RT9525GQW

RT9525 Linear Single Cell Li-Ion Battery Charger with Auto Power Path General Description Features The RT9525 is an integrated single cell Li-ion battery charger with Auto Power Path Management (APPM). No external MOSFETs are required. The RT9525 enters sleep mode when power is removed. Charging tasks are optimized by using a control algorithm to vary the charge rate including pre-charge mode, fast charge mode and constant voltage mode. For the RT9525, the charge current can also be programmed with an external resister. Additionally, the internal thermal feedback circuitry regulates the die temperature to optimize the charge rate for all ambient temperatures. The charging task will always be terminated in constant voltage mode when the charging current reduces to the termination current of 20% ICHG_FAST. Other features include under voltage protection z 28V Maximum Rating for VIN Power z Selectable Power Current Limit (0.1A / 0.5A / 1.5A) Integrated Power MOSFETs Auto Power Path Management (APPM) Programmable Charging Current Timer and Safe Charge Timer Under Voltage Protection Over Voltage Protection Power Good and Charger Status Indicator Optimized Charge Rate via Thermal Feedback 16-Lead WQFN Package RoHS Compliant and Halogen Free and over voltage protection for the VIN supply. z z z z z z z z z z Applications z Ordering Information z Digital Cameras PDAs and Smart Phones Portable Instruments RT9525 Pin Configurations (TOP VIEW) ISETA SYSOFF TIMER VIN Package Type QW : WQFN-16L 3x3 (W-Type) Lead Plating System G : Green (Halogen Free and Pb Free) Note : 16 15 14 13 Richtek products are : ` RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. TS BAT BAT EN 1 12 2 11 GND 3 JG = : Product Code JG=YM DNN YMDNN : Date Code DS9525-01 May 2011 6 7 9 8 EN2 EN1 PGOOD GND 5 Marking Information 10 17 4 NC SYS SYS CHG WQFN-16L 3x3 www.richtek.com 1 RT9525 Typical Application Circuit RT9525 Adapter or USB 13 VIN CIN 2.2µF 10, 11 CSYS 10µF 15 Disconnect Connect CTIMER 1µF 2, 3 CBAT 1µF + SYS 4 EN Chip Enable BAT SYSOFF 14 TIMER TS 1 ISETA 16 GND 6 EN1 5 EN2 RISETA 8, 17 (Exposed Pad) PGOOD 7 9 CHG Functional Pin Description Pin No. Pin Name Pin Function Thermistor Monitor Input. The TS pin connects to a battery’s thermistor to determine if the battery is too hot or too cold to charge. If the battery’s temperature is out of range, charging is paused until it re-enters the valid range. TS also detect whether the battery (with NTC) is present or not 1 TS 2, 3 BAT Battery Connect Pin. 4 EN Charge Enable, Active-low input. 200kΩ pull low. 5 EN2 6 EN1 7 PGOOD 8, GND 17 (Exposed Pad) 9 CHG Input Current Limit Configuration Setting. 12 NC Power Good Status Output. Active-low, open-drain output. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Charger Status Output. Active-low, open-drain output. System Connect Pin. Connect this pin to system load with a minimum 10uF MLCC to GND. No Internal Connection. 13 VIN Supply Voltage Input. 14 TIMER 15 SYSOFF 16 ISETA Safe Charge Timer Setting. System Disconnect Pin. Pull SYSOFF high to disconnect SYS from battery, connect to GND for normal operation. Internally pulled up by 1μA current source to BAT. Charge Current Set Input. Connect a resistor (RISETA) between ISET and GND. 10, 11 www.richtek.com 2 SYS DS9525-01 May 2011 RT9525 Function Block Diagram VIN SYS Control Circuit BAT 1µA Sleep Mode ISETA EN1 EN2 EN Current Set Block 200k Thermal Circuit Timer TIMER 200k Logic 200k OVP UVLO DS9525-01 May 2011 SYSOFF CC/CV/TR /APPM Multi Loop Controller TS TS CHG PGOOD GND www.richtek.com 3 RT9525 Absolute Maximum Ratings z z z z z z z z z z z (Note 1) Supply Input Voltage, VIN -----------------------------------------------------------------------------------------------CHG, PGOOD -------------------------------------------------------------------------------------------------------------Other Pins ------------------------------------------------------------------------------------------------------------------CHG, PGOOD Continuous Current -----------------------------------------------------------------------------------BAT Continuous Current (total in two pins) (Note 2) -----------------------------------------------------------Power Dissipation, PD @ TA = 25°C WQFN-16L 3x3 -----------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 3) WQFN-16L 3x3, θJA ------------------------------------------------------------------------------------------------------WQFN-16L 3x3, θJC -----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 4) HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------ Recommended Operating Conditions z z z z −0.3V to 28V −0.3V to 28V −0.3V to 6V 20mA 2.5A 1.471W 68°C/W 7.5°C/W 260°C 150°C −65°C to 150°C 2kV 200V (Note 5) Supply Input Voltage, VIN (EN2 = H, EN1 = L) --------------------------------------------------------------------Supply Input Voltage, VIN (EN2 = L, EN1 = X) --------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Ambient Temperature Range -------------------------------------------------------------------------------------------- 4.45V to 6V 4.65V to 6V −40°C to 125°C −40°C to 85°C Electrical Characteristics (VIN = 5V, VBAT = 4V, TA = 25°C, unless otherwise specification) Parameter Supply Input VIN Operating Range VIN Under Voltage Lockout Threshold VIN Under Voltage Lockout Hysteresis Symbol Test Conditions VUVLO VUVLO _hys Min Typ Max Unit 4.2 -- 6 V 3.1 3.3 3.5 V -- 240 -- mV --- 1 0.8 2 1.5 mA -- 195 333 μA -- 5 15 μA VIN Supply Current I IN VIN Suspend Current I SUS ISYS = IBAT = 0mA, EN = L ISYS = IBAT = 0mA, EN = H VIN = 5V, EN2 = EN1 = H BAT Sleep Leakage Current I SLEEP VBAT > VIN , (VIN = 0V) VIN − BAT VOS Rising VOS_H -- 200 300 mV VIN − BAT VOS Falling VOS_L 10 50 -- mV 4.16 4.2 4.23 V 5.3 5.5 5.7 V Voltage Regulation Battery Regulation Voltage VREG System Regulation Voltage VSYS 0 to 85°C, ILOAD = 20mA APPM Regulation Voltage VAPPM EN2 = L ,EN1 = H DPM Regulation Voltage VDPM EN2 = L VIN to VSYS MOSFET Ron RDS(ON) ILIM = 1000mA www.richtek.com 4 4.2 4.3 4.4 V 4.35 4.5 4.63 V -- 0.2 0.35 Ω To be continued DS9525-01 May 2011 RT9525 Parameter Symbol Test Conditions BAT to VSYS MOSFET Ron RDS(ON) VBAT = 4.2V,ISYS = 1A Re-charge threshold ΔVREGCGG Battery Regulation – Recharge-level ISETA Set Voltage (Fast Charge Phase) VISETA VBATT = 4V, RISETA = 1kΩ VIN Charge Setting Range I CHG VIN Charge Current I CHG VIN Current Limit I LIM Min Typ Max Unit -- 0.05 0.1 Ω 120 200 280 mV -- 2 -- V 100 -- 1200 mA Current Regulation VBATT = 4V, RISETA = 1kΩ EN2 = H, EN1 = L (1.5A mode) EN2 = L, EN1 = H (500mA mode) EN2 = L, EN1 = L (100mA mode) 570 1.2 600 1.5 630 1.8 mA A 450 475 500 mA 80 90 100 mA BAT Falling 2.75 2.85 2.95 V -- 200 -- mV 5 10 15 % 10 20 30 % EN2 = L, EN1 = L -- 3.3 -- % VCHG ICHG = 5mA -- 200 -- mV VPGOOD IPGOOD = 5mA -- 200 -- mV 1.5 -- --- 0.4 V TREG -- 125 -- °C TSD -- 155 -- °C ΔTSD -- 20 -- °C 6.25 6.5 6.75 V -- 100 -- mV -- 300 -- mV 1440 11520 1800 14400 2160 17280 s s -- 1.2 -- ms -- 50 -- μs Pre-Charge BAT Pre-Charge Threshold VPRECH BAT Pre-Charge Threshold ΔVPRECH Hysteresis Pre-Charge Current I PRECH Charge Termination Detection Termination Current Ratio to I TERM Fast Charge Termination Current Ratio to I TERM2 Fast Charge USB100mA Login Input/Output CHG Pull Down Voltage PGOOD Pull Down Voltage EN, EN1,EN2, SYSOFF Pin Threshold Protection Thermal Regulation Thermal Shutdown Temperature Thermal Shutdown Hysteresis VBAT = 2V VIH VIL OVP SET Voltage VOVP VIN Rising OVP Hysteresis Output Short Circuit Detection Threshold Time Pre-Charge Fault Time Fast charge Fault Time VOVP_hys VSHORT VBAT − VSYS t PCHG t FCHG PGOOD Deglitch Time t PGOOD CTIMER = 1μF (1/8 x tFCHG) CTIMER = 1μF Time measured from VIN : 0Æ5V 1μs rise-time to PGOOD = L Input Over Voltage Blanking Time t OVP To be continued DS9525-01 May 2011 www.richtek.com 5 RT9525 Parameter Pre-Charge to Fast-Charge Deglitch Time Fast-Charge to Pr-Charger Deglitch Time Termination Deglitch Time Recharge Deglitch Time Input Power Loss to SYS LDO Turn-Off Delay Time Packing Temperature Fault Detection Deglitch Time Short Circuit, Deglitch Time Short Circuit Recovery Time Symbol Test Conditions Min Typ Max Unit tPF -- 25 -- ms tfp -- 25 -- ms tTERMI -- 25 -- ms tRECHG -- 100 -- ms tNO-IN -- 25 -- ms tTS -- 25 -- ms tSHORT -- 250 -- μs 64 -- ms tSHORT_R Other NT C Bias Current INTC VIN > UVLO and VIN > VB AT + V OS_H 72 75 78 μA High Temperature Trip Point High Temperature Trip Point Hysteresis Low Temperature Trip Point VHOT VTS Falling 270 300 330 mV VHOT_h ys VTS Rising from V HOT -- 30 -- mV VCOLD VTS Rising 2000 2100 2200 mV VCOLD_hys VTS Falling from VCOLD -- 300 -- mV Low Temperature Trip Point Hysteresis Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. Guaranteed by design. Note 3. θJA is measured in natural convection at TA = 25°C on a high-effective thermal conductivity four-layer test board of JEDEC 51-7 thermal measurement standard. The measurement case position of θJC is on the exposed pad of the package. Note 4. Devices are ESD sensitive. Handling precaution is recommended. Note 5. The device is not guaranteed to function outside its operating conditions. www.richtek.com 6 DS9525-01 May 2011 RT9525 Typical Operating Characteristics SYSOFF On/Off Without Input Power Charger Detect Sequence V SYSOFF (5V/Div) VBAT (5V/Div) V SYS (5V/Div) IBAT (500mA/Div) EN (5V/Div) CHG (5V/Div) VBAT (2V/Div) IBAT (500mA/Div) VIN = NC, VBAT = 3.7V, 1.5A Mode, RISETA = 1kΩ, RSYS = 10kΩ VIN = 5V, VBAT = 3.7V, 1.5A Mode, RISETA = 1kΩ Time (10ms/Div) Time (5ms/Div) SYSOFF On/Off With Input Power OVP Fault V IN V SYSOFF (5V/Div) VBAT (5V/Div) V SYS (5V/Div) IBAT (200mA/Div) VIN (10V/Div) VSYS VBAT V SYS (2V/Div) IBAT (500mA/Div) VIN = 6V, VBAT = 3.7V, 1.5A Mode, RISETA = 1kΩ VBAT (1V/Div) Time (5ms/Div) Load Transient Response VIN (10V/Div) I IN (1A/Div) V SYS (5V/Div) I SYS (2A/Div) VBAT (5V/Div) IBAT (2A/Div) IBAT VIN = 5V to 15V, VBAT = 3.7V, 1.5A Mode, RISETA = 1kΩ, RSYS = 10Ω Time (50μs/Div) Charger CHG Status After Safety Timers Expired CHG (2V/Div) VIN (5V/Div) APPM, 1.5A Mode, VIN = 5V, VBAT = 3.7V RISETA = 1kΩ, ISYS = 0 to 2A Time (1ms/Div) DS9525-01 May 2011 VBAT (2V/Div) IBAT (500mA/Div) VIN = 5V, VBAT = 3.7V, RISETA = 620Ω Time (250μs/Div) www.richtek.com 7 RT9525 VSYS Short to GND Protection with Battery Battery Current vs. Charging Time 0.6 Battery Current (A) 0.5 VBAT (1V/Div) V SYS (1V/Div) 0.4 0.3 0.2 0.1 VBAT = 3.7V, VSYS = GND VIN = 5V, 500mA Mode 0 0 Time (25ms/Div) 2000 4000 6000 8000 10000 Charging Time (s) Battery Voltage vs. Charging Time Charging Current vs. Battery Voltage 700 4.5 VIN = 5V, RISETA = 1kΩ 600 Charging Current (mA)1 Battery Voltage (V) 3.6 2.7 1.8 0.9 500 400 300 1.5A Mode, VIN = 4.5V 1.5A Mode, VIN = 5V 1.5A Mode, VIN = 6V 500mA Mode, VIN = 5V 200 100 VIN = 5V, 500mA Mode 0 0 0 2000 4000 6000 8000 2 10000 2.5 Charging Current vs. RISETA 4 VIN = 5V, VBAT = 3.7V 1000 800 600 400 200 0 5.53 5.50 5.48 VOUT @ 0A (V) VOUT @ 0.5A (V) VOUT @ 1A (V) 5.45 5.43 5.40 5.38 VIN = 5V 5.35 0 1000 2000 3000 RISETA ((Ω)) www.richtek.com 8 4000 5000 4.5 Output Regulation Voltage vs. Temperature 1200 Charging Current (mA)1 3.5 5.55 Output Regulation Voltage (V)1 1400 3 Battery Voltage (V) Charging Time (s) 6000 -50 -25 0 25 50 75 100 125 Temperature (°C) DS9525-01 May 2011 RT9525 Dropout Voltage (In-Out) vs. Temperature OVP Threshold Voltage vs. Temperature 450 VBAT = 3.7V 400 6.51 Dropout Voltage (mV)1 OVP Threshold Voltage (V) 6.54 Rising 6.48 6.45 6.42 6.39 Falling 6.36 350 300 250 200 150 100 50 VIN = 5V, ISYS = 1A 0 6.33 -50 -25 0 25 50 75 100 -50 125 -25 0 50 75 100 125 Charger Current vs. Temperature Dropout Voltage (Bat-Out) vs. Temperature 70 550.00 60 481.25 Charger Current (mA)1 Dropout Voltage (mV) 25 Temperature (°C) Temperature (°C) 50 40 30 20 10 412.50 343.75 275.00 206.25 137.50 68.75 VIN = 3.7V, ISYS = 1A 0 -50 -25 0 25 50 75 Temperature (°C) DS9525-01 May 2011 100 125 0.00 VIN = 5V, VBAT = 3.7V, 500mA Mode -50 -25 0 25 50 75 100 125 Temperature (°C) www.richtek.com 9 RT9525 Application Information The RT9525 is a fully integrated single cell Li-ion battery charger ideal for portable applications. The internal thermal feedback circuitry regulates the die temperature to optimize the charge rate for all ambient temperatures. Other features include under voltage protection and over voltage protection. Pre-Charge Mode When the output voltage is lower than 2.8V, the charging current will be reduced to a fast charge current ratio set by RISETA to protect the battery life time. Fast Charge Mode When the output voltage is higher than 3V, the charging current will be equal to the fast charge current set by RISETA. Constant Voltage Mode When the output voltage is near 4.2V and the charging current falls below the termination current, after a deglitch time check of 25ms, the charger will become disabled and CHG will go from L to H. During the fast charge phase, several events may increase the timer duration. For example, the system load current may have activated the APPM loop which reduces the available charging current, the device has entered thermal regulation because the IC junction temperature has exceeded TREG. During each of these events, if 3V < VBAT < 4V, the internal timers are slowed down proportionately to the reduction in charging current. However, once the duration exceeds the fault time, the CHG output will flash at approximately 2Hz to indicate a fault condition and a charger current ~ 1mA. 2 tFCHG_true = tFCHG x VISETA tFCHG_true : modified timer in fast charge tFCHG : original timer in fast charge C tFCHG = 14400 sec x ( TIMER ) 1μF tFCHG tPCHG = 8 tPCHG : timer in pre-charge Time fault release : (1) Re-plug power Re-Charge Mode When the chip is in charge termination mode, the charging current will gradually go down to zero. However, once the voltage of the battery drops to below 4V, there will be a deglitch time of 100ms, and then the charging current will resume again. Charging Current Decision The charge current can be set according to the following equations : ICHG_FAST = VISETA / RISETA x 300 (A) ICHG_PRE = 10% x ICHG_FAST (A) where VISETA unit = V; RISETA unit = Ω Time Fault The Fast Charge Fault Time can be set according to the following equations : (2) Toggle /EN (3) Enter/Exit USB suspend mode (4) Removes Battery (5) OVP Note that the fast charge fault time is independent of the charge current. Power Good VIN Power Good (PGOOD = L) Input State VIN < VUVLO PGOOD Output High impedance VUVLO < VIN < VBAT + VOS_H High impedance VBAT + VOS_H < VIN < VOVP VIN > VOVP Low impedance High impedance Fast Charge Fault Time : tFCHG = 14400 x CTIMER (s) Pre-Charge Fault Time : tPCHG = 1/8 x tFCHG (s) where CTIMER unit is μF. www.richtek.com 10 DS9525-01 May 2011 RT9525 Charge State Indicator Charge State Charging Charging suspended by thermal loop Safety timers expired Charging done Recharging after termination IC disabled or no valid input power From (1), (2), the RT1 and RT2 can be calculated by the following equations : CHG Output Low (for first charge cycle) 2Hz flash RT1 = −1500μ × (RHOT + RCOLD ) + 3000μ 20 5625μ 2 x (RCOLD − RHOT )2 + 105μ × (RCOLD − RHOT ) 3000μ High impedance RT2 = (RT1 + RHOT ) 250μ × RT1 + 250μ × RHOT − 1 Battery Pack Temperature Monitoring Charge Enable The RT9525 features an external battery pack temperature monitoring input. The TS input connects to the NTC thermistor in the battery pack to monitor battery temperature and prevent dangerous over temperature conditions. If at any time the voltage at TS falls outside of the operating range, charging will be suspended. The timers maintain their values but suspend counting. When charging is suspended due to a battery pack temperature fault, the CHG pin remains low and continues to indicate charging. When EN is low, the charger turns on. When EN is high, the charger turn off. EN is pulled low for initial condition. VIN Input Current Limit EN2 EN1 VIN Input Current Limit L L 90mA L H 475mA H L 1.5A H H Suspend Mode Suspend Mode Set EN1 = EN2 = H, and the charger will enter Suspend Mode. In Suspend Mode, CHG is in high impedance and ISUS(MAX) < 330μA. 2.1V - RT1 TS RNTC RT2 + - 0.3V + Too Cold Power Switch Too Hot For the RT9525, there are three power scenarios : (1) When a battery and an external power supply (USB or adapter) are connected simultaneously : Figure 1 When temperature reaches at “Too Cold” state, RNTC = RCOLD (RT1 + RCOLD ) × RT2 × INTC = 2.1V (V) (RT1 + RCOLD ) + RT2 (1) where INTC = 75μ A (typ.) When temperature reaches at “Too Hot” state, RNTC = RHOT (RT1 + RHOT ) × RT2 × INTC = 0.3V (V) (RT1 + RHOT ) + RT2 If the system load requirements exceed that of the input current limit, the battery will be used to supplement the current to the load. However, if the system load requirements are less than that of the input current limit, the excess power from the external power supply will be used to charge the battery. (2) When only the battery is connected to the system : The battery provides the power to the system. (2) (3) When only an external power supply is connected to the system : The external power supply provides the power to the system. DS9525-01 May 2011 www.richtek.com 11 RT9525 Input DPM Mode Thermal Regulation and Thermal Shutdown For the RT9525, the input voltage is monitored when the USB100 or USB500 is selected. If the input voltage is lower than VDPM, the input current limit will be reduced to stop the input voltage from dropping any further. This can prevent the IC from damaging improperly configured or inadequately designed USB sources. The RT9525 provides a thermal regulation loop function to monitor the device temperature. If the die temperature rises above the regulation temperature, TREG, the charge current will automatically be reduced to lower the die temperature. However, in certain circumstances (such as high VIN, heavy system load, etc.) even with the thermal loop in place, the die temperature may still continue to increase. In this case, if the temperature rises above the thermal shutdown threshold, TSD, the internal switch between VIN and SYS will be turned off. The switch between the battery and SYS will remain on, however, to allow continuous battery power to the load. Once the die temperature decreases by ΔTSD, the internal switch between VIN and SYS will be turned on again and the device returns to normal thermal regulation. APPM Mode Once the sum of the charging and system load currents becomes higher than the maximum input current limit, the SYS pin voltage will be reduced. When the SYS pin voltage is reduced to VAPPM, the RT9525 will automatically operate in APPM mode. In this mode, the charging current is reduced while the SYS current is increased to maintain system output. In APPM mode, the battery termination function is disabled. Battery Supplement Mode Short Circuit Protect In APPM mode, the SYS voltage will continue to drop if the charge current is zero and the system load increases beyond the input current limit. When the SYS voltage decreases below the battery voltage, the battery will kick in to supplement the system load until the SYS voltage rises above the battery voltage. While in supplement mode, there is no battery supplement current regulation. However, a built in short circuit protection feature is available to prevent any abnormal current situations. While the battery is supplementing the load, if the difference between the battery and SYS voltage becomes more than the short circuit threshold voltage, SYS will be disabled. After a short circuit recovery time, tSHORT_R, the counter will be restarted. In supplement mode, the battery termination function is disabled. Note that for the battery supply mode exit condition, VBAT − VSYS < 0V. Battery Disconnect (SYSOFF input) The RT9525 features a SYSOFF input that allows the user to turn off the switch to disconnect the battery from the SYS pin. www.richtek.com 12 4.16 to 4.2 to 4.23V -40 to 85°C Battery Voltage Charging Current VRECH (EN2,EN1) = (H, L) or (L, H) ITERMI = 20% x ICHG-FAST VPRECH ITERM (EN2, EN1) = (L, H) ITERMI = 3.3% x ICHG_FAST ITERM2 ICHG_PRE = I0% x ICHG_FAST Time APPM Profile 1.5A Mode VIN 6V VSYS 5.5V VADPM 4.3V VBAT 4.0V 3A 2A IBAT 1A ISYS 0 IVIN -1A -2A -3A T1 T2 T3 T4 T5 T6 T7 DS9525-01 May 2011 RT9525 Thermal Considerations ISYS VSYS T1, T7 0 SYS Regulation Voltage T2, T6 < I VIN_OC − CHG_MAX SYS Regulation Voltage T3, T5 > IVIN_OC − CHG_MAX < IVIN_OC Auto Charge Voltage Threshold T4 > I VIN_OC VBAT − IBAT x RDS(ON) I VIN IBAT CHG_MAX CHG_MAX For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : PD(MAX) = (TJ(MAX) − TA) / θJA T2, T6 ISYS + CHG_MAX where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. CHG_MAX T3, T5 VIN_OC VIN_OC − I SYS T4 VIN_OC ISYS − IVIN_OC For recommended operating condition specifications of the RT9525, the maximum junction temperature is 125°C and TA is the ambient temperature. The junction to ambient thermal resistance, θJA, is layout dependent. For WQFN- USB 500mA Mode VUSB VSYS VAPPM VBAT 16L 3x3 packages, the thermal resistance, θJA, is 68°C/ W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : 5V 4.3V 4.0V PD(MAX) = (125°C − 25°C) / (68°C/W) = 1.471W for WQFN-16L 3x3 package 0.75A 0.5A IBAT 0.25A 0 ISYS IUSB -0.25A -0.5A -0.75A T1 T1, T7 T2, T6 T3, T5 T4 T1, T7 T2 T3 T4 T5 T6 T7 ISYS 0 < USB_OC − CHG_MAX > USB_OC − CHG_MAX < USB_OC VSYS SYS Regulation Voltage > USB_OC VBAT − IBAT x RDS(ON) SYS Regulation Voltage Auto Charge Voltage Threshold IUSB IBAT CHG_MAX CHG_MAX T2, T6 ISYS + CHG_MAX CHG_MAX T3, T5 USB_OC USB_OC − ISYS T4 USB_OC ISYS − USB_OC The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. For the RT9525 package, the derating curve in Figure 2 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. 1.60 Maximum Power Dissipation (W)1 T1, T7 Four-Layer PCB 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 0 25 50 75 100 125 Ambient Temperature (°C) Figure 2. Derating Curve for the RT9525 Package DS9525-01 May 2011 www.richtek.com 13 RT9525 Layout Considerations The RT9525 is a fully integrated low cost single cell Li-Ion battery charger ideal for portable applications. Careful PCB layout is necessary. For best performance, place all peripheral components as close to the IC as possible. A short connection is highly recommended. The following guidelines should be strictly followed when designing a PCB layout for the RT9525. ` Input and output capacitor should be placed close to IC and connected to ground plane. The trace of input in the PCB should be placed far away from the sensitive devices AND shielded by the ground. ` The GND and exposed pad should be connected to a strong ground plane for heat sinking and noise protection. ` The connection of R ISETA should be isolated from other noisy traces. A short wire is recommended to prevent EMI and noise coupling. GND RISETA GND CBAT BATT RTS CTIMER ISETA SYSOFF TIMER VIN The RISETA connection copper area should be minimized and kept far away from noise sources. Place CIN near the IC to improve performance. GND CIN 16 15 14 13 TS BAT BAT EN 1 12 2 11 GND 3 10 17 4 6 7 9 CSYS SYS 8 EN2 EN1 PGOOD GND 5 NC SYS SYS CHG GND should be connected to a strong ground plane for heat sinking and noise protection. SYS Figure 3. PCB Layout Guide www.richtek.com 14 DS9525-01 May 2011 RT9525 Outline Dimension D SEE DETAIL A D2 L 1 E E2 e b A A1 1 1 2 2 DETAIL A Pin #1 ID and Tie Bar Mark Options A3 Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.180 0.300 0.007 0.012 D 2.950 3.050 0.116 0.120 D2 1.300 1.750 0.051 0.069 E 2.950 3.050 0.116 0.120 E2 1.300 1.750 0.051 0.069 e L 0.500 0.350 0.020 0.450 0.014 0.018 W-Type 16L QFN 3x3 Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: marketing@richtek.com Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. DS9525-01 May 2011 www.richtek.com 15