Application Guide Power Equations Ohms Law/Power Wheel General Voltage & Current = 1 ( 0.707 ) x VRMS VP = √ 2VRMS = 1.414 VRMS VPP = 2VP VRMS = √ 0.5 VP ≈ 0.707 VP VAVG = ( 2 ) VP ≈ 0.637 VP √ 2IRMS ≈ 1.414 IRMS IP = IPP = 2IP Reactance IRMS = √ 0.5 IP ≈ 0.707 IP XC = IAVG = ( 2 ) IP ≈ 0.637 IP XL = Where: VP= Peak Voltage VPP = Peak to Peak Voltage VAVG = Average Voltage Vrms = RMS (root mean square) Voltage Where: Xc XL F C L = = = = = IAVG = Average Current 2 FL Reactance, in ohms, of a capacitance Reactance, in ohms, of an inductance Frequency in Hertz) Capacitance in Farads Inductance in Henrys Decibal IP= Peak Curent IPP = Peak to Peak Current ( 2 1FC ) Decibel (dB): A decibel (dB) is the fundamental measurement unit used in EMI measurements. IRMS = RMS (root mean square) Current Frequency & Time = 10 Log10 ( dB = 20 Log10 ( VOUT ) IN Duty Cycle: The ratio of “on” time to “off” time of the semiconductor switch (in PWM systems) or clock signal. F = ( T1 ) PR = 10 T = ( F1 ) VR = 10 Duty Cycle = Where: Pulse Width ( Cycle Time ) x 100 F = Frequency T = Time POUT dB Where: POUT = PIN = VOUT = VIN = PR = VR = PIN ) V (dB/10) (dB/20) Output Power Input Power Output Voltage Input Voltage Power Ratio Voltage Ratio (Current ratio is the same) Go Direct - For Product, Performance and Price VP MicroPower Di rect This note brings together a number of equations and conversion factors that are useful when applying a power supply. MicroPower Direct Go Direct For: Product Performance & Price At MicroPower Direct we have the product you need at the best price and right performance level. With nearly 2,000 standard DC/DC converter models and thousands of standard enclosed & open frame AC/DC power supplies, one is sure to offer the right solution for your application. New product families include: A800ERW! Low Cost 8W DIP This "Budget Saver" offers miniature size, high performance & low cost. Features include: Power Equations Specifications Efficiency Efficiency (η): The ratio of total output power to input power. Typically expressed as a percentage, efficiency is derived by the equation: • 10W to 300W • 1 to 4 Outputs • Universal AC Input • Meet EN60950 • Meet EN55022 B • Compact Size • Low Cost B3000RW! 30W in 1"x 2" Case MPD offers a wide variety of low cost standard DC/DC converters. These units offer many high performance features including: • 30W Output Power • 2:1 Input • 1" x 2" x 0.4" Case • 1.5 kV I/O Isolation • RoHS Compliant • Meet EN60950 • Industry Standard Pin-Outs MPD offers one of the widest selections of standard AC/DC and DC/DC power supplies in the industry. All are POUT Efficiency (%) = PIN KA X 100 ∆T θ (ºC/W) = Where: POUT = Output Power PIN = Input Power Power Average Power: In an ac circuit, the average value of ac power. For resistive circuits, this equals the square of the rms current times the circuit resistance, as given by: (IRMS)2R PA = Where: IRMS = rms value of the circuit current R = Circuit resistance in ohms True Power: The actual power consumed by an ac circuit. It is given by: PT = Where: VRMS x IRMS cos(φ) Where: L = K = A = ∆T = PD = PF PF = COS θ = ( PT PApp ) Thermal Internal Power Dissipation: Power dissipated as heat within the power supply during normal operation. Length of material Thermal conductivity of material Cross sectional area of material Temp drop across material Power flowing through material www.micropowerdirect.com Where: = PIN- POUT PD = ( PD PIN POUT η POUT η ) - POUT = Internal power dissipated = Input Power = Output Power = Efficiency %VL ∆ Line Regulation (%) %VIN ∆ Load Regulation (%) Where: VL VIN NLVOUT FLVOUT = = = = NLVOUT - FLVOUT FLVOUT x 100 x 100 Load Voltage Input Voltage (Line) Load Voltage @ No Load Load Voltage @ Full Load Conversion Factors Common Conversions CFM Area LFM = CFM = °C = (°F-32) 1.8 °F = 1.8 x °C + 32 °K = °F + 459.67 1.8 Area x LFM °K = °C + 273.15 1 Inch = 25.4 mm 1 mm = 0.03937 Inches 1m = 1 Ampere-Hour = PD PD Regulation IRMS = rms value of the circuit current VRMS = rms value of the circuit voltage Power Factor: For an ac input power supply, the ratio of true input power to apparent input power. offered at the lowest cost possible. When you need Power Supplies? Go Direct! See Us On The WEB!! L θ (ºC/W) = • 8W Output Power • 1.5 kV I/O Isolation • 2:1 Input Range • Miniature DIP Case • Standard Pin-Outs • Single /Dual Outputs • Lowest Cost AC/DC Power Supplies! MPD offers a full line of enclosed & open frame AC/DC power supplies. Ranging from 10W to 300W, these compact supplies meet international standards while offering a wide selection of models and low cost. Features include: Thermal Resistance: (θ) A measure of the opposition a material will have to the flow of heat. Used to calculate the temperature drop that occurs when power flows through a material or across the junction of two materials. 39.7 Inches 3,600 Coulombs 1 lB = 453.4924 Grams 1 Ounce = 28.3495 Grams 1 Gram = 0.0357 Ounces 1 kGram = 2.205 Pounds 1 Pound = 0.4523 kgrams 1 Watt = 1 Joule/Second 1 BTU/Sec = 1,054.8 Joules/Sec 1 Joule = 0.000948 BTU