34671 NXP | Alldatasheet
Document overview
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Technical content
Features
- No external MOSFET, reverse-blocking diode or current-sense resistor are required
- Guaranteed maximum 600mA programmable CC-mode current
- ±0.7% voltage accuracy over -20°C to 70°C
- ±5% current accuracy over -40°C to 85°C
- 28V maximum voltage for the power input wi th 11V 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
Figure 1. 34671 Simplified Application Diagram
ORDERING INFORMATION
Range (TA) Package MC34671AEP/R2 -40°C to 85°C 8-UDFN VIN ON OFF VIN GND CHG PPR EN BAT ISET FAST TO BATTERY TO MCU VIO 34671 CIN COUT RISET
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Figure 2. 34671 Simplified Internal Block Diagram
Figure 3. 34671 Pin Connections Table 1. 34671 Pin Definitions A functional description of each pin can be found in the Functional Pin Description section beginning on page 11. 1 VIN Input Input supply The supply input.
2 PPR Output Power present
Indication of the input power status. Open drain output. 3 CHG Output Charge indicator Indication of the charge status. Open drain output. 4 EN Input Enable Enable logic input. 6 FAST Output Fast charge indicator Indication of the fast charge status. Open drain output.
7 ISET Output CC-mode current
CC-mode current setting and monitoring pin. 8 BAT Output Charger output The charger output pin. Connect this pin to the Li-Ion battery. the large ground plane on the PCB to increase the thermal dissipation. The pad must be connected to GND electrically.
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ELECTRICAL CHARACTERISTICS
Table 2. Maximum Ratings permanent damage to the device.
- ESD testing is performed in accordance with the Human Body Model (HBM) (C ZAP = 100pF, RZAP = 1500Ω), and the Machine Model
- Device mounted on the Freescale EVB test board per JEDEC DESD51-2.
- Pin soldering temperature limit is for 10 seconds maximum dura tion. 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
and enter the core ID to view all orderable parts. (i.e. MC33xxxD enter 33xxx), and review parametrics.
Analog Integrated Circuit Device Data Freescale Semiconductor 5 34671 STATIC ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 3. Static Electrical Characteristics conditions, unless otherwise noted.
- Refer to the Power-on-Reset parameter for V IN turn on and turn off values.
- Supply current does not include the current delivered to the battery through the BAT pin.
- Not tested . Guaranteed by design.
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STATIC ELECTRICAL CHARACTERISTICS CHARGE THRESHOLDS Trickle-mode Rising Threshold Voltage VTRKL 2.6 2.7 2.8 V Trickle-mode Threshold Voltage Hysteresis VTRKLHYS 40 100 150 mV Recharge Falling Threshold Voltage VRECH 4.060 4.100 4.140 V Recharge Threshold Voltage Hysteresis VTHRCHG - 25 50 mV LOGIC INPUT AND OUTPUT EN Input High Threshold Voltage VIH 1.5 - - V EN Input Low Threshold Voltage VIL - - 0.5 V EN Input Leakage Current VEN = 3.0V IEN - 2.0 7.5 µA PPR and CHG Sink Current When the Output is Low VCHG =VPPR = 0.6V IPCSINKL 12 15 - mA PPR and CHG Leakage Current When the Output is High-impedance VCHG =VPPR = 5.0V IPCLEAKH - - 1.0 µA FAST Sink Current When the Output is Low VFAST = 0.5.0V IFSINKL 0.3 - - mA FAST Leakage Current When the Output is High-impedance VFAST = 3.0V IFLEAKH - - 1.0 µA CHARGE CURRENT THERMAL FOLDBACK Current Foldback Die Temperature Limit TLIMIT 95 110 125 °C Table 3. Static Electrical Characteristics (continued) conditions, unless otherwise noted.
Analog Integrated Circuit Device Data Freescale Semiconductor 7 34671 DYNAMIC ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS Table 4. Dynamic Electrical Characteristics
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ELECTRICAL PERFORMANCE CURVES ELECTRICAL PERFORMANCE CURVES Figure 4. Complete Charge Cycle Figure 5. VBAT vs VIN Figure 6. VIN Pin Supply Current vs VIN Figure 7. Constant Charge Current vs VIN Figure 8. Trickle Charge Current vs VIN Figure 9. VISET vs VIN
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ELECTRICAL PERFORMANCE CURVES Figure 16. RDS(ON) vs Temperature Figure 17. Recharge Voltage Threshold vs Temperature Figure 18. BAT Pin Supply Current vs Temperature Figure 19. VIN Pin Supply Current vs Temperature
Analog Integrated Circuit Device Data Freescale Semiconductor 11 34671 FUNCTIONAL DESCRIPTION INTRODUCTION FUNCTIONAL DESCRIPTION INTRODUCTION The MC34671 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 a 28V input voltage rating, which makes the handheld device safe even when connected to a wrong AC adapter. The MC34671 requires only two external capacitors and one resistor to build a fully functional charger for space- limited applications such as cell phones, Bluetooth accessories and MP3 players. Its ultra high-accuracy (±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 MC34671 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 1.0µF capacitor. 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 of current to drive an LED indicator. CHARGE INDICATOR (CHG) Open-drain logic output to indicate the charge status. The output is low when the MC34671 is charging, until the EOC conditions are reached. This pin is capable to sink at least 12.0mA of current to drive an 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 a high voltage, externally disables the charger. 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- mode threshold. This pin is capable to sink more than 0.3mA of 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 a high-impedance. 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: equ. 1 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 2.2µF or higher capacitor. EXPOSED PAD (EPAD) Exposed pad. It must be soldered on the large ground plane of the PCB to enhance the thermal conductivity. The pad must be connected to GND electrically. IBAT VISET
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Figure 20. 34671 Functional Internal Block Diagram generates the reference voltage for the charge control block. mode and the recharge cycle. the charge current to prevent further die temperature rise.
Analog Integrated Circuit Device Data Freescale Semiconductor 13 34671 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.
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regulate the output to 4.2V, and monitors the output voltage. monitors the input and the battery voltages. Figure 21. Charge Profile
Analog Integrated Circuit Device Data Freescale Semiconductor 15 34671 FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES voltage to monitor the actual charge current as given in equ. 1 during the whole charging cycle. 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 for more information). DC INPUT VOLTAGE The MC34671 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. V IN > VPOR 2. V IN - VBAT > VOS 3. V IN < 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 over- voltage protection threshold, the charger is disabled internally. The 28V input voltage rating eliminates the need of any additional input over-voltage protection circuitry. CHARGE-ENABLE INPUT The charge-enable input, EN, has a weak internal pull- down 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. INPUT POWER PRESENCE INDICATOR When VIN is applied and the voltage is above the power- on-reset 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 VIN- BAT comparator, do not affect the PPR output. The PPR pin is capable to sink at least 12.0mA of current when outputting a low voltage to drive an external LED. CHARGE STATUS INDICATORS The MC34671 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 power- good range, the CHG pin outputs high-impedance as well. The CHG pin has at least 12.0mA of current-sinking capability to drive an external LED, same as the PPR pin. FAST indicates whether the MC34671 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. CHARGE CURRENT THERMAL FOLDBACK An internal thermal feedback loop begins to reduce the charge current when the die temperature reaches 110°C to prevent further temperature rise. This feature protects the MC34671 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 MC34671. 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 worst- case conditions.
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Figure 22. Charge Cycle State Diagram
Analog Integrated Circuit Device Data Freescale Semiconductor 17 34671 TYPICAL APPLICATIONS INTRODUCTION TYPICAL APPLICATIONS INTRODUCTION INPUT CAPACITOR The input capacitor is used to reduce the input voltage transient that may cause instability. A 1.0µF, X5R, 16V-rated ceramic capacitor is recommended for most applications. OUTPUT CAPACITOR For stable operation, an X5R ceramic capacitor with a minimum 2.2µF nominal value is recommended at the output. Depending on the load transient current, larger capacitance may be required. CC-MODE CURRENT SETTING The CC-mode current can be programmed by the external resistor, RISET. A 1% accuracy resistor is recommended to guarantee 5% a current accuracy. 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 R DS(ON) is 700mΩ. The input voltage should be at least higher than VBAT + ICHG x 700mΩ to guarantee the programmed CC-mode current. THERMAL CONSIDERATIONS The MC34671 is available in a tiny 2x3 thermally- enhanced 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 MC34671 to charge the battery with the maximum current, while minimizing the die temperature.
APPLICATIONS
The MC34671 can be used in a stand-alone 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. Figure 23. Standalone Li+ Battery Charger
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When the charger is used in handheld systems with MCU control, the MC34671 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 MC34671 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. Figure 24. MCU Interfaced Charger
Analog Integrated Circuit Device Data Freescale Semiconductor 19 34671 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
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Analog Integrated Circuit Device Data Freescale Semiconductor 21 34671
REVISION HISTORY
REVISION DATE DESCRIPTION OF CHANGES 1.0 1/2008 • Initial Release
Rev. 1.0 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. Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc., 2007-8. All rights reserved. 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
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