RT9503A Fully Integrated Linear Single Cell Li-Ion Battery Charger with Power Path General Description Features The RT9503A is a fully integrated low cost single-cell LiIon battery charger IC ideal for portable applications. The RT9503A is capable of being powered up via the AC adapter and USB (Universal Serial Bus) port inputs. The RT9503A can automatically detect and select the AC adapter and the USB port as the power source for the charger. The RT9503A enters sleep mode when both supplies are removed. z The RT9503A 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 ratings of 100mA and 500mA, while the AC adapter charge current can be programmed up to 1A with an external resistor. The internal thermal feedback circuitry regulates the die temperature to optimize the charge rate for all ambient temperatures. The RT9503A features 18V and 7V maximum rating voltages for AC adapter and USB port inputs respectively. Other features include external programmable 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 z Automatic Input Supplies Selection 18V Maximum Rating for AC Adapter Integrated Selectable 100mA and 500mA USB Charge Current Internal Integrated Power MOSFETs 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 Halogen Free Applications z z z z Digital Cameras Cellular Phones PDAs , Smart Phones and MP3 Players Portable Instruments Pin Configurations RT9503A Richtek products are : ` RoHS compliant and compatible with the current require- 12 2 11 TS TIMER 9 EN GND 3 10 17 4 5 6 7 BATT 8 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) WQFN-16L 3x3 ments of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. DS9503A-01 April 2011 www.richtek.com 1 RT9503A Marking Information HK=YM DNN HK= : Product Code YMDNN : Date Code Typical Application Circuit System 10µF 16 3 4 VIN Adapter 1 RT9503A SYS CHG_S BATT AC_PGOOD ACIN TS TIMER 2 1µF RSETA 6 Battery Pack AC_ON 1µF USB BAT_ON 13 USB 12 1µF + 15 11 10 CTMR 0.1µF 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 Supply Input. 2 USB USB Charge Supply Input. 3 CHG_S Charge Status Indicator Output (open drain). 4 AC_PGOOD Wall Adaptor Power Good Indicator Output (open drain). 5, 17 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 6 7 8, 14 ISETA ISETU NC Wall Adaptor Supply Charge Current Set Point. USB Supply Charge Current Set Input (active low). No Internal Connection. 9 10 EN TIMER Charge Enable (Active Low). Safe Charge Timer Setting. 11 TS Temperature Sense Input. 12 BATT Battery Charge Current Output. 13 15 BAT_ON SYS Power Path Controller Output. Pull low to turn on the external P-MOSFET. System Voltage Detecting Input. 16 AC_ON P-MOSFET Switch Control Output (open drain). www.richtek.com 2 DS9503A-01 April 2011 RT9503A Function Block Diagram USB ACIN 2.5V Charge Input Selection USB P-MOSFET SENSE MOSFET OVP Comparator + OVP - ACIN P-MOSFET SENSE MOSFET Timer ISETA TIMER BATT GND ACIN/USB Temperature Sense VFB TS OVP DRV Precharge 1.5k AC_ON Logic Controller VCC/USB 7.5k AC_PGOOD Logic CHG_S VH BATT + - VOS 1µA + - 1µA ISETU EN Pre-Charge Phase 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 DS9503A-01 April 2011 www.richtek.com 3 RT9503A Table RT9503A 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 VACIN < 3V and < 3V? VUSBNO YES UVP MODE PFET OFF IBATT = 0 VACIN < VBATT and VUSB < VBATT? YES SLEEP MODE PFET OFF IBATT = 0 NO 1ms Delay & Start Timer VTS > 2.5V or VTS < 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 VBATT > 4.1 V? IBATT = Charge Current /CHG_S Strong Pull Down YES NO YES YES YES VBATT > 2.8V? NO IBATT < 0.1 ICHG? tCHARGE UP? ? tCHARGE UP? YES STANDBY PFET OFF IBATT = 0 VBATT > 4.1 V? NO NO www.richtek.com 4 NO YES VBATT > 2.8V? YES YES TIME FAULT DS9503A-01 April 2011 RT9503A Absolute Maximum Ratings z z z z z z z z z z (Note 1) Supply Input Voltage, ACIN -------------------------------------------------------------------------------------------Supply Input Voltage, USB -------------------------------------------------------------------------------------------CHG_S, 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 1.471W 68°C/W 7.5°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 Unit -- 3 -- V VBATT = 3V -- 3 -- V Supply Input ACIN UVP Rising Threshold Voltage VUV_ACIN USB UVP Rising Threshold Voltage VUV_USB ACIN/USB UVP Hysteresis VUV_HYS VBATT = 3V -- 100 -- mV ACIN/USB Standby Current ISTBY -- 300 500 μA BATT Sleep Leakage Current ISLEEP VBATT = 4.5V VACIN = 4V, VUSB = 4V, VBATT = 4.5V -- 5 15 μA 4.138 4.2 4.262 V Voltage Regulation BATT Regulation Voltage VREG IBATT = 60mA ACIN MOSFET Dropout VBATT = 4V, ICHG_AC = 1A 400 500 620 mV USB MOSFET Dropout VBATT = 4V, ICHG_USB = High 500 650 800 mV VBATT = 3.5V 2.43 2.48 2.53 V 100 -- 1000 mA -- 500 -- mA Current Regulation ISETA Set Voltage (Fast Charge Phase) Full Charge Setting Range ICHG_AC AC Charge Current Accuracy ICHG_AC VISETA_FCHG VBATT = 3.8V, RISET = 1.5kΩ To be continued DS9503A-01 April 2011 www.richtek.com 5 RT9503A Parameter Symbol Test Conditions Min Typ Max Unit VPRECH 2.7 2.8 2.9 V ΔVPRECH 60 100 140 mV 8 10 12 % 50 95 140 mV VBATT = 4.2V -- 10 -- % Precharge BATT Pre-charge Threshold BATT Pre-charge Threshold Hysteresis Pre-Charge Current I PCHG VBATT = 2V Recharge Threshold BATT Re-charge Falling Threshold ΔVRECH_L Hysteresis Charge Termination Detection Termination Current Ratio (Note5) I TERM Logic Input/Output CHG_S Pull Down Voltage VCHG_S ICHG_S = 5mA -- 213 -- mV AC_PGOOD Pull Down Voltage VPGOOD IPGOOD = 5mA -- 213 -- mV PGOOD Pull Down Voltage VPGOOD IPGOOD = 5mA -- 65 -- mV Logic-High EN Threshold Logic-Low Voltage EN Pin Input Current VIH 1.5 -- -- V VIL -- -- 0.4 V I EN -- -- 1.5 μA ISETU Threshold High Voltage VISETU_HIGH 1.5 -- Low Voltage VISETU_LOW -- -- 0.4 V I ISETU -- -- 1.5 μA -- 100 -- μs ISETU Pin Input Current V USB Charge Current & Timing Soft-Start Time t SS VISETA from 0V to 2.5V USB Charge Current I CHG_USB VACIN = 2.5V, VUSB = 5V, VBATT =3.5V, VISETU = 5V 400 450 500 mA USB Charge Current I CHG_USB VACIN = 2.5V, VUSB = 5V, VBATT = 3.5V, VISETU = 0V 60 80 100 mA TIMER Pin Source Current I TIME VTIMER = 2V -- 1 -- μA Pre-charge Fault Time t PCHG_F CTIMER = 0.1μF, fCLK = 7Hz 1720 2460 3200 s Charge Fault Time t FCHG_F CTIMER = 0.1μF, f CLK = 7Hz 13790 19700 25610 s I TS VTS = 1.5V -- 102 -- μA Timer Battery Temperature Sense TS Pin Source Current TS Pin Threshold High Voltage VTS_HIGH 0.485 0.5 0.515 V Low Voltage VTS_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 DS9503A-01 April 2011 RT9503A 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 Uni −50 -- 0 mV VBATT = 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 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 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. DS9503A-01 April 2011 www.richtek.com 7 RT9503A Typical Operating Characteristics Charge Current vs. RSETA 1200 Enable Threshold Voltage vs. Input Voltage Enable Threshold Voltage (V) VBATT = 3.8V, ACIN = 5V 1000 Charge Current (mA) 2.0 800 600 400 200 0 VBATT = 3.8V, ICharger = 500mA 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) VBATT = 3.8V, ICharger = 500mA 2.52 2.52 2.50 2.50 ISETA Voltage (V) ISETA Voltage (V) 2.54 2.48 2.46 2.44 6 6.3 6.6 VBATT = 3.8V, ACIN = 5V, ICharger = 500mA 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 (μA) TS Current (μA) 5.7 ISETA Voltage vs. Temperature ISETA Voltage vs. ACIN Voltage 2.54 5.4 Input Voltage (V) 101 100 99 98 97 101 100 99 98 97 96 VBATT = 3.8V, 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 96 VBATT = 3.8V, ACIN = 5V, ICharger = 500mA 95 -25 -15 -5 5 15 25 35 45 55 65 75 85 Temperature (°C) DS9503A-01 April 2011 RT9503A 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 0.0 4.22 4.20 4.18 4.16 4.14 4.5 4.8 5.1 5.4 5.7 6 6.3 6.6 -25 -15 ACIN Power On 15 25 35 45 VUSB (5V/Div) V SYS (5V/Div) V SYS (5V/Div) EN (5V/Div) EN (5V/Div) IACIN (1A/Div) IUSB (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) IUSB (1A/Div) Time (500μs/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) DS9503A-01 April 2011 5 Temperature (°C) USB Voltage (V) VBATT = 3.7V, ISYS = 500mA, ICharger = 500mA -5 ISYS = 500mA, ICharger = 500mA Time (500μs/Div) www.richtek.com 9 RT9503A Application Information The RT9503A is a fully integrated low cost single-cell LiIon battery charger for portable applications. The RT9503A can be adopted for two input power source including AC and USB inputs. 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 (3V), the RT9503A 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 below and OVP threshold levels, the switch Q1 will be turned on and Q2 will be turned off. So, the system load is powered directly from the adapter through the transistor Q1, and the battery is charged by the RT9503A. Once the ACIN voltage is higher than the OVP, the RT9503A 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 removed and USB input voltage is higher than UVP voltage level (3V), the RT9503A will operate in the USB Mode. In the USB Mode, ACIN P-MOSFET is turned off while 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 RT9503A 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. VACIN > UVP ACIN Mode USB Mode VACIN removed VUSB > UVP Power-Path Management The RT9503A powers the system and independently charging the battery while the input source is AC. This feature 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 Source is AC In this case, the system load is powered directly from the AC adapter through the transistor Q1. For RT9503A, Q1 and Q2 act as a switch as long as the RT9503A is ready. Once the AC voltage is ready (<OVP), the battery charge by the RT9503A internal MOSFET and Q1 starts regulating the output voltage supply system (Q2 is turn off). Once the AC voltage is higher than the operation voltage (>OVP), the RT9503A stop charging battery, Q1 turns off and Q2 starts to supply power for system. ISYS System RT9503A Q1 SYS Q2 BAT_ON AC_ON BATT ICharger + VIN ACIN USB USB Battery Figure 2. ACIN Input Case 2 : Input Source is USB In this case, the system load is powered directly from the battery through the switch Q2. Note that in this case, the system current over battery charge current will lead to battery discharge. System RT9503A Q1 SYS Sleep Mode Q2 BAT_ON AC_ON Both VACIN and VUSB removed ISYS BATT + ACIN VIN Battery ICharger USB USB Figure 1. Input Power Source Operation Mode Figure 3. USB Input www.richtek.com 10 DS9503A-01 April 2011 RT9503A VBATT 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 resistor. The protection threshold is set to 6.5V, but ACIN input voltage over 18V still leads the RT9503A 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 Over-Voltage Protection A ITS NTC TS Temperature Sense Battery 0.1µF to 10µF VTS = ITS × RNTC Turn off when VTS ≥ 2.5V or VTS ≤ 0.5V Figure 4. Temperature Sensing Configuration (ACIN < 6V), the comparator re-enables the output by running through the soft-start. VBATT + A Battery Temperature Monitoring The RT9503A continuously monitors battery temperature by measuring the voltage between the TS and GND pins. The RT9503A has an internal current source to provide the bias for the most common 10kΩ negative-temperature coefficient thermal resistor (NTC) (see Figure 4). The RT9503A 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 charging. The RT9503A stops charging and keeps monitoring the battery temperature when the temperature-sense 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 via the negative-temperature coefficient thermal resistor or by adding two external resistors. (see Figure 5.) The capacitor should be placed close to TS (Pin 11) and connected to the ground plane. The capacitance value (0.1μF to 10μF) should be selected according to the quality of PCB layout. It is recommended to use 10μF if the layout is poor for noise prevention. DS9503A-01 April 2011 ITS NTC Temperature Sense TS 0.1µF to 10µF RT1 Battery RT2 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 ISETA pin is used to determine the ACIN charge rate from 100mA to 1A. The charge current can be calculated as following equation. ICHG _ AC = K SET VSET RSETA The parameter KSET = 300 ; VSET = 2.5V. RSETA is the resistor connected between ISETA and GND. www.richtek.com 11 RT9503A 1200 communicate to the host processor. Note that ON indicates the open-drain transistor is turned on and LED bright. Charge Current (mA) 1000 800 CHG_S AC_PGOOD Charge ON ON Charge Done OFF ON Charge ON OFF Charge Done OFF OFF Charge State 600 ACIN 400 USB 200 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 RT9503A applies a pre-charge mode to the battery. This feature revives deeply discharged cells and protects battery life. The RT9503A internally determines the pre-charge rate as 10% of the fast-charge current. Battery Voltage Regulation The RT9503A monitors the battery voltage through the BATT pin. Once the battery voltage level closes in on the VREG threshold, the RT9503A voltage enters constant phase and the charging current begins to taper down. When battery voltage is over the VREG threshold, the RT9503A will stop charging but continue to monitor the battery voltage. However, when the battery voltage decreases 100mV below VREG, it will be recharged to preserve the battery voltage. Temperature Regulation and Thermal Protection In order to maximize the charge rate, the RT9503A 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 RT9503A throttles back on the charge current in order to maintain a junction temperature around the thermal regulation threshold (125°C). The RT9503A 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 from exceeding typical design conditions. External Timer As a safety mechanism, the RT9503A provides 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 TIMER pin (CTMR), if the TIMER pin is short to GND, the charge safety timer is disabled. As CTMR = 0.1μF, tPCHG_F is ~2460 secs and tFCHG_F is 8 x tPCHG_F. tPCHG_F = CTMR x 2460/0.1μ When timer faults, re-plug-in power or pull high and then pull low EN to release the fault condition. Selecting the Input and Output Capacitors 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 www.richtek.com 12 In most applications, the most important is the high frequency decoupling capacitor on the input of the RT9503A. A 1μF ceramic capacitor, placed in close proximity to input DS9503A-01 April 2011 RT9503A Thermal Considerations 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 Where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. For recommended operating condition specifications of RT9503A, the maximum junction temperature is 125°C and TA is the ambient temperature. The junction to ambient thermal resistance, θ JA , is layout dependent. For WQFN-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 : PD(MAX) = (125°C − 25°C) / (68°C/W) = 1.471W for WQFN-16L 3x3 package The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. For RT9503A package, the derating curve in Figure 7 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. DS9503A-01 April 2011 1.60 Maximum Power Dissipation (W)1 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 10μF ceramic capacitor to the input. The RT9503A requires a small output capacitor for loop stability. A 1μF ceramic capacitor placed between the BATT pin and GND is typically sufficient. 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 7. Derating Curves for RT9503A Package Layout Consideration The RT9503A 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 the RT9503A. ` 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. ` The GND should be connected to a strong ground plane for heat sinking and noise protection. ` Connection of the RSETA should be isolated from other noisy traces. A short wire is recommended to prevent EMI and noise coupling. ` Output capacitor should be placed close to the IC and connected to ground plane to reduce noise coupling. www.richtek.com 13 RT9503A The capacitors should be placed close to the IC and connected to ground plane. AC_ON SYS NC BAT_ON SYS 16 15 14 13 ACIN 1 USB 2 CHG_S 3 12 GND AC_PGOOD 4 6 7 Battery TS TIMER 17 9 EN 11 10 8 GND ISETA ISETU NC 5 BATT RSETA The GND should be connected to a strong ground plane for heat sinking and noise protection. Connection of RSETA should be isolated from other noisy traces. Figure 8. PCB Layout Guide www.richtek.com 14 DS9503A-01 April 2011 RT9503A 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. DS9503A-01 April 2011 www.richtek.com 15