Switch mode DC-DC converters Flashcards
What are some advantages of switch mode power supplies
Smaller transistor smaller current rating Heatsinks for cooling Greater power density Wider variety of input voltages
What are some disadvantages of switch mode power supplies
Noisy, slow due to filtering and less reliable
What are step up and step down and inverting converters called
Step up - Boost
Step down - Buck
Inverting - Buck- Boost
Give an example of DC-DC amplification
DC Motors
what is the equation for the energy stored in a Capacitor
E= 1/2 x C x V^2
What is the equation for energy stored in an inductor
E = 1/2 x L x I^2
When does the inductor charge
When switch is on
Describe the Buck converter circuit while charging
Switch on Diode off
Describe the Buck convertor while discharging
Switch off Diode On
What is the equation for the Voltage output of a buck convertor
Vout = Vin x D
What is the equation for the mean output current for a buck convertor
Iout = Iin/D
What is the power equation for a buck convertor
P= I x V
Pin=Pout
What in the equation for duty cycle
D = Ton/Tcycle
What is the equation for the load voltage in a buck convertor
VL =Vin - Vout
Given the current time graph what is the average current
Iavg = area under graph / T cycle
What are the equations for max and min current for a buck convertor
Imax = Iout x D + Iout Imin = Iout x D + I out
What does the load voltage equal for a Boost converter
Switch open VL= Vin-Vout
When switch is closed VL= Vin
What is the voltage equation for a boost converter
Vout= Vin/(1-D)
What is the current equation for a bust convertor
Iout = (1-D) x Iin
For an inverting (buck-boost) converter how do the input and output voltages relate
-Vout <>Vin
What is the Voltage across the load equal to during charging and discharging For a buck boost convertor
Charging VL= Vin
Discharging VL = -Vout
What is the voltage for a buck-boost converter
Vout= (DxVin)/(1-D)
What is the current equation for a buck-boost equation
Iout= (1-D) x Iin
What is true for all converters
Input power = output power
Buck, Boost and Inverting power supplies are called off-line power supplies, what does this mean
They cannot be used directly from the mains
