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| APW7077/A PWM Step-Up DC-DC Converter Features * * * * * * * * * Low Start-up Voltage 0.9V Fixed 300kHZ Operating Frequency Built-In Internal Soft Start Circuit Low Operating Current 3.3V and 5V (2.5%) Fixed (APW7077) or Adjustable Output Voltage (APW7077A) High Efficiency Up to 88% at 400mA Output Current High Output Current Up to 1A Compact Package: SOT-23-5 Lead Free Available (RoHS Compliant) General Description The APW7077/A series are multi- function PWM step-up DC-DC converter with an adaptive voltage mode controller and higher efficiency application from one to four cells battery packs. The APW7077/A series are set PWM operating mode, voltage-mode to follow portable application. And built-in driver pin, EXT pin, for connecting to an external transistor or MOSFET during light load, the device will automatically skip switching cycles to maintain high efficiency. The APW7077/A series consists of PW M controller, reference voltage, phase compensation, oscillator, soft-start, driver block. It will provide to operate suitable voltage without external compensation circuit. The APW7077/A series have fixed voltage and adjustable voltage version from a wide input voltage ranges 0.7V to 5.5V for step-up DC-DC converter. The start-up is guaranteed at 1V and the device is operating down to 0.7V. And providing up to 300mA loading current. Besides, low quiescent current (switch-off) is guaranteed. Applications * * * * * Cellular and Portable Phones Portable Audio Camcorders and Digital Still Camera Hand-held Instrument PDAs Pinouts EXT GND EXT GND 5 1 2 4 3 5 1 2 4 3 C E VOUT NC FB VDD CE SOT-23-5 (Top View) APW7077 SOT-23-5 (Top View) APW7077A 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 (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 1 www.anpec.com.tw APW7077/A Ordering and Marking Information APW7077/A Lead Free Code Handling Code Temp. Range Package Code Voltage Code Package Code B : SOT-23-5 Temp. Range I : -40 to 85 C Handling Code TU : Tube TR : Tape & Reel Voltage Code R : 3.3V Z : 5.0V Lead Free Code L : Lead Free Device Blank : Original Device APW7077A B : A77X X - Date Code APW7077 B : 77RX XX - Date Code, R : 3.3V Note: ANPEC lead-free products contain molding compounds/die attach materials and 100% matte tin plate termination finish; which are fully compliant with RoHS and compatible with both SnPb and lead-free soldiering operations. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J STD-020C for MSL classification at lead-free peak reflow temperature. Block Diagram VDD VOUT V DD Phase Compensation VDD NC PWM Controller Error Amp. Vref=1.0V RAMP GEN. PWM Comp. Oscillator Driver EXT GND V DD Voltage Reference Soft-Start CE APW 7077 VDD Phase Compensation VDD VDD VD D FB PWM Controller Error Amp. RAMP GEN. PWM Comp. Oscillator Driver EXT GND VDD Voltage Reference Soft-Start CE APW7077A Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 2 www.anpec.com.tw APW7077/A Absolute Maximum Ratings Symbol VDD VIO TA TJ TSTG TS VESD Supply voltage Input / output pins (CE, FB, EXT) Operating Ambient Temperature Range Junction Temperature Range Storage Temperature Range Soldering Temperature Minimum ESD Rating Parameter Value -0.3 to 7 -0.3 to 7 -40 to 85 -40 to 150 -65 to +150 300, 10 seconds 2 Unit V V C C C C kV Pin Descrpition Pin Number APW7077 1 5 4 X X 3 2 APW7077A 3 5 4 2 1 X X Pin Name CE EXT GND VDD FB NC VOUT Function Description Chip enable input. High = operating mode; Low = shutdown mode External MOSFET or transistor drive pin. Ground pins of the circuit. Supply voltage. FB: Internal 1.0V reference voltage. Use a resistor divider to set the output voltage from and VOUT = No internal connection to the pin. VOUT Provides bootstrap power to the IC. R2 1 + R1 VFB. Thermal Characteristics Symbol R JA Parameter Thermal Resistance - Junction to Ambient SOT-23-5 Value 200 Unit C/W Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 3 www.anpec.com.tw APW7077/A Electrical Characteristics (for all values TA = 25C, VOUT = 3.3V, unless otherwise noted) APW7077A Min Typ Max Symbol Step-Up Section VIN VDD Parameter Test Condition Unit Minimum Operating Input Voltage Operating Voltage Start-up Voltage VOUT = VDD VIN = VDD Io<10mA, VOUT = VDD (<5.5V) VOUT = 12V, Io<10mA, VDD = VIN 1.9 270 VDD = 3.3V, VFB = 0.5V 2.0V V V V V KHZ % % % mA mA V V % nA ms V mV A A A A V V A nA fSW DMAX Operating Frequency Oscillator Frequency Line Regulation Maximum Duty Cycle Maximum Duty Line Regulation 2.0V 2 50 Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 4 www.anpec.com.tw APW7077/A Electrical Characteristics (Cont.) (for all values TA = 25C, VOUT = 3.3V, unless otherwise noted) APW7077 Min Typ Max Symbol Step-Up Section VIN Parameter Test Condition Unit Minimum Operating Input Voltage Operating Voltage APW7077_33, Io<10mA Start-up Voltage APW7077_33, 10mA V V V V V V V KHZ % mA mA V V ms V mV A A A A V V A nA VHOLD fSW DMAX Hold Voltage Operating Frequency Maximum Duty Cycle Power MOSFET ISOURCE EXT Output Source Current Duty5%, EXT = 2.9V ISINK VOUT TSS EXT Output Sink Current APW7077-33 APW7077-50 Soft-start Time Soft-start Threshold Voltage Duty = 50% Soft-start Hysteresis Voltage Iq IOFF VCE ICE Operating Current Stand-by Current Switch-off Current Logic LOW (VIL) Logic HIGH (VIH) CE Pin Input Current Duty5%, EXT = 0.4V IIN = 0mA IIN = 0mA Control Section Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 5 www.anpec.com.tw APW7077/A Application Circuit Application Circuit for APW7077 VIN 10uH/1.5A SS12 VOUT=3.3V(APW7077-33) VOUT=5V(APW7077-50) CE EXT 100uF VOUT NC 1uF APW7077 APM2300A GND 100uF 10uF Application Circuit for APW7077A VIN 2.5~5.2V 2R2 4.7uF VDD CE APW7077A 10uH/1.5A SS12 9~12V/50mA FB EXT 10uF VOUT=(1+R2/R1)*1.0V 0.1uF APM2300A GND 1uF R2 820K/620K R1/75K CFF/1000pF Application Circuit for APW7077A VIN 10uH/1.5A SS12 3~5V FB 100uF VDD CE APW7077A VOUT=(1+R2/R1)*1.0V EXT APM2300A GND 10uF 100uF 1uF R2/300K R1/75K CFF/33pF *R1O 100K[ is recommended Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 6 www.anpec.com.tw APW7077/A Typical Characteristics Start-up/Hold Voltage vs. Output Current 1.6 1.4 1.6 1.4 Start-up/Hold Voltage vs. Output Current Input Voltage (V) VSTART-up 1 Input Voltage (V) 1.2 1.2 1 VSTART-up 0.8 0.8 Vhold 0.6 0.4 Vhold 0.6 0.4 0.2 0.2 VOUT=3.3V 0 0 50 100 150 200 250 300 0 0 50 100 150 200 VOUT=5.0V 250 300 Output Current (mA) Output Current (mA) Efficiency vs. Output Current 100 90 80 100 90 80 Efficiency vs. Output Current VDD=3V VDD=2V Efficiency(%) VDD=5V 70 60 50 40 30 20 1 10 100 Efficiency(%) VOUT=12V L=10F 70 60 50 40 30 20 1 10 VDD=3.3V VOUT=5V L=10H 100 1000 Output Current (mA) Output Current (mA) Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 7 www.anpec.com.tw APW7077/A Typical Characteristics (Cont.) Output Voltaget vs. Output Current 3.32 5.02 Output Voltaget vs. Output Current 3.315 5. 015 Output Voltage (V) 3.305 Output Voltage (V) 3.31 5.01 5. 005 VIN=2.5V 3.3 5 VIN=3.0V 3.295 VIN=1.2V 4. 995 VIN=2.0V 3.29 4.99 VIN=1.2V VIN=2.0V VOUT=5.0V 3.285 4. 985 VOUT=3.3V 3.28 0 200 400 600 800 1 0 00 4.98 0 200 400 600 800 1 0 00 Output Current (mA) Output Current (mA) Output Voltage vs. Temperature 3.40 3.38 3 30 Oscillation Frequency vs. Temperature Oscillation Frequency (kHz) -40 -20 0 20 40 60 80 3.36 3 20 Output Voltage (V) 3.34 3.32 3.30 3.28 3.26 3.24 3.22 3.20 3 10 3 00 2 90 2 80 2 70 -40 -20 0 20 40 60 80 Temperature (C) Temperature (C) Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 8 www.anpec.com.tw APW7077/A Typical Characteristics (Cont.) Load Transient Waveform Load Transient Waveform VIN=3.3V, VOUT=12V, IOUT=5mA->50mA->5mA L=10H, COUT=4.7F+0.1F, Cff=560pF CH1:VOUT, 100mV/DIV, Time=1ms/DIV CH4:IOUT, 20mA/DIV VIN=3.3V, VOUT=5V, IOUT=10mA->300mA->10mA L=10H, COUT=22F+22F+0.1F, Cff=33pF CH1:VOUT, 100mV/DIV, Time=1ms/DIV CH4:IOUT, 200mA/DIV EXT Driving Current vs. Supply Voltage 160 100 EXT Rds,on vs. Supply Voltage Sink/Source Current (mA) 140 120 100 ISINK (EXT=0.4V) ISOURCE (EXT=VDD-0.4V) Rds,on resistance () 80 10 EXT to VDD 60 40 EXT to GND 20 1 0 0 1 2 3 4 5 6 0 1 2 3 4 5 6 Supply Voltage (V) Supply Voltage (V) Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 9 www.anpec.com.tw APW7077/A Typical Characteristics (Cont.) Supply Current vs. Supply Voltage 250 2.5 Feedback Voltage vs. Supply Voltage 200 2 150 Switching Mode Feedback Voltage (V) 5.5 Supply Current (A) 1.5 100 1 Non Switching Mode 50 0.5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 Supply Voltage (V) Supply Voltage (V) Oscillation Frequency vs. Supply Voltage 350 100 90 Maximum Duty vs. Supply Voltage Oscillation Frequency (kHz) 300 250 Maximum Duty (%) 0 0.5 1 1. 5 2 2.5 3 3.5 4 4.5 5 5.5 80 70 60 50 40 30 20 200 150 100 50 10 0 0 0 0. 5 1 1. 5 2 2.5 3 3.5 4 4.5 5 5. 5 Supply Voltage (V) Supply Voltage (V) Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 10 www.anpec.com.tw APW7077/A Typical Characteristics (Cont.) Feedback Voltage vs. Temperature 1.020 1.015 Feedback Voltage (V) 1.010 1.005 1.000 0.995 0.990 0.985 0.980 -40 -20 0 20 40 60 80 Temperature (C) Function Description Operation The APW7077/A series are low noise fixed frequency voltage-mode PWM DC-DC controllers, and consist of start-up circuit, reference voltage, oscillator, loop compensation network, PWM control circuit, and low ON resistance driver. APW7077 provide on-chip feedback resistor and loop compensation network, the system designer can get the regulated fixed output voltage 3.3V and 5.0V with a small number of external components, it is optimized for battery powered portable products where large output current is required. APW7077A provide internal reference voltage 1.0V and output voltage setting by external resistance for higher voltage requirement. The quiescent current is typically 120uA (VOUT = 3.3V, fsw = 300kHz), and can be further reduced to about 1.0uA when the chip is disabled (VCE < 0.7V). Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 11 The APW7077/A operation can be best understood by referring to the block diagram. The error amplifier monitors the output voltage via the feedback resistor divider by comparing the feedback voltage with the reference voltage. When the feedback voltage is lower than the reference voltage, the error amplifier output will decrease. The error amplifier output is then compared with the oscillator ramp voltage at the PWM controller. When the feedback voltage is higher than the reference voltage, the error amplifier output increases and the duty cycle decreases. When the external power switch is on, the current ramps up in the inductor, storing energy in the magnetic field. When the external power switch is off, the energy stored in the magnetic field is transferred to the output filter capacitor and the load. The output filter capacitor stores the charge while the www.anpec.com.tw APW7077/A Function Description (Cont.) Operation (Cont.) inductor current is higher than the output current, then sustains the output voltage until the next switching cycle. As the load current is decreased, the switch transistor turns on for a shorter duty cycle. Under the light load condition, the controller will skip switching cycles to reduce power consumption, so that high efficiency is maintained at light loads. Fixed Output Voltage (for APW7077 only) The APW7077 VOUT is set by an integrate feedback resistor network. This is trimmed to a selected voltage 3.3 V or 5.0 V with an accuracy of +/-2.5%. Setting Output Voltage (for APW7077A only) For APW7077A, the output voltage is adjustable. The output voltage is set using the FB pin and a resistor divider connected to the output as shown in the typical operating circuit. The internal reference voltage is 1.0V with 2% variation, so the ratio of the feedback resistors sets the output voltage according to the following equation: R2 VOUT = (1 + ) x 1.0V R1 To avoid the thermal noise from feedback resistor, (R1+R2) resistance smaller than 1M and 1% variation is recommended. Soft Start There is a sof t start function is integration in APW7077/A series to avoid the over shooting when power on. When power is applied to the device, the soft start circuit first pumps up the output voltage to let VDD(or VOUT) approximately 1.65V at a fixed duty cycle 50%. This is the voltage level at which the controller can operate normally. When supply voltage more than 1.65V the internal reference voltage will be ramp up to let output voltage reach to setting voltage without over shooting issue whenever heavy load or light load condition. The soft start time 25ms is setting by internal circuit. Oscillator The oscillator frequency is internally set to 300 kHz at an accuracy of +/-10% and with low temperature coefficient of 3.3%/C. Enable/Disable Operation The APW7077/A series offer IC shutdown mode by chip enable pin (CE pin) to reduce current consumption. When voltage at pin CE is greater than 1.2 V, the chip will be enabled, which means the controller is in normal operation. When voltage at pin CE is less than 0.7 V, the chip is disabled, which means IC is shutdown and quiescent current become 1uA. The CE pin pull high to VDD(or VOUT) by internal resistor, and this resistance is greater than 1M . So this chip will enable normally when CE pin floating. Important: DO NOT apply a voltage between 0.7V to 1.2 V to pin CE as this is the CE pin' hysteresis s voltage range. Clearly defined output states can only be obtained by applying voltage out of this range. Compensation The device is designed to operate in continuous conduction mode. An internal compensation circuit was designed to guarantee stability over the full input/output voltage and full output load range. Step-up Converter Operating Mode The step-up DC-DC controller is designed to operate in continuous conduction mode (CCM) or discontinuous conduction mode (DCM). For a step up converter in a CCM, the duty cycle D is 12 www.anpec.com.tw Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 APW7077/A Function Description (Cont.) Step-up Converter Operating Mode (Cont.) given by D= V OUT - V IN The inductor peak current can be calculated as Ipk = V OUT x I O V IN + IL 2 V OUT In higher output voltage or small output current application, the step-up DC-DC controller operated in discontinuous conduction mode almost. For a step-up converter in a DCM, the duty cycle D is given by D= V V 2L OUT OUT - 1 V TS RLOAD VIN IN NOTES: D - On-time duty cycle IL - Average inductor current IPK - Peak inductor current IO - Desired dc output current VIN - Nominal operating dc input voltage VOUT - Desired dc output voltage ESR - Equivalent series resistance of the output capacitor Inductor Selection APW7077/A series are designed to work well with a 6.8 to 12uH inductors in most applications 10uH is a sufficiently low value to allow the use of a small surface mount coil, but large enough to maintain low ripple. Lower inductance values supply higher output current, but also increase the ripple and reduce efficiency. Higher inductor values reduce ripple and improve efficiency, but also limit output current. The inductor should have small DCR, usually less than 1m, to minimize loss. It is necessary to choose an inductor with a saturation current greater than the peak current which the inductor will encounter in the application. The inductor ripple current is important for a few reasons. One reason is because the peak switch current will be the average inductor current (IL) plus IL. As a side note, discontinuous operation occurs when the inductor current falls to zero during a switching cycle, or IL is greater than the average inductor current. Therefore, continuous conduction mode occurs External components values can be calculated from these equations, however, the optimized value should obtained through experimental results. Critical Inductance Value The minimum value of inductor to maintain continuous conduction mode can be determined by the following equation. L VOUT x D(1 - D) 2 fsw x IO x Ratio A system can be designed to operate in continuous mode for load currents above a certain level usually 20 to 50% (Ratio define as 0.2~0.5) of full load at minimum input voltage. When IO smaller than (IO*Ratio), the controller system will into DCM. IL is the ripple current flowing through the inductor, which affects the output voltage ripple and core losses. Based on 20%(Ratio=0.2) current ripple, VOUT=5V, IO=1A and VIN =1.8V system, the inductance value is calculated as 6.9uH and a 6.8uH inductor is used. The inductor current ripple has an expression IL = V IN x D fsw x L V OUT x I O (max) V IN (min) 13 The maximum DC input current can be calculated as I L (max) = Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 www.anpec.com.tw APW7077/A Function Description (Cont.) Inductor Selection (Cont.) when IL is less than the average inductor current. Care must be taken to make sure that the switch will not reach its current limit during normal operation. The inductor must also be sized accordingly. It should have a saturation current rating higher than the peak inductor current expected. The output voltage ripple is also affected by the total ripple current. Output Capacitor The output capacitor is used for sustaining the output voltage when the external MOSFET or bipolar transistor is switched on and smoothing the ripple voltage. The output capacitance needed is calculated in equations. If the regulator will be loaded uniformly, with very little load changes, and at lower current outputs, the input capacitor size can often be reduced. The size can also be reduced if the input of the regulator is very close to the source output. The size will generally need to be larger for applications where the regulator is supplying nearly the maximum rated output or if large load steps are expected. A minimum value of 10F should be used for the less stressful conditions while a 22F to 47F capacitor may be required for higher power and dynamic loads. Small ESR Tantalum or ceramic capacitor should be suitable and the total input ripple voltage can be calculated V IN = I L x ESR Design Example It is supposed that a step-up DC-DC controller with 3.3 V output delivering a maximum 1000 mA output current with 100 mV output ripple voltage powering from a 2.4 V input is to be designed. Design parameters: VIN = 2.4 V VOUT = 3.3 V IO = 1.0 A VOUT = 100 mV fsw= 300 kHZ Ratio = 0.2 (typical for small output ripple voltage) Assume the diode forward voltage and the transistor saturation voltage are both 0.3V. Determine the maximum steady state duty cycle at VIN = 2.4 V: D=0.273 Calculate the maximum inductance value which can generate the desired current output and the preferred delta inductor current to average inductor current ratio: L=10uH COUT (min) = IO(max) x D fsw x VOUT The ESR is also important because it determines the peak to peak output voltage ripple according to the approximate equation: ESR = ? VOUT ? IO With 1% output voltage ripple, low ESR capacitor should be used to reduce output ripple voltage. In general, a 100uF to 220uF low ESR (0.10 to 0.30) Tantalum capacitor should be appropriate. The choice of output capacitors is also somewhat arbitrary and depends on the design requirements for output voltage ripple. A minimum value of 10F is recommended and may be increased to a larger value. Input Capacitor The input capacitor can stabilize the input voltage and minimize peak current ripple from the source. The size used is dependant on the application and board layout. Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 14 www.anpec.com.tw APW7077/A Function Description (Cont.) Design Example(Cont.) Determine the average inductor current and peak inductor current: IL=1.38A IL=0.218A Ipk=1.45A Therefore, a 10 uH inductor with saturation current larger than 1.73 A can be selected as the initial trial. Determine the output capacitance value for the desired output ripple voltage: COUT=33uF The ESR of the output capacitor is 0.05. Therefore, a Tantalum capacitor with value of 33 uF to 47uF and ESR of 0.05 can be used as the output capacitor. However, according to experimental result, 220uF output capacitor gives better overall operational stability and smaller ripple voltage. External Component Selection Diode Selection The output diode for a boost regulator must be chosen correctly depending on the output voltage and the output current. The diode must be rated for a reverse voltage equal to or greater than the output voltage used. The average current rating must be greater than the maximum load current expected, and the peak current rating must be greater than the peak inductor current. During short circuit testing, or if short circuit conditions are possible in the application, the diode current rating must exceed the switch current limit. The diode is the largest source of loss in DC-DC converters. The most importance parameters which affect their efficiency are the forward voltage drop, VF, and the reverse recovery time, trr. The forward voltage drop creates a loss just by having a voltage across the device while a current flowing through it. The reverse recovery time generates a loss when the diode is reverse biased, and the current appears to actually flow backwards through the diode due to the minority carriers being swept from the P-N junction. Using Schottky diodes with lower forward voltage drop will decrease power dissipation and increase efficiency. External Switch Transistor An enhancement N-channel MOSFET or a bipolar NPN transistor can be used as the external switch transistor. Since enhancement MOSFET is a voltage driven device, it is a more efficient switch than a BJT transistor. However, the MOSFET requires a higher voltage to turn on as compared with BJT transistors. An enhancement N-channel MOSFET can be selected by the following guidelines: * Low ON-resistance, RDS(on). * Low gate threshold voltage, VGS(th), typically <1.5V, it is especially important for the low VOUT device, like VOUT = 2.4V. * Rated continuous drain current, ID, should be larger than the peak inductor current, i.e. ID > IPK. * Gate capacitance should be 1200 pF or less. For bipolar NPN transistor, medium power transistor with continuous collector current typically 1A to 5A and VCE(sat) < 0.2 V should be employed. The driving capability is determined by the DC current gain, HFE, of the transistor and the base resistor, Rb; and Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 15 www.anpec.com.tw APW7077/A External Component Selection (Cont.) External Switch Transistor (Cont.) the controller' EXT pin must be able to supply the s necessary driving current. Rb can be calculated by the following equation: Since the pulse current flows through the transistor, the exact Rb value should be finely tuned by the experiment. Generally, a small Rb value can increase the output current capability, but the efficiency will decrease due to more energy is used to drive the transistor. Moreover, a speed-up capacitor, Cb, should be connected in parallel with Rb to reduce switching loss and improve efficiency. Cb can be calculated by the equation below: It is due to the variation in the characteristics of the transistor used. The calculated value should be used as the initial test value and the optimized value should be obtained by the experiment. Layout Considerations Ground Plane One point grounding should be used for the output power return ground, the input power return ground, and the device switch ground to reduce noise. The input ground and output ground traces must be thick enough for current to flow through and for reducing ground bounce. Power Signal Traces Low resistance conducting paths should be used for the power carrying traces to reduce power loss so as to improve efficiency (short and thick traces for connecting the inductor L can also reduce stray inductance). Trace connections made to the inductor and schottky diode should be minimized to reduce power dissipation and increase overall efficiency. Output Capacitor The output capacitor should be placed close to the output terminals to obtain better smoothing effect on the output ripple. The output capacitor, COUT, should also be placed close to the IC. Any copper trace connections for the COUT capacitor can increase the series resistance, which directly effects output voltage ripple and efficiency. Switching Noise Decoupling Capacitor On APW7077 fixed voltage application, a 0.1F ceramic capacitor should be placed close to the VOUT pin and GND pin of the chip to filter the switching spikes in the output voltage monitored by the VOUT pin. Feedback Network On APW7077A application, the feedback networks should be connected directly to a dedicated analog ground plane and this ground plane must connect to the GND pin. If no analog ground plane is available then this ground must tie directly to the GND pin. The feedback network, resistors R1 and R2, should be kept close to the FB pin, and away from the inductor, to minimize copper trace connections that can inject noise into the system. Input Capacitor In APW7077A high output voltage application circuit, the input voltage(VIN) is tied to chip supply pin(VDD). The input capacitor CIN in VIN must be placed close to the IC. This will reduce copper trace resistance which effects input voltage ripple of the IC. For additional input voltage filtering, a 1F capacitor can be placed in parallel with CIN, close to the VDD pin, to shunt any high frequency noise to ground. 16 www.anpec.com.tw Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 APW7077/A Layout Considerations (Cont.) MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the semiconductor packages must be the correct size to insure proper solder connection interface between the board and the package. With the correct pad geometry, the packages will self align when subjected to a solder reflow process. Bottom Layer Demo Board Circuit Layout 1600 mil Top Layer Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 1300mil 17 www.anpec.com.tw APW7077/A Packaging Information SOT-23-5 e1 5 4 E1 E 1 2 3 e b D A2 A a L1 A1 L2 L Dim A A1 A2 b D E E1 e e1 L L1 L2 a Millimeters Min. 0.95 0.05 0.90 0.35 2.8 2.6 1.5 0.95 1.90 0.35 0.20 BSC 0.5 0 0.7 10 0.020 0 0.55 0.014 Max. 1.45 0.15 1.30 0.55 3.00 3.00 1.70 Min. 0.037 0.002 0.035 0.0138 0.110 0.102 0.059 Inches Max. 0.057 0.006 0.051 0.0217 0.118 0.118 0.067 0.037 0.075 0.022 0.008 BSC 0.028 10 Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 18 www.anpec.com.tw APW7077/A Physical Specifications Terminal Material Lead Solderability Solder-Plated Copper (Solder Material : 90/10 or 63/37 SnPb), 100%Sn Meets EIA Specification RSI86-91, ANSI/J-STD-002 Category 3. Reflow Condition (IR/Convection or VPR Reflow) TP Ramp-up tp Critical Zone T L to T P Temperature TL Tsmax tL Tsmin Ramp-down ts Preheat 25 t 25 C to Peak Time Classificatin Reflow Profiles Profile Feature Average ramp-up rate (TL to TP) Preheat - Temperature Min (Tsmin) - Temperature Max (Tsmax) - Time (min to max) (ts) Time maintained above: - Temperature (T L) - Time (tL) Peak/Classificatioon Temperature (Tp) Time within 5C of actual Peak Temperature (tp) Ramp-down Rate Sn-Pb Eutectic Assembly 3C/second max. 100C 150C 60-120 seconds 183C 60-150 seconds See table 1 10-30 seconds Pb-Free Assembly 3C/second max. 150C 200C 60-180 seconds 217C 60-150 seconds See table 2 20-40 seconds 6C/second max. 6C/second max. 6 minutes max. 8 minutes max. Time 25C to Peak Temperature Notes: All temperatures refer to topside of the package .Measured on the body surface. 19 www.anpec.com.tw Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 APW7077/A Classificatin Reflow Profiles(Cont.) Table 1. SnPb Entectic Process - Package Peak Reflow Temperature s Package Thickness Volume mm 3 Volume mm 3 <350 350 <2.5 mm 240 +0/-5C 225 +0/-5C 2.5 mm 225 +0/-5C 225 +0/-5C Table 2. Pb-free Process - Package Classification Reflow Temperatures Package Thickness Volume mm 3 Volume mm 3 Volume mm 3 <350 350-2000 >2000 <1.6 mm 260 +0C* 260 +0C* 260 +0C* 1.6 mm - 2.5 mm 260 +0C* 250 +0C* 245 +0C* 2.5 mm 250 +0C* 245 +0C* 245 +0C* *Tolerance: The device manufacturer/supplier shall assure process compatibility up to and including the stated classification temperature (this means Peak reflow temperature +0C. For example 260C+0C) at the rated MSL level. Reliability test program Test item SOLDERABILITY HOLT PCT TST ESD Latch-Up Method MIL-STD-883D-2003 MIL-STD-883D-1005.7 JESD-22-B,A102 MIL-STD-883D-1011.9 MIL-STD-883D-3015.7 JESD 78 Description 245C, 5 SEC 1000 Hrs Bias @125C 168 Hrs, 100%RH, 121C -65C~150C, 200 Cycles VHBM > 2KV, VMM > 200V 10ms, 1tr > 100mA Carrier Tape & Reel Dimensions t E Po P P1 D F W Bo Ao D1 Ko Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 20 www.anpec.com.tw APW7077/A Carrier Tape & Reel Dimensions(Cont.) T2 J C A B T1 Application A 1781 B C J T1 8.4 2 P1 T2 1.5 0.3 Ao W 8.00.3 Bo P 4 0.1 Ko 1.4 0.1 E 1.75 0.1 t 0.20.03 72 1.0 13.0 + 0.2 2.5 0.15 D D1 1.5 +0.1 Po 4.0 0.1 SOT-23-5 F 3.5 0.05 1.5 +0.1 2.0 0.1 3.15 0.1 3.2 0.1 (mm) Cover Tape Dimensions Application SOT-23-5 Carrier Width 8 Cover Tape Width 5.3 Devices Per Reel 3000 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 : 7F, No. 137, Lane 235, Pac Chiao Rd., Hsin Tien City, Taipei Hsien, Taiwan, R. O. C. Tel : 886-2-89191368 Fax : 886-2-89191369 Copyright (c) ANPEC Electronics Corp. Rev. A.4 - Sep, 2005 21 www.anpec.com.tw |
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