HX3033A-AFC

HX1001 HX3033A Step-up DC/DC Converter Features Description  2.2V Start-up Input Voltage The HX3033A is a compact, high efficiency, and  18V at 700mA from 5V Input low voltage step-up DC/DC converter with an  Up to 90% Efficiency Adaptive Current Mode PWM control loop,  No External MONSFET Required includes an error amplifier, ramp generator,  Small SOT-23-6L Package comparator, switch pass element and driver in which providing a stable and high efficient Applications operation over a wide range of load currents. It operates in stable waveforms without external  PDA  DSC  LCD Panel  RF-Tags  MP3  Portable Instrument The HX3033A is available in a low profile  Wireless Equipment SOT-23-6L package. w w w. h x s e m i . c o m compensation. HX3033A can operate from an input voltage as low as 2.2V. HX3033A can generate 18V up to 700mA from a 5V supply. 1 HX3033A Typical Application Circuit DC+ 2.5V~5V L 10 uH C3 100uF Electrolytic Capacitor C1 47uF 3 4 D 1 SK52 VDD EN 2 SW VOUT 5V ~ 18V HX3033A 1 AGND PGND 6 FB R1 5 C2 47uF C4 220uF Electrolytic Capacitor R2 * VOUT = 1.212V • [1 + (R1/R2)]. Pin Assignment and Function PIN NAME FUNCTION 1 AGND Analog Ground 2 SW Switch Node For Output 3 VDD Output Voltage Sense Input 4 EN ON/OFF Control (High Enable) 5 FB Feedback 6 PGND Power Ground Absolute Maximum Ratings (Note 1)  Supply Voltage………………………………………………………………………....... −0.3V ~ 6V  SW Pin Switch Voltage…………………………………………………………………−0.3V ~ 22V  SW Pin Switch Current ………………………………………………………………...…………..4.5A  Other I/O Pin Voltages……………………………………………………….. −0.3V ~ (VDD + 0.3V)  Package Thermal Resistance (SOT-23-6L) θJA…………………………..…………………………………………………………….+220℃/W  Operating Temperature Range(Note 2)……………………………………………….-40℃ ~ +85℃  Maximum Junction Temperature………………………………………….………….………..+150℃  Storage Temperature Range ……………………………………………………….−65℃ ~ +150℃  Lead Temperature (Soldering 10sec)... ………………………………………………………..+265℃ Note 1: Stresses beyond those listed Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note2: The HX3033A is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. www.hxsemi.com 2 HX3033A Electrical Characteristics Operating Conditions: TA=25℃, VIN=5V, VOUT=18V, R1=430K, R2=30K, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VSTART Start-up Voltage IOUT = 1mA 2.2 V VHOLD Hold-up Voltage IOUT = 1mA 1.7 V Operating VDD Range VDD Pin Voltage VDD IQ Supply Current (Quiescent) IOFF Supply Current (Shutdown) VFB Feedback VENH EN High Threshold VENL EN Low Threshold IEN FOSC ΔFOSC V 692 μA VIN=3.6V 630 μA VEN=0V 52 μA 1.188 Voltage FB Pin Bias Current 5 VIN=2.5V Reference IFB 2.5 1.212 1.236 nA 100 VEN Rising 1 V 0.6 VEN(H),VEN=2V V V 8 μA VEN(L),VEN=0.5V 0.15 μA Switching Frequency IOUT = 500mA 400 KHz Frequency Change VDD: 3V→5V 20 KHz EN Input Current DC Maximum Duty 90 % RSW SW ON Resistance 300 mΩ Note: The EN pin shall be tied to VDD pin and inhibit to act the ON/OFF state whenever the VDD pin voltage may reach to 5.5V or above. www.hxsemi.com 3 HX3033A Typical Performance Characteristics Operating Conditions: TA=25℃, R1=430K, R2=30K, unless otherwise specified. www.hxsemi.com 4 HX3033A Start up (VIN=5V, VOUT=18V, ILOAD=0.5A) SW Waveform (VIN=5V, VOUT=18V, ILOAD=0.5A) SW 10.0V/div VOUT 5.0V/div EN 5.0V/div M 1.00µs www.hxsemi.com M 5.00ms 5 HX3033A Pin Information AGND (Pin 1): Analog Ground. SW (Pin 2): Switch Pin. Connect inductor between SW and VIN. Keep these PCB trace lengths as short and wide as possible to reduce EMI and voltage overshoot. VDD (Pin 3): Output Voltage Sense Input. The NMOS switch gate drive is derived from the greater of VOUT and VIN. EN (Pin 4): Logic Controlled Shutdown Input. EN=High: Normal free running operation. EN=Low: Shutdown. FB (Pin 5): Feedback Input to the gm Error Amplifier. Connect resistor divider tap to this pin. PGND (Pin 6): Power Ground. Block Diagram VDD 3 A 2 SW FB 5 EN 4 1,6 www.hxsemi.com 6 GND HX3033A Application Information Inductor Selection For most applications, the value of the inductor will fall in the range of 1H to 4.7H. Its value is chosen based on the desired ripple current. Large value inductors lower ripple current and small value inductors result in higher ripple currents. Higher VIN or VOUT also increases the ripple current as shown in equation. A reasonable starting point for setting ripple current is △IL = 0.72A (40% of 1.8A). The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. Thus, a 2.16A rated inductor should be enough for most applications (1.8A + 0.36A). For better efficiency, choose a low DC-resistance inductor. Different core materials and shapes will change the size/current and price/current relationship of an inductor. Toroid or shielded pot cores in ferrite or perm alloy materials are small and don’t radiate much energy, but generally cost more than powdered iron core inductors with similar electrical characteristics. The choice of which style inductor to use often depends more on the price vs. size requirements and any radiated field/EMI requirements than on what VOUT requires to operate. Output and Input Capacitor Selection In continuous mode, the source current of the top MOSFET is a square wave of duty cycle VOUT/VIN. To prevent large voltage transients, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by: This formula has a maximum at VIN = 2VOUT, where IRMS = IOUT/2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Note that the capacitor manufacturer’s ripple current ratings are often based on 2000 hours of life. This makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher temperature than required. Always consult the manufacturer if there is any question. The selection of COUT is driven by the required effective series resistance (ESR).Typically, once the ESR requirement for COUT has been met, the RMS current rating generally far exceeds the IRIPPLE(P-P) requirement. The output ripple ΔVOUT is determined by: Where f = operating frequency, COUT = output capacitance and ΔIL = ripple current in the inductor. For a fixed output voltage, the output ripple is highest at maximum input voltage since ΔIL increases with input voltage. Aluminum electrolytic and dry tantalum capacitors are both available in surface mount configurations. In the case of tantalum, it is critical that the capacitors are surge tested for use in switching power supplies. An excellent choice is the AVX TPS series of surface mount tantalum. These are specially constructed and tested for low ESR. www.hxsemi.com 7 HX3033A Efficiency Considerations The efficiency of a switching regulator is equal to the output power divided by the input power times 100%. It is often useful to analyze individual losses to determine what is limiting the efficiency and which change would produce the most improvement. Efficiency can be expressed as: Efficiency = 100% - (L1+ L2+ L3+ ...) where L1, L2, etc. are the individual losses as a percentage of input power. Although all dissipative elements in the circuit produce losses, two main sources usually account for most of the losses: VIN quiescent current and I2R losses. The VIN quiescent current loss dominates the efficiency loss at very low load currents whereas the I2R loss dominates the efficiency loss at medium to high load currents. In a typical efficiency plot, the efficiency curve at very low load currents can be misleading since the actual power lost is of no consequence. 1. The VIN quiescent current is due to two components: the DC bias current as given in the electrical characteristics and the internal main switch and synchronous switch gate charge currents. The gate charge current results from switching the gate capacitance of the internal power MOSFET switches. Each time the gate is switched from high to low to high again, a packet of charge △Q moves from VIN to ground. The resulting △Q/△t is the current out of VIN that is typically larger than the DC bias current. In continuous mode, IGATECHG = f (QT+QB) where QT and QB are the gate charges of the internal top and bottom switches. Both the DC bias and gate charge losses are proportional to VIN and thus their effects will be more pronounced at higher supply voltages. 2. I2R losses are calculated from the resistances of the internal switches, RSW and external inductor RL. In continuous mode the average output current flowing through inductor L is “chopped” between the main switch and the synchronous switch. Thus, the series resistance looking into the SW pin is a function of both top and bottom MOSFET RDS(ON) and the duty cycle (DC) as follows: RSW = RDS(ON)TOP x DC + RDS(ON)BOT x (1-DC) The RDS(ON) for both the top and bottom MOSFETs can be obtained from the Typical Performance Characteristics curves. Thus, to obtain I2R losses, simply add RSW to RL and multiply the result by the square of the average output current. Other losses including CIN and COUT ESR dissipative losses and inductor core losses generally account for less than 2% of the total loss. Board Layout Suggestions When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the HX3033A. Check the following in your layout: 1. The power traces, consisting of the GND trace, the SW trace and the VIN trace should be kept short, direct and wide. 2. Put the input capacitor as close as possible to the device pins (VIN and GND). 3. SW node is with high frequency voltage swing and should be kept small area. Keep analog components away from SW node to prevent stray capacitive noise pick-up. 4. Connect all analog grounds to a command node and then connect the command node to the power ground behind the output capacitors. www.hxsemi.com 8 HX3033A Packaging Information SOT-23-6L Package Outline Dimension Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 1.050 1.250 0.041 0.049 A1 0.000 0.100 0.000 0.004 A2 1.050 1.150 0.041 0.045 b 0.300 0.500 0.012 0.020 c 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 1.500 1.700 0.059 0.067 E1 2.650 2.950 0.104 0.116 e 0.950(BSC) 0.037(BSC) e1 1.800 2.000 0.071 0.079 L 0.300 0.600 0.012 0.024 θ 0° 8° 0° 8° Subject changes without notice. www.hxsemi.com 9 Information furnished by Hexin Semiconductor is believed to be accurate and reliable. However, no responsibility is assumed for its use.