APW7215 Fixed 600kHz Step-UP Converter for White LEDs Features General Description • Wide Input Voltage from 2.7V to 6V • Fixed 600kHz Switching Frequency The APW7215 is a current-mode and fixed frequency 600kHz boost converter with an integrated N-FET to drive • Reference Voltage : 0.2V • PWM brightness control with wide frequency white LEDs. The series connection allows the LED current to be identical for uniform brightness. Its low on-resistance of NFET and low feedback voltage reduce power loss and achieve range of 5KHz to 100KHz • Build-in Power MOSFET: 0.3Ω • Over-Voltage Protection • Under Voltage Lockout Protection • Over Temperature Protection • <1µA Quiescent Current during Shutdown • TDFN2x2-6 Package • Halogen and Lead Free Available (RoHS high efficiency. 600kHz Constant switching frequency allows using small-size inductor and both of input and output capacitors. An over voltage protection function, which monitors the output voltage via LX pin, stops switching of the IC if the LX voltage exceeds the over voltage threshold. An internal soft-start circuit eliminates the inrush current during start-up. The APW7215 also integrates under-voltage lockout and Compliant) over-temperature protection to protect the IC in abnormal conditions. The APW7215 is available in TDFN2x2-6 Applications package. • White LED Display Backlighting • Cell Phone and Smart Phone • PDA, PMP, MP3 • Digital Camera Pin Configuration FB 1 6 VIN NC 2 5 EN GND 3 4 LX APW7215 TDFN2x2-6 Top View Simplified Application Circuit VIN VOUT L1 22µH C1 1µF VIN LX C2 1µF 10 strings GND EN FB PWM Dimming R1 ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and advise customers to obtain the latest version of relevant information to verify before placing orders. Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 1 www.anpec.com.tw APW7215 Ordering and Marking Information Package Code QB: TDFN2x2-6 APW7215 Assembly Material Handling Code Temperature Range Package Code APW7215QB: W15 X Operating Ambient Temperature Range I : -40 to 85oC Handling Code TR : Tape & Reel Assembly Material G : Halogen and Lead Free Device X - Date Code Note: ANPEC lead-free products contain molding compounds/die attach materials and 100% matte tin plate termination finish; which are fully compliant with RoHS. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J-STD-020D for MSL classification at lead-free peak reflow temperature. ANPEC defines “Green” to mean lead-free (RoHS compliant) and halogen free (Br or Cl does not exceed 900ppm by weight in homogeneous material and total of Br and Cl does not exceed 1500ppm by weight). Absolute Maximum Ratings Symbol (Note 1) Rating Unit VIN Pin to GND -0.3 to 7 V FB and EN to GND -0.3 ~ VIN V VLX LX Pin to GND -0.3 to 40 V PD Power Dissipation TJ Maximum Junction Temperature VIN Parameter TSTG Storage Temperature Range TSDR Maximum Lead Soldering Temperature, 10 Seconds Internally Limit W 150 °C -65 to 150 °C 260 °C Note1: Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability Thermal Characteristics Symbol θJA θJC Parameter Typical Value Junction-to-Ambient Resistance in free air (Note 2) Junction-to-Case Resistance TDFN2x2-6 TDFN2x2-6 Unit 165 o 20 o C/W C/W Note 2: θJA is measured with the component mounted on a high effective thermal conductivity test board in free air. Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 2 www.anpec.com.tw APW7215 Recommended Operating Conditions (Note 3) Symbol Parameter Range Unit VIN VIN Input Voltage 2.7 ~ 6 V CIN Input Capacitor 1~ µF Output Capacitor 1~ µF COUT L1 Converter Output Inductor 4.7 ~ 22 µH TA Ambient Temperature -40 ~ 85 °C TJ Junction Temperature -40 ~ 125 °C Note 3: Please refer to the typical application circuit. Electrical Characteristics Refer to the typical application circuits. These specifications apply over. VIN=3.6V, TA=25°C. Symbol Parameter APW7215 Test Conditions Unit Min. Typ. Max. 2.7 - 6 SUPPLY VOLTAGE AND CURRENT VIN Input Voltage Range VFB = 0.4V, no switching - - 800 µA VFB = GND, switching - 1.2 1.7 mA EN = GND - - 1 µA UVLO Threshold Voltage VIN Rising 2.2 2.4 2.6 V UVLO Hysteresis Voltage VIN Falling 50 100 200 mV Regulated Feedback Voltage VIN=2.7V ~ 6V, TA = 25°C 194 200 206 mV FB Input Current VFB=1.23V -1 - 1 µA 540 600 660 kHz VIN=3.6V - 0.3 0.7 VIN=3V - - 0.7 VEN=0V, VLX=35V, VIN = 6V - - 100 µA 92 95 98 % 36 38 40 V 1.5 - - A IDD1 IDD2 V Input DC Bias Current ISD UNDER-VOLTAGE LOCKOUT REFERENCE AND OUTPUT VOLTAGES VREF IFB INTERNAL POWER SWITCH FSW Switching Frequency RON Power Switch On Resistance LX Leakage Current DMAX LX Maximum Duty Cycle Ω OUTPUT OVER VOLTAGE PROTECTION VLX_OVP Over Voltage Threshold VLX Rising POWER SWITCH CURRENT LIMIT ILIM N-Channel MOSFET Current Limit Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 Duty = DMAX 3 www.anpec.com.tw APW7215 Electrical Characteristics(Cont.) Refer to the typical application circuits. These specifications apply over. VIN=3.6V, TA=25°C. Symbol Parameter APW7215 Test Conditions Min. Typ. Unit Max. ENABLE AND SHUTDOWN Enable Voltage Threshold VEN Rising 1 - - V Shutdown Voltage Threshold VEN Falling - - 0.4 V EN Pulled Low Resistance - 800 - kΩ Use VEN=3V to enable to device, PWM Dimmimg Frequency=5k to 100k Hz - 4.7 - % Over-Temperature Protection (Note 4) TJ Rising - 150 - °C Over-Temperature Protection Hysteresis (Note 4) TJ Falling - 40 - °C EN Minimum On Pulsed Width OVER-TEMPERATURE PROTECTION TOTP Note 4: Guaranteed by design, not production tested. Pin Description PIN. FUNCTION TDFN-2x2-6 NAME 1 FB Feedback Pin. Connect this pin to cathode of the lowest LED and current-sense resistor (R1). Calculate resistor value according to R1=VREF/ILED. 2 NC 3 GND No Commend. 4 LX Switch pin. Connect this pin to inductor/diode here. 5 EN Enable Control Input. Forcing this pin above 1.0V enables the device, or forcing this pin below 0.4V to shut it down. In shutdown, all functions are disabled to decrease the supply current below 1µA. 6 VIN Main Supply Pin. Must be closely decoupled to GND with a 1µF or greater ceramic capacitor. Exposed Pad GND Connecting this pad to GND. Power and signal ground pin. Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 4 www.anpec.com.tw APW7215 Typical Operating Characteristics EN Dimming Cycle vs. LED Current Vin Input Voltage vs. Efficiency 21 100.0 18 LED Current (mA) Efficiency (%) 90.0 80.0 70.0 15 12 9 - 5K Hz - 50K Hz - 100K Hz 6 60.0 3 50.0 2.5 3 3.5 4 4.5 5 5.5 0 6 0 10 20 30 Vin Input Voltage (V) 60 70 80 90 100 100 Maximum Duty Cycle (%) 20.5 20.3 LED Current (mA) 50 Vin Input Voltage vs. Max Duty Cycle Vin Input Voltage vs. LED Current 20.1 19.9 19.7 19.5 3 40 EN Dimming Cycle (%) 3.25 3.5 3.75 4 4.25 4.5 4.75 99.5 99 98.5 98 97.5 97 2.5 5 3 3.5 4 4.5 5 5.5 6 6.5 Vin Input Voltage (V) Vin Input voltage (V) EN Dimming cycle vs. Feedback Voltage Vin Input Voltage vs. RON 200 0.5 180 Feedback Voltage(mV) RON (ohm) 0.4 0.3 0.2 0.1 160 140 120 100 80 60 - 5K Hz - 50K Hz - 100K Hz 40 20 0 2.5 0 3 3.5 4 4.5 5 5.5 6 20 40 60 80 100 EN Dimming cycle (%) Vin Input Voltage (V) Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 0 5 www.anpec.com.tw APW7215 Typical Operating Characteristics Efficiency vs. LED Current 100 Efficiency (%) 90 80 70 60 - Vin=4.2V - Vin=3.6V 50 40 10 20 30 40 50 60 70 80 90 100 110 LED Current (mA) Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 6 www.anpec.com.tw APW7215 Operating Waveforms Dimming, 100K Hz@50% duty Normal Operation 1 CH1 3 CH3 4 CH4 2 CH2 CH1:VOUT-20V/div CH2:Lx-20V/div CH3:VFB-200mV/div CH4:IL-500mA/div Time:2us/div CH1:VOUT-20V/div CH2:VLX-20V/div CH3:VEN-2V/div CH4:IL-500mA/div Time:2us/div OVP Power On CH1 CH1 CH3 CH3 CH4 CH4 CH2 CH2 CH1:VOUT-20V/div CH2:VLX-20V/div CH3:VEN-2V/div CH4:IL-2A/div Time:2ms/div Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 CH1:VOUT-20V/div CH2:VLX-20V/div CH3:VEN-2V/div CH4:IL-1A/div Time:4ms/div 7 www.anpec.com.tw APW7215 Operating Waveforms Power Off CH1 CH3 CH4 CH2 CH1:VOUT-20V/div CH2:VLX-20V/div CH3:VEN-2V/div CH4:IL-500mA/div Time:200ms/div Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 8 www.anpec.com.tw APW7215 Block Diagram VIN VLX_OVP UVLO LX EN Control Logic Thermal Shutdown Σ Oscillator ICMP EAMP FB GND COMP VREF NC Soft-start Typical Application Circuits VIN ILED L1 VOUT 22µH C1 1µF VIN LX C2 1µF 10 strings GND EN FB PWM Dimming Control Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 R1 9 www.anpec.com.tw APW7215 Function Description Main Control Loop Over-Temperature Protection (OTP) The APW7215 is a constant frequency current-mode The over-temperature circuit limits the junction tempera- switching regulator. During normal operation, the internal N-channel power MOSFET is turned on each cycle ture of the APW7215. When the junction temperature exceeds 150 oC, a thermal sensor turns off the power when the oscillator sets an internal RS latch and turned off when an internal comparator (ICMP) resets the latch. MOSFET, allowing the device to cool. The thermal sensor allows the converter to start a soft-start process and The peak inductor current at which ICMP resets the RS latch is controlled by the voltage on the internal COMP regulate the LEDs current again after the junction temperature cools by 40oC. The OTP is designed with a 40oC node, which is the output of the error amplifier (EAMP). An external current-sense resistor connected between cath- hysteresis to lower the average Junction Temperature (TJ) during continuous thermal overload conditions, in- ode of the lowest LED and ground allows the EAMP to receive a current feedback voltage VFB at FB pin. When the creasing the lifetime of the device. Enable/Shutdown LEDs voltage decreases to cause the LEDs current to decrease, it causes a slightly decrease in VFB relative to Driving EN to ground places the APW7215 in shutdown the reference voltage, which in turn causes the internal COMP voltage to increase until the LEDs current reaches mode. When in shutdown, the internal power MOSFET turns off, all internal circuitry shuts down and the quies- the set point. cent supply current reduces to 1µA maximum. This pin also could be used as a digital input allowing brightness VIN Under-Voltage Lockout (UVLO) controlled by using a PWM signal with frequency from 5kHz to 100kHz. The 0% duty cycle of PWM signal corre- The Under-Voltage Lockout (UVLO) circuit compares the input voltage at VIN with the UVLO threshold (2.4V rising, typical) to ensure the input voltage is high enough for sponds to zero LEDs current and 100% corresponds to full one. If use EN Pin to enable the device, suggestion reliable operation. The 100mV (typ) hysteresis prevents supply transients from causing a restart. Once the input dimmimg duty range is from 15% to 100% at 100kHz dimmimg frequency. voltage exceeds the UVLO rising threshold, startup begins. When the input voltage falls below the UVLO falling Open-LED Protection threshold, the controller turns off the converter. In driving LED applications, the feedback voltage on FB Soft-Start The APW7215 has a built-in soft-start to control the N chan- pin falls down if one of the LEDs, in series, is failed. Meanwhile, the converter unceasingly boosts the output nel MOSFET current raises during start-up. During softstart, an internal ramp voltage connected to one of the voltage like an open-loop operation. Therefore, an overvoltage protection monitoring the output voltage via LX inverting inputs of the current limit comparator. The inductor current limit is proportional to the voltage. When pin prevents the LX and the output voltages from exceeding their maximum voltage ratings. Once the voltage on the threshold voltage of the internal soft-start comparator is reached, the full current limit is released. the LX pin rises above the OVP threshold, the converter stops switching and prevents the output voltage from Current-Limit Protection rising. The converter can work again when the LX voltage falls below the falling of OVP voltage threshold. The APW7215 monitors the inductor current flowing through the N-channel MOSFET, and limits the current peak at current-limit level to prevent loads and the device from damages in overload conditions. Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 10 www.anpec.com.tw APW7215 Application Information Input Capacitor Selection The peak inductor current is calculated as the following equation: 1 V ⋅ (VOUT − VIN ) IPEAK = IIN(MAX ) + ⋅ IN 2 VOUT ⋅ L ⋅ FSW The input capacitor (CIN) reduces the ripple of the input current drawn from the input supply and reduces noise injection into the IC. The reflected ripple voltage will be smaller when an input capacitor with larger capacitance is used. For reliable operation, it is recommended to VIN select the capacitor with maximum voltage rating at least 1.2 times of the maximum input voltage. The capacitors IL IIN LX N-FET CIN IOUT D1 VOUT ESR ISW should be placed close to the VIN and the GND. COUT Inductor Selection IL Selecting an inductor with low dc resistance reduces conduction losses and achieves high efficiency. The efficiency ILIM is moderated whilst using small chip inductor which op- IPEAK ∆IL erates with higher inductor core losses. Therefore, it is necessary to take further consideration while choosing IIN an adequate inductor. Mainly, the inductor value determines the inductor ripple current: larger inductor value ISW results in smaller inductor ripple current and lower conduction losses of the converter. However, larger inductor value generates slower load transient response. A reasonable design rule is to set the ripple current, ∆IL, to be 30% to 50% of the maximum average inductor current, IL(AVG). The inductor value can be obtained as below, V L ≥ IN VOUT ID 2 VOUT − VIN η × × F ⋅I SW OUT (MAX ) ∆IL IL (AVG ) IOUT Output Capacitor Selection where The current-mode control scheme of the APW7215 al- VIN = input voltage lows the usage of tiny ceramic capacitors. The higher capacitor value provides good load transients response. VOUT = output voltage FSW = switching frequency in MHz Ceramic capacitors with low ESR values have the lowest output voltage ripple and are recommended. If required, IOUT = maximum output current in amp. η = Efficiency tantalum capacitors may be used as well. The output ripple is the sum of the voltages across the ESR and the ideal ∆IL /IL(AVG) = inductor ripple current/average current output capacitor. (0.3 to 0.5 typical) To avoid the saturation of the inductor, the inductor should be rated at least for the maximum input current of the Δ VOUT = ΔVESR + ΔVCOUT ∆VCOUT ≈ converter plus the inductor ripple current. The maximum input current is calculated as below: IIN(MAX ) = V − VIN ⋅ OUT V ⋅ OUT FSW ∆VESR ≈ IPEAK ⋅ RESR IOUT (MAX ) ⋅ VOUT VIN ⋅ η Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 IOUT COUT where IPEAK is the peak inductor current. 11 www.anpec.com.tw APW7215 Application Information (Cont.) Output Capacitor Selection (Cont.) Recommended Minimum Footprint For ceramic capacitor application, the output voltage ripple The via diameter= 0.012 is dominated by the ∆VCOUT. When choosing the input and output ceramic capacitors, the X5R or X7R with their good Hole size =0.008 t e m p e r a t u r e an d v o l t a g e c h a r ac t e r i s t i c s a r e recommended. 0.012 0.051 Output Voltage Setting In figure 1, the converter regulates the voltage on FB pin, connected with the cathode of the lowest LED and the 0.026 current- sense resistor R1 at VREF. Therefore, the current (ILED), flowing via the LEDs and the R1, is calculated by 0.0315 the following equation: ILED = 0.00875 0.0216 Unit: Inch TDFN 2x2-6 VREF R1 layout The via diameter= 0.3048 Hole size =0.2032 Layout Consideration 0.2222 5 0.54864 0.3048 For all switching power supplies, the layout is an important step in the design especially at high peak currents 1.2954 and switching frequencies. If the layout is not carefully done, the regulator might show noise problems and duty cycle jitter. 0.6604 1. The input capacitor should be placed close to the VIN 0.8 and the GND without any via holes for good input voltage filtering. Unit : mm TDFN2x2-6 2. To minimize copper trace connections that can inject noise into the system, the inductor should be placed as close as possible to the LX pin to minimize the noise coupling into other circuits. 3. Since the feedback pin and network is a high impedance circuit the feedback network should be routed away from the inductor. The feedback pin and feedback network should be shielded with a ground plane or trace to minimize noise coupling into this circuit. 4. A star ground connection or ground plane minimizes ground shifts and noise is recommended. Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 12 www.anpec.com.tw APW7215 Package Information TDFN2x2-6 A b E D D2 A1 A3 L K E2 Pin 1 Corner e TDFN2x2-6 S Y M B O L MIN. MAX. MIN. MAX. A 0.70 0.80 0.028 0.031 A1 0.00 0.05 0.000 0.002 0.007 MILLIMETERS A3 INCHES 0.20 REF 0.008 REF 0.012 b 0.18 0.30 D 1.90 2.10 0.075 0.083 0.063 D2 1.00 1.60 0.039 E 1.90 2.10 0.075 0.083 E2 0.60 1.00 0.024 0.039 0.45 0.012 e 0.65 BSC L 0.30 K 0.20 0.026 BSC 0.018 0.008 Note : 1. Followed from JEDEC MO-229 WCCC. Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 13 www.anpec.com.tw APW7215 Carrier Tape & Reel Dimensions P0 P2 P1 A B0 W F E1 OD0 K0 A0 A OD1 B B T SECTION A-A SECTION B-B H A d T1 Application TDFN2x2-6 A H T1 C d D W E1 F 330.0±2.00 50 MIN. 12.4+2.00 -0.00 13.0+0.50 -0.20 1.5 MIN. 20.2 MIN. 12.0±0.30 1.75±0.10 5.5±0.05 P0 P1 P2 D0 D1 T A0 B0 K0 2.0±0.05 1.5+0.10 -0.00 1.5 MIN. 0.6+0.00 -0.40 2.35+0.20 2.35+0.20 1.30±0.20 4.0±0.10 8.0±0.10 (mm) Devices Per Unit Package Type Unit Quantity TDFN2x2-6 Tape & Reel 3000 Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 14 www.anpec.com.tw APW7215 Taping Direction Information TDFN2x2-6 USER DIRECTION OF FEED Classification Profile Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 15 www.anpec.com.tw APW7215 Classification Reflow Profiles Profile Feature Sn-Pb Eutectic Assembly Pb-Free Assembly 100 °C 150 °C 60-120 seconds 150 °C 200 °C 60-120 seconds 3 °C/second max. 3°C/second max. 183 °C 60-150 seconds 217 °C 60-150 seconds See Classification Temp in table 1 See Classification Temp in table 2 Time (tP)** within 5°C of the specified classification temperature (Tc) 20** seconds 30** seconds Average ramp-down rate (Tp to Tsmax) 6 °C/second max. 6 °C/second max. 6 minutes max. 8 minutes max. Preheat & Soak Temperature min (Tsmin) Temperature max (Tsmax) Time (Tsmin to Tsmax) (ts) Average ramp-up rate (Tsmax to TP) Liquidous temperature (TL) Time at liquidous (tL) Peak package body Temperature (Tp)* Time 25°C to peak temperature * Tolerance for peak profile Temperature (Tp) is defined as a supplier minimum and a user maximum. ** Tolerance for time at peak profile temperature (tp) is defined as a supplier minimum and a user maximum. Table 1. SnPb Eutectic Process – Classification Temperatures (Tc) Package Volume mm Thickness <350 <2.5 mm 235 °C ≥2.5 mm 220 °C Table 2. Pb-free Process – Classification Temperatures (Tc) Package Thickness <1.6 mm 1.6 mm – 2.5 mm ≥2.5 mm Volume mm <350 260 °C 260 °C 250 °C 3 3 Volume mm ≥350 220 °C 220 °C Volume mm 350-2000 260 °C 250 °C 245 °C 3 3 Volume mm >2000 260 °C 245 °C 245 °C 3 Reliability Test Program Test item SOLDERABILITY HOLT PCT TCT HBM MM Latch-Up Method JESD-22, B102 JESD-22, A108 JESD-22, A102 JESD-22, A104 MIL-STD-883-3015.7 JESD-22, A115 JESD 78 Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 16 Description 5 Sec, 245°C 1000 Hrs, Bias @ Tj=125°C 168 Hrs, 100%RH, 2atm, 121°C 500 Cycles, -65°C~150°C VHBM≧2KV VMM≧200V 10ms, 1tr≧100mA www.anpec.com.tw APW7215 Customer Service Anpec Electronics Corp. Head Office : No.6, Dusing 1st Road, SBIP, Hsin-Chu, Taiwan, R.O.C. Tel : 886-3-5642000 Fax : 886-3-5642050 Taipei Branch : 2F, No. 11, Lane 218, Sec 2 Jhongsing Rd., Sindian City, Taipei County 23146, Taiwan Tel : 886-2-2910-3838 Fax : 886-2-2917-3838 Copyright ANPEC Electronics Corp. Rev. A.2 - Oct., 2012 17 www.anpec.com.tw