 81829 Muenchen, Germany +44 1296 380 456 (English) +46 8 52200080 (English) +49 89 92103 559 (German) +33 1 69 35 48 48 (French) www.freescale.com/support Japan: Freescale Semiconductor Japan Ltd. Headquarters ARCO Tower 15F 1-8-1, Shimo-Meguro, Meguro-ku, Tokyo 153-0064 Japan 0120 191014 or +81 3 5437 9125 support.japan@freescale.com Asia/Pacific: Freescale Semiconductor Hong Kong Ltd. Technical Information Center 2 Dai King Street Tai Po Industrial Estate Tai Po, N.T., Hong Kong +800 2666 8080 support.asia@freescale.com For Literature Requests Only: Freescale Semiconductor Literature Distribution Center P.O. Box 5405 Denver, Colorado 80217 1-800-441-2447 or 303-675-2140 Fax: 303-675-2150 LDCForFreescaleSemiconductor@hibbertgroup.com Information in this document is provided solely to enable system and software implementers to use Freescale Semiconductor products. There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document. Freescale Semiconductor reserves the right to make changes without further notice to any products herein. Freescale Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Freescale Semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "Typical" parameters that may be provided in Freescale Semiconductor data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals", must be validated for each customer application by customer's technical experts. Freescale Semiconductor does not convey any license under its patent rights nor the rights of others. Freescale Semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Freescale Semiconductor product could create a situation where personal injury or death may occur. Should Buyer purchase or use Freescale Semiconductor products for any such unintended or unauthorized application, Buyer shall indemnify and hold Freescale Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Freescale Semiconductor was negligent regarding the design or manufacture of the part. FreescaleTM and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. (c) Freescale Semiconductor, Inc., 2007-8. All rights reserved. MC34673 Rev. 1.0 01/2008 |
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