RT9503 Fully Integrated Linear Single Cell Li-Ion Battery Charger with Power Path General Description Features The RT9503 is a fully integrated low cost single-cell LiIon battery charger IC ideal for portable applications. The RT9503 is capable of being powered up from AC adapter and the USB (Universal Serial Bus) port inputs. The RT9503 can automatically detect and select the AC adapter and the USB port as the power source for the charger. The RT9503 enters sleep mode when both supplies are removed. z Automatic Input Supplies Selection z 18V Maximum Rating for AC Adapter Integrated Selectable 100mA and 500mA USB Charge Current Internal Integrated Power FETs AC Adapter Power Good Status Indicator Charge Status Indicator External Capacitor Programmable Safety Timer Under Voltage Protection Over Voltage Protection Automatic Recharge Feature Battery Temperature Monitoring Small 16-Lead WQFN Package Thermal Feedback Optimizing Charge Rate Power Path Controller RoHS Compliant and 100% Lead (Pb)-Free The RT9503 optimizes the charging task by using a control algorithm including preconditioning mode, fast charge mode and constant voltage mode. The charging task is terminated as the charge current drops below the preset threshold. The USB charge current can be selected from preset ratings100mA and 500mA, while the AC adapter charge current can be programmed up to 1A with an external resister. The internal thermal feedback circuitry regulates the die temperature to optimize the charge rate for all ambient temperatures. The RT9503 features 18V and 7V maximum rating voltages for AC adapter and USB port inputs respectively. The other features are external programmed safety timer, under voltage protection, over voltage protection for AC adapter supply, battery temperature monitoring, power supply status indicators and charge status indicator. z z z z z z z z z z z z z Applications z z z z Digital Cameras Cellular Phones PDAs and Smart Phones and MP3 Portable Instruments Pin Configurations RT9503 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. 12 BATT 2 11 TS TIMER EN GND 3 10 17 4 9 5 6 7 ISETU NC Note : 1 GND Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free) 16 15 14 13 ACIN USB CHG_S AC_PGOOD ISETA Package Type QW : WQFN-16L 3x3 (W-Type) NC BAT_ON AC_ON Ordering Information SYS (TOP VIEW) 8 WQFN-16L 3x3 Marking Information For marking information, contact our sales representative directly or through a Richtek distributor located in your area. DS9503-03 April 2011 www.richtek.com 1 RT9503 Typical Application Circuit System 10uF 16 3 4 V IN Adapter 1 RT9503 SYS BAT_ON 13 CHG_S BATT ACIN TS TIMER 2 1uF 6 USB 12 1uF AC_PGOOD 1uF USB Battery Pack AC_ON + 15 11 10 CT 0.1uF Chip Enable EN 9 ISETA 7 ISETU GND 5, Exposed Pad (17) Functional Pin Description Pin No. Pin Name Pin Function 1 ACIN Wall Adaptor Charge Input Supply. 2 USB USB Charge Input Supply. 3 CHG_S Charge Status Indicator Output (open drain). 4 AC_PGOOD Wall Adaptor Power Good Indicator Output (open drain). 5 GND Ground. 6 ISETA Wall Adaptor Supply Charge Current Set Point. 7 ISETU USB Supply Charge Current Set Input (active low). 8, 14 NC No Internal Connection. 9 EN Charge Enable (Active Low). 10 TIMER Safe Charge Timer Setting. 11 TS Temperature Sense Input. 12 BATT Battery Charge Current Output. 13 BAT_ON Power path controller output, low to turn on the external P-MOSFET. 15 SYS System Voltage Detecting Pin. 16 AC_ON P-MOSFET Switch Control Output (open drain). 17 (Exposed Pad) GND www.richtek.com 2 The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. DS9503-03 April 2011 RT9503 Function Block Diagram ACIN USB OVP Comparator + OVP - 2.5V Charge Input Selection USB P-MOSFET SENSE MOSFET ACIN P-MOSFET SENSE MOSFET Timer ISETA TIMER BATT GND 2.5V VREF 0.5V Thermal Sense 125 C Temperature Fault ACIN/USB VFB Temperature Sense 0.25V TS OVP DRV AC_ON Precharge Logic Loop Controller 1.5k 7.5k VREF Thermal Sense Termination Comparator 0.25V + 0.9V - VOS + - + - 1uA Pre-Charge Phase CHG_S VH Charge Disable BATT 1uA EN PGOOD Logic + ISETU VCC/USB BAT_ON Hys SYS Fast Charge Phase Constant Voltage Phase & Re-Charge Phase Standby Phase Programmed Charge Current Battery Voltage Charging Current 4.1V Recharge Threshold 1/10 Programmed Charge Current 2.8V Precharge Threshold Charge Complete Charging I-V Curve DS9503-03 April 2011 www.richtek.com 3 RT9503 Table RT9503 Flow Chart Start-Up Precharge Phase Fast Charge Phase Recharge Phase Standby/Fault ACIN/USB Power Up DISABLE UVP SLEEP Start-Up DISABLE MODE PFET OFF IBATT = 0 YES V /CE > 1.4V ? NO NO V ACIN < 4.3V and < 3.9V? V USB NO YES UVP MODE PFET OFF IBATT = 0 V ACIN < V BATT and V USB < V BATT ? YES SLEEP MODE PFET OFF IBATT = 0 NO 1ms Delay & Start Timer V TS > 2.5V or V TS < 0.5V? OVP MODE NO RECHAR GE YES TEMP FAULT /CHG_S HIGH IMPEDANCE IBATT = 0.1 Charge Current /CHG_S Strong Pull Down NO V BATT > 4.1 V? IBATT = Charge Current /CHG_S Strong Pull Down YES NO YES YES YES V BATT > 2.8V? NO IBATT < 0.1 ICHG ? T CHARGE UP? ? TCHARGE UP? YES STANDBY PFET OFF IBATT = 0 V BATT > 4.1 V? NO NO www.richtek.com 4 NO YES V BATT > 2.8V? YES YES TIME FAULT DS9503-03 April 2011 RT9503 Absolute Maximum Ratings z z z z z z z z z z (Note 1) Supply Input Voltage, ACIN --------------------------------------------------------------------------------------------Supply Input Voltage, USB ---------------------------------------------------------------------------------------------CHG_SB, AC_PGOOD, AC_ON --------------------------------------------------------------------------------------Other Pins ------------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C WQFN-16L 3x3 -----------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WQFN-16L 3x3, θJA ------------------------------------------------------------------------------------------------------WQFN-16L 3x3, θJC -----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------ Recommended Operating Conditions z z z z −0.3V to 18V −0.3V to 7V −0.3V to 18V −0.3V to 5.5V 1.667W 60°C/W 8.2°C/W 260°C 150°C −65°C to 150°C 2kV 200V (Note 4) Supply Input Voltage Range, ACIN -----------------------------------------------------------------------------------Supply Input Voltage Range, USB ------------------------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Ambient Temperature Range -------------------------------------------------------------------------------------------- 4.5V to 12V 4.1V to 6V −20°C to 125°C −20°C to 85°C Electrical Characteristics (ACIN = USB = 5V, TA = 25°C, unless otherwise specification) Parameter Symbol Test Conditions Min Typ Max Units 4.1 4.3 4.5 V Supply Input ACIN UVP Rising Threshold Voltage VUV_ACIN USB UVP Rising Threshold Voltage VUV_USB VBATT = 3V 3.7 3.9 4.1 V ACIN/USB UVP Hysteresis VUV_HYS VBATT = 3V 40 100 140 mV ACIN/USB Standby Current ISTBY VBA TT = 4.5V -- 300 500 uA ACIN/USB Shutdown Current ISHDN VEN = High -- 50 100 uA ISLEEP VACIN = 4V, V USB = 4V, VBATT = 4.5V -- 5 15 uA VREG IBATT = 60mA 4.158 4.2 4.242 V BATT Sleep Leakage Current Voltage Regulation BATT Regulation Voltage ACIN MOSFET Dropout V BATT = 4V, ICHG = 1A 400 500 620 mV ACIN MOSFET Dropout V BATT = 4V, IUSB = High 500 650 800 mV Current Regulation ISETA Set Voltage (Fast Charge Phase) VISETA_FCHG VBATT = 3.5V 2.43 2.48 2.53 V Full Charge Setting Range ICHG_AC 100 -- 1000 mA AC Charge Current Accuracy ICHG_AC -- 500 -- mA VBATT = 3.8V, RISET = 1.5kΩ To be continued DS9503-03 April 2011 www.richtek.com 5 RT9503 Parameter Symbol Test Conditions Min Typ Max Units V PRECH 2.7 2.8 2.9 V ΔVPRECH 60 100 140 mV 8 10 12 % 50 95 140 mV V BATT = 4.2V -- 10 -- % Precharge BATT Pre-charge Threshold BATT Pre-charge Threshold Hysteresis Pre-Charge Current IPCHG VBATT = 2V Recharge Threshold BATT Re-charge Falling Threshold ΔVRECH_L Hysteresis Charge Termination Detection Termination Current Ratio (Note5) ITERM Logic Input/Output CHG_S Pull Down Voltage V CHG_S ICHG_S = 5mA -- 213 -- mV AC_PGOOD Pull Down Voltage V PGOOD IPGOOD = 5mA -- 213 -- mV PGOOD Pull Down Voltage V PGOOD TBD; IPGOOD = 5mA -- 65 -- mV EN Threshold Logic-High Voltage V IH 1.5 -- -- V Logic-Low Voltage V IL -- -- 0.4 V IEN -- -- 1.5 uA EN Pin Input Current ISETU Threshold High Voltage V ISETU_HIGH 1.5 -- Low Voltage V ISETU_LOW -- -- 0.4 V IISETU -- -- 1.5 uA -- 100 -- us ISETU Pin Input Current V USB Charge Current & Timing Soft-Start Time TSS VISETA from 0V to 2.5V USB Charge Current ICHG_USB VACIN = 3.5V, V USB = 5V, VBATT =3.5V, ISETU = 5V 400 450 500 mA USB Charge Current ICHG_USB VACIN = 3.5V, VUSB = 5V, VBATT = 3.5V, ISETU = 0V 60 80 100 mA TIME Pin Source Current ITIME VTIMER = 2V -- 1 -- uA Pre-charge Fault Time T PCHG_F CTIMER = 0.1uF, fCLK = 7Hz 1720 2460 3200 s Charge Fault Time T FCHG_F CTIMER = 0.1uF, fCLK = 7Hz 13790 19700 25610 s ITS VTS = 1.5V 96 102 108 uA Timer Battery Temperature Sense TS Pin Source Current TS Pin Threshold High Voltage V TS_HIGH 0.485 0.5 0.515 V Low Voltage V TS_LOW 2.45 2.5 2.55 V -- 125 -- °C -- 6.5 -- V -- −20 mV Protection Thermal Regulation OVP SET Voltage Internal Default Power Path Controller BAT_ON Pull Low As SYS Falling, VBATT = 4V, −150 SYS-BAT To be continued www.richtek.com 6 DS9503-03 April 2011 RT9503 Parameter BAT_ON Pull High BAT_ON Pull Low Switch Resistance BAT_ON Pull High Switch Resistance Symbol Test Conditions As SYS Raising, VBATT = 4V, SYS-BAT Min Typ Max Units −50 -- 0 mV VBAT = 4V -- 10 -- Ω VACIN = 5V -- 30 -- Ω 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. θJA is measured in the natural convection at TA = 25°C on a high effective four layers thermal conductivity test board of JEDEC 51-7 thermal measurement standard. The case point of θJC is on the expose pad for the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Guaranteed by design. DS9503-03 April 2011 www.richtek.com 7 RT9503 Typical Operating Characteristics Charge Current vs. RSETA Enable Threshold Voltage vs. Input Voltage 1200 2.0 1000 Charge Current (mA) VBATT = 3.8V, ICharger = 500mA Enable Threshold Voltage (V) VBATT = 3.8V, ACIN = 5V 800 600 400 200 0 1.6 Rising 1.2 0.8 Falling 0.4 0.0 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 4.5 4.8 5.1 RSETA (k ٛ) (kΩ) 2.54 6 6.3 6.6 VBATT = 3.8V, ACIN = 5V, ICharger = 500mA VBATT = 3.8V, ICharger = 500mA 2.52 ISETA Voltage (V) 2.52 ISETA Voltage (V) 5.7 ISETA Voltage vs. Temperature ISETA Voltage vs. ACIN Voltage 2.54 2.50 2.48 2.46 2.44 2.50 2.48 2.46 2.44 2.42 2.42 2.40 2.40 4.5 4.8 5.1 5.4 5.7 6 6.3 -25 -15 6.6 -5 5 15 25 35 45 55 65 75 85 Temperature (°C) ACIN Voltage (V) TS Current vs. Input Voltage TS Current vs. Temperature 105 105 104 104 103 103 102 102 TS Current (uA) TS Current (uA) 5.4 Input Voltage (V) 101 100 99 98 97 101 100 99 98 97 96 VBATT = 3.8V, ICharger = 500mA 95 96 VBATT = 3.8V, ACIN = 5V, ICharger = 500mA 95 4.5 4.8 5.1 5.4 5.7 Input Voltage (V) www.richtek.com 8 6 6.3 6.6 -25 -15 -5 5 15 25 35 45 55 65 75 85 Temperature (°C) DS9503-03 April 2011 RT9503 ISETU Threshold Voltage vs. USB Voltage Regulation Voltage vs. Temperature 4.26 VBATT = 3.8V ACIN = 5V, ICharger = 500mA 4.24 1.6 Regulation Voltage (V) ISETU Threshold Voltage (V) 2.0 Rising 1.2 0.8 Falling 0.4 4.22 4.20 4.18 4.16 4.14 0.0 4.5 4.8 5.1 5.4 5.7 6 6.3 -25 -15 6.6 ACIN Power On 15 25 35 45 VUSB (5V/Div) V SYS (5V/Div) V SYS (5V/Div) EN (5V/Div) EN (5V/Div) I ACIN (1A/Div) I USB (1A/Div) Time (1ms/Div) ACIN Power Off USB Power Off VIN (5V/Div) VUSB (5V/Div) V SYS (5V/Div) V SYS (5V/Div) VBATT (5V/Div) VBATT (5V/Div) I ACIN (1A/Div) I USB (1A/Div) Time (500us/Div) 65 75 85 VBATT = 3.7V, ISYS = 500mA, ICharger = 500mA Time (1ms/Div) ISYS = 500mA, ICharger = 500mA 55 USB Power On VACIN (5V/Div) DS9503-03 April 2011 5 Temperature (°C) USB Voltage (V) VBATT = 3.7V, ISYS = 500mA, ICharger = 500mA -5 ISYS = 500mA, ICharger = 500mA Time (500us/Div) www.richtek.com 9 RT9503 Application Information The RT9503 is a fully integrated low cost single-cell LiIon battery charger for portable applications. The RT9503 can be adopted for two input power source, AC USB Input. It will automatically select the input source and operate in different mode as below. AC Mode : When the AC input voltage (ACIN) is higher than the UVP voltage level (4.3V), the RT9503 will enter AC Mode. In the AC Mode, ACIN P-MOSFET is turned on and USB P-MOSFET is turned off. When ACIN voltage is between the UVP and OVP threshold levels, the switch Q1 will be turned on and Q2 will be turned off. So, the system oad is powered directly from the adapter through the transistor Q1, and the battery is charged by the RT9503. Once the ACIN voltage is higher than the OVP or is lower than the UVP threshold, the RT9503 stops charging, and then Q1 will be turned off and Q2 will be turned on to supply the system by battery. USB Mode : When AC input voltage (ACIN) is lower than UVP voltage level and USB input voltage is higher than UVP voltage level (3.9V), the RT9503 will operate in the USB Mode. In the USB Mode, ACIN P-MOSFET and Q1 are turned off and USB P-MOSFET and Q2 are turned on. The system load is powered directly from the USB/Battery through the switch Q2. Note that in this mode, the battery will be discharged once the system current is higher than the battery charge current. Sleep Mode : The RT9503 will enter Sleep Mode when both AC and USB input voltage are removed. This feature provides low leakage current from the battery during the absence of input supply. V ACIN > UVP ACIN Mode USB Mode Power-Path Management The RT9503 powers the system and independently charging the battery while the input is AC. This features reduces the charge time, allows for proper charge termination, and allows the system to run with an absent or defective battery pack. Case 1 : Input is AC In this case, the system load is powered directly from the AC adapter through the transistor Q1. For RT9503, Q1 and Q2 act as a switch as long as the RT9503 is ready. Once the AC voltage is ready (>UVP and <OVP), the battery charge by RT9503 internal MOSFET and Q1 starts regulating the output voltage supply system (Q2 is turn off). Once the AC voltage over operation voltage (<UVP or >OVP), the RT9503 stop charge battery, Q1 turns off and Q2 starts supply power for system. ISYS System RT9503 Q1 SYS Q2 BAT_ON AC_ON BATT ICharger V IN + Battery ACIN USB USB Figure 2. ACIN Input Case 2 : Input is USB In this case, the system load is powered directly from the battery through the switch Q2 (Q1 is turn off). Note in this case, the system current over battery charge current will lead to battery discharge. System V ACIN < UVP V USB > UVP RT9503 Q1 SYS Q2 BAT_ON AC_ON ISYS Sleep Mode BATT V ACIN < UVP V USB < UVP + ACIN V IN Battery ICharger USB USB Figure 1. Input Power Source Operation Mode Figure 3. USB Input www.richtek.com 10 DS9503-03 April 2011 RT9503 ACIN Over-Voltage Protection V BATT + The ACIN input voltage is monitored by an internal OVP comparator. The comparator has an accurate reference of 2.5V from the band-gap reference. The OVP threshold is set by the internal resistive. The protection threshold is set to 6.5V, but ACIN input voltage over 18V still leads the RT9503 to damage. When the input voltage exceeds the threshold, the comparator outputs a logic signal to turn off the power P-MOSFET to prevent the high input voltage from damaging the electronics in the handheld system. When the input over Voltage condition is removed (ACIN < 6V), the comparator re-enables the output by running through the soft-start. A ITS NTC TS Temperature Sense Battery 0.1uF to 10uF VTS = ITS × RNTC Turn off when VTS ≥ 2.5V or VTS ≤ 0.5V Figure 4. Temperature Sensing Configuration V BATT + Battery Temperature Monitoring A The RT9503 continuously monitors battery temperature by measuring the voltage between the TS and GND pins. The RT9503 has an internal current source to provide the bias for the most common 10kΩ negative-temperature coefficient thermal resistor (NTC) (see Figure 4). The RT9503 compares the voltage on the TS pin against the internal VTS_HIGH and VTS_LOW thresholds to determine if charging is allowed. When the temperature outside the VTS_HIGH and VTS_LOW thresholds is detected, the device will immediately stop the charge. The RT9503 stops charge and keep monitoring the battery temperature when the temperature sense input voltage is back to the threshold between VTS_HIGH and VTS_LOW, the charger will be resumed. Charge is resumed when the temperature returns to the normal range. However the user may modify thresholds by the negative-temperature coefficient thermal resistor or adding two external resistors. (see Figure 5.) The capacitor should be placed close to TS (Pin 9) and connected to the ground plane. The capacitance value (0.1uF to 10uF) should be selected according to the quality of PCB layout. It is recommended to use 10uF if the layout is poor if prevent noise. DS9503-03 April 2011 ITS NTC Temperature Sense TS R T1 Battery R T2 0.1uF to 10uF RT2 × (RT1 + RNTC ) RT1 + RT2 + RNTC Turn off when VTS ≥ 2.5V or VTS ≤ 0.5V VTS = ITS Figure 5. Temperature Sensing Circuit Fast-Charge Current Setting Case 1: ACIN Mode The RT9503 offers ISETA pin to determine the ACIN charge rate from 100mA to 1.2A. The charge current can be calculated as following equation. Icharge_ac = K SET VSET RSETA The parameter KSET = 300 ; VSET = 2.5V. RSETA is the resistor connected between the ISETA and GND. www.richtek.com 11 RT9503 indicates the open-drain transistor is turned on and LED bright. 1200 Charge Current (mA) 1000 Charge State 800 CHG_S AC_PGOOD Charge ON ON Charge Done OFF ON Charge ON OFF Charge Done OFF OFF ACIN 600 USB 400 200 Temperature Regulation and Thermal Protection 0 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 (k) RRSETA SETA(kΩ) Figure 6. AC Mode Charge Current Setting Case 2 : USB Mode When charging from a USB port, the ISETU pin can be used to determine the charge current of 100mA or 500mA. A low-level signal of ISETU pin sets the charge current at 100mA and a high level signal sets the charge current at 500mA. Pre- Charge Current Setting During a charge cycle if the battery voltage is below the VPRECH threshold, the RT9503 applies a pre-charge mode to the battery. This feature revives deeply discharged cells and protects battery life. The RT9503 internal determines the pre-charge rate as 10% of the fast-charge current. Battery Voltage Regulation The RT9503 monitors the battery voltage through the BATT pin. Once the battery voltage level closes to the VREG threshold, the RT9503 voltage enters constant phase and the charging current begins to taper down. When battery voltage is over the VREG threshold, the RT9503 will stop charge and keep to monitor the battery voltage. However, when the battery voltage decreases 100mV below the VREG, it will be recharged to keep the battery voltage. Charge Status Outputs The open-drain CHG_S and AC_PGOOD outputs indicate various charger operations as shown in the following table. These status pins can be used to drive LEDs or communicate to the host processor. Note that ON www.richtek.com 12 In order to maximize charge rate, the RT9503 features a junction temperature regulation loop. If the power dissipation of the IC results in a junction temperature greater than the thermal regulation threshold (125°C), the RT9503 throttles back on the charge current in order to maintain a junction temperature around the thermal regulation threshold (125°C). The RT9503 monitors the junction temperature, TJ, of the die and disconnects the battery from the input if TJ exceeds 125°C. This operation continues until junction temperature falls below thermal regulation threshold (125°C) by the hysteresis level. This feature prevents the maximum power dissipation not exceeded typical design conditions. External Timer As a safety mechanism the RT9503 has a userprogrammable timer that monitors the pre-charge and fast charge time. This timer (charge safety timer) is started at the beginning of the pre-charge and fast charge period. The safety charge timeout value is set by the value of an external capacitor connected to the TMR pin (CTMR), if pin TMR is short to GND, the charge safety timer is disabled. As CTMR = 0.1uF, TPRECH is ~2460 secs and TFAULT is 8 x TPRECH. TPRECH = CTMR x 2460/0.1u As timer fault, re-plug-in power or pull high and re-pull low EN can release the fault condition. As a safety mechanism, the RT9503 has a userprogrammable timer that monitors the pre-charge and fast charge time. This timer(charge safe timer) is started at the beginning of the pre-charge and fast-charge period. The safety charge timeout value is set by an external capacitor (CT) connected between TIMER pin and GND. The timeout fault condition can be released by resetting DS9503-03 April 2011 RT9503 Selecting the Input and Output Capacitors In most applications, the most important is the high frequency decoupling capacitor on the input of the RT9503. A 1uF ceramic capacitor, placed in close proximity to input pin and GND pin is recommended. In some applications depending on the power supply characteristics and cable length, it may be necessary to add an additional 10uF ceramic capacitor to the input. The RT9503 requires a small output capacitor for loop stability. A 1uF ceramic capacitor placed between the BATT pin and GND is typically sufficient. Thermal Considerations For continuous operation, do not exceed absolute maximum operation junction temperature. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can be calculated by following formula : PD(MAX) = ( TJ(MAX) - TA ) / θJA 1.8 Maximum Power Dissipation (W) the input power or the EN pin. If the TIMER is shorted to GND, the charge safety timer will be disabled. Four Layers PCB 1.6 1.4 1.2 WQFN-16L 3x3 1.0 0.8 0.6 0.4 0.2 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 7. Derating Curves for RT9503 Package Layout Consideration The RT9503 is a fully integrated low cost single-cell LiIon battery charger ideal for portable applications. Careful PCB layout is necessary. The following guidelines should be strictly followed to achieve best performance of RT9503. ` Input capacitor should be placed close to the IC and connected to the ground plane. The trace of the input in the PCB should be placed far away from the sensitive devices or shielded by the ground. Where T J(MAX) is the maximum operation junction temperature 125°C, TA is the ambient temperature and the θJA is the junction to ambient thermal resistance. ` The GND should be connected to a strong ground plane for heat sinking and noise protection. For recommended operating conditions specification, where TJ(MAX) is the maximum junction temperature of the die (125°C) and TA is the ambient temperature. The junction to ambient thermal resistance θJA is layout dependent. For WQFN-16L 3x3 packages, the thermal resistance θJA is 60°C/W on the standard JEDEC 51-7 four layers thermal test board. The maximum power dissipation at TA = 25°C can be calculated by following formula : ` Output capacitor should be placed close to the IC and connected to ground plane to reduce noise coupling. ` The connection of the RSETA should be isolated from other noisy traces. The short wire is recommended to prevent EMI and noise coupling. PD(MAX) = (125°C − 25°C) / (60°C/W) = 1.667W for WQFN-16L 3x3 packages The maximum power dissipation depends on operating ambient temperature for fixed T J(MAX) and thermal resistance θJA. For WQFN-16L 3x3 package, the Figure 7 of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. DS9503-03 April 2011 www.richtek.com 13 RT9503 The capacitors should be placed close to the IC and connected to ground plane. SYS NC BAT_ON AC_ON SYS 16 15 14 13 ACIN 1 USB 2 CHG_S 3 12 BATT Battery TS GND 10 TIMER 17 9 EN 11 AC_PGOOD 4 6 7 8 GND ISETA ISETU NC 5 RSETA The GND should be connected to a strong ground plane for heat sinking and noise protection. The connection of R SETA should be isolated from other noisy traces. Figure 8 www.richtek.com 14 DS9503-03 April 2011 RT9503 Outline Dimension D SEE DETAIL A D2 L 1 E E2 e b A3 Symbol 1 2 2 DETAIL A Pin #1 ID and Tie Bar Mark Options A A1 1 Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. 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: [email protected] 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. DS9503-03 April 2011 www.richtek.com 15