AAT3670

PRODUCT DATASHEET AAT3670 BatteryManagerTM General Description The AAT3670 BatteryManager is a highly integrated single-cell lithium-ion/polymer (Li-ion) battery charger and system power management IC that enables simultaneous battery charging and full system usage without compromising the battery’s charge cycle life. It operates with low-voltage AC adapter (ADP) and USB inputs and requires a minimum number of external components. The AAT3670 selects ADP or USB to power the system load and charge the battery when ADP/USB power is available. The AAT3670 precisely regulates battery charge voltage and current for 4.2V Li-ion cells. Charge current can be programmed up to 1.6A for ADP charging and 0.9A or 0.1A for USB charging by resistors on the ADPSET / USBSET pins. The charge termination current threshold is set by an external resistor on the TERM pin. The AAT3670 has a voltage-sensed charge current reduction loop that enables system operation without a power shortage. When the input voltage falls below the programmable charge reduction threshold, the device automatically reduces the charge current until the input voltage returns to the threshold voltage. Battery temperature and charge state are fully monitored for fault conditions. In the event of a battery over-voltage/short-circuit/over-temperature condition, the charger will automatically shut down, protecting the charging device, control system, and battery. Two status monitor output pins (STAT1 and STAT2) are provided to indicate battery charge status by directly driving external LEDs. The AAT3670 is available in a Pb-free, thermallyenhanced, space-saving 24-pin 4x4mm QFN package. 1.6A Dynamic Battery Charger and Power Manager Features • ADP, USB, or Battery Powers System Load Through Internal Current-Limited Switches • Simultaneous Battery Charging and System Usage • Voltage Sensed Charge Reduction Loop to Minimize Charge Time, Even While the System Operates • Digitized Thermal Loop • Battery Power Enable (ENBAT) • Battery Charge Timer (CT) • Battery Temperature Monitoring (TS) • Battery Charge Status Report (STATx) • Automatic Recharge Sequencing • Battery Under-Voltage, Over-Voltage, and OverCurrent Protection • System Load Current Limiting • Thermal Protection • 24-pin 4x4mm QFN Package Applications • • • • • • Cellular Telephones Digital Still Cameras Personal Data Assistants (PDAs) Hand Held PCs MP3 Players and PMP Other Li-ion Battery Powered Devices Typical Application STAT1 STAT2 Adapter Input CADP 10µF USB Input CUSB 10µF Enable Enable Battery to OUT USB Hi/Lo Select EN ENBAT USBSEL ADPSET USBSET ADPLIM USBLIM RADPSET RUSBSET RADPLIM RUSBLIM GND RTERM CHRADP CHRUSB CT TERM CT USB VTS RT TS ADP OUT BATS BAT CBAT 10µF Single Cell Li-Ion/Poly Battery System Load AAT3670 T 3670.2008.04.1.5 www.analogictech.com 1 PRODUCT DATASHEET AAT3670 AAT3670 BatteryManagerTM Pin Descriptions Pin # 1 2, 3 4, 5 6 7 8 9 10 11 12 13 1.6A Dynamic Battery Charger and Power Manager Name USBSEL OUT BAT ADP VTS TS BATS CHRADP ADPLIM USBLIM ADPSET Type I O I/O I O I I I/O I I I Function Logic input. High for 100% USB charge current set by USBSET; low for 20% (constant current charge mode) or 50% (trickle charge mode) charge current set by the USBSET resistor. System load output; a capacitor with a minimum value of 10µF (including all capacitance on the load of OUT) is required. Battery pack input/output. For best operation, a 1µF ceramic capacitor should be placed between BAT and GND. AC adapter input, source of system load and battery charging. Minimum 1µF input capacitor. Voltage reference for battery temperature sensing. Battery temperature sensing input. Use an NTC resistor from TS pin to ground and a 1% standard resistor that has equal resistance of the NTC at 25°C from VTS to TS for battery temperature sensing. Tie TS pin to ground to disable the temperature sensing function. Battery sense pin. ADP voltage sensed charge reduction programmable pin. A resistor divider from ADP to this pin and GND sets the charge reduction threshold. When this pin is open, the charge reduction threshold is 4.6V. If this pin is tied to the ADP pin, the charge reduction is disabled. Connect a resistor to this pin to set the ADP input current limit (including load switch and charger currents). Connect a resistor to this pin to set the USB input current limit (including load switch and charger currents). Connect a resistor to this pin to set the ADP charge current (for trickle charge and constant current charge). The CC current set by this pin should be less than the current limit set by ADPLIM, otherwise the CC current will be limited by ADPLIM. Connect a resistor to this pin to set the USB charge current (for trickle charge and constant current charge). The CC current set by this pin should be less than the current limit set by USBLIM, otherwise the CC current will be limited by USBLIM. Common ground. Connect a resistor to this pin to program the charge termination current threshold. No termination current setting when this pin is pulled up to a logic high level. ADP/USB enable input. High or floating (internal pull-up) to enable ADP/USB switch and ADP/ USB battery charging; low to disable ADP/USB switch and ADP/USB battery charging. Battery charge timer input pin. Connect a capacitor to this pin to set the ADP charge timers. No time-out for USB charging. Timers are disabled when this pin is grounded. The timer is suspended if the battery temperature is not within 0 to 50ºC or is in charge reduction (either due to the supply voltage dropping or the device temperature rising) is activated. The timer continues where it left off after the battery temperature returns to normal and the device is out of the charge reduction loops. Open drain charger status reporting. Open drain charger status reporting. No connection. USB input, source of system load and battery charging when ADP is not available. Minimum 1µF input capacitor. USB voltage sensed charge reduction programmable pin. A resistor divider from USB to this pin and GND sets the charge reduction threshold. When this pin is open, the charge reduction threshold is 4.5V. If this pin is tied to the USB pin, charge reduction is disabled. Battery load switch enable, active high. Exposed paddle (bottom). Connect to ground as closely as possible to the device. 14 15 16 17 USBSET GND TERM EN I I/O I I 18 CT I 19 20 21 22 23 24 EP STAT2 STAT1 N/C USB CHRUSB ENBAT O O I I/O I 2 www.analogictech.com 3670.2008.04.1.5 PRODUCT DATASHEET AAT3670 AAT3670 BatteryManagerTM Pin Configuration QFN44-24 (Top View) 1.6A Dynamic Battery Charger and Power Manager STAT2 STAT1 N/C USB CHRUSB ENBAT 24 23 22 21 20 19 USBSEL OUT OUT BAT BAT ADP 1 2 3 4 5 6 10 11 12 7 8 9 18 17 16 15 14 13 CT EN TERM GND USBSET ADPSET USBLIM ADPLIM CHRADP BATS TS VTS Absolute Maximum Ratings1 Symbol VP VP VN TJ TLEAD Description ADP, USB, BAT, OUT, BATS VUVLO Yes Switch On No No Thermal Loop Enable Sleep Mode No Enable Dynamic Charge VEN_BAT > VEN Fault Condition Monitor OV, OT, OC No Yes Shutdown Mode No Device Temp. Monitor TJ > 110degC Yes Yes Connect ADP to BAT and OUT Yes Battery Temp. Sense VTS1 < TS < VTS2 No Battery Temperature Fault Expire Charge Timer (Enable on Charger reset) Thermal Loop Current Reduction Power Share Recharge Test VRCH > VBAT ? Yes Preconditioning Test VMIN > VBAT Yes Low Current Conditioning Charge Set No No Current Limit Test IOUT > ILIM Yes Current Phase Test VEOC > VBAT Yes Constant Current Charging Mode Reduce Charging Current to BAT No Voltage Phase Test IBAT > ITERM No IOUT + IBAT > ILIM ? No Yes Constant Voltage Charge Mode Charge Reduction Mode Yes Yes Charge Complete Voltage Regulation Enable Input Voltage Level Test VADP < VCHR_TH No Figure 2: AAT3670 Operational Flow Chart. 3670.2008.04.1.5 www.analogictech.com 19 PRODUCT DATASHEET AAT3670 BatteryManagerTM Applications Information AC Adapter/USB System Power Charging Adapter Input Mode In the adapter mode, constant current charge levels up to 1.6A may be programmed by the user. The AAT3670 system control will always select the adapter input over the USB supply input when ever voltage is present on the ADP pin. The ADP input will operate over a range from 4.35V to 5.5V. The constant fast charge current for the adapter input mode is set by the RADPSET resistor connected between the ADPSET pin and ground. The battery preconditioning or trickle charge current is fixed at 10% of the programmed fast charge constant current level. Refer to Table 2 for recommended RADPSET values for a desired constant current charge level. Battery charging states will be indicated via the STAT1 and STAT2 display LEDs. Please refer to the Battery Charge Status Indication discussion for further details on data reporting. Eq. 1: VADPCHR = 1.6A Dynamic Battery Charger and Power Manager The following equation may be used to approximate the ADP charge reduction threshold above or below 4.5V: 2.0V (R12/[R12 + R11]) where R11 and R12 < 500kΩ. VADP ADP R11 850k CHRADP VCHR = 2.0V R12 650k ADP Charge Reduction Under normal operation, the AAT3670 should be operated from an adapter power source with a sufficient capacity to supply the desired constant charge current plus any additional load which may be placed on the source by the operating system. In the event that the power source to the ADP pin is unable to provide the programmed fast charge constant current, or if the system under charge must also share supply current with other functions, the AAT3670 will automatically reduce the ADP fast charge current level to maintain the integrity of the source supply, power the operating system, and charge the battery cell with the remaining available current. The ADP charge reduction system becomes active when the voltage on the ADP input falls below the ADP charge reduction threshold (VCHRADP), which is preset to 4.6V. Should the input supply drop below the VCHRADP threshold, the charge reduction system will reduce the fast charge current level in a linear fashion until the voltage sensed on the ADP input recovers to a point above the charge reduction threshold voltage. The ADP charge reduction threshold (VCHRADP) may be externally set to a value other than 4.6V by placing a resistor divider network between the ADP pin and ground with the center connected to the CHRADP pin. The ADP charge reduction feature may be disabled by shorting the CHRADP pin directly to the ADP input pin. Figure 3: Internal Equivalent Circuit for the CHRADP Pin. Adapter Input Charge Inhibit and Resume The AAT3670 has an under-voltage lockout (UVLO) and power on reset feature to protect the charger IC in the event the input supply to the adapter pin drops below the UVLO threshold. Under a UVLO condition, the charger will suspend the charging process. When power is re-applied to the adapter pin or the UVLO condition recovers, the system charge control will asses the state of charge on the battery cell and will automatically resume charging in the appropriate mode for the condition of the battery. USB Input Mode The AAT3670 provides an input for intelligent USB charging. When no voltage is present on the adapter input pin, the charge controller will automatically switch to accepting power from the USB input. The USB charge mode provides two programmable fast charge levels, USB high (USBH) and USB low (USBL). The USBH mode can be set as high as 900mA; however for most applications utilizing a USB port as the source supply, 500mA is the typical 20 www.analogictech.com 3670.2008.04.1.5 PRODUCT DATASHEET AAT3670 BatteryManagerTM 1.6A Dynamic Battery Charger and Power Manager The following equation may be used to approximate a USB charge reduction threshold below 4.5V: default USBH value and USBL is subsequently set for 100mA. In the USBL fast charge mode, the constant charging current is set to 20 percent of the programmed USBH. More simply put, the USBL low fast charge level = USBH divided by five. The USBH or USBL modes may be externally selected by USB select pin (USBSEL). In the USBH mode, the battery cell preconditioning or trickle charge current is fixed at 10 percent of the programmed fast charge constant current. In the USBL mode, the trickle charge current is only reduced to 50 percent of the programmed fast charge constant current level. When the USBSEL pin is connected to a logic high level, the USBH level will be active. Conversely, when USBSEL is pulled to a logic low level (ground) the USBL level will be used for fast charging. Refer to Table 2 for the recommended RUSBSET value to program the desired USB input constant current charge levels. Eq. 2: VUSBCHR = where R1 and R2 < 1MΩ 2.0V (R2/[R2 + R1]) VUSB USB R1 1.0M CHRUSB VCHR = 2.0V R2 800k USB Charge Reduction In many instances, product system designers have an issue of not knowing the real properties of a potential USB port to be used to supply power to the battery charger. Typical powered USB ports commonly found on desktop and notebook PCs should supply up to 500mA. In the event a USB port being used to supply the charger is unable to provide the programmed fast charge current, or if the system under charge must also share supply current with other functions causing an overload to the USB port, the AAT3670 will automatically reduce USB fast charge current to maintain port integrity and protect the host system. The USB charge reduction system becomes active when the voltage on the USB input falls below the USB charge reduction threshold (VCHRUSB), which is typically 4.5V. Regardless of which USB charge function is selected (USBH or USBL), the charge reduction system will reduce the fast charge current level in a linear fashion until the voltage sensed on the USB input recovers above the charge reduction threshold voltage. The USB charge reduction threshold (VCHRUSB) may be externally set to a value lower than 4.5V by placing a resistor divider network between VUSB and ground with the center connected to the CHRUSB pin. The USB charge reduction feature may be disabled by shorting the CHRUSB pin directly to the USB input pin. Figure 4: Internal Equivalent Circuit for the CHRUSB Pin. USB Input Charge Inhibit and Resume The AAT3670 under-voltage lockout (UVLO) and poweron reset feature will function when the USB input pin voltage level drops below the UVLO threshold. At this point the charger will suspend charging. When power is re-applied to the USB pin or the UVLO condition recovers, the system charge control will assess the state of charge on the battery cell and will automatically resume charging in the appropriate mode for the condition of the battery. End of Charge Termination The AAT3670 provides a user-programmable charge termination current at the end of the charge cycles. When the battery cell voltage as sensed by the BATS pin reaches 4.2V, the charge control will transition from constant current fast charge mode to constant voltage mode. In constant voltage mode, the battery cell voltage will be regulated at 4.2V. The charge current will drop as the battery reaches its full charge capacity. When the charge current drops to the programmed end of charge (EOC) current, the charge cycle is complete and the charge controller terminates the charging process. 3670.2008.04.1.5 www.analogictech.com 21 PRODUCT DATASHEET AAT3670 BatteryManagerTM 1.6A Dynamic Battery Charger and Power Manager System Power Output The power to the system is supplied via the OUT pin. OUT will source power from either the ADP or USB inputs when an external power source is applied. When the battery charging function is complete and the charging power source is removed, the system will be powered from the battery via Load Switch 3, referring to the AAT3670 block diagram. The maximum current that can be supplied from the ADP or USB inputs to a system load is bounded by the user programmed ADPLIM and USBLIM level. If the current consumption from the system load exceeds that of the ADP or USB input sources, the IC will draw current from the battery to make up the difference as long as the battery cell voltage remains above 2.9V. Power from the battery to the OUT pin is controlled by the ENBAT function. When the ENBAT is disabled the leakage current from the battery to the load is less than 1µA. The charge termination current is user programmed by the value of RTERM, which is connected between the TERM pin and ground. Use the values listed in Table 1 to set the desired charge termination current. The programmed charge termination current will remain at the same set level regardless of which fast charge ADP, USBH or USBL constant current mode is selected. ITERM (mA) 320 174 125 95 77 64 58 50 49 42 37 RTERM (kΩ) 11.0 21.0 30.9 41.2 51.1 61.9 71.5 80.6 90.9 100.0 110.0 Table 1: Charge Termination Current Programming Resistor Values. If the desired end of charge termination current level is not listed in Table 1, the TERM resistor value may be calculated by the following equation: For the Adapter input mode: Battery Connection and Battery Voltage Sensing Battery Connection The single cell Li-ion battery should be connected between the BAT pin and ground. The internal load switching network will connect the battery to the system load and apply the charging current. Battery Voltage Sensing The BATS pin is provided to employ an accurate voltage sensing capability to measure the terminal voltage at the battery cell being charged. This function reduces measured battery cell voltage error between the battery terminal and the charge control IC. The AAT3670 charge control circuit will base charging mode states upon the voltage sensed at the BATS pin. The BATS pin must be connected to the battery terminal for correct operation. If the battery voltage sense function is not needed, the BATS pin should be terminated directly to the BAT pin. If there is concern of the battery sense function inadvertently becoming an open circuit, the BATS pin may be terminated to the BAT pin using a 10kΩ resistor. Under normal operation, the connection to the battery terminal will be close to 0Ω; if the BATS connection becomes an open circuit, the 10kΩ will provide feedback to the BATS pin from the BAT connection will a 1mV or less loss in sensed voltage accuracy. RTERM = K · Where: ⎛ VTERM⎞ ⎝ ICC ⎠ K = KI_TERM = 2000 VTERM = 2V ICC = Fast charge constant current The constants K and VTERM are specified in the Typical Characteristics section of this datasheet. The end-of-charge termination current function can be disabled by pulling the TERM pin high via connecting the TERM pin to the BAT pin. In this state, the end-of-charge function will be disabled and the battery will float charge in the constant voltage mode indefinitely or until the cell voltage is brought below the constant voltage threshold. 22 www.analogictech.com 3670.2008.04.1.5 PRODUCT DATASHEET AAT3670 BatteryManagerTM Enable The AAT3670 provides an enable function to control the charger IC on and off. The enable (EN) pin is active high. When pulled to a logic low level, the AAT3670 will be shut down and forced into the sleep state. Charging will be halted regardless of the battery voltage or charging state. When the device is re-enabled, the charge control circuit will automatically reset and resume charging functions with the appropriate charging mode based on the battery charge state and measured cell voltage. 1.6A Dynamic Battery Charger and Power Manager the VUSBSEL(L) threshold to enable the USBL charge level; the USBL charge current will be set to 20% of the set USBH level. For typical USB charging applications, the USBH and USBL functions are fixed for 500mA and 100mA USB fast charge levels. However, the charge level of USBH may be set from 50mA to 900mA and USBL will in turn be fixed at 20% of the USBH level depending upon the system design requirements for a given USB charge application. Refer to Table 2 and Figure 5 for recommended RUSBSET values. ICC (mA) 50 90 100 150 200 250 300 400 500 650 800 900 1000 1200 1500 1600 Battery Enable Since the AAT3670 provides battery power switching as well as charging function, a battery enable pin (ENBAT) is provided so the power from the battery via the BAT pin to the OUT pin may be externally controlled. The ENBAT function allows the user to control power to the systems regardless of charging state, input power source, or charge enable (EN) state. It may be desirable for some system designs to disconnect the battery from the load during charging. This may be accomplished by pulling the ENBAT pin low, while the device is enabled for charging (EN high). ADP RSET (kΩ) 1300 681 590 412 309 249 205 154 121 93.1 73.2 64.9 57.6 48.7 38.3 34.8 USBH RSET (kΩ) 750 453 383 249 187 150 124 90.9 71.5 54.9 43.2 38.3 USBL RSET (kΩ) 150 80.6 71.5 47.5 34.8 Programming Charge Current The fast charge constant current charge level for both adapter and USB input modes are programmed with set resistors placed between the ADPSET or USBSET pins and ground. The accuracy of the fast charge constant current and the preconditioning trickle charge current are dominated by the tolerance of the set resistor used. For this reason, 1% tolerance metal film resistors are recommended for this set resistor function. Fast charge constant current levels from 50mA to 1.6A may be set by selecting the appropriate resistor value from Table 2. The RADPSET resistor should be connected between the ADPSET pin and ground. The USB input fast charge constant current charge control provides up to 900mA of charge current and is set in the USBH mode. The USBSEL pin is used to select the high or low charge current levels in the USB charge mode. When the USBSEL pin is pulled to a voltage level above the VUSBSEL(H) threshold, the USBH current level will be selected. Conversely, this pin should be pulled below Table 2: RSET Values. 1800 1600 IFASTCHARGE (mA) 1400 1200 1000 800 600 400 200 0 10 100 1000 10000 USBH USBL ADP RSET (kΩ) Figure 5: Fast Charge Current vs. Set Resistor (VIN = 5V; VBAT = 3.5V). 3670.2008.04.1.5 www.analogictech.com 23 PRODUCT DATASHEET AAT3670 BatteryManagerTM 1.6A Dynamic Battery Charger and Power Manager The thermal loop control re-evaluates the internal die temperature every three seconds and adjusts the fast charge current back up in small steps up to the full fast charge current level or until an equilibrium current is discovered and maximized for the given ambient temperature condition. In this manner, the thermal loop controls the system charge level. The AAT3670 will always provide the highest possible level of constant current in the fast charge mode for any given ambient temperature condition. If the desired current charge current level is not listed in Table 2, the ADPSET and USBSET resistor values may be calculated by the following equations: For the Adapter input mode: RADPSET = K · Where: ⎛ VADPSET⎞ ⎝ ICC ⎠ K = KI_CCADP = 29300 VADPSET = 2V ICC = Fast Charge Constant Current For the USB input mode: Programmable Watchdog Timer The AAT3670 contains a watchdog timing circuit which operates only in adapter charging mode. Typically a 0.1µF ceramic capacitor is connected between the CT pin and ground. When a 0.1µF ceramic capacitor is used, the device will time a shutdown condition if the trickle charge mode exceeds 45 minutes. When the device transitions to the trickle charge to the fast charge constant current mode and then to the constant voltage mode, the timing counter is reset and will time out after 3 hours for each mode. Summary for a 0.1µF used for the timing capacitor: Trickle Charge (TC) time out = 45 minutes Fast Charge Constant Current (CC) time out = 3 hours Constant Voltage (VC) mode time out = 3 hours The CT pin is driven by a constant current source and will provide a linear response to increases in the timing capacitor value. Thus, if the timing capacitor were to be doubled from the nominal 0.1µF value, the time out time of the CC + CV modes would be doubled. The corresponding trickle charge time out time would be the combined CC + VC time divided by 8. If the programmable watchdog timer function is not needed it may be disabled the terminating the CT pin to ground. The CT pin should not be left floating or unterminated; this will cause errors in the internal timing control circuit. The charge timer control will suspend the timing count in any given mode in the event a fault condition occurs. Such fault conditions include digital thermal loop charge current reduction, ADP or USB charge reduction, battery temperature fault, and battery current sharing with the output during the charging cycle. When the fault condition recovers, the counter will resume the timing function. The charge timer will automatically reset when the AAT3670 enable pin is reset or cycled off and on. RUSBSET = K · Where: ⎛ VUSBSET⎞ ⎝ ICC ⎠ K = KI_CCUSBH = 17900 (USBH) K = KI_CCUSBL = 3600 (USBL) VUSBSET = 2V ICC = Fast Charge Constant Current All constants K and VADP/USBSET are specified in the Typical Characteristics section of this datasheet. Protection Circuitry Thermal Loop Control Due to the integrated nature of the linear charging control pass devices for both the adapter and USB modes, a special thermal loop control system has been employed to maximize charging current under all operating conditions. The thermal management system measures the internal circuit die temperature and reduces the charge current when the device exceeds a preset internal temperature control threshold. Once the thermal loop control becomes active, the constant charge current is initially reduced by a factor of 0.44. The initial thermal loop current can be estimated by the following equations: In ADP mode: ITLOOP = ICCADP · 0.44 In USB mode: ITLOOP = ICCUSBH · 0.44 24 www.analogictech.com 3670.2008.04.1.5 PRODUCT DATASHEET AAT3670 BatteryManagerTM 1.6A Dynamic Battery Charger and Power Manager If the desired charge current limit level is not listed in Table 3, the ADPLIM and USBLIM set resistor values may be calculated by the following equations: For the Adapter input mode: The constant current provided to charge the timing capacitor is very small and this pin is susceptible to noise and changes in capacitance value. Therefore, the timing capacitor should be physically located on the printed circuit board layout as close as possible to the CT pin. Since the accuracy of the internal timer is determined by the capacitance value, a 10% tolerance or better ceramic capacitor is recommended. Ceramic capacitor materials such as X7R and X5R type are a good choice for this application. RADPLIM = K · Where: ⎛ VADPLIM⎞ ⎝ ICC ⎠ Over-Current Protection The AAT3670 provides over-current protection to both the battery and system output modes for both the ADP and USB input sources. The over-current protection threshold is user programmable and independent from the constant charge current setting. The set resistor RADPLIM is connected between the ADPLIM pin and ground to program the ADP power path current limit up to 1.6A. The set resistor RUSBLIM is connected between the USBLIM pin and ground to program the USB power path current limit up to 900mA. For both the ADP and USB charge paths, the programmed constant current fast charge level may not exceed the respective ADPLIM and USBLIM set points. Refer to Table 3 for the ADPLIM and USBLIM programming resistor values. ICC (mA) 50 90 100 150 200 250 300 400 500 650 800 900 1000 1200 1500 1600 K = KI_LIM_ADP = 27800 VADPLIM = 2V ICC = Fast Charge Constant Current For the USB input mode: RUSBLIM = K · Where: ⎛ VUSBLIM⎞ ⎝ ICC ⎠ K = KI_LIM_USBH = 17600 (USBH) K = KI_LIM_USBL = 3500 (USBL) VUSBLIM = 2V ICC = Fast Charge Constant Current All constants K and VADP/USBLIM are specified in the Typical Characteristics section of this datasheet. RADPLIM (kΩ) 1300 681 590 412 309 249 205 154 121 93.1 73.2 64.9 57.6 48.7 38.3 34.8 RUSBLIM (kΩ) 750 453 383 249 187 150 124 90.9 71.5 54.9 43.2 38.3 Over-Voltage Protection An over-voltage event is defined as a condition where the voltage on the BATS pin exceeds the maximum battery charge voltage and is set by the over-voltage protection threshold (VOVP). If an over-voltage condition occurs, the AAT3670 charge control will shutdown the device until voltage on the BATS pin drops below the over-voltage protection threshold (VOVP). The AAT3670 will resume normal charging operation once the battery over-voltage condition is removed. During an over-voltage event, the STAT2 LED will report a system fault. Over-Temperature Shutdown The AAT3670 has a thermal protection control circuit which will shut down charging functions should the internal die temperature exceed the preset thermal limit threshold. Table 3: Current Limit Programming Resistor Values. 3670.2008.04.1.5 www.analogictech.com 25 PRODUCT DATASHEET AAT3670 BatteryManagerTM Battery Temperature Fault Monitoring In the event of a battery over-temperature condition, the charge control will turn off the internal charge path regulation device and report the fault condition via the STAT2 display LED. After the system recovers from a temperature fault, the device will resume charging operation. The AAT3670 checks battery temperature before starting the charge cycle, as well as during all stages of charging. Typically, batteries employ the use of a negative temperature coefficient (NTC) thermistor that is integrated into the battery package. Most commonly used NTC thermistors used in battery packs are approximately 10kΩ at room temperature (25°C). However, the AAT3670 TS pin, in conjunction with the VTS pin, permits the use of almost any value of NTC thermistor. There are two pins associated with the battery temperature sensing function, TS and VTS. The battery pack thermistor should be connected between the TS pin and ground. The VTS pin is provided to allow the user to program battery temperature sense thresholds depending upon the value of the NTC thermistor used in a given battery pack. A resistor (RT) connected between the VTS pin and the TS pin will set a bias for the NTC thermistor function. The TS function has been designed such that a default NTC thermistor value of 10kΩ will then require a 10k resistor for RT. To determine the actual operating temperature window for the the NTC thermistor and the TS pin, one must first specify the NTC thermistor to be used, then refer to the thermistor datasheet to determine its characteristics. The internal battery temperature sensing system is comprised of two comparators which establish a voltage window for safe operation. The thresholds for the TS operating window are bounded by the TS1 and TS2 specifications. Referring to the electrical characteristics table in this datasheet, the TS1 threshold = 0.30 · VVTS and the TS2 threshold = 0.72 · VVTS. The VTS pin is capable of sourcing up to 2mA. If the use of the battery temperature sense function is not required, it may be disabled by disconnecting the VTS pin from the TS pin and terminating the TS pin to ground. The VTS pin can be left floating. 1.6A Dynamic Battery Charger and Power Manager Status Indicator Display System charging status may be displayed using one or two LEDs in conjunction with the STAT1 and STAT2 pins on the AAT3670. These two pins are simple switches to connect the status LED cathodes to ground. It is not necessary to use both display LEDs if a user simply wants to have a single lamp to show “charging” or “not charging”. This can be accomplished by using the STAT1 pin and a single LED. Using two LEDs and both STAT pins simply gives the user more information for the various charging states. Refer to Table 4 for LED display definitions. VTS RT TS 0.72 · VVTS Battery Cold Fault + RNTC T Battery Hot Fault + 0.30 · VVTS Figure 6: Battery Temperature Sense Circuit. VTS RT TS 0.72V Battery Cold Fault + RADJ 0.30V RNTC T Battery Hot Fault + Battery Charge Status Indication The AAT3670 indicates the status of the battery under charge using two status LED driver outputs. These two LEDs can indicate simple functions such as no battery charge activity, battery charging, charge complete and charge fault. Figure 7: Battery Temperature Sense Circuit with Externally Adjusted Window Threshold. 26 www.analogictech.com 3670.2008.04.1.5 PRODUCT DATASHEET AAT3670 BatteryManagerTM Event Description End of Charge (TERM Current Reached in CVM), Battery OV, Timeout, or Charge Disabled No Battery (With Charge Enabled) Battery Charging (Including Suspended Charging Due to Battery OT/UT, or Device OT ) 1.6A Dynamic Battery Charger and Power Manager STAT1 OFF Flash (1Hz, 40% duty) ON Event Description Charge Disabled, No Battery, End of Charge, or Charging Without Faults Faults (Battery OV/OT/UT, or Device OT) or Timeout STAT2 OFF ON Table 4: LED Status Indicator (STATx Pulled Up to a Voltage Source with Resistors and LED). The LED anodes should be connected to USB, ADP, BAT, or OUT depending upon the system design requirements. The LEDs should be biased with as little current as necessary to create reasonable illumination. A ballast resistor should be placed between the status LED cathodes and the STAT1/2 pins. LED current consumption will add to the over thermal power budget for the device package, hence it is good reason to keep the LED drive current to a minimum. 2mA should be sufficient to drive most common low cost green or red LEDs. It is not recommended to exceed 8mA for driving an individual status LED. The required ballast resistor value can be estimated using the following formulas: For connection to the adapter supply: Example: RB(STAT2) = (3.6V - 3.2V) 2mA = 200Ω Note: Green LED forward voltage (VF) is typically 3.2V @ 2mA. No Battery Present Indication If the AAT3670 charger IC is powered and enabled from either the ADP or USB input, yet no battery is connected to the BAT and BATS pins, the STAT1 LED will flash at a 1Hz rate with an approximate 40% duty cycle when a 10µF capacitor is connected between the BAT pin and ground. The flash rate of the STAT1 LED can be adjusted by changing the value of the battery output (BAT pin) capacitor. If the capacitor value is increased above 20µF, the no battery detect flashing function will be defeated. The flash rate of the no battery detect function may be approximated by the following equation: Eq. 3: RB(STAT1/2) = (VADP - VF(LED)) ILED(STAT1/2) Example: RB(STAT1) = (5.5V - 2.0V) 2mA = 1.75kΩ Note: Red LED forward voltage (VF) is typically 2.0V @ 2mA. For connection to the USB supply: Where: Eq. 6: C = I·T V Eq. 4: RB(STAT1/2) = (VUSB - VF(LED)) ILED(STAT1/2) C = Capacitor value I = Start up source current from the BAT pin = 5µA V = Difference voltage between the end of charge voltage and the battery recharge threshold = 0.2V T = Rate of LED flashing in seconds Example: RB(STAT2) = (5.0V - 3.2V) 2mA = 900Ω Note: Green LED forward voltage (VF) is typically 3.2V @ 2mA. For connection to the BAT supply: Thermal Considerations The AAT3670 is available in a 4x4mm 24-pin QFN package which can provide up to 2.0W of power dissipation when it is properly bonded to a printed circuit board, but can achieve a maximum thermal resistance of 37°C/W with printed circuit board enhancement. Many considerations should be taken into account when designing the printed circuit board layout as well as the placement of the charger IC package in proximity to other heat generating devices in a given application design. The ambi- Eq. 5: RB(STAT1/2) = (VBAT - VF(LED)) ILED(STAT1/2) 3670.2008.04.1.5 www.analogictech.com 27 PRODUCT DATASHEET AAT3670 BatteryManagerTM 1.6A Dynamic Battery Charger and Power Manager Given: VADP = 5.0V VBAT = 3.0V ICC = 1A IOP = 0.75mA TJ = 110°C θJA = 37°C/W IOUT = 0 RDS(ON) = 0.4Ω Using Equation 7, calculate the device power dissipation for the stated condition: ent temperature around the charger IC will also have an effect on the thermal limits of a battery charging application. The maximum limits that can be expected for a given ambient condition can be estimated by the following discussion: First, the maximum power dissipation for a given situation should the calculated: Eq. 7: PD = [(VIN - VBAT) · ICC + (VIN · IOP) + (IOUT2 · RDS(ON)) Where: PD VIN VBAT ICC IOP IOUT RDS(ON) = Total power dissipation by the device = either VADP or VUSB, depending on which mode is selected = Battery voltage as seen at the BAT pin = Maximum constant fast charge current programmed for the application = Quiescent current consumed by the charger IC for normal operation = Load current to system from the OUT pin = On-resistance of load switch between ADP or USB and OUT Eq. 9: PD = (5.0V - 3.0V)(1A) + (5.0V · 0.75mA) + (02 · 0.4Ω) = 2.00375W The maximum ambient temperature before the AAT3670 thermal loop becomes active can now be calculated using Equation 8: Eq. 10: TA = 110°C - (37°C/W · 2.00375W) Next, the maximum operating ambient temperature for a given application can be estimated based on the thermal resistance of the 4x4 QFN package when sufficiently mounted to a PCB layout and the internal thermal loop temperature threshold. = 35.86°C Therefore, under the stated conditions for this worstcase power dissipation example, the AAT3670 will enter the thermal loop and lower the fast charge constant current when the ambient operating temperature rises above 35.86°C. Eq. 8: TA = TJ - (θJA · PD) Where: TA = Ambient temperature in °C TJ = Maximum device junction temperature below the thermal loop threshold PD = Total power dissipation by the device θJA = Package thermal resistance in °C/W Example: For an application where the fast charge current for the adapter mode is set to 1A, VADP = 5.0V, and the worstcase battery voltage at 3.0V with the system load disabled, what is the maximum ambient temperature where the thermal limiting will become active? Capacitor Selection Input Capacitor In general, it is good design practice to place a decoupling capacitor between the ADP and USB pins and ground. An input capacitor in the range of 1µF to 22µF is recommended. If the source supply is unregulated, it may be necessary to increase the capacitance to keep the input voltage above the under-voltage lockout threshold during device enable and when battery charging is initiated. If the AAT3670 adapter input is to be used in a system with an external power supply source, such as a typical AC-to-DC wall adapter, then a CIN capacitor in the range of 10µF should be used. A larger input capacitor in this application will minimize switching or power bounce effects when the power supply is “hot plugged” in. Likewise, a 10µF or greater input capacitor is recommended for the 28 www.analogictech.com 3670.2008.04.1.5 PRODUCT DATASHEET AAT3670 BatteryManagerTM 1.6A Dynamic Battery Charger and Power Manager Printed Circuit Board Layout Considerations For the best results, it is recommended to physically place the battery pack as close as possible to the AAT3670 BAT pin as possible. To minimize voltage drops on the PCB, keep the high current carrying traces adequately wide. For maximum power dissipation of the AAT3670 QFN package, the metal substrate should be solder bonded to the board. It is also recommended to maximize the substrate contact to the PCB ground plane layer to further increase local heat dissipation. Refer to the AAT3670 evaluation board for a good layout example. USB input to help buffer the effects of USB source power switching, noise and input cable impedance. Output Capacitor The AAT3670 only requires a 1µF ceramic capacitor on the BAT pin to maintain circuit stability. This value should be increased to 10µF or more if the battery connection is made any distance from the charger output. If the AAT3670 is to be used in applications where the battery can be removed from the charger, such as with the case with desktop charging cradles, an output capacitor greater than 10µF, but less than 20µF, may be required to retard the device from cycling on and off when no battery is present. J6 USB 21 J8 USB 12 345 J2 USBSEL 123 D1 R11 D2 R10 1K R13 TBD D3A SOT-23 R12 TBD C2 10µF 1K J1 1 2 3 D3B CT U1 J7 1 2 24 23 22 21 20 19 C4 0.01µF ENBAT CHRUSB ENBAT STAT1 USB STAT2 N/C 1 USBSEL OUT OUT BAT BAT CT EN TERM GND USBSET 18 17 16 15 14 13 J3 1 2 3 OUT J5 1 2 3 C5 10µF 2 3 4 R9 71.5K R8 71.5K R7 57.6K ENABLE C3 10µF 5 6 1 2 ADP C1 10µF AAT3670 7 8 9 10 11 12 R1 100K R2 100K TS R3 R4 R5 R6 TBD TBD 34.8K 39.2K Figure 8: AAT3670 Evaluation Board Schematic. 3670.2008.04.1.5 www.analogictech.com ADPLIM BATS USBLIM VTS BAT J4 ADP CHRADP ADPSET TS 29 PRODUCT DATASHEET AAT3670 AAT3670 BatteryManagerTM 1.6A Dynamic Battery Charger and Power Manager Figure 9: AAT3670 Evaluation Board Top Side Layout. Figure 10: AAT3670 Evaluation Board Bottom Side Layout. 30 www.analogictech.com 3670.2008.04.1.5 PRODUCT DATASHEET AAT3670 AAT3670 BatteryManagerTM Ordering Information Package QFN44-24 1.6A Dynamic Battery Charger and Power Manager Marking1 TFXYY Part Number (Tape and Reel)2 AAT3670ISK-4.2-T1 All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/about/quality.aspx. Package Information3 QFN44-24 0.305 ± 0.075 0.4 ± 0.05 19 18 24 1 Pin 1 Identification Pin 1 Dot By Marking 4.000 ± 0.050 0.5 BSC R0.030Max 13 12 7 6 4.000 ± 0.050 2.7 ± 0.05 Top View Bottom View 2.7 ± 0.05 0.214 ± 0.036 0.025 ± 0.025 Side View All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. Advanced Analogic Technologies, Inc. 3230 Scott Boulevard, Santa Clara, CA 95054 Phone (408) 737-4600 Fax (408) 737-4611 © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders. 3670.2008.04.1.5 www.analogictech.com 0.900 ± 0.050 0.300 × 45° 31