PowerWise® Design University
POWER 100 - DC to DC Converter Basics
In order to improve the stability of a system with two poles separated a decade in frequency, it is necessary to:
Insert a pole at a frequency between the two poles
Insert a zero at a frequency higher than where the phase becomes 180 degrees
Insert a zero at a frequency lower than where phase becomes 180 degrees
Insert a pole at a frequency higher than both the poles
How is the input current of a switched capacitor regulator related to the output current? hint: Ignore Iq?
Iout = Iin * Gain
Iin = Iout * Gain
Either of the above
None of the above
What is one of the main reasons for poorer efficiency of the charge pump regulators compared to inductive regulators?
The capacitors can be switched faster
The charge pump granularity is too smooth
The inductors can be switched faster
The charge pump gain can only be discrete and finite
At what ambient temperature will the LDO under following conditions reach Thermal shutdown: uSMD5 package with ThetaJa = 255 degC/Watt, Vout = 1.8V, Iout = 100mA, Vin = 2.5V, Thermal shutdown temp = 160C?
178C
143C
97C
115C
Which of the following is NOT a technique for fine adjustment of the gain of a switched capacitor regulator?
Change the switch resistance
Change the switching frequency
Change the output capacitor
Change the fly capacitor
What determines the DCM/CCM boundary?
Output voltage ripple
Inductor current ripple
Input voltage ripple
none of the above
What is the best choice for Cout, given the following buck regulator requirements: Vin=3Vmin, 3.6Vmax; Vout=1.8V; Switching frequency=1MHz, maximum inductor ripple current allowable = 20%, Iout load = 400mA min, 1A max; maximum Vout ripple allowable = 2% Vout ripple?
4uF
20uF
1uF
2uF
Which of the following topology generates the least output voltage ripple?
The linear regulator
The charge pump regulator
The inductive regulator
The magnetic boost regulator
In a system with only one pole, the least (most negative) phase angle value reached is:
0 degrees
180 degrees
+90 degrees
-90 degrees
When is low (more negative or higher absolute magnitude) PSRR critical?
When the input comes from a Lithium Ion battery
When the input voltage has a lot of ripple
When the output needs to support digital processors
When the output load is nonlinear
What is the magnitude of the reverse breakdown voltage for a lightly doped silicon diode?
0.2V
0.7V
3V
8V
Which of the following type of capacitors has the lowest ESR?
Aluminum Electrolytic
Specialty Polymer
Multi-Layered Ceramic Capacitor (MLCC)
Tantalum
